michael@0: 
michael@0: /* pngread.c - read a PNG file
michael@0:  *
michael@0:  * Last changed in libpng 1.6.10 [March 6, 2014]
michael@0:  * Copyright (c) 1998-2014 Glenn Randers-Pehrson
michael@0:  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
michael@0:  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
michael@0:  *
michael@0:  * This code is released under the libpng license.
michael@0:  * For conditions of distribution and use, see the disclaimer
michael@0:  * and license in png.h
michael@0:  *
michael@0:  * This file contains routines that an application calls directly to
michael@0:  * read a PNG file or stream.
michael@0:  */
michael@0: 
michael@0: #include "pngpriv.h"
michael@0: #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
michael@0: #  include <errno.h>
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_SUPPORTED
michael@0: 
michael@0: /* Create a PNG structure for reading, and allocate any memory needed. */
michael@0: PNG_FUNCTION(png_structp,PNGAPI
michael@0: png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
michael@0:     png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
michael@0: {
michael@0: #ifndef PNG_USER_MEM_SUPPORTED
michael@0:    png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
michael@0:       error_fn, warn_fn, NULL, NULL, NULL);
michael@0: #else
michael@0:    return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
michael@0:        warn_fn, NULL, NULL, NULL);
michael@0: }
michael@0: 
michael@0: /* Alternate create PNG structure for reading, and allocate any memory
michael@0:  * needed.
michael@0:  */
michael@0: PNG_FUNCTION(png_structp,PNGAPI
michael@0: png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
michael@0:     png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
michael@0:     png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
michael@0: {
michael@0:    png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
michael@0:       error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
michael@0: #endif /* PNG_USER_MEM_SUPPORTED */
michael@0: 
michael@0:    if (png_ptr != NULL)
michael@0:    {
michael@0:       png_ptr->mode = PNG_IS_READ_STRUCT;
michael@0: 
michael@0:       /* Added in libpng-1.6.0; this can be used to detect a read structure if
michael@0:        * required (it will be zero in a write structure.)
michael@0:        */
michael@0: #     ifdef PNG_SEQUENTIAL_READ_SUPPORTED
michael@0:          png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE;
michael@0: #     endif
michael@0: 
michael@0: #     ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
michael@0:          png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
michael@0: 
michael@0:          /* In stable builds only warn if an application error can be completely
michael@0:           * handled.
michael@0:           */
michael@0: #        if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
michael@0:             png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
michael@0: #        endif
michael@0: #     endif
michael@0: 
michael@0:       /* TODO: delay this, it can be done in png_init_io (if the app doesn't
michael@0:        * do it itself) avoiding setting the default function if it is not
michael@0:        * required.
michael@0:        */
michael@0:       png_set_read_fn(png_ptr, NULL, NULL);
michael@0:    }
michael@0: 
michael@0:    return png_ptr;
michael@0: }
michael@0: 
michael@0: 
michael@0: #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
michael@0: /* Read the information before the actual image data.  This has been
michael@0:  * changed in v0.90 to allow reading a file that already has the magic
michael@0:  * bytes read from the stream.  You can tell libpng how many bytes have
michael@0:  * been read from the beginning of the stream (up to the maximum of 8)
michael@0:  * via png_set_sig_bytes(), and we will only check the remaining bytes
michael@0:  * here.  The application can then have access to the signature bytes we
michael@0:  * read if it is determined that this isn't a valid PNG file.
michael@0:  */
michael@0: void PNGAPI
michael@0: png_read_info(png_structrp png_ptr, png_inforp info_ptr)
michael@0: {
michael@0: #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
michael@0:    int keep;
michael@0: #endif
michael@0: 
michael@0:    png_debug(1, "in png_read_info");
michael@0: 
michael@0:    if (png_ptr == NULL || info_ptr == NULL)
michael@0:       return;
michael@0: 
michael@0:    /* Read and check the PNG file signature. */
michael@0:    png_read_sig(png_ptr, info_ptr);
michael@0: 
michael@0:    for (;;)
michael@0:    {
michael@0:       png_uint_32 length = png_read_chunk_header(png_ptr);
michael@0:       png_uint_32 chunk_name = png_ptr->chunk_name;
michael@0: 
michael@0:       /* IDAT logic needs to happen here to simplify getting the two flags
michael@0:        * right.
michael@0:        */
michael@0:       if (chunk_name == png_IDAT)
michael@0:       {
michael@0:          if (!(png_ptr->mode & PNG_HAVE_IHDR))
michael@0:             png_chunk_error(png_ptr, "Missing IHDR before IDAT");
michael@0: 
michael@0:          else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
michael@0:              !(png_ptr->mode & PNG_HAVE_PLTE))
michael@0:             png_chunk_error(png_ptr, "Missing PLTE before IDAT");
michael@0: 
michael@0:          else if (png_ptr->mode & PNG_AFTER_IDAT)
michael@0:             png_chunk_benign_error(png_ptr, "Too many IDATs found");
michael@0: 
michael@0:          png_ptr->mode |= PNG_HAVE_IDAT;
michael@0:       }
michael@0: 
michael@0:       else if (png_ptr->mode & PNG_HAVE_IDAT)
michael@0:          png_ptr->mode |= PNG_AFTER_IDAT;
michael@0: 
michael@0:       /* This should be a binary subdivision search or a hash for
michael@0:        * matching the chunk name rather than a linear search.
michael@0:        */
michael@0:       if (chunk_name == png_IHDR)
michael@0:          png_handle_IHDR(png_ptr, info_ptr, length);
michael@0: 
michael@0:       else if (chunk_name == png_IEND)
michael@0:          png_handle_IEND(png_ptr, info_ptr, length);
michael@0: 
michael@0: #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
michael@0:       else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
michael@0:       {
michael@0:          png_handle_unknown(png_ptr, info_ptr, length, keep);
michael@0: 
michael@0:          if (chunk_name == png_PLTE)
michael@0:             png_ptr->mode |= PNG_HAVE_PLTE;
michael@0: 
michael@0:          else if (chunk_name == png_IDAT)
michael@0:          {
michael@0:             png_ptr->idat_size = 0; /* It has been consumed */
michael@0:             break;
michael@0:          }
michael@0:       }
michael@0: #endif
michael@0:       else if (chunk_name == png_PLTE)
michael@0:          png_handle_PLTE(png_ptr, info_ptr, length);
michael@0: 
michael@0:       else if (chunk_name == png_IDAT)
michael@0:       {
michael@0: #ifdef PNG_READ_APNG_SUPPORTED
michael@0:          png_have_info(png_ptr, info_ptr);
michael@0: #endif
michael@0:          png_ptr->idat_size = length;
michael@0:          break;
michael@0:       }
michael@0: 
michael@0: #ifdef PNG_READ_bKGD_SUPPORTED
michael@0:       else if (chunk_name == png_bKGD)
michael@0:          png_handle_bKGD(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_cHRM_SUPPORTED
michael@0:       else if (chunk_name == png_cHRM)
michael@0:          png_handle_cHRM(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_gAMA_SUPPORTED
michael@0:       else if (chunk_name == png_gAMA)
michael@0:          png_handle_gAMA(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_hIST_SUPPORTED
michael@0:       else if (chunk_name == png_hIST)
michael@0:          png_handle_hIST(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_oFFs_SUPPORTED
michael@0:       else if (chunk_name == png_oFFs)
michael@0:          png_handle_oFFs(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_pCAL_SUPPORTED
michael@0:       else if (chunk_name == png_pCAL)
michael@0:          png_handle_pCAL(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_sCAL_SUPPORTED
michael@0:       else if (chunk_name == png_sCAL)
michael@0:          png_handle_sCAL(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_pHYs_SUPPORTED
michael@0:       else if (chunk_name == png_pHYs)
michael@0:          png_handle_pHYs(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_sBIT_SUPPORTED
michael@0:       else if (chunk_name == png_sBIT)
michael@0:          png_handle_sBIT(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_sRGB_SUPPORTED
michael@0:       else if (chunk_name == png_sRGB)
michael@0:          png_handle_sRGB(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_iCCP_SUPPORTED
michael@0:       else if (chunk_name == png_iCCP)
michael@0:          png_handle_iCCP(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_sPLT_SUPPORTED
michael@0:       else if (chunk_name == png_sPLT)
michael@0:          png_handle_sPLT(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_tEXt_SUPPORTED
michael@0:       else if (chunk_name == png_tEXt)
michael@0:          png_handle_tEXt(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_tIME_SUPPORTED
michael@0:       else if (chunk_name == png_tIME)
michael@0:          png_handle_tIME(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_tRNS_SUPPORTED
michael@0:       else if (chunk_name == png_tRNS)
michael@0:          png_handle_tRNS(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_zTXt_SUPPORTED
michael@0:       else if (chunk_name == png_zTXt)
michael@0:          png_handle_zTXt(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_iTXt_SUPPORTED
michael@0:       else if (chunk_name == png_iTXt)
michael@0:          png_handle_iTXt(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_APNG_SUPPORTED
michael@0:       else if (chunk_name == png_acTL)
michael@0:          png_handle_acTL(png_ptr, info_ptr, length);
michael@0: 
michael@0:       else if (chunk_name == png_fcTL)
michael@0:          png_handle_fcTL(png_ptr, info_ptr, length);
michael@0: 
michael@0:       else if (chunk_name == png_fdAT)
michael@0:          png_handle_fdAT(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0:       else
michael@0:          png_handle_unknown(png_ptr, info_ptr, length,
michael@0:             PNG_HANDLE_CHUNK_AS_DEFAULT);
michael@0:    }
michael@0: }
michael@0: #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
michael@0: 
michael@0: #ifdef PNG_READ_APNG_SUPPORTED
michael@0: void PNGAPI
michael@0: png_read_frame_head(png_structp png_ptr, png_infop info_ptr)
michael@0: {
michael@0:     png_byte have_chunk_after_DAT; /* after IDAT or after fdAT */
michael@0: 
michael@0:     png_debug(0, "Reading frame head");
michael@0: 
michael@0:     if (!(png_ptr->mode & PNG_HAVE_acTL))
michael@0:         png_error(png_ptr, "attempt to png_read_frame_head() but "
michael@0:                            "no acTL present");
michael@0: 
michael@0:     /* do nothing for the main IDAT */
michael@0:     if (png_ptr->num_frames_read == 0)
michael@0:         return;
michael@0: 
michael@0:     png_read_reset(png_ptr);
michael@0:     png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
michael@0:     png_ptr->mode &= ~PNG_HAVE_fcTL;
michael@0: 
michael@0:     have_chunk_after_DAT = 0;
michael@0:     for (;;)
michael@0:     {
michael@0:         png_uint_32 length = png_read_chunk_header(png_ptr);
michael@0: 
michael@0:         if (png_ptr->chunk_name == png_IDAT)
michael@0:         {
michael@0:             /* discard trailing IDATs for the first frame */
michael@0:             if (have_chunk_after_DAT || png_ptr->num_frames_read > 1)
michael@0:                 png_error(png_ptr, "png_read_frame_head(): out of place IDAT");
michael@0:             png_crc_finish(png_ptr, length);
michael@0:         }
michael@0: 
michael@0:         else if (png_ptr->chunk_name == png_fcTL)
michael@0:         {
michael@0:             png_handle_fcTL(png_ptr, info_ptr, length);
michael@0:             have_chunk_after_DAT = 1;
michael@0:         }
michael@0: 
michael@0:         else if (png_ptr->chunk_name == png_fdAT)
michael@0:         {
michael@0:             png_ensure_sequence_number(png_ptr, length);
michael@0: 
michael@0:             /* discard trailing fdATs for frames other than the first */
michael@0:             if (!have_chunk_after_DAT && png_ptr->num_frames_read > 1)
michael@0:                 png_crc_finish(png_ptr, length - 4);
michael@0:             else if(png_ptr->mode & PNG_HAVE_fcTL)
michael@0:             {
michael@0:                 png_ptr->idat_size = length - 4;
michael@0:                 png_ptr->mode |= PNG_HAVE_IDAT;
michael@0: 
michael@0:                 break;
michael@0:             }
michael@0:             else
michael@0:                 png_error(png_ptr, "png_read_frame_head(): out of place fdAT");
michael@0:         }
michael@0:         else
michael@0:         {
michael@0:             png_warning(png_ptr, "Skipped (ignored) a chunk "
michael@0:                                  "between APNG chunks");
michael@0:             png_crc_finish(png_ptr, length);
michael@0:         }
michael@0:     }
michael@0: }
michael@0: #endif /* PNG_READ_APNG_SUPPORTED */
michael@0: 
michael@0: /* Optional call to update the users info_ptr structure */
michael@0: void PNGAPI
michael@0: png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
michael@0: {
michael@0:    png_debug(1, "in png_read_update_info");
michael@0: 
michael@0:    if (png_ptr != NULL)
michael@0:    {
michael@0:       if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
michael@0:       {
michael@0:          png_read_start_row(png_ptr);
michael@0: 
michael@0: #        ifdef PNG_READ_TRANSFORMS_SUPPORTED
michael@0:             png_read_transform_info(png_ptr, info_ptr);
michael@0: #        else
michael@0:             PNG_UNUSED(info_ptr)
michael@0: #        endif
michael@0:       }
michael@0: 
michael@0:       /* New in 1.6.0 this avoids the bug of doing the initializations twice */
michael@0:       else
michael@0:          png_app_error(png_ptr,
michael@0:             "png_read_update_info/png_start_read_image: duplicate call");
michael@0:    }
michael@0: }
michael@0: 
michael@0: #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
michael@0: /* Initialize palette, background, etc, after transformations
michael@0:  * are set, but before any reading takes place.  This allows
michael@0:  * the user to obtain a gamma-corrected palette, for example.
michael@0:  * If the user doesn't call this, we will do it ourselves.
michael@0:  */
michael@0: void PNGAPI
michael@0: png_start_read_image(png_structrp png_ptr)
michael@0: {
michael@0:    png_debug(1, "in png_start_read_image");
michael@0: 
michael@0:    if (png_ptr != NULL)
michael@0:    {
michael@0:       if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
michael@0:          png_read_start_row(png_ptr);
michael@0: 
michael@0:       /* New in 1.6.0 this avoids the bug of doing the initializations twice */
michael@0:       else
michael@0:          png_app_error(png_ptr,
michael@0:             "png_start_read_image/png_read_update_info: duplicate call");
michael@0:    }
michael@0: }
michael@0: #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
michael@0: 
michael@0: #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
michael@0: #ifdef PNG_MNG_FEATURES_SUPPORTED
michael@0: /* Undoes intrapixel differencing,
michael@0:  * NOTE: this is apparently only supported in the 'sequential' reader.
michael@0:  */
michael@0: static void
michael@0: png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
michael@0: {
michael@0:    png_debug(1, "in png_do_read_intrapixel");
michael@0: 
michael@0:    if (
michael@0:        (row_info->color_type & PNG_COLOR_MASK_COLOR))
michael@0:    {
michael@0:       int bytes_per_pixel;
michael@0:       png_uint_32 row_width = row_info->width;
michael@0: 
michael@0:       if (row_info->bit_depth == 8)
michael@0:       {
michael@0:          png_bytep rp;
michael@0:          png_uint_32 i;
michael@0: 
michael@0:          if (row_info->color_type == PNG_COLOR_TYPE_RGB)
michael@0:             bytes_per_pixel = 3;
michael@0: 
michael@0:          else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
michael@0:             bytes_per_pixel = 4;
michael@0: 
michael@0:          else
michael@0:             return;
michael@0: 
michael@0:          for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
michael@0:          {
michael@0:             *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
michael@0:             *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
michael@0:          }
michael@0:       }
michael@0:       else if (row_info->bit_depth == 16)
michael@0:       {
michael@0:          png_bytep rp;
michael@0:          png_uint_32 i;
michael@0: 
michael@0:          if (row_info->color_type == PNG_COLOR_TYPE_RGB)
michael@0:             bytes_per_pixel = 6;
michael@0: 
michael@0:          else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
michael@0:             bytes_per_pixel = 8;
michael@0: 
michael@0:          else
michael@0:             return;
michael@0: 
michael@0:          for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
michael@0:          {
michael@0:             png_uint_32 s0   = (*(rp    ) << 8) | *(rp + 1);
michael@0:             png_uint_32 s1   = (*(rp + 2) << 8) | *(rp + 3);
michael@0:             png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
michael@0:             png_uint_32 red  = (s0 + s1 + 65536) & 0xffff;
michael@0:             png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
michael@0:             *(rp    ) = (png_byte)((red >> 8) & 0xff);
michael@0:             *(rp + 1) = (png_byte)(red & 0xff);
michael@0:             *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
michael@0:             *(rp + 5) = (png_byte)(blue & 0xff);
michael@0:          }
michael@0:       }
michael@0:    }
michael@0: }
michael@0: #endif /* PNG_MNG_FEATURES_SUPPORTED */
michael@0: 
michael@0: void PNGAPI
michael@0: png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
michael@0: {
michael@0:    png_row_info row_info;
michael@0: 
michael@0:    if (png_ptr == NULL)
michael@0:       return;
michael@0: 
michael@0:    png_debug2(1, "in png_read_row (row %lu, pass %d)",
michael@0:        (unsigned long)png_ptr->row_number, png_ptr->pass);
michael@0: 
michael@0:    /* png_read_start_row sets the information (in particular iwidth) for this
michael@0:     * interlace pass.
michael@0:     */
michael@0:    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
michael@0:       png_read_start_row(png_ptr);
michael@0: 
michael@0:    /* 1.5.6: row_info moved out of png_struct to a local here. */
michael@0:    row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
michael@0:    row_info.color_type = png_ptr->color_type;
michael@0:    row_info.bit_depth = png_ptr->bit_depth;
michael@0:    row_info.channels = png_ptr->channels;
michael@0:    row_info.pixel_depth = png_ptr->pixel_depth;
michael@0:    row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
michael@0: 
michael@0:    if (png_ptr->row_number == 0 && png_ptr->pass == 0)
michael@0:    {
michael@0:    /* Check for transforms that have been set but were defined out */
michael@0: #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
michael@0:    if (png_ptr->transformations & PNG_INVERT_MONO)
michael@0:       png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
michael@0: #endif
michael@0: 
michael@0: #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
michael@0:    if (png_ptr->transformations & PNG_FILLER)
michael@0:       png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
michael@0: #endif
michael@0: 
michael@0: #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
michael@0:     !defined(PNG_READ_PACKSWAP_SUPPORTED)
michael@0:    if (png_ptr->transformations & PNG_PACKSWAP)
michael@0:       png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
michael@0: #endif
michael@0: 
michael@0: #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
michael@0:    if (png_ptr->transformations & PNG_PACK)
michael@0:       png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
michael@0: #endif
michael@0: 
michael@0: #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
michael@0:    if (png_ptr->transformations & PNG_SHIFT)
michael@0:       png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
michael@0: #endif
michael@0: 
michael@0: #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
michael@0:    if (png_ptr->transformations & PNG_BGR)
michael@0:       png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
michael@0: #endif
michael@0: 
michael@0: #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
michael@0:    if (png_ptr->transformations & PNG_SWAP_BYTES)
michael@0:       png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
michael@0: #endif
michael@0:    }
michael@0: 
michael@0: #ifdef PNG_READ_INTERLACING_SUPPORTED
michael@0:    /* If interlaced and we do not need a new row, combine row and return.
michael@0:     * Notice that the pixels we have from previous rows have been transformed
michael@0:     * already; we can only combine like with like (transformed or
michael@0:     * untransformed) and, because of the libpng API for interlaced images, this
michael@0:     * means we must transform before de-interlacing.
michael@0:     */
michael@0:    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
michael@0:    {
michael@0:       switch (png_ptr->pass)
michael@0:       {
michael@0:          case 0:
michael@0:             if (png_ptr->row_number & 0x07)
michael@0:             {
michael@0:                if (dsp_row != NULL)
michael@0:                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
michael@0:                png_read_finish_row(png_ptr);
michael@0:                return;
michael@0:             }
michael@0:             break;
michael@0: 
michael@0:          case 1:
michael@0:             if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
michael@0:             {
michael@0:                if (dsp_row != NULL)
michael@0:                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
michael@0: 
michael@0:                png_read_finish_row(png_ptr);
michael@0:                return;
michael@0:             }
michael@0:             break;
michael@0: 
michael@0:          case 2:
michael@0:             if ((png_ptr->row_number & 0x07) != 4)
michael@0:             {
michael@0:                if (dsp_row != NULL && (png_ptr->row_number & 4))
michael@0:                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
michael@0: 
michael@0:                png_read_finish_row(png_ptr);
michael@0:                return;
michael@0:             }
michael@0:             break;
michael@0: 
michael@0:          case 3:
michael@0:             if ((png_ptr->row_number & 3) || png_ptr->width < 3)
michael@0:             {
michael@0:                if (dsp_row != NULL)
michael@0:                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
michael@0: 
michael@0:                png_read_finish_row(png_ptr);
michael@0:                return;
michael@0:             }
michael@0:             break;
michael@0: 
michael@0:          case 4:
michael@0:             if ((png_ptr->row_number & 3) != 2)
michael@0:             {
michael@0:                if (dsp_row != NULL && (png_ptr->row_number & 2))
michael@0:                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
michael@0: 
michael@0:                png_read_finish_row(png_ptr);
michael@0:                return;
michael@0:             }
michael@0:             break;
michael@0: 
michael@0:          case 5:
michael@0:             if ((png_ptr->row_number & 1) || png_ptr->width < 2)
michael@0:             {
michael@0:                if (dsp_row != NULL)
michael@0:                   png_combine_row(png_ptr, dsp_row, 1/*display*/);
michael@0: 
michael@0:                png_read_finish_row(png_ptr);
michael@0:                return;
michael@0:             }
michael@0:             break;
michael@0: 
michael@0:          default:
michael@0:          case 6:
michael@0:             if (!(png_ptr->row_number & 1))
michael@0:             {
michael@0:                png_read_finish_row(png_ptr);
michael@0:                return;
michael@0:             }
michael@0:             break;
michael@0:       }
michael@0:    }
michael@0: #endif
michael@0: 
michael@0:    if (!(png_ptr->mode & PNG_HAVE_IDAT))
michael@0:       png_error(png_ptr, "Invalid attempt to read row data");
michael@0: 
michael@0:    /* Fill the row with IDAT data: */
michael@0:    png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
michael@0: 
michael@0:    if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
michael@0:    {
michael@0:       if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
michael@0:          png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
michael@0:             png_ptr->prev_row + 1, png_ptr->row_buf[0]);
michael@0:       else
michael@0:          png_error(png_ptr, "bad adaptive filter value");
michael@0:    }
michael@0: 
michael@0:    /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
michael@0:     * 1.5.6, while the buffer really is this big in current versions of libpng
michael@0:     * it may not be in the future, so this was changed just to copy the
michael@0:     * interlaced count:
michael@0:     */
michael@0:    memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
michael@0: 
michael@0: #ifdef PNG_MNG_FEATURES_SUPPORTED
michael@0:    if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
michael@0:        (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
michael@0:    {
michael@0:       /* Intrapixel differencing */
michael@0:       png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
michael@0:    }
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_TRANSFORMS_SUPPORTED
michael@0:    if (png_ptr->transformations)
michael@0:       png_do_read_transformations(png_ptr, &row_info);
michael@0: #endif
michael@0: 
michael@0:    /* The transformed pixel depth should match the depth now in row_info. */
michael@0:    if (png_ptr->transformed_pixel_depth == 0)
michael@0:    {
michael@0:       png_ptr->transformed_pixel_depth = row_info.pixel_depth;
michael@0:       if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
michael@0:          png_error(png_ptr, "sequential row overflow");
michael@0:    }
michael@0: 
michael@0:    else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
michael@0:       png_error(png_ptr, "internal sequential row size calculation error");
michael@0: 
michael@0: #ifdef PNG_READ_INTERLACING_SUPPORTED
michael@0:    /* Blow up interlaced rows to full size */
michael@0:    if (png_ptr->interlaced &&
michael@0:       (png_ptr->transformations & PNG_INTERLACE))
michael@0:    {
michael@0:       if (png_ptr->pass < 6)
michael@0:          png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
michael@0:             png_ptr->transformations);
michael@0: 
michael@0:       if (dsp_row != NULL)
michael@0:          png_combine_row(png_ptr, dsp_row, 1/*display*/);
michael@0: 
michael@0:       if (row != NULL)
michael@0:          png_combine_row(png_ptr, row, 0/*row*/);
michael@0:    }
michael@0: 
michael@0:    else
michael@0: #endif
michael@0:    {
michael@0:       if (row != NULL)
michael@0:          png_combine_row(png_ptr, row, -1/*ignored*/);
michael@0: 
michael@0:       if (dsp_row != NULL)
michael@0:          png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
michael@0:    }
michael@0:    png_read_finish_row(png_ptr);
michael@0: 
michael@0:    if (png_ptr->read_row_fn != NULL)
michael@0:       (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
michael@0: 
michael@0: }
michael@0: #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
michael@0: 
michael@0: #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
michael@0: /* Read one or more rows of image data.  If the image is interlaced,
michael@0:  * and png_set_interlace_handling() has been called, the rows need to
michael@0:  * contain the contents of the rows from the previous pass.  If the
michael@0:  * image has alpha or transparency, and png_handle_alpha()[*] has been
michael@0:  * called, the rows contents must be initialized to the contents of the
michael@0:  * screen.
michael@0:  *
michael@0:  * "row" holds the actual image, and pixels are placed in it
michael@0:  * as they arrive.  If the image is displayed after each pass, it will
michael@0:  * appear to "sparkle" in.  "display_row" can be used to display a
michael@0:  * "chunky" progressive image, with finer detail added as it becomes
michael@0:  * available.  If you do not want this "chunky" display, you may pass
michael@0:  * NULL for display_row.  If you do not want the sparkle display, and
michael@0:  * you have not called png_handle_alpha(), you may pass NULL for rows.
michael@0:  * If you have called png_handle_alpha(), and the image has either an
michael@0:  * alpha channel or a transparency chunk, you must provide a buffer for
michael@0:  * rows.  In this case, you do not have to provide a display_row buffer
michael@0:  * also, but you may.  If the image is not interlaced, or if you have
michael@0:  * not called png_set_interlace_handling(), the display_row buffer will
michael@0:  * be ignored, so pass NULL to it.
michael@0:  *
michael@0:  * [*] png_handle_alpha() does not exist yet, as of this version of libpng
michael@0:  */
michael@0: 
michael@0: void PNGAPI
michael@0: png_read_rows(png_structrp png_ptr, png_bytepp row,
michael@0:     png_bytepp display_row, png_uint_32 num_rows)
michael@0: {
michael@0:    png_uint_32 i;
michael@0:    png_bytepp rp;
michael@0:    png_bytepp dp;
michael@0: 
michael@0:    png_debug(1, "in png_read_rows");
michael@0: 
michael@0:    if (png_ptr == NULL)
michael@0:       return;
michael@0: 
michael@0:    rp = row;
michael@0:    dp = display_row;
michael@0:    if (rp != NULL && dp != NULL)
michael@0:       for (i = 0; i < num_rows; i++)
michael@0:       {
michael@0:          png_bytep rptr = *rp++;
michael@0:          png_bytep dptr = *dp++;
michael@0: 
michael@0:          png_read_row(png_ptr, rptr, dptr);
michael@0:       }
michael@0: 
michael@0:    else if (rp != NULL)
michael@0:       for (i = 0; i < num_rows; i++)
michael@0:       {
michael@0:          png_bytep rptr = *rp;
michael@0:          png_read_row(png_ptr, rptr, NULL);
michael@0:          rp++;
michael@0:       }
michael@0: 
michael@0:    else if (dp != NULL)
michael@0:       for (i = 0; i < num_rows; i++)
michael@0:       {
michael@0:          png_bytep dptr = *dp;
michael@0:          png_read_row(png_ptr, NULL, dptr);
michael@0:          dp++;
michael@0:       }
michael@0: }
michael@0: #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
michael@0: 
michael@0: #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
michael@0: /* Read the entire image.  If the image has an alpha channel or a tRNS
michael@0:  * chunk, and you have called png_handle_alpha()[*], you will need to
michael@0:  * initialize the image to the current image that PNG will be overlaying.
michael@0:  * We set the num_rows again here, in case it was incorrectly set in
michael@0:  * png_read_start_row() by a call to png_read_update_info() or
michael@0:  * png_start_read_image() if png_set_interlace_handling() wasn't called
michael@0:  * prior to either of these functions like it should have been.  You can
michael@0:  * only call this function once.  If you desire to have an image for
michael@0:  * each pass of a interlaced image, use png_read_rows() instead.
michael@0:  *
michael@0:  * [*] png_handle_alpha() does not exist yet, as of this version of libpng
michael@0:  */
michael@0: void PNGAPI
michael@0: png_read_image(png_structrp png_ptr, png_bytepp image)
michael@0: {
michael@0:    png_uint_32 i, image_height;
michael@0:    int pass, j;
michael@0:    png_bytepp rp;
michael@0: 
michael@0:    png_debug(1, "in png_read_image");
michael@0: 
michael@0:    if (png_ptr == NULL)
michael@0:       return;
michael@0: 
michael@0: #ifdef PNG_READ_INTERLACING_SUPPORTED
michael@0:    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
michael@0:    {
michael@0:       pass = png_set_interlace_handling(png_ptr);
michael@0:       /* And make sure transforms are initialized. */
michael@0:       png_start_read_image(png_ptr);
michael@0:    }
michael@0:    else
michael@0:    {
michael@0:       if (png_ptr->interlaced && !(png_ptr->transformations & PNG_INTERLACE))
michael@0:       {
michael@0:          /* Caller called png_start_read_image or png_read_update_info without
michael@0:           * first turning on the PNG_INTERLACE transform.  We can fix this here,
michael@0:           * but the caller should do it!
michael@0:           */
michael@0:          png_warning(png_ptr, "Interlace handling should be turned on when "
michael@0:             "using png_read_image");
michael@0:          /* Make sure this is set correctly */
michael@0:          png_ptr->num_rows = png_ptr->height;
michael@0:       }
michael@0: 
michael@0:       /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
michael@0:        * the above error case.
michael@0:        */
michael@0:       pass = png_set_interlace_handling(png_ptr);
michael@0:    }
michael@0: #else
michael@0:    if (png_ptr->interlaced)
michael@0:       png_error(png_ptr,
michael@0:           "Cannot read interlaced image -- interlace handler disabled");
michael@0: 
michael@0:    pass = 1;
michael@0: #endif
michael@0: 
michael@0:    image_height=png_ptr->height;
michael@0: 
michael@0:    for (j = 0; j < pass; j++)
michael@0:    {
michael@0:       rp = image;
michael@0:       for (i = 0; i < image_height; i++)
michael@0:       {
michael@0:          png_read_row(png_ptr, *rp, NULL);
michael@0:          rp++;
michael@0:       }
michael@0:    }
michael@0: }
michael@0: #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
michael@0: 
michael@0: #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
michael@0: /* Read the end of the PNG file.  Will not read past the end of the
michael@0:  * file, will verify the end is accurate, and will read any comments
michael@0:  * or time information at the end of the file, if info is not NULL.
michael@0:  */
michael@0: void PNGAPI
michael@0: png_read_end(png_structrp png_ptr, png_inforp info_ptr)
michael@0: {
michael@0: #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
michael@0:    int keep;
michael@0: #endif
michael@0: 
michael@0:    png_debug(1, "in png_read_end");
michael@0: 
michael@0:    if (png_ptr == NULL)
michael@0:       return;
michael@0: 
michael@0:    /* If png_read_end is called in the middle of reading the rows there may
michael@0:     * still be pending IDAT data and an owned zstream.  Deal with this here.
michael@0:     */
michael@0: #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
michael@0:    if (!png_chunk_unknown_handling(png_ptr, png_IDAT))
michael@0: #endif
michael@0:       png_read_finish_IDAT(png_ptr);
michael@0: 
michael@0: #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
michael@0:    /* Report invalid palette index; added at libng-1.5.10 */
michael@0:    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
michael@0:       png_ptr->num_palette_max > png_ptr->num_palette)
michael@0:      png_benign_error(png_ptr, "Read palette index exceeding num_palette");
michael@0: #endif
michael@0: 
michael@0:    do
michael@0:    {
michael@0:       png_uint_32 length = png_read_chunk_header(png_ptr);
michael@0:       png_uint_32 chunk_name = png_ptr->chunk_name;
michael@0: 
michael@0:       if (chunk_name == png_IEND)
michael@0:          png_handle_IEND(png_ptr, info_ptr, length);
michael@0: 
michael@0:       else if (chunk_name == png_IHDR)
michael@0:          png_handle_IHDR(png_ptr, info_ptr, length);
michael@0: 
michael@0:       else if (info_ptr == NULL)
michael@0:          png_crc_finish(png_ptr, length);
michael@0: 
michael@0: #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
michael@0:       else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
michael@0:       {
michael@0:          if (chunk_name == png_IDAT)
michael@0:          {
michael@0:             if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
michael@0:                png_benign_error(png_ptr, "Too many IDATs found");
michael@0:          }
michael@0:          png_handle_unknown(png_ptr, info_ptr, length, keep);
michael@0:          if (chunk_name == png_PLTE)
michael@0:             png_ptr->mode |= PNG_HAVE_PLTE;
michael@0:       }
michael@0: #endif
michael@0: 
michael@0:       else if (chunk_name == png_IDAT)
michael@0:       {
michael@0:          /* Zero length IDATs are legal after the last IDAT has been
michael@0:           * read, but not after other chunks have been read.
michael@0:           */
michael@0:          if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
michael@0:             png_benign_error(png_ptr, "Too many IDATs found");
michael@0: 
michael@0:          png_crc_finish(png_ptr, length);
michael@0:       }
michael@0:       else if (chunk_name == png_PLTE)
michael@0:          png_handle_PLTE(png_ptr, info_ptr, length);
michael@0: 
michael@0: #ifdef PNG_READ_bKGD_SUPPORTED
michael@0:       else if (chunk_name == png_bKGD)
michael@0:          png_handle_bKGD(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_cHRM_SUPPORTED
michael@0:       else if (chunk_name == png_cHRM)
michael@0:          png_handle_cHRM(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_gAMA_SUPPORTED
michael@0:       else if (chunk_name == png_gAMA)
michael@0:          png_handle_gAMA(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_hIST_SUPPORTED
michael@0:       else if (chunk_name == png_hIST)
michael@0:          png_handle_hIST(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_oFFs_SUPPORTED
michael@0:       else if (chunk_name == png_oFFs)
michael@0:          png_handle_oFFs(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_pCAL_SUPPORTED
michael@0:       else if (chunk_name == png_pCAL)
michael@0:          png_handle_pCAL(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_sCAL_SUPPORTED
michael@0:       else if (chunk_name == png_sCAL)
michael@0:          png_handle_sCAL(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_pHYs_SUPPORTED
michael@0:       else if (chunk_name == png_pHYs)
michael@0:          png_handle_pHYs(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_sBIT_SUPPORTED
michael@0:       else if (chunk_name == png_sBIT)
michael@0:          png_handle_sBIT(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_sRGB_SUPPORTED
michael@0:       else if (chunk_name == png_sRGB)
michael@0:          png_handle_sRGB(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_iCCP_SUPPORTED
michael@0:       else if (chunk_name == png_iCCP)
michael@0:          png_handle_iCCP(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_sPLT_SUPPORTED
michael@0:       else if (chunk_name == png_sPLT)
michael@0:          png_handle_sPLT(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_tEXt_SUPPORTED
michael@0:       else if (chunk_name == png_tEXt)
michael@0:          png_handle_tEXt(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_tIME_SUPPORTED
michael@0:       else if (chunk_name == png_tIME)
michael@0:          png_handle_tIME(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_tRNS_SUPPORTED
michael@0:       else if (chunk_name == png_tRNS)
michael@0:          png_handle_tRNS(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_zTXt_SUPPORTED
michael@0:       else if (chunk_name == png_zTXt)
michael@0:          png_handle_zTXt(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_READ_iTXt_SUPPORTED
michael@0:       else if (chunk_name == png_iTXt)
michael@0:          png_handle_iTXt(png_ptr, info_ptr, length);
michael@0: #endif
michael@0: 
michael@0:       else
michael@0:          png_handle_unknown(png_ptr, info_ptr, length,
michael@0:             PNG_HANDLE_CHUNK_AS_DEFAULT);
michael@0:    } while (!(png_ptr->mode & PNG_HAVE_IEND));
michael@0: }
michael@0: #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
michael@0: 
michael@0: /* Free all memory used in the read struct */
michael@0: static void
michael@0: png_read_destroy(png_structrp png_ptr)
michael@0: {
michael@0:    png_debug(1, "in png_read_destroy");
michael@0: 
michael@0: #ifdef PNG_READ_GAMMA_SUPPORTED
michael@0:    png_destroy_gamma_table(png_ptr);
michael@0: #endif
michael@0: 
michael@0:    png_free(png_ptr, png_ptr->big_row_buf);
michael@0:    png_free(png_ptr, png_ptr->big_prev_row);
michael@0:    png_free(png_ptr, png_ptr->read_buffer);
michael@0: 
michael@0: #ifdef PNG_READ_QUANTIZE_SUPPORTED
michael@0:    png_free(png_ptr, png_ptr->palette_lookup);
michael@0:    png_free(png_ptr, png_ptr->quantize_index);
michael@0: #endif
michael@0: 
michael@0:    if (png_ptr->free_me & PNG_FREE_PLTE)
michael@0:       png_zfree(png_ptr, png_ptr->palette);
michael@0:    png_ptr->free_me &= ~PNG_FREE_PLTE;
michael@0: 
michael@0: #if defined(PNG_tRNS_SUPPORTED) || \
michael@0:     defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
michael@0:    if (png_ptr->free_me & PNG_FREE_TRNS)
michael@0:       png_free(png_ptr, png_ptr->trans_alpha);
michael@0:    png_ptr->free_me &= ~PNG_FREE_TRNS;
michael@0: #endif
michael@0: 
michael@0:    inflateEnd(&png_ptr->zstream);
michael@0: 
michael@0: #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
michael@0:    png_free(png_ptr, png_ptr->save_buffer);
michael@0: #endif
michael@0: 
michael@0: #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) &&\
michael@0:    defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
michael@0:    png_free(png_ptr, png_ptr->unknown_chunk.data);
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
michael@0:    png_free(png_ptr, png_ptr->chunk_list);
michael@0: #endif
michael@0: 
michael@0:    /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
michael@0:     * callbacks are still set at this point.  They are required to complete the
michael@0:     * destruction of the png_struct itself.
michael@0:     */
michael@0: }
michael@0: 
michael@0: /* Free all memory used by the read */
michael@0: void PNGAPI
michael@0: png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
michael@0:     png_infopp end_info_ptr_ptr)
michael@0: {
michael@0:    png_structrp png_ptr = NULL;
michael@0: 
michael@0:    png_debug(1, "in png_destroy_read_struct");
michael@0: 
michael@0:    if (png_ptr_ptr != NULL)
michael@0:       png_ptr = *png_ptr_ptr;
michael@0: 
michael@0:    if (png_ptr == NULL)
michael@0:       return;
michael@0: 
michael@0:    /* libpng 1.6.0: use the API to destroy info structs to ensure consistent
michael@0:     * behavior.  Prior to 1.6.0 libpng did extra 'info' destruction in this API.
michael@0:     * The extra was, apparently, unnecessary yet this hides memory leak bugs.
michael@0:     */
michael@0:    png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
michael@0:    png_destroy_info_struct(png_ptr, info_ptr_ptr);
michael@0: 
michael@0:    *png_ptr_ptr = NULL;
michael@0:    png_read_destroy(png_ptr);
michael@0:    png_destroy_png_struct(png_ptr);
michael@0: }
michael@0: 
michael@0: void PNGAPI
michael@0: png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
michael@0: {
michael@0:    if (png_ptr == NULL)
michael@0:       return;
michael@0: 
michael@0:    png_ptr->read_row_fn = read_row_fn;
michael@0: }
michael@0: 
michael@0: 
michael@0: #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
michael@0: #ifdef PNG_INFO_IMAGE_SUPPORTED
michael@0: void PNGAPI
michael@0: png_read_png(png_structrp png_ptr, png_inforp info_ptr,
michael@0:                            int transforms,
michael@0:                            voidp params)
michael@0: {
michael@0:    if (png_ptr == NULL || info_ptr == NULL)
michael@0:       return;
michael@0: 
michael@0:    /* png_read_info() gives us all of the information from the
michael@0:     * PNG file before the first IDAT (image data chunk).
michael@0:     */
michael@0:    png_read_info(png_ptr, info_ptr);
michael@0:    if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
michael@0:       png_error(png_ptr, "Image is too high to process with png_read_png()");
michael@0: 
michael@0:    /* -------------- image transformations start here ------------------- */
michael@0:    /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
michael@0:     * is not implemented.  This will only happen in de-configured (non-default)
michael@0:     * libpng builds.  The results can be unexpected - png_read_png may return
michael@0:     * short or mal-formed rows because the transform is skipped.
michael@0:     */
michael@0: 
michael@0:    /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
michael@0:     */
michael@0:    if (transforms & PNG_TRANSFORM_SCALE_16)
michael@0:      /* Added at libpng-1.5.4. "strip_16" produces the same result that it
michael@0:       * did in earlier versions, while "scale_16" is now more accurate.
michael@0:       */
michael@0: #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
michael@0:       png_set_scale_16(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
michael@0: #endif
michael@0: 
michael@0:    /* If both SCALE and STRIP are required pngrtran will effectively cancel the
michael@0:     * latter by doing SCALE first.  This is ok and allows apps not to check for
michael@0:     * which is supported to get the right answer.
michael@0:     */
michael@0:    if (transforms & PNG_TRANSFORM_STRIP_16)
michael@0: #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
michael@0:       png_set_strip_16(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
michael@0: #endif
michael@0: 
michael@0:    /* Strip alpha bytes from the input data without combining with
michael@0:     * the background (not recommended).
michael@0:     */
michael@0:    if (transforms & PNG_TRANSFORM_STRIP_ALPHA)
michael@0: #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
michael@0:       png_set_strip_alpha(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
michael@0: #endif
michael@0: 
michael@0:    /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
michael@0:     * byte into separate bytes (useful for paletted and grayscale images).
michael@0:     */
michael@0:    if (transforms & PNG_TRANSFORM_PACKING)
michael@0: #ifdef PNG_READ_PACK_SUPPORTED
michael@0:       png_set_packing(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
michael@0: #endif
michael@0: 
michael@0:    /* Change the order of packed pixels to least significant bit first
michael@0:     * (not useful if you are using png_set_packing).
michael@0:     */
michael@0:    if (transforms & PNG_TRANSFORM_PACKSWAP)
michael@0: #ifdef PNG_READ_PACKSWAP_SUPPORTED
michael@0:       png_set_packswap(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
michael@0: #endif
michael@0: 
michael@0:    /* Expand paletted colors into true RGB triplets
michael@0:     * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
michael@0:     * Expand paletted or RGB images with transparency to full alpha
michael@0:     * channels so the data will be available as RGBA quartets.
michael@0:     */
michael@0:    if (transforms & PNG_TRANSFORM_EXPAND)
michael@0: #ifdef PNG_READ_EXPAND_SUPPORTED
michael@0:       png_set_expand(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
michael@0: #endif
michael@0: 
michael@0:    /* We don't handle background color or gamma transformation or quantizing.
michael@0:     */
michael@0: 
michael@0:    /* Invert monochrome files to have 0 as white and 1 as black
michael@0:     */
michael@0:    if (transforms & PNG_TRANSFORM_INVERT_MONO)
michael@0: #ifdef PNG_READ_INVERT_SUPPORTED
michael@0:       png_set_invert_mono(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
michael@0: #endif
michael@0: 
michael@0:    /* If you want to shift the pixel values from the range [0,255] or
michael@0:     * [0,65535] to the original [0,7] or [0,31], or whatever range the
michael@0:     * colors were originally in:
michael@0:     */
michael@0:    if (transforms & PNG_TRANSFORM_SHIFT)
michael@0: #ifdef PNG_READ_SHIFT_SUPPORTED
michael@0:       if (info_ptr->valid & PNG_INFO_sBIT)
michael@0:          png_set_shift(png_ptr, &info_ptr->sig_bit);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
michael@0: #endif
michael@0: 
michael@0:    /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
michael@0:    if (transforms & PNG_TRANSFORM_BGR)
michael@0: #ifdef PNG_READ_BGR_SUPPORTED
michael@0:       png_set_bgr(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
michael@0: #endif
michael@0: 
michael@0:    /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
michael@0:    if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
michael@0: #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
michael@0:       png_set_swap_alpha(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
michael@0: #endif
michael@0: 
michael@0:    /* Swap bytes of 16-bit files to least significant byte first */
michael@0:    if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
michael@0: #ifdef PNG_READ_SWAP_SUPPORTED
michael@0:       png_set_swap(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
michael@0: #endif
michael@0: 
michael@0: /* Added at libpng-1.2.41 */
michael@0:    /* Invert the alpha channel from opacity to transparency */
michael@0:    if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
michael@0: #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
michael@0:       png_set_invert_alpha(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
michael@0: #endif
michael@0: 
michael@0: /* Added at libpng-1.2.41 */
michael@0:    /* Expand grayscale image to RGB */
michael@0:    if (transforms & PNG_TRANSFORM_GRAY_TO_RGB)
michael@0: #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
michael@0:       png_set_gray_to_rgb(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
michael@0: #endif
michael@0: 
michael@0: /* Added at libpng-1.5.4 */
michael@0:    if (transforms & PNG_TRANSFORM_EXPAND_16)
michael@0: #ifdef PNG_READ_EXPAND_16_SUPPORTED
michael@0:       png_set_expand_16(png_ptr);
michael@0: #else
michael@0:       png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
michael@0: #endif
michael@0: 
michael@0:    /* We don't handle adding filler bytes */
michael@0: 
michael@0:    /* We use png_read_image and rely on that for interlace handling, but we also
michael@0:     * call png_read_update_info therefore must turn on interlace handling now:
michael@0:     */
michael@0:    (void)png_set_interlace_handling(png_ptr);
michael@0: 
michael@0:    /* Optional call to gamma correct and add the background to the palette
michael@0:     * and update info structure.  REQUIRED if you are expecting libpng to
michael@0:     * update the palette for you (i.e., you selected such a transform above).
michael@0:     */
michael@0:    png_read_update_info(png_ptr, info_ptr);
michael@0: 
michael@0:    /* -------------- image transformations end here ------------------- */
michael@0: 
michael@0:    png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
michael@0:    if (info_ptr->row_pointers == NULL)
michael@0:    {
michael@0:       png_uint_32 iptr;
michael@0: 
michael@0:       info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
michael@0:           info_ptr->height * (sizeof (png_bytep))));
michael@0: 
michael@0:       for (iptr=0; iptr<info_ptr->height; iptr++)
michael@0:          info_ptr->row_pointers[iptr] = NULL;
michael@0: 
michael@0:       info_ptr->free_me |= PNG_FREE_ROWS;
michael@0: 
michael@0:       for (iptr = 0; iptr < info_ptr->height; iptr++)
michael@0:          info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
michael@0:             png_malloc(png_ptr, info_ptr->rowbytes));
michael@0:    }
michael@0: 
michael@0:    png_read_image(png_ptr, info_ptr->row_pointers);
michael@0:    info_ptr->valid |= PNG_INFO_IDAT;
michael@0: 
michael@0:    /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
michael@0:    png_read_end(png_ptr, info_ptr);
michael@0: 
michael@0:    PNG_UNUSED(params)
michael@0: }
michael@0: #endif /* PNG_INFO_IMAGE_SUPPORTED */
michael@0: #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
michael@0: 
michael@0: #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
michael@0: /* SIMPLIFIED READ
michael@0:  *
michael@0:  * This code currently relies on the sequential reader, though it could easily
michael@0:  * be made to work with the progressive one.
michael@0:  */
michael@0: /* Arguments to png_image_finish_read: */
michael@0: 
michael@0: /* Encoding of PNG data (used by the color-map code) */
michael@0: #  define P_NOTSET  0 /* File encoding not yet known */
michael@0: #  define P_sRGB    1 /* 8-bit encoded to sRGB gamma */
michael@0: #  define P_LINEAR  2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
michael@0: #  define P_FILE    3 /* 8-bit encoded to file gamma, not sRGB or linear */
michael@0: #  define P_LINEAR8 4 /* 8-bit linear: only from a file value */
michael@0: 
michael@0: /* Color-map processing: after libpng has run on the PNG image further
michael@0:  * processing may be needed to conver the data to color-map indicies.
michael@0:  */
michael@0: #define PNG_CMAP_NONE      0
michael@0: #define PNG_CMAP_GA        1 /* Process GA data to a color-map with alpha */
michael@0: #define PNG_CMAP_TRANS     2 /* Process GA data to a background index */
michael@0: #define PNG_CMAP_RGB       3 /* Process RGB data */
michael@0: #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
michael@0: 
michael@0: /* The following document where the background is for each processing case. */
michael@0: #define PNG_CMAP_NONE_BACKGROUND      256
michael@0: #define PNG_CMAP_GA_BACKGROUND        231
michael@0: #define PNG_CMAP_TRANS_BACKGROUND     254
michael@0: #define PNG_CMAP_RGB_BACKGROUND       256
michael@0: #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
michael@0: 
michael@0: typedef struct
michael@0: {
michael@0:    /* Arguments: */
michael@0:    png_imagep image;
michael@0:    png_voidp  buffer;
michael@0:    png_int_32 row_stride;
michael@0:    png_voidp  colormap;
michael@0:    png_const_colorp background;
michael@0:    /* Local variables: */
michael@0:    png_voidp       local_row;
michael@0:    png_voidp       first_row;
michael@0:    ptrdiff_t       row_bytes;           /* step between rows */
michael@0:    int             file_encoding;       /* E_ values above */
michael@0:    png_fixed_point gamma_to_linear;     /* For P_FILE, reciprocal of gamma */
michael@0:    int             colormap_processing; /* PNG_CMAP_ values above */
michael@0: } png_image_read_control;
michael@0: 
michael@0: /* Do all the *safe* initialization - 'safe' means that png_error won't be
michael@0:  * called, so setting up the jmp_buf is not required.  This means that anything
michael@0:  * called from here must *not* call png_malloc - it has to call png_malloc_warn
michael@0:  * instead so that control is returned safely back to this routine.
michael@0:  */
michael@0: static int
michael@0: png_image_read_init(png_imagep image)
michael@0: {
michael@0:    if (image->opaque == NULL)
michael@0:    {
michael@0:       png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
michael@0:           png_safe_error, png_safe_warning);
michael@0: 
michael@0:       /* And set the rest of the structure to NULL to ensure that the various
michael@0:        * fields are consistent.
michael@0:        */
michael@0:       memset(image, 0, (sizeof *image));
michael@0:       image->version = PNG_IMAGE_VERSION;
michael@0: 
michael@0:       if (png_ptr != NULL)
michael@0:       {
michael@0:          png_infop info_ptr = png_create_info_struct(png_ptr);
michael@0: 
michael@0:          if (info_ptr != NULL)
michael@0:          {
michael@0:             png_controlp control = png_voidcast(png_controlp,
michael@0:                png_malloc_warn(png_ptr, (sizeof *control)));
michael@0: 
michael@0:             if (control != NULL)
michael@0:             {
michael@0:                memset(control, 0, (sizeof *control));
michael@0: 
michael@0:                control->png_ptr = png_ptr;
michael@0:                control->info_ptr = info_ptr;
michael@0:                control->for_write = 0;
michael@0: 
michael@0:                image->opaque = control;
michael@0:                return 1;
michael@0:             }
michael@0: 
michael@0:             /* Error clean up */
michael@0:             png_destroy_info_struct(png_ptr, &info_ptr);
michael@0:          }
michael@0: 
michael@0:          png_destroy_read_struct(&png_ptr, NULL, NULL);
michael@0:       }
michael@0: 
michael@0:       return png_image_error(image, "png_image_read: out of memory");
michael@0:    }
michael@0: 
michael@0:    return png_image_error(image, "png_image_read: opaque pointer not NULL");
michael@0: }
michael@0: 
michael@0: /* Utility to find the base format of a PNG file from a png_struct. */
michael@0: static png_uint_32
michael@0: png_image_format(png_structrp png_ptr)
michael@0: {
michael@0:    png_uint_32 format = 0;
michael@0: 
michael@0:    if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
michael@0:       format |= PNG_FORMAT_FLAG_COLOR;
michael@0: 
michael@0:    if (png_ptr->color_type & PNG_COLOR_MASK_ALPHA)
michael@0:       format |= PNG_FORMAT_FLAG_ALPHA;
michael@0: 
michael@0:    /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
michael@0:     * sets the png_struct fields; that's all we are interested in here.  The
michael@0:     * precise interaction with an app call to png_set_tRNS and PNG file reading
michael@0:     * is unclear.
michael@0:     */
michael@0:    else if (png_ptr->num_trans > 0)
michael@0:       format |= PNG_FORMAT_FLAG_ALPHA;
michael@0: 
michael@0:    if (png_ptr->bit_depth == 16)
michael@0:       format |= PNG_FORMAT_FLAG_LINEAR;
michael@0: 
michael@0:    if (png_ptr->color_type & PNG_COLOR_MASK_PALETTE)
michael@0:       format |= PNG_FORMAT_FLAG_COLORMAP;
michael@0: 
michael@0:    return format;
michael@0: }
michael@0: 
michael@0: /* Is the given gamma significantly different from sRGB?  The test is the same
michael@0:  * one used in pngrtran.c when deciding whether to do gamma correction.  The
michael@0:  * arithmetic optimizes the division by using the fact that the inverse of the
michael@0:  * file sRGB gamma is 2.2
michael@0:  */
michael@0: static int
michael@0: png_gamma_not_sRGB(png_fixed_point g)
michael@0: {
michael@0:    if (g < PNG_FP_1)
michael@0:    {
michael@0:       /* An uninitialized gamma is assumed to be sRGB for the simplified API. */
michael@0:       if (g == 0)
michael@0:          return 0;
michael@0: 
michael@0:       return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
michael@0:    }
michael@0: 
michael@0:    return 1;
michael@0: }
michael@0: 
michael@0: /* Do the main body of a 'png_image_begin_read' function; read the PNG file
michael@0:  * header and fill in all the information.  This is executed in a safe context,
michael@0:  * unlike the init routine above.
michael@0:  */
michael@0: static int
michael@0: png_image_read_header(png_voidp argument)
michael@0: {
michael@0:    png_imagep image = png_voidcast(png_imagep, argument);
michael@0:    png_structrp png_ptr = image->opaque->png_ptr;
michael@0:    png_inforp info_ptr = image->opaque->info_ptr;
michael@0: 
michael@0:    png_set_benign_errors(png_ptr, 1/*warn*/);
michael@0:    png_read_info(png_ptr, info_ptr);
michael@0: 
michael@0:    /* Do this the fast way; just read directly out of png_struct. */
michael@0:    image->width = png_ptr->width;
michael@0:    image->height = png_ptr->height;
michael@0: 
michael@0:    {
michael@0:       png_uint_32 format = png_image_format(png_ptr);
michael@0: 
michael@0:       image->format = format;
michael@0: 
michael@0: #ifdef PNG_COLORSPACE_SUPPORTED
michael@0:       /* Does the colorspace match sRGB?  If there is no color endpoint
michael@0:        * (colorant) information assume yes, otherwise require the
michael@0:        * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set.  If the
michael@0:        * colorspace has been determined to be invalid ignore it.
michael@0:        */
michael@0:       if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
michael@0:          & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
michael@0:             PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
michael@0:          image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
michael@0: #endif
michael@0:    }
michael@0: 
michael@0:    /* We need the maximum number of entries regardless of the format the
michael@0:     * application sets here.
michael@0:     */
michael@0:    {
michael@0:       png_uint_32 cmap_entries;
michael@0: 
michael@0:       switch (png_ptr->color_type)
michael@0:       {
michael@0:          case PNG_COLOR_TYPE_GRAY:
michael@0:             cmap_entries = 1U << png_ptr->bit_depth;
michael@0:             break;
michael@0: 
michael@0:          case PNG_COLOR_TYPE_PALETTE:
michael@0:             cmap_entries = png_ptr->num_palette;
michael@0:             break;
michael@0: 
michael@0:          default:
michael@0:             cmap_entries = 256;
michael@0:             break;
michael@0:       }
michael@0: 
michael@0:       if (cmap_entries > 256)
michael@0:          cmap_entries = 256;
michael@0: 
michael@0:       image->colormap_entries = cmap_entries;
michael@0:    }
michael@0: 
michael@0:    return 1;
michael@0: }
michael@0: 
michael@0: #ifdef PNG_STDIO_SUPPORTED
michael@0: int PNGAPI
michael@0: png_image_begin_read_from_stdio(png_imagep image, FILE* file)
michael@0: {
michael@0:    if (image != NULL && image->version == PNG_IMAGE_VERSION)
michael@0:    {
michael@0:       if (file != NULL)
michael@0:       {
michael@0:          if (png_image_read_init(image))
michael@0:          {
michael@0:             /* This is slightly evil, but png_init_io doesn't do anything other
michael@0:              * than this and we haven't changed the standard IO functions so
michael@0:              * this saves a 'safe' function.
michael@0:              */
michael@0:             image->opaque->png_ptr->io_ptr = file;
michael@0:             return png_safe_execute(image, png_image_read_header, image);
michael@0:          }
michael@0:       }
michael@0: 
michael@0:       else
michael@0:          return png_image_error(image,
michael@0:             "png_image_begin_read_from_stdio: invalid argument");
michael@0:    }
michael@0: 
michael@0:    else if (image != NULL)
michael@0:       return png_image_error(image,
michael@0:          "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
michael@0: 
michael@0:    return 0;
michael@0: }
michael@0: 
michael@0: int PNGAPI
michael@0: png_image_begin_read_from_file(png_imagep image, const char *file_name)
michael@0: {
michael@0:    if (image != NULL && image->version == PNG_IMAGE_VERSION)
michael@0:    {
michael@0:       if (file_name != NULL)
michael@0:       {
michael@0:          FILE *fp = fopen(file_name, "rb");
michael@0: 
michael@0:          if (fp != NULL)
michael@0:          {
michael@0:             if (png_image_read_init(image))
michael@0:             {
michael@0:                image->opaque->png_ptr->io_ptr = fp;
michael@0:                image->opaque->owned_file = 1;
michael@0:                return png_safe_execute(image, png_image_read_header, image);
michael@0:             }
michael@0: 
michael@0:             /* Clean up: just the opened file. */
michael@0:             (void)fclose(fp);
michael@0:          }
michael@0: 
michael@0:          else
michael@0:             return png_image_error(image, strerror(errno));
michael@0:       }
michael@0: 
michael@0:       else
michael@0:          return png_image_error(image,
michael@0:             "png_image_begin_read_from_file: invalid argument");
michael@0:    }
michael@0: 
michael@0:    else if (image != NULL)
michael@0:       return png_image_error(image,
michael@0:          "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
michael@0: 
michael@0:    return 0;
michael@0: }
michael@0: #endif /* PNG_STDIO_SUPPORTED */
michael@0: 
michael@0: static void PNGCBAPI
michael@0: png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
michael@0: {
michael@0:    if (png_ptr != NULL)
michael@0:    {
michael@0:       png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
michael@0:       if (image != NULL)
michael@0:       {
michael@0:          png_controlp cp = image->opaque;
michael@0:          if (cp != NULL)
michael@0:          {
michael@0:             png_const_bytep memory = cp->memory;
michael@0:             png_size_t size = cp->size;
michael@0: 
michael@0:             if (memory != NULL && size >= need)
michael@0:             {
michael@0:                memcpy(out, memory, need);
michael@0:                cp->memory = memory + need;
michael@0:                cp->size = size - need;
michael@0:                return;
michael@0:             }
michael@0: 
michael@0:             png_error(png_ptr, "read beyond end of data");
michael@0:          }
michael@0:       }
michael@0: 
michael@0:       png_error(png_ptr, "invalid memory read");
michael@0:    }
michael@0: }
michael@0: 
michael@0: int PNGAPI png_image_begin_read_from_memory(png_imagep image,
michael@0:    png_const_voidp memory, png_size_t size)
michael@0: {
michael@0:    if (image != NULL && image->version == PNG_IMAGE_VERSION)
michael@0:    {
michael@0:       if (memory != NULL && size > 0)
michael@0:       {
michael@0:          if (png_image_read_init(image))
michael@0:          {
michael@0:             /* Now set the IO functions to read from the memory buffer and
michael@0:              * store it into io_ptr.  Again do this in-place to avoid calling a
michael@0:              * libpng function that requires error handling.
michael@0:              */
michael@0:             image->opaque->memory = png_voidcast(png_const_bytep, memory);
michael@0:             image->opaque->size = size;
michael@0:             image->opaque->png_ptr->io_ptr = image;
michael@0:             image->opaque->png_ptr->read_data_fn = png_image_memory_read;
michael@0: 
michael@0:             return png_safe_execute(image, png_image_read_header, image);
michael@0:          }
michael@0:       }
michael@0: 
michael@0:       else
michael@0:          return png_image_error(image,
michael@0:             "png_image_begin_read_from_memory: invalid argument");
michael@0:    }
michael@0: 
michael@0:    else if (image != NULL)
michael@0:       return png_image_error(image,
michael@0:          "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
michael@0: 
michael@0:    return 0;
michael@0: }
michael@0: 
michael@0: /* Utility function to skip chunks that are not used by the simplified image
michael@0:  * read functions and an appropriate macro to call it.
michael@0:  */
michael@0: #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
michael@0: static void
michael@0: png_image_skip_unused_chunks(png_structrp png_ptr)
michael@0: {
michael@0:    /* Prepare the reader to ignore all recognized chunks whose data will not
michael@0:     * be used, i.e., all chunks recognized by libpng except for those
michael@0:     * involved in basic image reading:
michael@0:     *
michael@0:     *    IHDR, PLTE, IDAT, IEND
michael@0:     *
michael@0:     * Or image data handling:
michael@0:     *
michael@0:     *    tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
michael@0:     *
michael@0:     * This provides a small performance improvement and eliminates any
michael@0:     * potential vulnerability to security problems in the unused chunks.
michael@0:     *
michael@0:     * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
michael@0:     * too.  This allows the simplified API to be compiled without iCCP support,
michael@0:     * however if the support is there the chunk is still checked to detect
michael@0:     * errors (which are unfortunately quite common.)
michael@0:     */
michael@0:    {
michael@0:          static PNG_CONST png_byte chunks_to_process[] = {
michael@0:             98,  75,  71,  68, '\0',  /* bKGD */
michael@0:             99,  72,  82,  77, '\0',  /* cHRM */
michael@0:            103,  65,  77,  65, '\0',  /* gAMA */
michael@0: #        ifdef PNG_READ_iCCP_SUPPORTED
michael@0:            105,  67,  67,  80, '\0',  /* iCCP */
michael@0: #        endif
michael@0:            115,  66,  73,  84, '\0',  /* sBIT */
michael@0:            115,  82,  71,  66, '\0',  /* sRGB */
michael@0:            };
michael@0: 
michael@0:        /* Ignore unknown chunks and all other chunks except for the
michael@0:         * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
michael@0:         */
michael@0:        png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
michael@0:          NULL, -1);
michael@0: 
michael@0:        /* But do not ignore image data handling chunks */
michael@0:        png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
michael@0:          chunks_to_process, (sizeof chunks_to_process)/5);
michael@0:     }
michael@0: }
michael@0: 
michael@0: #  define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
michael@0: #else
michael@0: #  define PNG_SKIP_CHUNKS(p) ((void)0)
michael@0: #endif /* PNG_HANDLE_AS_UNKNOWN_SUPPORTED */
michael@0: 
michael@0: /* The following macro gives the exact rounded answer for all values in the
michael@0:  * range 0..255 (it actually divides by 51.2, but the rounding still generates
michael@0:  * the correct numbers 0..5
michael@0:  */
michael@0: #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
michael@0: 
michael@0: /* Utility functions to make particular color-maps */
michael@0: static void
michael@0: set_file_encoding(png_image_read_control *display)
michael@0: {
michael@0:    png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
michael@0:    if (png_gamma_significant(g))
michael@0:    {
michael@0:       if (png_gamma_not_sRGB(g))
michael@0:       {
michael@0:          display->file_encoding = P_FILE;
michael@0:          display->gamma_to_linear = png_reciprocal(g);
michael@0:       }
michael@0: 
michael@0:       else
michael@0:          display->file_encoding = P_sRGB;
michael@0:    }
michael@0: 
michael@0:    else
michael@0:       display->file_encoding = P_LINEAR8;
michael@0: }
michael@0: 
michael@0: static unsigned int
michael@0: decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
michael@0: {
michael@0:    if (encoding == P_FILE) /* double check */
michael@0:       encoding = display->file_encoding;
michael@0: 
michael@0:    if (encoding == P_NOTSET) /* must be the file encoding */
michael@0:    {
michael@0:       set_file_encoding(display);
michael@0:       encoding = display->file_encoding;
michael@0:    }
michael@0: 
michael@0:    switch (encoding)
michael@0:    {
michael@0:       case P_FILE:
michael@0:          value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
michael@0:          break;
michael@0: 
michael@0:       case P_sRGB:
michael@0:          value = png_sRGB_table[value];
michael@0:          break;
michael@0: 
michael@0:       case P_LINEAR:
michael@0:          break;
michael@0: 
michael@0:       case P_LINEAR8:
michael@0:          value *= 257;
michael@0:          break;
michael@0: 
michael@0:       default:
michael@0:          png_error(display->image->opaque->png_ptr,
michael@0:             "unexpected encoding (internal error)");
michael@0:          break;
michael@0:    }
michael@0: 
michael@0:    return value;
michael@0: }
michael@0: 
michael@0: static png_uint_32
michael@0: png_colormap_compose(png_image_read_control *display,
michael@0:    png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
michael@0:    png_uint_32 background, int encoding)
michael@0: {
michael@0:    /* The file value is composed on the background, the background has the given
michael@0:     * encoding and so does the result, the file is encoded with P_FILE and the
michael@0:     * file and alpha are 8-bit values.  The (output) encoding will always be
michael@0:     * P_LINEAR or P_sRGB.
michael@0:     */
michael@0:    png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
michael@0:    png_uint_32 b = decode_gamma(display, background, encoding);
michael@0: 
michael@0:    /* The alpha is always an 8-bit value (it comes from the palette), the value
michael@0:     * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
michael@0:     */
michael@0:    f = f * alpha + b * (255-alpha);
michael@0: 
michael@0:    if (encoding == P_LINEAR)
michael@0:    {
michael@0:       /* Scale to 65535; divide by 255, approximately (in fact this is extremely
michael@0:        * accurate, it divides by 255.00000005937181414556, with no overflow.)
michael@0:        */
michael@0:       f *= 257; /* Now scaled by 65535 */
michael@0:       f += f >> 16;
michael@0:       f = (f+32768) >> 16;
michael@0:    }
michael@0: 
michael@0:    else /* P_sRGB */
michael@0:       f = PNG_sRGB_FROM_LINEAR(f);
michael@0: 
michael@0:    return f;
michael@0: }
michael@0: 
michael@0: /* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
michael@0:  * be 8-bit.
michael@0:  */
michael@0: static void
michael@0: png_create_colormap_entry(png_image_read_control *display,
michael@0:    png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
michael@0:    png_uint_32 alpha, int encoding)
michael@0: {
michael@0:    png_imagep image = display->image;
michael@0:    const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) ?
michael@0:       P_LINEAR : P_sRGB;
michael@0:    const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
michael@0:       (red != green || green != blue);
michael@0: 
michael@0:    if (ip > 255)
michael@0:       png_error(image->opaque->png_ptr, "color-map index out of range");
michael@0: 
michael@0:    /* Update the cache with whether the file gamma is significantly different
michael@0:     * from sRGB.
michael@0:     */
michael@0:    if (encoding == P_FILE)
michael@0:    {
michael@0:       if (display->file_encoding == P_NOTSET)
michael@0:          set_file_encoding(display);
michael@0: 
michael@0:       /* Note that the cached value may be P_FILE too, but if it is then the
michael@0:        * gamma_to_linear member has been set.
michael@0:        */
michael@0:       encoding = display->file_encoding;
michael@0:    }
michael@0: 
michael@0:    if (encoding == P_FILE)
michael@0:    {
michael@0:       png_fixed_point g = display->gamma_to_linear;
michael@0: 
michael@0:       red = png_gamma_16bit_correct(red*257, g);
michael@0:       green = png_gamma_16bit_correct(green*257, g);
michael@0:       blue = png_gamma_16bit_correct(blue*257, g);
michael@0: 
michael@0:       if (convert_to_Y || output_encoding == P_LINEAR)
michael@0:       {
michael@0:          alpha *= 257;
michael@0:          encoding = P_LINEAR;
michael@0:       }
michael@0: 
michael@0:       else
michael@0:       {
michael@0:          red = PNG_sRGB_FROM_LINEAR(red * 255);
michael@0:          green = PNG_sRGB_FROM_LINEAR(green * 255);
michael@0:          blue = PNG_sRGB_FROM_LINEAR(blue * 255);
michael@0:          encoding = P_sRGB;
michael@0:       }
michael@0:    }
michael@0: 
michael@0:    else if (encoding == P_LINEAR8)
michael@0:    {
michael@0:       /* This encoding occurs quite frequently in test cases because PngSuite
michael@0:        * includes a gAMA 1.0 chunk with most images.
michael@0:        */
michael@0:       red *= 257;
michael@0:       green *= 257;
michael@0:       blue *= 257;
michael@0:       alpha *= 257;
michael@0:       encoding = P_LINEAR;
michael@0:    }
michael@0: 
michael@0:    else if (encoding == P_sRGB && (convert_to_Y || output_encoding == P_LINEAR))
michael@0:    {
michael@0:       /* The values are 8-bit sRGB values, but must be converted to 16-bit
michael@0:        * linear.
michael@0:        */
michael@0:       red = png_sRGB_table[red];
michael@0:       green = png_sRGB_table[green];
michael@0:       blue = png_sRGB_table[blue];
michael@0:       alpha *= 257;
michael@0:       encoding = P_LINEAR;
michael@0:    }
michael@0: 
michael@0:    /* This is set if the color isn't gray but the output is. */
michael@0:    if (encoding == P_LINEAR)
michael@0:    {
michael@0:       if (convert_to_Y)
michael@0:       {
michael@0:          /* NOTE: these values are copied from png_do_rgb_to_gray */
michael@0:          png_uint_32 y = (png_uint_32)6968 * red  + (png_uint_32)23434 * green +
michael@0:             (png_uint_32)2366 * blue;
michael@0: 
michael@0:          if (output_encoding == P_LINEAR)
michael@0:             y = (y + 16384) >> 15;
michael@0: 
michael@0:          else
michael@0:          {
michael@0:             /* y is scaled by 32768, we need it scaled by 255: */
michael@0:             y = (y + 128) >> 8;
michael@0:             y *= 255;
michael@0:             y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
michael@0:             encoding = P_sRGB;
michael@0:          }
michael@0: 
michael@0:          blue = red = green = y;
michael@0:       }
michael@0: 
michael@0:       else if (output_encoding == P_sRGB)
michael@0:       {
michael@0:          red = PNG_sRGB_FROM_LINEAR(red * 255);
michael@0:          green = PNG_sRGB_FROM_LINEAR(green * 255);
michael@0:          blue = PNG_sRGB_FROM_LINEAR(blue * 255);
michael@0:          alpha = PNG_DIV257(alpha);
michael@0:          encoding = P_sRGB;
michael@0:       }
michael@0:    }
michael@0: 
michael@0:    if (encoding != output_encoding)
michael@0:       png_error(image->opaque->png_ptr, "bad encoding (internal error)");
michael@0: 
michael@0:    /* Store the value. */
michael@0:    {
michael@0: #     ifdef PNG_FORMAT_AFIRST_SUPPORTED
michael@0:          const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
michael@0:             (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
michael@0: #     else
michael@0: #        define afirst 0
michael@0: #     endif
michael@0: #     ifdef PNG_FORMAT_BGR_SUPPORTED
michael@0:          const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) ? 2 : 0;
michael@0: #     else
michael@0: #        define bgr 0
michael@0: #     endif
michael@0: 
michael@0:       if (output_encoding == P_LINEAR)
michael@0:       {
michael@0:          png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
michael@0: 
michael@0:          entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
michael@0: 
michael@0:          /* The linear 16-bit values must be pre-multiplied by the alpha channel
michael@0:           * value, if less than 65535 (this is, effectively, composite on black
michael@0:           * if the alpha channel is removed.)
michael@0:           */
michael@0:          switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
michael@0:          {
michael@0:             case 4:
michael@0:                entry[afirst ? 0 : 3] = (png_uint_16)alpha;
michael@0:                /* FALL THROUGH */
michael@0: 
michael@0:             case 3:
michael@0:                if (alpha < 65535)
michael@0:                {
michael@0:                   if (alpha > 0)
michael@0:                   {
michael@0:                      blue = (blue * alpha + 32767U)/65535U;
michael@0:                      green = (green * alpha + 32767U)/65535U;
michael@0:                      red = (red * alpha + 32767U)/65535U;
michael@0:                   }
michael@0: 
michael@0:                   else
michael@0:                      red = green = blue = 0;
michael@0:                }
michael@0:                entry[afirst + (2 ^ bgr)] = (png_uint_16)blue;
michael@0:                entry[afirst + 1] = (png_uint_16)green;
michael@0:                entry[afirst + bgr] = (png_uint_16)red;
michael@0:                break;
michael@0: 
michael@0:             case 2:
michael@0:                entry[1 ^ afirst] = (png_uint_16)alpha;
michael@0:                /* FALL THROUGH */
michael@0: 
michael@0:             case 1:
michael@0:                if (alpha < 65535)
michael@0:                {
michael@0:                   if (alpha > 0)
michael@0:                      green = (green * alpha + 32767U)/65535U;
michael@0: 
michael@0:                   else
michael@0:                      green = 0;
michael@0:                }
michael@0:                entry[afirst] = (png_uint_16)green;
michael@0:                break;
michael@0: 
michael@0:             default:
michael@0:                break;
michael@0:          }
michael@0:       }
michael@0: 
michael@0:       else /* output encoding is P_sRGB */
michael@0:       {
michael@0:          png_bytep entry = png_voidcast(png_bytep, display->colormap);
michael@0: 
michael@0:          entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
michael@0: 
michael@0:          switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
michael@0:          {
michael@0:             case 4:
michael@0:                entry[afirst ? 0 : 3] = (png_byte)alpha;
michael@0:             case 3:
michael@0:                entry[afirst + (2 ^ bgr)] = (png_byte)blue;
michael@0:                entry[afirst + 1] = (png_byte)green;
michael@0:                entry[afirst + bgr] = (png_byte)red;
michael@0:                break;
michael@0: 
michael@0:             case 2:
michael@0:                entry[1 ^ afirst] = (png_byte)alpha;
michael@0:             case 1:
michael@0:                entry[afirst] = (png_byte)green;
michael@0:                break;
michael@0: 
michael@0:             default:
michael@0:                break;
michael@0:          }
michael@0:       }
michael@0: 
michael@0: #     ifdef afirst
michael@0: #        undef afirst
michael@0: #     endif
michael@0: #     ifdef bgr
michael@0: #        undef bgr
michael@0: #     endif
michael@0:    }
michael@0: }
michael@0: 
michael@0: static int
michael@0: make_gray_file_colormap(png_image_read_control *display)
michael@0: {
michael@0:    unsigned int i;
michael@0: 
michael@0:    for (i=0; i<256; ++i)
michael@0:       png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
michael@0: 
michael@0:    return i;
michael@0: }
michael@0: 
michael@0: static int
michael@0: make_gray_colormap(png_image_read_control *display)
michael@0: {
michael@0:    unsigned int i;
michael@0: 
michael@0:    for (i=0; i<256; ++i)
michael@0:       png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
michael@0: 
michael@0:    return i;
michael@0: }
michael@0: #define PNG_GRAY_COLORMAP_ENTRIES 256
michael@0: 
michael@0: static int
michael@0: make_ga_colormap(png_image_read_control *display)
michael@0: {
michael@0:    unsigned int i, a;
michael@0: 
michael@0:    /* Alpha is retained, the output will be a color-map with entries
michael@0:     * selected by six levels of alpha.  One transparent entry, 6 gray
michael@0:     * levels for all the intermediate alpha values, leaving 230 entries
michael@0:     * for the opaque grays.  The color-map entries are the six values
michael@0:     * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
michael@0:     * relevant entry.
michael@0:     *
michael@0:     * if (alpha > 229) // opaque
michael@0:     * {
michael@0:     *    // The 231 entries are selected to make the math below work:
michael@0:     *    base = 0;
michael@0:     *    entry = (231 * gray + 128) >> 8;
michael@0:     * }
michael@0:     * else if (alpha < 26) // transparent
michael@0:     * {
michael@0:     *    base = 231;
michael@0:     *    entry = 0;
michael@0:     * }
michael@0:     * else // partially opaque
michael@0:     * {
michael@0:     *    base = 226 + 6 * PNG_DIV51(alpha);
michael@0:     *    entry = PNG_DIV51(gray);
michael@0:     * }
michael@0:     */
michael@0:    i = 0;
michael@0:    while (i < 231)
michael@0:    {
michael@0:       unsigned int gray = (i * 256 + 115) / 231;
michael@0:       png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
michael@0:    }
michael@0: 
michael@0:    /* 255 is used here for the component values for consistency with the code
michael@0:     * that undoes premultiplication in pngwrite.c.
michael@0:     */
michael@0:    png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
michael@0: 
michael@0:    for (a=1; a<5; ++a)
michael@0:    {
michael@0:       unsigned int g;
michael@0: 
michael@0:       for (g=0; g<6; ++g)
michael@0:          png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
michael@0:             P_sRGB);
michael@0:    }
michael@0: 
michael@0:    return i;
michael@0: }
michael@0: 
michael@0: #define PNG_GA_COLORMAP_ENTRIES 256
michael@0: 
michael@0: static int
michael@0: make_rgb_colormap(png_image_read_control *display)
michael@0: {
michael@0:    unsigned int i, r;
michael@0: 
michael@0:    /* Build a 6x6x6 opaque RGB cube */
michael@0:    for (i=r=0; r<6; ++r)
michael@0:    {
michael@0:       unsigned int g;
michael@0: 
michael@0:       for (g=0; g<6; ++g)
michael@0:       {
michael@0:          unsigned int b;
michael@0: 
michael@0:          for (b=0; b<6; ++b)
michael@0:             png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
michael@0:                P_sRGB);
michael@0:       }
michael@0:    }
michael@0: 
michael@0:    return i;
michael@0: }
michael@0: 
michael@0: #define PNG_RGB_COLORMAP_ENTRIES 216
michael@0: 
michael@0: /* Return a palette index to the above palette given three 8-bit sRGB values. */
michael@0: #define PNG_RGB_INDEX(r,g,b) \
michael@0:    ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
michael@0: 
michael@0: static int
michael@0: png_image_read_colormap(png_voidp argument)
michael@0: {
michael@0:    png_image_read_control *display =
michael@0:       png_voidcast(png_image_read_control*, argument);
michael@0:    const png_imagep image = display->image;
michael@0: 
michael@0:    const png_structrp png_ptr = image->opaque->png_ptr;
michael@0:    const png_uint_32 output_format = image->format;
michael@0:    const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) ?
michael@0:       P_LINEAR : P_sRGB;
michael@0: 
michael@0:    unsigned int cmap_entries;
michael@0:    unsigned int output_processing;        /* Output processing option */
michael@0:    unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
michael@0: 
michael@0:    /* Background information; the background color and the index of this color
michael@0:     * in the color-map if it exists (else 256).
michael@0:     */
michael@0:    unsigned int background_index = 256;
michael@0:    png_uint_32 back_r, back_g, back_b;
michael@0: 
michael@0:    /* Flags to accumulate things that need to be done to the input. */
michael@0:    int expand_tRNS = 0;
michael@0: 
michael@0:    /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
michael@0:     * very difficult to do, the results look awful, and it is difficult to see
michael@0:     * what possible use it is because the application can't control the
michael@0:     * color-map.
michael@0:     */
michael@0:    if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
michael@0:          png_ptr->num_trans > 0) /* alpha in input */ &&
michael@0:       ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
michael@0:    {
michael@0:       if (output_encoding == P_LINEAR) /* compose on black */
michael@0:          back_b = back_g = back_r = 0;
michael@0: 
michael@0:       else if (display->background == NULL /* no way to remove it */)
michael@0:          png_error(png_ptr,
michael@0:             "a background color must be supplied to remove alpha/transparency");
michael@0: 
michael@0:       /* Get a copy of the background color (this avoids repeating the checks
michael@0:        * below.)  The encoding is 8-bit sRGB or 16-bit linear, depending on the
michael@0:        * output format.
michael@0:        */
michael@0:       else
michael@0:       {
michael@0:          back_g = display->background->green;
michael@0:          if (output_format & PNG_FORMAT_FLAG_COLOR)
michael@0:          {
michael@0:             back_r = display->background->red;
michael@0:             back_b = display->background->blue;
michael@0:          }
michael@0:          else
michael@0:             back_b = back_r = back_g;
michael@0:       }
michael@0:    }
michael@0: 
michael@0:    else if (output_encoding == P_LINEAR)
michael@0:       back_b = back_r = back_g = 65535;
michael@0: 
michael@0:    else
michael@0:       back_b = back_r = back_g = 255;
michael@0: 
michael@0:    /* Default the input file gamma if required - this is necessary because
michael@0:     * libpng assumes that if no gamma information is present the data is in the
michael@0:     * output format, but the simplified API deduces the gamma from the input
michael@0:     * format.
michael@0:     */
michael@0:    if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
michael@0:    {
michael@0:       /* Do this directly, not using the png_colorspace functions, to ensure
michael@0:        * that it happens even if the colorspace is invalid (though probably if
michael@0:        * it is the setting will be ignored)  Note that the same thing can be
michael@0:        * achieved at the application interface with png_set_gAMA.
michael@0:        */
michael@0:       if (png_ptr->bit_depth == 16 &&
michael@0:          (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
michael@0:          png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
michael@0: 
michael@0:       else
michael@0:          png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
michael@0: 
michael@0:       png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
michael@0:    }
michael@0: 
michael@0:    /* Decide what to do based on the PNG color type of the input data.  The
michael@0:     * utility function png_create_colormap_entry deals with most aspects of the
michael@0:     * output transformations; this code works out how to produce bytes of
michael@0:     * color-map entries from the original format.
michael@0:     */
michael@0:    switch (png_ptr->color_type)
michael@0:    {
michael@0:       case PNG_COLOR_TYPE_GRAY:
michael@0:          if (png_ptr->bit_depth <= 8)
michael@0:          {
michael@0:             /* There at most 256 colors in the output, regardless of
michael@0:              * transparency.
michael@0:              */
michael@0:             unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
michael@0: 
michael@0:             cmap_entries = 1U << png_ptr->bit_depth;
michael@0:             if (cmap_entries > image->colormap_entries)
michael@0:                png_error(png_ptr, "gray[8] color-map: too few entries");
michael@0: 
michael@0:             step = 255 / (cmap_entries - 1);
michael@0:             output_processing = PNG_CMAP_NONE;
michael@0: 
michael@0:             /* If there is a tRNS chunk then this either selects a transparent
michael@0:              * value or, if the output has no alpha, the background color.
michael@0:              */
michael@0:             if (png_ptr->num_trans > 0)
michael@0:             {
michael@0:                trans = png_ptr->trans_color.gray;
michael@0: 
michael@0:                if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
michael@0:                   back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
michael@0:             }
michael@0: 
michael@0:             /* png_create_colormap_entry just takes an RGBA and writes the
michael@0:              * corresponding color-map entry using the format from 'image',
michael@0:              * including the required conversion to sRGB or linear as
michael@0:              * appropriate.  The input values are always either sRGB (if the
michael@0:              * gamma correction flag is 0) or 0..255 scaled file encoded values
michael@0:              * (if the function must gamma correct them).
michael@0:              */
michael@0:             for (i=val=0; i<cmap_entries; ++i, val += step)
michael@0:             {
michael@0:                /* 'i' is a file value.  While this will result in duplicated
michael@0:                 * entries for 8-bit non-sRGB encoded files it is necessary to
michael@0:                 * have non-gamma corrected values to do tRNS handling.
michael@0:                 */
michael@0:                if (i != trans)
michael@0:                   png_create_colormap_entry(display, i, val, val, val, 255,
michael@0:                      P_FILE/*8-bit with file gamma*/);
michael@0: 
michael@0:                /* Else this entry is transparent.  The colors don't matter if
michael@0:                 * there is an alpha channel (back_alpha == 0), but it does no
michael@0:                 * harm to pass them in; the values are not set above so this
michael@0:                 * passes in white.
michael@0:                 *
michael@0:                 * NOTE: this preserves the full precision of the application
michael@0:                 * supplied background color when it is used.
michael@0:                 */
michael@0:                else
michael@0:                   png_create_colormap_entry(display, i, back_r, back_g, back_b,
michael@0:                      back_alpha, output_encoding);
michael@0:             }
michael@0: 
michael@0:             /* We need libpng to preserve the original encoding. */
michael@0:             data_encoding = P_FILE;
michael@0: 
michael@0:             /* The rows from libpng, while technically gray values, are now also
michael@0:              * color-map indicies; however, they may need to be expanded to 1
michael@0:              * byte per pixel.  This is what png_set_packing does (i.e., it
michael@0:              * unpacks the bit values into bytes.)
michael@0:              */
michael@0:             if (png_ptr->bit_depth < 8)
michael@0:                png_set_packing(png_ptr);
michael@0:          }
michael@0: 
michael@0:          else /* bit depth is 16 */
michael@0:          {
michael@0:             /* The 16-bit input values can be converted directly to 8-bit gamma
michael@0:              * encoded values; however, if a tRNS chunk is present 257 color-map
michael@0:              * entries are required.  This means that the extra entry requires
michael@0:              * special processing; add an alpha channel, sacrifice gray level
michael@0:              * 254 and convert transparent (alpha==0) entries to that.
michael@0:              *
michael@0:              * Use libpng to chop the data to 8 bits.  Convert it to sRGB at the
michael@0:              * same time to minimize quality loss.  If a tRNS chunk is present
michael@0:              * this means libpng must handle it too; otherwise it is impossible
michael@0:              * to do the exact match on the 16-bit value.
michael@0:              *
michael@0:              * If the output has no alpha channel *and* the background color is
michael@0:              * gray then it is possible to let libpng handle the substitution by
michael@0:              * ensuring that the corresponding gray level matches the background
michael@0:              * color exactly.
michael@0:              */
michael@0:             data_encoding = P_sRGB;
michael@0: 
michael@0:             if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
michael@0:                png_error(png_ptr, "gray[16] color-map: too few entries");
michael@0: 
michael@0:             cmap_entries = make_gray_colormap(display);
michael@0: 
michael@0:             if (png_ptr->num_trans > 0)
michael@0:             {
michael@0:                unsigned int back_alpha;
michael@0: 
michael@0:                if (output_format & PNG_FORMAT_FLAG_ALPHA)
michael@0:                   back_alpha = 0;
michael@0: 
michael@0:                else
michael@0:                {
michael@0:                   if (back_r == back_g && back_g == back_b)
michael@0:                   {
michael@0:                      /* Background is gray; no special processing will be
michael@0:                       * required.
michael@0:                       */
michael@0:                      png_color_16 c;
michael@0:                      png_uint_32 gray = back_g;
michael@0: 
michael@0:                      if (output_encoding == P_LINEAR)
michael@0:                      {
michael@0:                         gray = PNG_sRGB_FROM_LINEAR(gray * 255);
michael@0: 
michael@0:                         /* And make sure the corresponding palette entry
michael@0:                          * matches.
michael@0:                          */
michael@0:                         png_create_colormap_entry(display, gray, back_g, back_g,
michael@0:                            back_g, 65535, P_LINEAR);
michael@0:                      }
michael@0: 
michael@0:                      /* The background passed to libpng, however, must be the
michael@0:                       * sRGB value.
michael@0:                       */
michael@0:                      c.index = 0; /*unused*/
michael@0:                      c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
michael@0: 
michael@0:                      /* NOTE: does this work without expanding tRNS to alpha?
michael@0:                       * It should be the color->gray case below apparently
michael@0:                       * doesn't.
michael@0:                       */
michael@0:                      png_set_background_fixed(png_ptr, &c,
michael@0:                         PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
michael@0:                         0/*gamma: not used*/);
michael@0: 
michael@0:                      output_processing = PNG_CMAP_NONE;
michael@0:                      break;
michael@0:                   }
michael@0: 
michael@0:                   back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
michael@0:                }
michael@0: 
michael@0:                /* output_processing means that the libpng-processed row will be
michael@0:                 * 8-bit GA and it has to be processing to single byte color-map
michael@0:                 * values.  Entry 254 is replaced by either a completely
michael@0:                 * transparent entry or by the background color at full
michael@0:                 * precision (and the background color is not a simple gray leve
michael@0:                 * in this case.)
michael@0:                 */
michael@0:                expand_tRNS = 1;
michael@0:                output_processing = PNG_CMAP_TRANS;
michael@0:                background_index = 254;
michael@0: 
michael@0:                /* And set (overwrite) color-map entry 254 to the actual
michael@0:                 * background color at full precision.
michael@0:                 */
michael@0:                png_create_colormap_entry(display, 254, back_r, back_g, back_b,
michael@0:                   back_alpha, output_encoding);
michael@0:             }
michael@0: 
michael@0:             else
michael@0:                output_processing = PNG_CMAP_NONE;
michael@0:          }
michael@0:          break;
michael@0: 
michael@0:       case PNG_COLOR_TYPE_GRAY_ALPHA:
michael@0:          /* 8-bit or 16-bit PNG with two channels - gray and alpha.  A minimum
michael@0:           * of 65536 combinations.  If, however, the alpha channel is to be
michael@0:           * removed there are only 256 possibilities if the background is gray.
michael@0:           * (Otherwise there is a subset of the 65536 possibilities defined by
michael@0:           * the triangle between black, white and the background color.)
michael@0:           *
michael@0:           * Reduce 16-bit files to 8-bit and sRGB encode the result.  No need to
michael@0:           * worry about tRNS matching - tRNS is ignored if there is an alpha
michael@0:           * channel.
michael@0:           */
michael@0:          data_encoding = P_sRGB;
michael@0: 
michael@0:          if (output_format & PNG_FORMAT_FLAG_ALPHA)
michael@0:          {
michael@0:             if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
michael@0:                png_error(png_ptr, "gray+alpha color-map: too few entries");
michael@0: 
michael@0:             cmap_entries = make_ga_colormap(display);
michael@0: 
michael@0:             background_index = PNG_CMAP_GA_BACKGROUND;
michael@0:             output_processing = PNG_CMAP_GA;
michael@0:          }
michael@0: 
michael@0:          else /* alpha is removed */
michael@0:          {
michael@0:             /* Alpha must be removed as the PNG data is processed when the
michael@0:              * background is a color because the G and A channels are
michael@0:              * independent and the vector addition (non-parallel vectors) is a
michael@0:              * 2-D problem.
michael@0:              *
michael@0:              * This can be reduced to the same algorithm as above by making a
michael@0:              * colormap containing gray levels (for the opaque grays), a
michael@0:              * background entry (for a transparent pixel) and a set of four six
michael@0:              * level color values, one set for each intermediate alpha value.
michael@0:              * See the comments in make_ga_colormap for how this works in the
michael@0:              * per-pixel processing.
michael@0:              *
michael@0:              * If the background is gray, however, we only need a 256 entry gray
michael@0:              * level color map.  It is sufficient to make the entry generated
michael@0:              * for the background color be exactly the color specified.
michael@0:              */
michael@0:             if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
michael@0:                (back_r == back_g && back_g == back_b))
michael@0:             {
michael@0:                /* Background is gray; no special processing will be required. */
michael@0:                png_color_16 c;
michael@0:                png_uint_32 gray = back_g;
michael@0: 
michael@0:                if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
michael@0:                   png_error(png_ptr, "gray-alpha color-map: too few entries");
michael@0: 
michael@0:                cmap_entries = make_gray_colormap(display);
michael@0: 
michael@0:                if (output_encoding == P_LINEAR)
michael@0:                {
michael@0:                   gray = PNG_sRGB_FROM_LINEAR(gray * 255);
michael@0: 
michael@0:                   /* And make sure the corresponding palette entry matches. */
michael@0:                   png_create_colormap_entry(display, gray, back_g, back_g,
michael@0:                      back_g, 65535, P_LINEAR);
michael@0:                }
michael@0: 
michael@0:                /* The background passed to libpng, however, must be the sRGB
michael@0:                 * value.
michael@0:                 */
michael@0:                c.index = 0; /*unused*/
michael@0:                c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
michael@0: 
michael@0:                png_set_background_fixed(png_ptr, &c,
michael@0:                   PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
michael@0:                   0/*gamma: not used*/);
michael@0: 
michael@0:                output_processing = PNG_CMAP_NONE;
michael@0:             }
michael@0: 
michael@0:             else
michael@0:             {
michael@0:                png_uint_32 i, a;
michael@0: 
michael@0:                /* This is the same as png_make_ga_colormap, above, except that
michael@0:                 * the entries are all opaque.
michael@0:                 */
michael@0:                if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
michael@0:                   png_error(png_ptr, "ga-alpha color-map: too few entries");
michael@0: 
michael@0:                i = 0;
michael@0:                while (i < 231)
michael@0:                {
michael@0:                   png_uint_32 gray = (i * 256 + 115) / 231;
michael@0:                   png_create_colormap_entry(display, i++, gray, gray, gray,
michael@0:                      255, P_sRGB);
michael@0:                }
michael@0: 
michael@0:                /* NOTE: this preserves the full precision of the application
michael@0:                 * background color.
michael@0:                 */
michael@0:                background_index = i;
michael@0:                png_create_colormap_entry(display, i++, back_r, back_g, back_b,
michael@0:                   output_encoding == P_LINEAR ? 65535U : 255U, output_encoding);
michael@0: 
michael@0:                /* For non-opaque input composite on the sRGB background - this
michael@0:                 * requires inverting the encoding for each component.  The input
michael@0:                 * is still converted to the sRGB encoding because this is a
michael@0:                 * reasonable approximate to the logarithmic curve of human
michael@0:                 * visual sensitivity, at least over the narrow range which PNG
michael@0:                 * represents.  Consequently 'G' is always sRGB encoded, while
michael@0:                 * 'A' is linear.  We need the linear background colors.
michael@0:                 */
michael@0:                if (output_encoding == P_sRGB) /* else already linear */
michael@0:                {
michael@0:                   /* This may produce a value not exactly matching the
michael@0:                    * background, but that's ok because these numbers are only
michael@0:                    * used when alpha != 0
michael@0:                    */
michael@0:                   back_r = png_sRGB_table[back_r];
michael@0:                   back_g = png_sRGB_table[back_g];
michael@0:                   back_b = png_sRGB_table[back_b];
michael@0:                }
michael@0: 
michael@0:                for (a=1; a<5; ++a)
michael@0:                {
michael@0:                   unsigned int g;
michael@0: 
michael@0:                   /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
michael@0:                    * by an 8-bit alpha value (0..255).
michael@0:                    */
michael@0:                   png_uint_32 alpha = 51 * a;
michael@0:                   png_uint_32 back_rx = (255-alpha) * back_r;
michael@0:                   png_uint_32 back_gx = (255-alpha) * back_g;
michael@0:                   png_uint_32 back_bx = (255-alpha) * back_b;
michael@0: 
michael@0:                   for (g=0; g<6; ++g)
michael@0:                   {
michael@0:                      png_uint_32 gray = png_sRGB_table[g*51] * alpha;
michael@0: 
michael@0:                      png_create_colormap_entry(display, i++,
michael@0:                         PNG_sRGB_FROM_LINEAR(gray + back_rx),
michael@0:                         PNG_sRGB_FROM_LINEAR(gray + back_gx),
michael@0:                         PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
michael@0:                   }
michael@0:                }
michael@0: 
michael@0:                cmap_entries = i;
michael@0:                output_processing = PNG_CMAP_GA;
michael@0:             }
michael@0:          }
michael@0:          break;
michael@0: 
michael@0:       case PNG_COLOR_TYPE_RGB:
michael@0:       case PNG_COLOR_TYPE_RGB_ALPHA:
michael@0:          /* Exclude the case where the output is gray; we can always handle this
michael@0:           * with the cases above.
michael@0:           */
michael@0:          if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
michael@0:          {
michael@0:             /* The color-map will be grayscale, so we may as well convert the
michael@0:              * input RGB values to a simple grayscale and use the grayscale
michael@0:              * code above.
michael@0:              *
michael@0:              * NOTE: calling this apparently damages the recognition of the
michael@0:              * transparent color in background color handling; call
michael@0:              * png_set_tRNS_to_alpha before png_set_background_fixed.
michael@0:              */
michael@0:             png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
michael@0:                -1);
michael@0:             data_encoding = P_sRGB;
michael@0: 
michael@0:             /* The output will now be one or two 8-bit gray or gray+alpha
michael@0:              * channels.  The more complex case arises when the input has alpha.
michael@0:              */
michael@0:             if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
michael@0:                png_ptr->num_trans > 0) &&
michael@0:                (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
michael@0:             {
michael@0:                /* Both input and output have an alpha channel, so no background
michael@0:                 * processing is required; just map the GA bytes to the right
michael@0:                 * color-map entry.
michael@0:                 */
michael@0:                expand_tRNS = 1;
michael@0: 
michael@0:                if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
michael@0:                   png_error(png_ptr, "rgb[ga] color-map: too few entries");
michael@0: 
michael@0:                cmap_entries = make_ga_colormap(display);
michael@0:                background_index = PNG_CMAP_GA_BACKGROUND;
michael@0:                output_processing = PNG_CMAP_GA;
michael@0:             }
michael@0: 
michael@0:             else
michael@0:             {
michael@0:                /* Either the input or the output has no alpha channel, so there
michael@0:                 * will be no non-opaque pixels in the color-map; it will just be
michael@0:                 * grayscale.
michael@0:                 */
michael@0:                if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
michael@0:                   png_error(png_ptr, "rgb[gray] color-map: too few entries");
michael@0: 
michael@0:                /* Ideally this code would use libpng to do the gamma correction,
michael@0:                 * but if an input alpha channel is to be removed we will hit the
michael@0:                 * libpng bug in gamma+compose+rgb-to-gray (the double gamma
michael@0:                 * correction bug).  Fix this by dropping the gamma correction in
michael@0:                 * this case and doing it in the palette; this will result in
michael@0:                 * duplicate palette entries, but that's better than the
michael@0:                 * alternative of double gamma correction.
michael@0:                 */
michael@0:                if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
michael@0:                   png_ptr->num_trans > 0) &&
michael@0:                   png_gamma_not_sRGB(png_ptr->colorspace.gamma))
michael@0:                {
michael@0:                   cmap_entries = make_gray_file_colormap(display);
michael@0:                   data_encoding = P_FILE;
michael@0:                }
michael@0: 
michael@0:                else
michael@0:                   cmap_entries = make_gray_colormap(display);
michael@0: 
michael@0:                /* But if the input has alpha or transparency it must be removed
michael@0:                 */
michael@0:                if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
michael@0:                   png_ptr->num_trans > 0)
michael@0:                {
michael@0:                   png_color_16 c;
michael@0:                   png_uint_32 gray = back_g;
michael@0: 
michael@0:                   /* We need to ensure that the application background exists in
michael@0:                    * the colormap and that completely transparent pixels map to
michael@0:                    * it.  Achieve this simply by ensuring that the entry
michael@0:                    * selected for the background really is the background color.
michael@0:                    */
michael@0:                   if (data_encoding == P_FILE) /* from the fixup above */
michael@0:                   {
michael@0:                      /* The app supplied a gray which is in output_encoding, we
michael@0:                       * need to convert it to a value of the input (P_FILE)
michael@0:                       * encoding then set this palette entry to the required
michael@0:                       * output encoding.
michael@0:                       */
michael@0:                      if (output_encoding == P_sRGB)
michael@0:                         gray = png_sRGB_table[gray]; /* now P_LINEAR */
michael@0: 
michael@0:                      gray = PNG_DIV257(png_gamma_16bit_correct(gray,
michael@0:                         png_ptr->colorspace.gamma)); /* now P_FILE */
michael@0: 
michael@0:                      /* And make sure the corresponding palette entry contains
michael@0:                       * exactly the required sRGB value.
michael@0:                       */
michael@0:                      png_create_colormap_entry(display, gray, back_g, back_g,
michael@0:                         back_g, 0/*unused*/, output_encoding);
michael@0:                   }
michael@0: 
michael@0:                   else if (output_encoding == P_LINEAR)
michael@0:                   {
michael@0:                      gray = PNG_sRGB_FROM_LINEAR(gray * 255);
michael@0: 
michael@0:                      /* And make sure the corresponding palette entry matches.
michael@0:                       */
michael@0:                      png_create_colormap_entry(display, gray, back_g, back_g,
michael@0:                         back_g, 0/*unused*/, P_LINEAR);
michael@0:                   }
michael@0: 
michael@0:                   /* The background passed to libpng, however, must be the
michael@0:                    * output (normally sRGB) value.
michael@0:                    */
michael@0:                   c.index = 0; /*unused*/
michael@0:                   c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
michael@0: 
michael@0:                   /* NOTE: the following is apparently a bug in libpng. Without
michael@0:                    * it the transparent color recognition in
michael@0:                    * png_set_background_fixed seems to go wrong.
michael@0:                    */
michael@0:                   expand_tRNS = 1;
michael@0:                   png_set_background_fixed(png_ptr, &c,
michael@0:                      PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
michael@0:                      0/*gamma: not used*/);
michael@0:                }
michael@0: 
michael@0:                output_processing = PNG_CMAP_NONE;
michael@0:             }
michael@0:          }
michael@0: 
michael@0:          else /* output is color */
michael@0:          {
michael@0:             /* We could use png_quantize here so long as there is no transparent
michael@0:              * color or alpha; png_quantize ignores alpha.  Easier overall just
michael@0:              * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
michael@0:              * Consequently we always want libpng to produce sRGB data.
michael@0:              */
michael@0:             data_encoding = P_sRGB;
michael@0: 
michael@0:             /* Is there any transparency or alpha? */
michael@0:             if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
michael@0:                png_ptr->num_trans > 0)
michael@0:             {
michael@0:                /* Is there alpha in the output too?  If so all four channels are
michael@0:                 * processed into a special RGB cube with alpha support.
michael@0:                 */
michael@0:                if (output_format & PNG_FORMAT_FLAG_ALPHA)
michael@0:                {
michael@0:                   png_uint_32 r;
michael@0: 
michael@0:                   if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
michael@0:                      png_error(png_ptr, "rgb+alpha color-map: too few entries");
michael@0: 
michael@0:                   cmap_entries = make_rgb_colormap(display);
michael@0: 
michael@0:                   /* Add a transparent entry. */
michael@0:                   png_create_colormap_entry(display, cmap_entries, 255, 255,
michael@0:                      255, 0, P_sRGB);
michael@0: 
michael@0:                   /* This is stored as the background index for the processing
michael@0:                    * algorithm.
michael@0:                    */
michael@0:                   background_index = cmap_entries++;
michael@0: 
michael@0:                   /* Add 27 r,g,b entries each with alpha 0.5. */
michael@0:                   for (r=0; r<256; r = (r << 1) | 0x7f)
michael@0:                   {
michael@0:                      png_uint_32 g;
michael@0: 
michael@0:                      for (g=0; g<256; g = (g << 1) | 0x7f)
michael@0:                      {
michael@0:                         png_uint_32 b;
michael@0: 
michael@0:                         /* This generates components with the values 0, 127 and
michael@0:                          * 255
michael@0:                          */
michael@0:                         for (b=0; b<256; b = (b << 1) | 0x7f)
michael@0:                            png_create_colormap_entry(display, cmap_entries++,
michael@0:                               r, g, b, 128, P_sRGB);
michael@0:                      }
michael@0:                   }
michael@0: 
michael@0:                   expand_tRNS = 1;
michael@0:                   output_processing = PNG_CMAP_RGB_ALPHA;
michael@0:                }
michael@0: 
michael@0:                else
michael@0:                {
michael@0:                   /* Alpha/transparency must be removed.  The background must
michael@0:                    * exist in the color map (achieved by setting adding it after
michael@0:                    * the 666 color-map).  If the standard processing code will
michael@0:                    * pick up this entry automatically that's all that is
michael@0:                    * required; libpng can be called to do the background
michael@0:                    * processing.
michael@0:                    */
michael@0:                   unsigned int sample_size =
michael@0:                      PNG_IMAGE_SAMPLE_SIZE(output_format);
michael@0:                   png_uint_32 r, g, b; /* sRGB background */
michael@0: 
michael@0:                   if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
michael@0:                      png_error(png_ptr, "rgb-alpha color-map: too few entries");
michael@0: 
michael@0:                   cmap_entries = make_rgb_colormap(display);
michael@0: 
michael@0:                   png_create_colormap_entry(display, cmap_entries, back_r,
michael@0:                         back_g, back_b, 0/*unused*/, output_encoding);
michael@0: 
michael@0:                   if (output_encoding == P_LINEAR)
michael@0:                   {
michael@0:                      r = PNG_sRGB_FROM_LINEAR(back_r * 255);
michael@0:                      g = PNG_sRGB_FROM_LINEAR(back_g * 255);
michael@0:                      b = PNG_sRGB_FROM_LINEAR(back_b * 255);
michael@0:                   }
michael@0: 
michael@0:                   else
michael@0:                   {
michael@0:                      r = back_r;
michael@0:                      g = back_g;
michael@0:                      b = back_g;
michael@0:                   }
michael@0: 
michael@0:                   /* Compare the newly-created color-map entry with the one the
michael@0:                    * PNG_CMAP_RGB algorithm will use.  If the two entries don't
michael@0:                    * match, add the new one and set this as the background
michael@0:                    * index.
michael@0:                    */
michael@0:                   if (memcmp((png_const_bytep)display->colormap +
michael@0:                         sample_size * cmap_entries,
michael@0:                      (png_const_bytep)display->colormap +
michael@0:                         sample_size * PNG_RGB_INDEX(r,g,b),
michael@0:                      sample_size) != 0)
michael@0:                   {
michael@0:                      /* The background color must be added. */
michael@0:                      background_index = cmap_entries++;
michael@0: 
michael@0:                      /* Add 27 r,g,b entries each with created by composing with
michael@0:                       * the background at alpha 0.5.
michael@0:                       */
michael@0:                      for (r=0; r<256; r = (r << 1) | 0x7f)
michael@0:                      {
michael@0:                         for (g=0; g<256; g = (g << 1) | 0x7f)
michael@0:                         {
michael@0:                            /* This generates components with the values 0, 127
michael@0:                             * and 255
michael@0:                             */
michael@0:                            for (b=0; b<256; b = (b << 1) | 0x7f)
michael@0:                               png_create_colormap_entry(display, cmap_entries++,
michael@0:                                  png_colormap_compose(display, r, P_sRGB, 128,
michael@0:                                     back_r, output_encoding),
michael@0:                                  png_colormap_compose(display, g, P_sRGB, 128,
michael@0:                                     back_g, output_encoding),
michael@0:                                  png_colormap_compose(display, b, P_sRGB, 128,
michael@0:                                     back_b, output_encoding),
michael@0:                                  0/*unused*/, output_encoding);
michael@0:                         }
michael@0:                      }
michael@0: 
michael@0:                      expand_tRNS = 1;
michael@0:                      output_processing = PNG_CMAP_RGB_ALPHA;
michael@0:                   }
michael@0: 
michael@0:                   else /* background color is in the standard color-map */
michael@0:                   {
michael@0:                      png_color_16 c;
michael@0: 
michael@0:                      c.index = 0; /*unused*/
michael@0:                      c.red = (png_uint_16)back_r;
michael@0:                      c.gray = c.green = (png_uint_16)back_g;
michael@0:                      c.blue = (png_uint_16)back_b;
michael@0: 
michael@0:                      png_set_background_fixed(png_ptr, &c,
michael@0:                         PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
michael@0:                         0/*gamma: not used*/);
michael@0: 
michael@0:                      output_processing = PNG_CMAP_RGB;
michael@0:                   }
michael@0:                }
michael@0:             }
michael@0: 
michael@0:             else /* no alpha or transparency in the input */
michael@0:             {
michael@0:                /* Alpha in the output is irrelevant, simply map the opaque input
michael@0:                 * pixels to the 6x6x6 color-map.
michael@0:                 */
michael@0:                if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
michael@0:                   png_error(png_ptr, "rgb color-map: too few entries");
michael@0: 
michael@0:                cmap_entries = make_rgb_colormap(display);
michael@0:                output_processing = PNG_CMAP_RGB;
michael@0:             }
michael@0:          }
michael@0:          break;
michael@0: 
michael@0:       case PNG_COLOR_TYPE_PALETTE:
michael@0:          /* It's already got a color-map.  It may be necessary to eliminate the
michael@0:           * tRNS entries though.
michael@0:           */
michael@0:          {
michael@0:             unsigned int num_trans = png_ptr->num_trans;
michael@0:             png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
michael@0:             png_const_colorp colormap = png_ptr->palette;
michael@0:             const int do_background = trans != NULL &&
michael@0:                (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
michael@0:             unsigned int i;
michael@0: 
michael@0:             /* Just in case: */
michael@0:             if (trans == NULL)
michael@0:                num_trans = 0;
michael@0: 
michael@0:             output_processing = PNG_CMAP_NONE;
michael@0:             data_encoding = P_FILE; /* Don't change from color-map indicies */
michael@0:             cmap_entries = png_ptr->num_palette;
michael@0:             if (cmap_entries > 256)
michael@0:                cmap_entries = 256;
michael@0: 
michael@0:             if (cmap_entries > image->colormap_entries)
michael@0:                png_error(png_ptr, "palette color-map: too few entries");
michael@0: 
michael@0:             for (i=0; i < cmap_entries; ++i)
michael@0:             {
michael@0:                if (do_background && i < num_trans && trans[i] < 255)
michael@0:                {
michael@0:                   if (trans[i] == 0)
michael@0:                      png_create_colormap_entry(display, i, back_r, back_g,
michael@0:                         back_b, 0, output_encoding);
michael@0: 
michael@0:                   else
michael@0:                   {
michael@0:                      /* Must compose the PNG file color in the color-map entry
michael@0:                       * on the sRGB color in 'back'.
michael@0:                       */
michael@0:                      png_create_colormap_entry(display, i,
michael@0:                         png_colormap_compose(display, colormap[i].red, P_FILE,
michael@0:                            trans[i], back_r, output_encoding),
michael@0:                         png_colormap_compose(display, colormap[i].green, P_FILE,
michael@0:                            trans[i], back_g, output_encoding),
michael@0:                         png_colormap_compose(display, colormap[i].blue, P_FILE,
michael@0:                            trans[i], back_b, output_encoding),
michael@0:                         output_encoding == P_LINEAR ? trans[i] * 257U :
michael@0:                            trans[i],
michael@0:                         output_encoding);
michael@0:                   }
michael@0:                }
michael@0: 
michael@0:                else
michael@0:                   png_create_colormap_entry(display, i, colormap[i].red,
michael@0:                      colormap[i].green, colormap[i].blue,
michael@0:                      i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
michael@0:             }
michael@0: 
michael@0:             /* The PNG data may have indicies packed in fewer than 8 bits, it
michael@0:              * must be expanded if so.
michael@0:              */
michael@0:             if (png_ptr->bit_depth < 8)
michael@0:                png_set_packing(png_ptr);
michael@0:          }
michael@0:          break;
michael@0: 
michael@0:       default:
michael@0:          png_error(png_ptr, "invalid PNG color type");
michael@0:          /*NOT REACHED*/
michael@0:          break;
michael@0:    }
michael@0: 
michael@0:    /* Now deal with the output processing */
michael@0:    if (expand_tRNS && png_ptr->num_trans > 0 &&
michael@0:       (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
michael@0:       png_set_tRNS_to_alpha(png_ptr);
michael@0: 
michael@0:    switch (data_encoding)
michael@0:    {
michael@0:       default:
michael@0:          png_error(png_ptr, "bad data option (internal error)");
michael@0:          break;
michael@0: 
michael@0:       case P_sRGB:
michael@0:          /* Change to 8-bit sRGB */
michael@0:          png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
michael@0:          /* FALL THROUGH */
michael@0: 
michael@0:       case P_FILE:
michael@0:          if (png_ptr->bit_depth > 8)
michael@0:             png_set_scale_16(png_ptr);
michael@0:          break;
michael@0:    }
michael@0: 
michael@0:    if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
michael@0:       png_error(png_ptr, "color map overflow (BAD internal error)");
michael@0: 
michael@0:    image->colormap_entries = cmap_entries;
michael@0: 
michael@0:    /* Double check using the recorded background index */
michael@0:    switch (output_processing)
michael@0:    {
michael@0:       case PNG_CMAP_NONE:
michael@0:          if (background_index != PNG_CMAP_NONE_BACKGROUND)
michael@0:             goto bad_background;
michael@0:          break;
michael@0: 
michael@0:       case PNG_CMAP_GA:
michael@0:          if (background_index != PNG_CMAP_GA_BACKGROUND)
michael@0:             goto bad_background;
michael@0:          break;
michael@0: 
michael@0:       case PNG_CMAP_TRANS:
michael@0:          if (background_index >= cmap_entries ||
michael@0:             background_index != PNG_CMAP_TRANS_BACKGROUND)
michael@0:             goto bad_background;
michael@0:          break;
michael@0: 
michael@0:       case PNG_CMAP_RGB:
michael@0:          if (background_index != PNG_CMAP_RGB_BACKGROUND)
michael@0:             goto bad_background;
michael@0:          break;
michael@0: 
michael@0:       case PNG_CMAP_RGB_ALPHA:
michael@0:          if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
michael@0:             goto bad_background;
michael@0:          break;
michael@0: 
michael@0:       default:
michael@0:          png_error(png_ptr, "bad processing option (internal error)");
michael@0: 
michael@0:       bad_background:
michael@0:          png_error(png_ptr, "bad background index (internal error)");
michael@0:    }
michael@0: 
michael@0:    display->colormap_processing = output_processing;
michael@0: 
michael@0:    return 1/*ok*/;
michael@0: }
michael@0: 
michael@0: /* The final part of the color-map read called from png_image_finish_read. */
michael@0: static int
michael@0: png_image_read_and_map(png_voidp argument)
michael@0: {
michael@0:    png_image_read_control *display = png_voidcast(png_image_read_control*,
michael@0:       argument);
michael@0:    png_imagep image = display->image;
michael@0:    png_structrp png_ptr = image->opaque->png_ptr;
michael@0:    int passes;
michael@0: 
michael@0:    /* Called when the libpng data must be transformed into the color-mapped
michael@0:     * form.  There is a local row buffer in display->local and this routine must
michael@0:     * do the interlace handling.
michael@0:     */
michael@0:    switch (png_ptr->interlaced)
michael@0:    {
michael@0:       case PNG_INTERLACE_NONE:
michael@0:          passes = 1;
michael@0:          break;
michael@0: 
michael@0:       case PNG_INTERLACE_ADAM7:
michael@0:          passes = PNG_INTERLACE_ADAM7_PASSES;
michael@0:          break;
michael@0: 
michael@0:       default:
michael@0:          png_error(png_ptr, "unknown interlace type");
michael@0:    }
michael@0: 
michael@0:    {
michael@0:       png_uint_32  height = image->height;
michael@0:       png_uint_32  width = image->width;
michael@0:       int          proc = display->colormap_processing;
michael@0:       png_bytep    first_row = png_voidcast(png_bytep, display->first_row);
michael@0:       ptrdiff_t    step_row = display->row_bytes;
michael@0:       int pass;
michael@0: 
michael@0:       for (pass = 0; pass < passes; ++pass)
michael@0:       {
michael@0:          unsigned int     startx, stepx, stepy;
michael@0:          png_uint_32      y;
michael@0: 
michael@0:          if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
michael@0:          {
michael@0:             /* The row may be empty for a short image: */
michael@0:             if (PNG_PASS_COLS(width, pass) == 0)
michael@0:                continue;
michael@0: 
michael@0:             startx = PNG_PASS_START_COL(pass);
michael@0:             stepx = PNG_PASS_COL_OFFSET(pass);
michael@0:             y = PNG_PASS_START_ROW(pass);
michael@0:             stepy = PNG_PASS_ROW_OFFSET(pass);
michael@0:          }
michael@0: 
michael@0:          else
michael@0:          {
michael@0:             y = 0;
michael@0:             startx = 0;
michael@0:             stepx = stepy = 1;
michael@0:          }
michael@0: 
michael@0:          for (; y<height; y += stepy)
michael@0:          {
michael@0:             png_bytep inrow = png_voidcast(png_bytep, display->local_row);
michael@0:             png_bytep outrow = first_row + y * step_row;
michael@0:             png_const_bytep end_row = outrow + width;
michael@0: 
michael@0:             /* Read read the libpng data into the temporary buffer. */
michael@0:             png_read_row(png_ptr, inrow, NULL);
michael@0: 
michael@0:             /* Now process the row according to the processing option, note
michael@0:              * that the caller verifies that the format of the libpng output
michael@0:              * data is as required.
michael@0:              */
michael@0:             outrow += startx;
michael@0:             switch (proc)
michael@0:             {
michael@0:                case PNG_CMAP_GA:
michael@0:                   for (; outrow < end_row; outrow += stepx)
michael@0:                   {
michael@0:                      /* The data is always in the PNG order */
michael@0:                      unsigned int gray = *inrow++;
michael@0:                      unsigned int alpha = *inrow++;
michael@0:                      unsigned int entry;
michael@0: 
michael@0:                      /* NOTE: this code is copied as a comment in
michael@0:                       * make_ga_colormap above.  Please update the
michael@0:                       * comment if you change this code!
michael@0:                       */
michael@0:                      if (alpha > 229) /* opaque */
michael@0:                      {
michael@0:                         entry = (231 * gray + 128) >> 8;
michael@0:                      }
michael@0:                      else if (alpha < 26) /* transparent */
michael@0:                      {
michael@0:                         entry = 231;
michael@0:                      }
michael@0:                      else /* partially opaque */
michael@0:                      {
michael@0:                         entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
michael@0:                      }
michael@0: 
michael@0:                      *outrow = (png_byte)entry;
michael@0:                   }
michael@0:                   break;
michael@0: 
michael@0:                case PNG_CMAP_TRANS:
michael@0:                   for (; outrow < end_row; outrow += stepx)
michael@0:                   {
michael@0:                      png_byte gray = *inrow++;
michael@0:                      png_byte alpha = *inrow++;
michael@0: 
michael@0:                      if (alpha == 0)
michael@0:                         *outrow = PNG_CMAP_TRANS_BACKGROUND;
michael@0: 
michael@0:                      else if (gray != PNG_CMAP_TRANS_BACKGROUND)
michael@0:                         *outrow = gray;
michael@0: 
michael@0:                      else
michael@0:                         *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
michael@0:                   }
michael@0:                   break;
michael@0: 
michael@0:                case PNG_CMAP_RGB:
michael@0:                   for (; outrow < end_row; outrow += stepx)
michael@0:                   {
michael@0:                      *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
michael@0:                      inrow += 3;
michael@0:                   }
michael@0:                   break;
michael@0: 
michael@0:                case PNG_CMAP_RGB_ALPHA:
michael@0:                   for (; outrow < end_row; outrow += stepx)
michael@0:                   {
michael@0:                      unsigned int alpha = inrow[3];
michael@0: 
michael@0:                      /* Because the alpha entries only hold alpha==0.5 values
michael@0:                       * split the processing at alpha==0.25 (64) and 0.75
michael@0:                       * (196).
michael@0:                       */
michael@0: 
michael@0:                      if (alpha >= 196)
michael@0:                         *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
michael@0:                            inrow[2]);
michael@0: 
michael@0:                      else if (alpha < 64)
michael@0:                         *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
michael@0: 
michael@0:                      else
michael@0:                      {
michael@0:                         /* Likewise there are three entries for each of r, g
michael@0:                          * and b.  We could select the entry by popcount on
michael@0:                          * the top two bits on those architectures that
michael@0:                          * support it, this is what the code below does,
michael@0:                          * crudely.
michael@0:                          */
michael@0:                         unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
michael@0: 
michael@0:                         /* Here are how the values map:
michael@0:                          *
michael@0:                          * 0x00 .. 0x3f -> 0
michael@0:                          * 0x40 .. 0xbf -> 1
michael@0:                          * 0xc0 .. 0xff -> 2
michael@0:                          *
michael@0:                          * So, as above with the explicit alpha checks, the
michael@0:                          * breakpoints are at 64 and 196.
michael@0:                          */
michael@0:                         if (inrow[0] & 0x80) back_i += 9; /* red */
michael@0:                         if (inrow[0] & 0x40) back_i += 9;
michael@0:                         if (inrow[0] & 0x80) back_i += 3; /* green */
michael@0:                         if (inrow[0] & 0x40) back_i += 3;
michael@0:                         if (inrow[0] & 0x80) back_i += 1; /* blue */
michael@0:                         if (inrow[0] & 0x40) back_i += 1;
michael@0: 
michael@0:                         *outrow = (png_byte)back_i;
michael@0:                      }
michael@0: 
michael@0:                      inrow += 4;
michael@0:                   }
michael@0:                   break;
michael@0: 
michael@0:                default:
michael@0:                   break;
michael@0:             }
michael@0:          }
michael@0:       }
michael@0:    }
michael@0: 
michael@0:    return 1;
michael@0: }
michael@0: 
michael@0: static int
michael@0: png_image_read_colormapped(png_voidp argument)
michael@0: {
michael@0:    png_image_read_control *display = png_voidcast(png_image_read_control*,
michael@0:       argument);
michael@0:    png_imagep image = display->image;
michael@0:    png_controlp control = image->opaque;
michael@0:    png_structrp png_ptr = control->png_ptr;
michael@0:    png_inforp info_ptr = control->info_ptr;
michael@0: 
michael@0:    int passes = 0; /* As a flag */
michael@0: 
michael@0:    PNG_SKIP_CHUNKS(png_ptr);
michael@0: 
michael@0:    /* Update the 'info' structure and make sure the result is as required; first
michael@0:     * make sure to turn on the interlace handling if it will be required
michael@0:     * (because it can't be turned on *after* the call to png_read_update_info!)
michael@0:     */
michael@0:    if (display->colormap_processing == PNG_CMAP_NONE)
michael@0:       passes = png_set_interlace_handling(png_ptr);
michael@0: 
michael@0:    png_read_update_info(png_ptr, info_ptr);
michael@0: 
michael@0:    /* The expected output can be deduced from the colormap_processing option. */
michael@0:    switch (display->colormap_processing)
michael@0:    {
michael@0:       case PNG_CMAP_NONE:
michael@0:          /* Output must be one channel and one byte per pixel, the output
michael@0:           * encoding can be anything.
michael@0:           */
michael@0:          if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
michael@0:             info_ptr->color_type == PNG_COLOR_TYPE_GRAY) &&
michael@0:             info_ptr->bit_depth == 8)
michael@0:             break;
michael@0: 
michael@0:          goto bad_output;
michael@0: 
michael@0:       case PNG_CMAP_TRANS:
michael@0:       case PNG_CMAP_GA:
michael@0:          /* Output must be two channels and the 'G' one must be sRGB, the latter
michael@0:           * can be checked with an exact number because it should have been set
michael@0:           * to this number above!
michael@0:           */
michael@0:          if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
michael@0:             info_ptr->bit_depth == 8 &&
michael@0:             png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
michael@0:             image->colormap_entries == 256)
michael@0:             break;
michael@0: 
michael@0:          goto bad_output;
michael@0: 
michael@0:       case PNG_CMAP_RGB:
michael@0:          /* Output must be 8-bit sRGB encoded RGB */
michael@0:          if (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
michael@0:             info_ptr->bit_depth == 8 &&
michael@0:             png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
michael@0:             image->colormap_entries == 216)
michael@0:             break;
michael@0: 
michael@0:          goto bad_output;
michael@0: 
michael@0:       case PNG_CMAP_RGB_ALPHA:
michael@0:          /* Output must be 8-bit sRGB encoded RGBA */
michael@0:          if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
michael@0:             info_ptr->bit_depth == 8 &&
michael@0:             png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
michael@0:             image->colormap_entries == 244 /* 216 + 1 + 27 */)
michael@0:             break;
michael@0: 
michael@0:          /* goto bad_output; */
michael@0:          /* FALL THROUGH */
michael@0: 
michael@0:       default:
michael@0:       bad_output:
michael@0:          png_error(png_ptr, "bad color-map processing (internal error)");
michael@0:    }
michael@0: 
michael@0:    /* Now read the rows.  Do this here if it is possible to read directly into
michael@0:     * the output buffer, otherwise allocate a local row buffer of the maximum
michael@0:     * size libpng requires and call the relevant processing routine safely.
michael@0:     */
michael@0:    {
michael@0:       png_voidp first_row = display->buffer;
michael@0:       ptrdiff_t row_bytes = display->row_stride;
michael@0: 
michael@0:       /* The following expression is designed to work correctly whether it gives
michael@0:        * a signed or an unsigned result.
michael@0:        */
michael@0:       if (row_bytes < 0)
michael@0:       {
michael@0:          char *ptr = png_voidcast(char*, first_row);
michael@0:          ptr += (image->height-1) * (-row_bytes);
michael@0:          first_row = png_voidcast(png_voidp, ptr);
michael@0:       }
michael@0: 
michael@0:       display->first_row = first_row;
michael@0:       display->row_bytes = row_bytes;
michael@0:    }
michael@0: 
michael@0:    if (passes == 0)
michael@0:    {
michael@0:       int result;
michael@0:       png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
michael@0: 
michael@0:       display->local_row = row;
michael@0:       result = png_safe_execute(image, png_image_read_and_map, display);
michael@0:       display->local_row = NULL;
michael@0:       png_free(png_ptr, row);
michael@0: 
michael@0:       return result;
michael@0:    }
michael@0: 
michael@0:    else
michael@0:    {
michael@0:       png_alloc_size_t row_bytes = display->row_bytes;
michael@0: 
michael@0:       while (--passes >= 0)
michael@0:       {
michael@0:          png_uint_32      y = image->height;
michael@0:          png_bytep        row = png_voidcast(png_bytep, display->first_row);
michael@0: 
michael@0:          while (y-- > 0)
michael@0:          {
michael@0:             png_read_row(png_ptr, row, NULL);
michael@0:             row += row_bytes;
michael@0:          }
michael@0:       }
michael@0: 
michael@0:       return 1;
michael@0:    }
michael@0: }
michael@0: 
michael@0: /* Just the row reading part of png_image_read. */
michael@0: static int
michael@0: png_image_read_composite(png_voidp argument)
michael@0: {
michael@0:    png_image_read_control *display = png_voidcast(png_image_read_control*,
michael@0:       argument);
michael@0:    png_imagep image = display->image;
michael@0:    png_structrp png_ptr = image->opaque->png_ptr;
michael@0:    int passes;
michael@0: 
michael@0:    switch (png_ptr->interlaced)
michael@0:    {
michael@0:       case PNG_INTERLACE_NONE:
michael@0:          passes = 1;
michael@0:          break;
michael@0: 
michael@0:       case PNG_INTERLACE_ADAM7:
michael@0:          passes = PNG_INTERLACE_ADAM7_PASSES;
michael@0:          break;
michael@0: 
michael@0:       default:
michael@0:          png_error(png_ptr, "unknown interlace type");
michael@0:    }
michael@0: 
michael@0:    {
michael@0:       png_uint_32  height = image->height;
michael@0:       png_uint_32  width = image->width;
michael@0:       ptrdiff_t    step_row = display->row_bytes;
michael@0:       unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1;
michael@0:       int pass;
michael@0: 
michael@0:       for (pass = 0; pass < passes; ++pass)
michael@0:       {
michael@0:          unsigned int     startx, stepx, stepy;
michael@0:          png_uint_32      y;
michael@0: 
michael@0:          if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
michael@0:          {
michael@0:             /* The row may be empty for a short image: */
michael@0:             if (PNG_PASS_COLS(width, pass) == 0)
michael@0:                continue;
michael@0: 
michael@0:             startx = PNG_PASS_START_COL(pass) * channels;
michael@0:             stepx = PNG_PASS_COL_OFFSET(pass) * channels;
michael@0:             y = PNG_PASS_START_ROW(pass);
michael@0:             stepy = PNG_PASS_ROW_OFFSET(pass);
michael@0:          }
michael@0: 
michael@0:          else
michael@0:          {
michael@0:             y = 0;
michael@0:             startx = 0;
michael@0:             stepx = channels;
michael@0:             stepy = 1;
michael@0:          }
michael@0: 
michael@0:          for (; y<height; y += stepy)
michael@0:          {
michael@0:             png_bytep inrow = png_voidcast(png_bytep, display->local_row);
michael@0:             png_bytep outrow;
michael@0:             png_const_bytep end_row;
michael@0: 
michael@0:             /* Read the row, which is packed: */
michael@0:             png_read_row(png_ptr, inrow, NULL);
michael@0: 
michael@0:             outrow = png_voidcast(png_bytep, display->first_row);
michael@0:             outrow += y * step_row;
michael@0:             end_row = outrow + width * channels;
michael@0: 
michael@0:             /* Now do the composition on each pixel in this row. */
michael@0:             outrow += startx;
michael@0:             for (; outrow < end_row; outrow += stepx)
michael@0:             {
michael@0:                png_byte alpha = inrow[channels];
michael@0: 
michael@0:                if (alpha > 0) /* else no change to the output */
michael@0:                {
michael@0:                   unsigned int c;
michael@0: 
michael@0:                   for (c=0; c<channels; ++c)
michael@0:                   {
michael@0:                      png_uint_32 component = inrow[c];
michael@0: 
michael@0:                      if (alpha < 255) /* else just use component */
michael@0:                      {
michael@0:                         /* This is PNG_OPTIMIZED_ALPHA, the component value
michael@0:                          * is a linear 8-bit value.  Combine this with the
michael@0:                          * current outrow[c] value which is sRGB encoded.
michael@0:                          * Arithmetic here is 16-bits to preserve the output
michael@0:                          * values correctly.
michael@0:                          */
michael@0:                         component *= 257*255; /* =65535 */
michael@0:                         component += (255-alpha)*png_sRGB_table[outrow[c]];
michael@0: 
michael@0:                         /* So 'component' is scaled by 255*65535 and is
michael@0:                          * therefore appropriate for the sRGB to linear
michael@0:                          * conversion table.
michael@0:                          */
michael@0:                         component = PNG_sRGB_FROM_LINEAR(component);
michael@0:                      }
michael@0: 
michael@0:                      outrow[c] = (png_byte)component;
michael@0:                   }
michael@0:                }
michael@0: 
michael@0:                inrow += channels+1; /* components and alpha channel */
michael@0:             }
michael@0:          }
michael@0:       }
michael@0:    }
michael@0: 
michael@0:    return 1;
michael@0: }
michael@0: 
michael@0: /* The do_local_background case; called when all the following transforms are to
michael@0:  * be done:
michael@0:  *
michael@0:  * PNG_RGB_TO_GRAY
michael@0:  * PNG_COMPOSITE
michael@0:  * PNG_GAMMA
michael@0:  *
michael@0:  * This is a work-round for the fact that both the PNG_RGB_TO_GRAY and
michael@0:  * PNG_COMPOSITE code performs gamma correction, so we get double gamma
michael@0:  * correction.  The fix-up is to prevent the PNG_COMPOSITE operation happening
michael@0:  * inside libpng, so this routine sees an 8 or 16-bit gray+alpha row and handles
michael@0:  * the removal or pre-multiplication of the alpha channel.
michael@0:  */
michael@0: static int
michael@0: png_image_read_background(png_voidp argument)
michael@0: {
michael@0:    png_image_read_control *display = png_voidcast(png_image_read_control*,
michael@0:       argument);
michael@0:    png_imagep image = display->image;
michael@0:    png_structrp png_ptr = image->opaque->png_ptr;
michael@0:    png_inforp info_ptr = image->opaque->info_ptr;
michael@0:    png_uint_32 height = image->height;
michael@0:    png_uint_32 width = image->width;
michael@0:    int pass, passes;
michael@0: 
michael@0:    /* Double check the convoluted logic below.  We expect to get here with
michael@0:     * libpng doing rgb to gray and gamma correction but background processing
michael@0:     * left to the png_image_read_background function.  The rows libpng produce
michael@0:     * might be 8 or 16-bit but should always have two channels; gray plus alpha.
michael@0:     */
michael@0:    if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
michael@0:       png_error(png_ptr, "lost rgb to gray");
michael@0: 
michael@0:    if ((png_ptr->transformations & PNG_COMPOSE) != 0)
michael@0:       png_error(png_ptr, "unexpected compose");
michael@0: 
michael@0:    if (png_get_channels(png_ptr, info_ptr) != 2)
michael@0:       png_error(png_ptr, "lost/gained channels");
michael@0: 
michael@0:    /* Expect the 8-bit case to always remove the alpha channel */
michael@0:    if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
michael@0:       (image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
michael@0:       png_error(png_ptr, "unexpected 8-bit transformation");
michael@0: 
michael@0:    switch (png_ptr->interlaced)
michael@0:    {
michael@0:       case PNG_INTERLACE_NONE:
michael@0:          passes = 1;
michael@0:          break;
michael@0: 
michael@0:       case PNG_INTERLACE_ADAM7:
michael@0:          passes = PNG_INTERLACE_ADAM7_PASSES;
michael@0:          break;
michael@0: 
michael@0:       default:
michael@0:          png_error(png_ptr, "unknown interlace type");
michael@0:    }
michael@0: 
michael@0:    /* Use direct access to info_ptr here because otherwise the simplified API
michael@0:     * would require PNG_EASY_ACCESS_SUPPORTED (just for this.)  Note this is
michael@0:     * checking the value after libpng expansions, not the original value in the
michael@0:     * PNG.
michael@0:     */
michael@0:    switch (info_ptr->bit_depth)
michael@0:    {
michael@0:       default:
michael@0:          png_error(png_ptr, "unexpected bit depth");
michael@0:          break;
michael@0: 
michael@0:       case 8:
michael@0:          /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
michael@0:           * to be removed by composing on a background: either the row if
michael@0:           * display->background is NULL or display->background->green if not.
michael@0:           * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
michael@0:           */
michael@0:          {
michael@0:             png_bytep first_row = png_voidcast(png_bytep, display->first_row);
michael@0:             ptrdiff_t step_row = display->row_bytes;
michael@0: 
michael@0:             for (pass = 0; pass < passes; ++pass)
michael@0:             {
michael@0:                png_bytep        row = png_voidcast(png_bytep,
michael@0:                                                    display->first_row);
michael@0:                unsigned int     startx, stepx, stepy;
michael@0:                png_uint_32      y;
michael@0: 
michael@0:                if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
michael@0:                {
michael@0:                   /* The row may be empty for a short image: */
michael@0:                   if (PNG_PASS_COLS(width, pass) == 0)
michael@0:                      continue;
michael@0: 
michael@0:                   startx = PNG_PASS_START_COL(pass);
michael@0:                   stepx = PNG_PASS_COL_OFFSET(pass);
michael@0:                   y = PNG_PASS_START_ROW(pass);
michael@0:                   stepy = PNG_PASS_ROW_OFFSET(pass);
michael@0:                }
michael@0: 
michael@0:                else
michael@0:                {
michael@0:                   y = 0;
michael@0:                   startx = 0;
michael@0:                   stepx = stepy = 1;
michael@0:                }
michael@0: 
michael@0:                if (display->background == NULL)
michael@0:                {
michael@0:                   for (; y<height; y += stepy)
michael@0:                   {
michael@0:                      png_bytep inrow = png_voidcast(png_bytep,
michael@0:                         display->local_row);
michael@0:                      png_bytep outrow = first_row + y * step_row;
michael@0:                      png_const_bytep end_row = outrow + width;
michael@0: 
michael@0:                      /* Read the row, which is packed: */
michael@0:                      png_read_row(png_ptr, inrow, NULL);
michael@0: 
michael@0:                      /* Now do the composition on each pixel in this row. */
michael@0:                      outrow += startx;
michael@0:                      for (; outrow < end_row; outrow += stepx)
michael@0:                      {
michael@0:                         png_byte alpha = inrow[1];
michael@0: 
michael@0:                         if (alpha > 0) /* else no change to the output */
michael@0:                         {
michael@0:                            png_uint_32 component = inrow[0];
michael@0: 
michael@0:                            if (alpha < 255) /* else just use component */
michael@0:                            {
michael@0:                               /* Since PNG_OPTIMIZED_ALPHA was not set it is
michael@0:                                * necessary to invert the sRGB transfer
michael@0:                                * function and multiply the alpha out.
michael@0:                                */
michael@0:                               component = png_sRGB_table[component] * alpha;
michael@0:                               component += png_sRGB_table[outrow[0]] *
michael@0:                                  (255-alpha);
michael@0:                               component = PNG_sRGB_FROM_LINEAR(component);
michael@0:                            }
michael@0: 
michael@0:                            outrow[0] = (png_byte)component;
michael@0:                         }
michael@0: 
michael@0:                         inrow += 2; /* gray and alpha channel */
michael@0:                      }
michael@0:                   }
michael@0:                }
michael@0: 
michael@0:                else /* constant background value */
michael@0:                {
michael@0:                   png_byte background8 = display->background->green;
michael@0:                   png_uint_16 background = png_sRGB_table[background8];
michael@0: 
michael@0:                   for (; y<height; y += stepy)
michael@0:                   {
michael@0:                      png_bytep inrow = png_voidcast(png_bytep,
michael@0:                         display->local_row);
michael@0:                      png_bytep outrow = first_row + y * step_row;
michael@0:                      png_const_bytep end_row = outrow + width;
michael@0: 
michael@0:                      /* Read the row, which is packed: */
michael@0:                      png_read_row(png_ptr, inrow, NULL);
michael@0: 
michael@0:                      /* Now do the composition on each pixel in this row. */
michael@0:                      outrow += startx;
michael@0:                      for (; outrow < end_row; outrow += stepx)
michael@0:                      {
michael@0:                         png_byte alpha = inrow[1];
michael@0: 
michael@0:                         if (alpha > 0) /* else use background */
michael@0:                         {
michael@0:                            png_uint_32 component = inrow[0];
michael@0: 
michael@0:                            if (alpha < 255) /* else just use component */
michael@0:                            {
michael@0:                               component = png_sRGB_table[component] * alpha;
michael@0:                               component += background * (255-alpha);
michael@0:                               component = PNG_sRGB_FROM_LINEAR(component);
michael@0:                            }
michael@0: 
michael@0:                            outrow[0] = (png_byte)component;
michael@0:                         }
michael@0: 
michael@0:                         else
michael@0:                            outrow[0] = background8;
michael@0: 
michael@0:                         inrow += 2; /* gray and alpha channel */
michael@0:                      }
michael@0: 
michael@0:                      row += display->row_bytes;
michael@0:                   }
michael@0:                }
michael@0:             }
michael@0:          }
michael@0:          break;
michael@0: 
michael@0:       case 16:
michael@0:          /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must
michael@0:           * still be done and, maybe, the alpha channel removed.  This code also
michael@0:           * handles the alpha-first option.
michael@0:           */
michael@0:          {
michael@0:             png_uint_16p first_row = png_voidcast(png_uint_16p,
michael@0:                display->first_row);
michael@0:             /* The division by two is safe because the caller passed in a
michael@0:              * stride which was multiplied by 2 (below) to get row_bytes.
michael@0:              */
michael@0:             ptrdiff_t    step_row = display->row_bytes / 2;
michael@0:             int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
michael@0:             unsigned int outchannels = 1+preserve_alpha;
michael@0:             int swap_alpha = 0;
michael@0: 
michael@0: #           ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
michael@0:                if (preserve_alpha && (image->format & PNG_FORMAT_FLAG_AFIRST))
michael@0:                   swap_alpha = 1;
michael@0: #           endif
michael@0: 
michael@0:             for (pass = 0; pass < passes; ++pass)
michael@0:             {
michael@0:                unsigned int     startx, stepx, stepy;
michael@0:                png_uint_32      y;
michael@0: 
michael@0:                /* The 'x' start and step are adjusted to output components here.
michael@0:                 */
michael@0:                if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
michael@0:                {
michael@0:                   /* The row may be empty for a short image: */
michael@0:                   if (PNG_PASS_COLS(width, pass) == 0)
michael@0:                      continue;
michael@0: 
michael@0:                   startx = PNG_PASS_START_COL(pass) * outchannels;
michael@0:                   stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
michael@0:                   y = PNG_PASS_START_ROW(pass);
michael@0:                   stepy = PNG_PASS_ROW_OFFSET(pass);
michael@0:                }
michael@0: 
michael@0:                else
michael@0:                {
michael@0:                   y = 0;
michael@0:                   startx = 0;
michael@0:                   stepx = outchannels;
michael@0:                   stepy = 1;
michael@0:                }
michael@0: 
michael@0:                for (; y<height; y += stepy)
michael@0:                {
michael@0:                   png_const_uint_16p inrow;
michael@0:                   png_uint_16p outrow = first_row + y*step_row;
michael@0:                   png_uint_16p end_row = outrow + width * outchannels;
michael@0: 
michael@0:                   /* Read the row, which is packed: */
michael@0:                   png_read_row(png_ptr, png_voidcast(png_bytep,
michael@0:                      display->local_row), NULL);
michael@0:                   inrow = png_voidcast(png_const_uint_16p, display->local_row);
michael@0: 
michael@0:                   /* Now do the pre-multiplication on each pixel in this row.
michael@0:                    */
michael@0:                   outrow += startx;
michael@0:                   for (; outrow < end_row; outrow += stepx)
michael@0:                   {
michael@0:                      png_uint_32 component = inrow[0];
michael@0:                      png_uint_16 alpha = inrow[1];
michael@0: 
michael@0:                      if (alpha > 0) /* else 0 */
michael@0:                      {
michael@0:                         if (alpha < 65535) /* else just use component */
michael@0:                         {
michael@0:                            component *= alpha;
michael@0:                            component += 32767;
michael@0:                            component /= 65535;
michael@0:                         }
michael@0:                      }
michael@0: 
michael@0:                      else
michael@0:                         component = 0;
michael@0: 
michael@0:                      outrow[swap_alpha] = (png_uint_16)component;
michael@0:                      if (preserve_alpha)
michael@0:                         outrow[1 ^ swap_alpha] = alpha;
michael@0: 
michael@0:                      inrow += 2; /* components and alpha channel */
michael@0:                   }
michael@0:                }
michael@0:             }
michael@0:          }
michael@0:          break;
michael@0:    }
michael@0: 
michael@0:    return 1;
michael@0: }
michael@0: 
michael@0: /* The guts of png_image_finish_read as a png_safe_execute callback. */
michael@0: static int
michael@0: png_image_read_direct(png_voidp argument)
michael@0: {
michael@0:    png_image_read_control *display = png_voidcast(png_image_read_control*,
michael@0:       argument);
michael@0:    png_imagep image = display->image;
michael@0:    png_structrp png_ptr = image->opaque->png_ptr;
michael@0:    png_inforp info_ptr = image->opaque->info_ptr;
michael@0: 
michael@0:    png_uint_32 format = image->format;
michael@0:    int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
michael@0:    int do_local_compose = 0;
michael@0:    int do_local_background = 0; /* to avoid double gamma correction bug */
michael@0:    int passes = 0;
michael@0: 
michael@0:    /* Add transforms to ensure the correct output format is produced then check
michael@0:     * that the required implementation support is there.  Always expand; always
michael@0:     * need 8 bits minimum, no palette and expanded tRNS.
michael@0:     */
michael@0:    png_set_expand(png_ptr);
michael@0: 
michael@0:    /* Now check the format to see if it was modified. */
michael@0:    {
michael@0:       png_uint_32 base_format = png_image_format(png_ptr) &
michael@0:          ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */;
michael@0:       png_uint_32 change = format ^ base_format;
michael@0:       png_fixed_point output_gamma;
michael@0:       int mode; /* alpha mode */
michael@0: 
michael@0:       /* Do this first so that we have a record if rgb to gray is happening. */
michael@0:       if (change & PNG_FORMAT_FLAG_COLOR)
michael@0:       {
michael@0:          /* gray<->color transformation required. */
michael@0:          if (format & PNG_FORMAT_FLAG_COLOR)
michael@0:             png_set_gray_to_rgb(png_ptr);
michael@0: 
michael@0:          else
michael@0:          {
michael@0:             /* libpng can't do both rgb to gray and
michael@0:              * background/pre-multiplication if there is also significant gamma
michael@0:              * correction, because both operations require linear colors and
michael@0:              * the code only supports one transform doing the gamma correction.
michael@0:              * Handle this by doing the pre-multiplication or background
michael@0:              * operation in this code, if necessary.
michael@0:              *
michael@0:              * TODO: fix this by rewriting pngrtran.c (!)
michael@0:              *
michael@0:              * For the moment (given that fixing this in pngrtran.c is an
michael@0:              * enormous change) 'do_local_background' is used to indicate that
michael@0:              * the problem exists.
michael@0:              */
michael@0:             if (base_format & PNG_FORMAT_FLAG_ALPHA)
michael@0:                do_local_background = 1/*maybe*/;
michael@0: 
michael@0:             png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
michael@0:                PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
michael@0:          }
michael@0: 
michael@0:          change &= ~PNG_FORMAT_FLAG_COLOR;
michael@0:       }
michael@0: 
michael@0:       /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
michael@0:        */
michael@0:       {
michael@0:          png_fixed_point input_gamma_default;
michael@0: 
michael@0:          if ((base_format & PNG_FORMAT_FLAG_LINEAR) &&
michael@0:             (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
michael@0:             input_gamma_default = PNG_GAMMA_LINEAR;
michael@0:          else
michael@0:             input_gamma_default = PNG_DEFAULT_sRGB;
michael@0: 
michael@0:          /* Call png_set_alpha_mode to set the default for the input gamma; the
michael@0:           * output gamma is set by a second call below.
michael@0:           */
michael@0:          png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
michael@0:       }
michael@0: 
michael@0:       if (linear)
michael@0:       {
michael@0:          /* If there *is* an alpha channel in the input it must be multiplied
michael@0:           * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
michael@0:           */
michael@0:          if (base_format & PNG_FORMAT_FLAG_ALPHA)
michael@0:             mode = PNG_ALPHA_STANDARD; /* associated alpha */
michael@0: 
michael@0:          else
michael@0:             mode = PNG_ALPHA_PNG;
michael@0: 
michael@0:          output_gamma = PNG_GAMMA_LINEAR;
michael@0:       }
michael@0: 
michael@0:       else
michael@0:       {
michael@0:          mode = PNG_ALPHA_PNG;
michael@0:          output_gamma = PNG_DEFAULT_sRGB;
michael@0:       }
michael@0: 
michael@0:       /* If 'do_local_background' is set check for the presence of gamma
michael@0:        * correction; this is part of the work-round for the libpng bug
michael@0:        * described above.
michael@0:        *
michael@0:        * TODO: fix libpng and remove this.
michael@0:        */
michael@0:       if (do_local_background)
michael@0:       {
michael@0:          png_fixed_point gtest;
michael@0: 
michael@0:          /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
michael@0:           * gamma correction, the screen gamma hasn't been set on png_struct
michael@0:           * yet; it's set below.  png_struct::gamma, however, is set to the
michael@0:           * final value.
michael@0:           */
michael@0:          if (png_muldiv(&gtest, output_gamma, png_ptr->colorspace.gamma,
michael@0:                PNG_FP_1) && !png_gamma_significant(gtest))
michael@0:             do_local_background = 0;
michael@0: 
michael@0:          else if (mode == PNG_ALPHA_STANDARD)
michael@0:          {
michael@0:             do_local_background = 2/*required*/;
michael@0:             mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
michael@0:          }
michael@0: 
michael@0:          /* else leave as 1 for the checks below */
michael@0:       }
michael@0: 
michael@0:       /* If the bit-depth changes then handle that here. */
michael@0:       if (change & PNG_FORMAT_FLAG_LINEAR)
michael@0:       {
michael@0:          if (linear /*16-bit output*/)
michael@0:             png_set_expand_16(png_ptr);
michael@0: 
michael@0:          else /* 8-bit output */
michael@0:             png_set_scale_16(png_ptr);
michael@0: 
michael@0:          change &= ~PNG_FORMAT_FLAG_LINEAR;
michael@0:       }
michael@0: 
michael@0:       /* Now the background/alpha channel changes. */
michael@0:       if (change & PNG_FORMAT_FLAG_ALPHA)
michael@0:       {
michael@0:          /* Removing an alpha channel requires composition for the 8-bit
michael@0:           * formats; for the 16-bit it is already done, above, by the
michael@0:           * pre-multiplication and the channel just needs to be stripped.
michael@0:           */
michael@0:          if (base_format & PNG_FORMAT_FLAG_ALPHA)
michael@0:          {
michael@0:             /* If RGB->gray is happening the alpha channel must be left and the
michael@0:              * operation completed locally.
michael@0:              *
michael@0:              * TODO: fix libpng and remove this.
michael@0:              */
michael@0:             if (do_local_background)
michael@0:                do_local_background = 2/*required*/;
michael@0: 
michael@0:             /* 16-bit output: just remove the channel */
michael@0:             else if (linear) /* compose on black (well, pre-multiply) */
michael@0:                png_set_strip_alpha(png_ptr);
michael@0: 
michael@0:             /* 8-bit output: do an appropriate compose */
michael@0:             else if (display->background != NULL)
michael@0:             {
michael@0:                png_color_16 c;
michael@0: 
michael@0:                c.index = 0; /*unused*/
michael@0:                c.red = display->background->red;
michael@0:                c.green = display->background->green;
michael@0:                c.blue = display->background->blue;
michael@0:                c.gray = display->background->green;
michael@0: 
michael@0:                /* This is always an 8-bit sRGB value, using the 'green' channel
michael@0:                 * for gray is much better than calculating the luminance here;
michael@0:                 * we can get off-by-one errors in that calculation relative to
michael@0:                 * the app expectations and that will show up in transparent
michael@0:                 * pixels.
michael@0:                 */
michael@0:                png_set_background_fixed(png_ptr, &c,
michael@0:                   PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
michael@0:                   0/*gamma: not used*/);
michael@0:             }
michael@0: 
michael@0:             else /* compose on row: implemented below. */
michael@0:             {
michael@0:                do_local_compose = 1;
michael@0:                /* This leaves the alpha channel in the output, so it has to be
michael@0:                 * removed by the code below.  Set the encoding to the 'OPTIMIZE'
michael@0:                 * one so the code only has to hack on the pixels that require
michael@0:                 * composition.
michael@0:                 */
michael@0:                mode = PNG_ALPHA_OPTIMIZED;
michael@0:             }
michael@0:          }
michael@0: 
michael@0:          else /* output needs an alpha channel */
michael@0:          {
michael@0:             /* This is tricky because it happens before the swap operation has
michael@0:              * been accomplished; however, the swap does *not* swap the added
michael@0:              * alpha channel (weird API), so it must be added in the correct
michael@0:              * place.
michael@0:              */
michael@0:             png_uint_32 filler; /* opaque filler */
michael@0:             int where;
michael@0: 
michael@0:             if (linear)
michael@0:                filler = 65535;
michael@0: 
michael@0:             else
michael@0:                filler = 255;
michael@0: 
michael@0: #           ifdef PNG_FORMAT_AFIRST_SUPPORTED
michael@0:                if (format & PNG_FORMAT_FLAG_AFIRST)
michael@0:                {
michael@0:                   where = PNG_FILLER_BEFORE;
michael@0:                   change &= ~PNG_FORMAT_FLAG_AFIRST;
michael@0:                }
michael@0: 
michael@0:                else
michael@0: #           endif
michael@0:                where = PNG_FILLER_AFTER;
michael@0: 
michael@0:             png_set_add_alpha(png_ptr, filler, where);
michael@0:          }
michael@0: 
michael@0:          /* This stops the (irrelevant) call to swap_alpha below. */
michael@0:          change &= ~PNG_FORMAT_FLAG_ALPHA;
michael@0:       }
michael@0: 
michael@0:       /* Now set the alpha mode correctly; this is always done, even if there is
michael@0:        * no alpha channel in either the input or the output because it correctly
michael@0:        * sets the output gamma.
michael@0:        */
michael@0:       png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
michael@0: 
michael@0: #     ifdef PNG_FORMAT_BGR_SUPPORTED
michael@0:          if (change & PNG_FORMAT_FLAG_BGR)
michael@0:          {
michael@0:             /* Check only the output format; PNG is never BGR; don't do this if
michael@0:              * the output is gray, but fix up the 'format' value in that case.
michael@0:              */
michael@0:             if (format & PNG_FORMAT_FLAG_COLOR)
michael@0:                png_set_bgr(png_ptr);
michael@0: 
michael@0:             else
michael@0:                format &= ~PNG_FORMAT_FLAG_BGR;
michael@0: 
michael@0:             change &= ~PNG_FORMAT_FLAG_BGR;
michael@0:          }
michael@0: #     endif
michael@0: 
michael@0: #     ifdef PNG_FORMAT_AFIRST_SUPPORTED
michael@0:          if (change & PNG_FORMAT_FLAG_AFIRST)
michael@0:          {
michael@0:             /* Only relevant if there is an alpha channel - it's particularly
michael@0:              * important to handle this correctly because do_local_compose may
michael@0:              * be set above and then libpng will keep the alpha channel for this
michael@0:              * code to remove.
michael@0:              */
michael@0:             if (format & PNG_FORMAT_FLAG_ALPHA)
michael@0:             {
michael@0:                /* Disable this if doing a local background,
michael@0:                 * TODO: remove this when local background is no longer required.
michael@0:                 */
michael@0:                if (do_local_background != 2)
michael@0:                   png_set_swap_alpha(png_ptr);
michael@0:             }
michael@0: 
michael@0:             else
michael@0:                format &= ~PNG_FORMAT_FLAG_AFIRST;
michael@0: 
michael@0:             change &= ~PNG_FORMAT_FLAG_AFIRST;
michael@0:          }
michael@0: #     endif
michael@0: 
michael@0:       /* If the *output* is 16-bit then we need to check for a byte-swap on this
michael@0:        * architecture.
michael@0:        */
michael@0:       if (linear)
michael@0:       {
michael@0:          PNG_CONST png_uint_16 le = 0x0001;
michael@0: 
michael@0:          if (*(png_const_bytep)&le)
michael@0:             png_set_swap(png_ptr);
michael@0:       }
michael@0: 
michael@0:       /* If change is not now 0 some transformation is missing - error out. */
michael@0:       if (change)
michael@0:          png_error(png_ptr, "png_read_image: unsupported transformation");
michael@0:    }
michael@0: 
michael@0:    PNG_SKIP_CHUNKS(png_ptr);
michael@0: 
michael@0:    /* Update the 'info' structure and make sure the result is as required; first
michael@0:     * make sure to turn on the interlace handling if it will be required
michael@0:     * (because it can't be turned on *after* the call to png_read_update_info!)
michael@0:     *
michael@0:     * TODO: remove the do_local_background fixup below.
michael@0:     */
michael@0:    if (!do_local_compose && do_local_background != 2)
michael@0:       passes = png_set_interlace_handling(png_ptr);
michael@0: 
michael@0:    png_read_update_info(png_ptr, info_ptr);
michael@0: 
michael@0:    {
michael@0:       png_uint_32 info_format = 0;
michael@0: 
michael@0:       if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
michael@0:          info_format |= PNG_FORMAT_FLAG_COLOR;
michael@0: 
michael@0:       if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
michael@0:       {
michael@0:          /* do_local_compose removes this channel below. */
michael@0:          if (!do_local_compose)
michael@0:          {
michael@0:             /* do_local_background does the same if required. */
michael@0:             if (do_local_background != 2 ||
michael@0:                (format & PNG_FORMAT_FLAG_ALPHA) != 0)
michael@0:                info_format |= PNG_FORMAT_FLAG_ALPHA;
michael@0:          }
michael@0:       }
michael@0: 
michael@0:       else if (do_local_compose) /* internal error */
michael@0:          png_error(png_ptr, "png_image_read: alpha channel lost");
michael@0: 
michael@0:       if (info_ptr->bit_depth == 16)
michael@0:          info_format |= PNG_FORMAT_FLAG_LINEAR;
michael@0: 
michael@0: #     ifdef PNG_FORMAT_BGR_SUPPORTED
michael@0:          if (png_ptr->transformations & PNG_BGR)
michael@0:             info_format |= PNG_FORMAT_FLAG_BGR;
michael@0: #     endif
michael@0: 
michael@0: #     ifdef PNG_FORMAT_AFIRST_SUPPORTED
michael@0:          if (do_local_background == 2)
michael@0:          {
michael@0:             if (format & PNG_FORMAT_FLAG_AFIRST)
michael@0:                info_format |= PNG_FORMAT_FLAG_AFIRST;
michael@0:          }
michael@0: 
michael@0:          if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
michael@0:             ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
michael@0:             (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
michael@0:          {
michael@0:             if (do_local_background == 2)
michael@0:                png_error(png_ptr, "unexpected alpha swap transformation");
michael@0: 
michael@0:             info_format |= PNG_FORMAT_FLAG_AFIRST;
michael@0:          }
michael@0: #     endif
michael@0: 
michael@0:       /* This is actually an internal error. */
michael@0:       if (info_format != format)
michael@0:          png_error(png_ptr, "png_read_image: invalid transformations");
michael@0:    }
michael@0: 
michael@0:    /* Now read the rows.  If do_local_compose is set then it is necessary to use
michael@0:     * a local row buffer.  The output will be GA, RGBA or BGRA and must be
michael@0:     * converted to G, RGB or BGR as appropriate.  The 'local_row' member of the
michael@0:     * display acts as a flag.
michael@0:     */
michael@0:    {
michael@0:       png_voidp first_row = display->buffer;
michael@0:       ptrdiff_t row_bytes = display->row_stride;
michael@0: 
michael@0:       if (linear)
michael@0:          row_bytes *= 2;
michael@0: 
michael@0:       /* The following expression is designed to work correctly whether it gives
michael@0:        * a signed or an unsigned result.
michael@0:        */
michael@0:       if (row_bytes < 0)
michael@0:       {
michael@0:          char *ptr = png_voidcast(char*, first_row);
michael@0:          ptr += (image->height-1) * (-row_bytes);
michael@0:          first_row = png_voidcast(png_voidp, ptr);
michael@0:       }
michael@0: 
michael@0:       display->first_row = first_row;
michael@0:       display->row_bytes = row_bytes;
michael@0:    }
michael@0: 
michael@0:    if (do_local_compose)
michael@0:    {
michael@0:       int result;
michael@0:       png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
michael@0: 
michael@0:       display->local_row = row;
michael@0:       result = png_safe_execute(image, png_image_read_composite, display);
michael@0:       display->local_row = NULL;
michael@0:       png_free(png_ptr, row);
michael@0: 
michael@0:       return result;
michael@0:    }
michael@0: 
michael@0:    else if (do_local_background == 2)
michael@0:    {
michael@0:       int result;
michael@0:       png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
michael@0: 
michael@0:       display->local_row = row;
michael@0:       result = png_safe_execute(image, png_image_read_background, display);
michael@0:       display->local_row = NULL;
michael@0:       png_free(png_ptr, row);
michael@0: 
michael@0:       return result;
michael@0:    }
michael@0: 
michael@0:    else
michael@0:    {
michael@0:       png_alloc_size_t row_bytes = display->row_bytes;
michael@0: 
michael@0:       while (--passes >= 0)
michael@0:       {
michael@0:          png_uint_32      y = image->height;
michael@0:          png_bytep        row = png_voidcast(png_bytep, display->first_row);
michael@0: 
michael@0:          while (y-- > 0)
michael@0:          {
michael@0:             png_read_row(png_ptr, row, NULL);
michael@0:             row += row_bytes;
michael@0:          }
michael@0:       }
michael@0: 
michael@0:       return 1;
michael@0:    }
michael@0: }
michael@0: 
michael@0: int PNGAPI
michael@0: png_image_finish_read(png_imagep image, png_const_colorp background,
michael@0:    void *buffer, png_int_32 row_stride, void *colormap)
michael@0: {
michael@0:    if (image != NULL && image->version == PNG_IMAGE_VERSION)
michael@0:    {
michael@0:       png_uint_32 check;
michael@0: 
michael@0:       if (row_stride == 0)
michael@0:          row_stride = PNG_IMAGE_ROW_STRIDE(*image);
michael@0: 
michael@0:       if (row_stride < 0)
michael@0:          check = -row_stride;
michael@0: 
michael@0:       else
michael@0:          check = row_stride;
michael@0: 
michael@0:       if (image->opaque != NULL && buffer != NULL &&
michael@0:          check >= PNG_IMAGE_ROW_STRIDE(*image))
michael@0:       {
michael@0:          if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
michael@0:             (image->colormap_entries > 0 && colormap != NULL))
michael@0:          {
michael@0:             int result;
michael@0:             png_image_read_control display;
michael@0: 
michael@0:             memset(&display, 0, (sizeof display));
michael@0:             display.image = image;
michael@0:             display.buffer = buffer;
michael@0:             display.row_stride = row_stride;
michael@0:             display.colormap = colormap;
michael@0:             display.background = background;
michael@0:             display.local_row = NULL;
michael@0: 
michael@0:             /* Choose the correct 'end' routine; for the color-map case all the
michael@0:              * setup has already been done.
michael@0:              */
michael@0:             if (image->format & PNG_FORMAT_FLAG_COLORMAP)
michael@0:                result =
michael@0:                   png_safe_execute(image, png_image_read_colormap, &display) &&
michael@0:                   png_safe_execute(image, png_image_read_colormapped, &display);
michael@0: 
michael@0:             else
michael@0:                result =
michael@0:                   png_safe_execute(image, png_image_read_direct, &display);
michael@0: 
michael@0:             png_image_free(image);
michael@0:             return result;
michael@0:          }
michael@0: 
michael@0:          else
michael@0:             return png_image_error(image,
michael@0:                "png_image_finish_read[color-map]: no color-map");
michael@0:       }
michael@0: 
michael@0:       else
michael@0:          return png_image_error(image,
michael@0:             "png_image_finish_read: invalid argument");
michael@0:    }
michael@0: 
michael@0:    else if (image != NULL)
michael@0:       return png_image_error(image,
michael@0:          "png_image_finish_read: damaged PNG_IMAGE_VERSION");
michael@0: 
michael@0:    return 0;
michael@0: }
michael@0: 
michael@0: #endif /* PNG_SIMPLIFIED_READ_SUPPORTED */
michael@0: #endif /* PNG_READ_SUPPORTED */