The Tor Browser / file revision

 /*

  * jctrans.c

  *

  * Copyright (C) 1995-1998, Thomas G. Lane.

  * Modified 2000-2009 by Guido Vollbeding.

  * This file is part of the Independent JPEG Group's software.

  * For conditions of distribution and use, see the accompanying README file.

  *

  * This file contains library routines for transcoding compression,

  * that is, writing raw DCT coefficient arrays to an output JPEG file.

  * The routines in jcapimin.c will also be needed by a transcoder.

  */

 #define JPEG_INTERNALS

 #include "jinclude.h"

 #include "jpeglib.h"

 /* Forward declarations */

 LOCAL(void) transencode_master_selection

 	JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays));

 LOCAL(void) transencode_coef_controller

 	JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays));

 /*

  * Compression initialization for writing raw-coefficient data.

  * Before calling this, all parameters and a data destination must be set up.

  * Call jpeg_finish_compress() to actually write the data.

  *

  * The number of passed virtual arrays must match cinfo->num_components.

  * Note that the virtual arrays need not be filled or even realized at

  * the time write_coefficients is called; indeed, if the virtual arrays

  * were requested from this compression object's memory manager, they

  * typically will be realized during this routine and filled afterwards.

  */

 GLOBAL(void)

 jpeg_write_coefficients (j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays)

 {

   if (cinfo->global_state != CSTATE_START)

     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

   /* Mark all tables to be written */

   jpeg_suppress_tables(cinfo, FALSE);

   /* (Re)initialize error mgr and destination modules */

   (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);

   (*cinfo->dest->init_destination) (cinfo);

   /* Perform master selection of active modules */

   transencode_master_selection(cinfo, coef_arrays);

   /* Wait for jpeg_finish_compress() call */

   cinfo->next_scanline = 0;	/* so jpeg_write_marker works */

   cinfo->global_state = CSTATE_WRCOEFS;

 }

 /*

  * Initialize the compression object with default parameters,

  * then copy from the source object all parameters needed for lossless

  * transcoding.  Parameters that can be varied without loss (such as

  * scan script and Huffman optimization) are left in their default states.

  */

 GLOBAL(void)

 jpeg_copy_critical_parameters (j_decompress_ptr srcinfo,

 			       j_compress_ptr dstinfo)

 {

   JQUANT_TBL ** qtblptr;

   jpeg_component_info *incomp, *outcomp;

   JQUANT_TBL *c_quant, *slot_quant;

   int tblno, ci, coefi;

   /* Safety check to ensure start_compress not called yet. */

   if (dstinfo->global_state != CSTATE_START)

     ERREXIT1(dstinfo, JERR_BAD_STATE, dstinfo->global_state);

   /* Copy fundamental image dimensions */

   dstinfo->image_width = srcinfo->image_width;

   dstinfo->image_height = srcinfo->image_height;

   dstinfo->input_components = srcinfo->num_components;

   dstinfo->in_color_space = srcinfo->jpeg_color_space;

 #if JPEG_LIB_VERSION >= 70

   dstinfo->jpeg_width = srcinfo->output_width;

   dstinfo->jpeg_height = srcinfo->output_height;

   dstinfo->min_DCT_h_scaled_size = srcinfo->min_DCT_h_scaled_size;

   dstinfo->min_DCT_v_scaled_size = srcinfo->min_DCT_v_scaled_size;

 #endif

   /* Initialize all parameters to default values */

   jpeg_set_defaults(dstinfo);

   /* jpeg_set_defaults may choose wrong colorspace, eg YCbCr if input is RGB.

    * Fix it to get the right header markers for the image colorspace.

    */

   jpeg_set_colorspace(dstinfo, srcinfo->jpeg_color_space);

   dstinfo->data_precision = srcinfo->data_precision;

   dstinfo->CCIR601_sampling = srcinfo->CCIR601_sampling;

   /* Copy the source's quantization tables. */

   for (tblno = 0; tblno < NUM_QUANT_TBLS; tblno++) {

     if (srcinfo->quant_tbl_ptrs[tblno] != NULL) {

       qtblptr = & dstinfo->quant_tbl_ptrs[tblno];

       if (*qtblptr == NULL)

 	*qtblptr = jpeg_alloc_quant_table((j_common_ptr) dstinfo);

       MEMCOPY((*qtblptr)->quantval,

 	      srcinfo->quant_tbl_ptrs[tblno]->quantval,

 	      SIZEOF((*qtblptr)->quantval));

       (*qtblptr)->sent_table = FALSE;

     }

   }

   /* Copy the source's per-component info.

    * Note we assume jpeg_set_defaults has allocated the dest comp_info array.

    */

   dstinfo->num_components = srcinfo->num_components;

   if (dstinfo->num_components < 1 || dstinfo->num_components > MAX_COMPONENTS)

     ERREXIT2(dstinfo, JERR_COMPONENT_COUNT, dstinfo->num_components,

 	     MAX_COMPONENTS);

   for (ci = 0, incomp = srcinfo->comp_info, outcomp = dstinfo->comp_info;

        ci < dstinfo->num_components; ci++, incomp++, outcomp++) {

     outcomp->component_id = incomp->component_id;

     outcomp->h_samp_factor = incomp->h_samp_factor;

     outcomp->v_samp_factor = incomp->v_samp_factor;

     outcomp->quant_tbl_no = incomp->quant_tbl_no;

     /* Make sure saved quantization table for component matches the qtable

      * slot.  If not, the input file re-used this qtable slot.

      * IJG encoder currently cannot duplicate this.

      */

     tblno = outcomp->quant_tbl_no;

     if (tblno < 0 || tblno >= NUM_QUANT_TBLS ||

 	srcinfo->quant_tbl_ptrs[tblno] == NULL)

       ERREXIT1(dstinfo, JERR_NO_QUANT_TABLE, tblno);

     slot_quant = srcinfo->quant_tbl_ptrs[tblno];

     c_quant = incomp->quant_table;

     if (c_quant != NULL) {

       for (coefi = 0; coefi < DCTSIZE2; coefi++) {

 	if (c_quant->quantval[coefi] != slot_quant->quantval[coefi])

 	  ERREXIT1(dstinfo, JERR_MISMATCHED_QUANT_TABLE, tblno);

       }

     }

     /* Note: we do not copy the source's Huffman table assignments;

      * instead we rely on jpeg_set_colorspace to have made a suitable choice.

      */

   }

   /* Also copy JFIF version and resolution information, if available.

    * Strictly speaking this isn't "critical" info, but it's nearly

    * always appropriate to copy it if available.  In particular,

    * if the application chooses to copy JFIF 1.02 extension markers from

    * the source file, we need to copy the version to make sure we don't

    * emit a file that has 1.02 extensions but a claimed version of 1.01.

    * We will *not*, however, copy version info from mislabeled "2.01" files.

    */

   if (srcinfo->saw_JFIF_marker) {

     if (srcinfo->JFIF_major_version == 1) {

       dstinfo->JFIF_major_version = srcinfo->JFIF_major_version;

       dstinfo->JFIF_minor_version = srcinfo->JFIF_minor_version;

     }

     dstinfo->density_unit = srcinfo->density_unit;

     dstinfo->X_density = srcinfo->X_density;

     dstinfo->Y_density = srcinfo->Y_density;

   }

 }

 /*

  * Master selection of compression modules for transcoding.

  * This substitutes for jcinit.c's initialization of the full compressor.

  */

 LOCAL(void)

 transencode_master_selection (j_compress_ptr cinfo,

 			      jvirt_barray_ptr * coef_arrays)

 {

   /* Although we don't actually use input_components for transcoding,

    * jcmaster.c's initial_setup will complain if input_components is 0.

    */

   cinfo->input_components = 1;

   /* Initialize master control (includes parameter checking/processing) */

   jinit_c_master_control(cinfo, TRUE /* transcode only */);

   /* Entropy encoding: either Huffman or arithmetic coding. */

   if (cinfo->arith_code) {

 #ifdef C_ARITH_CODING_SUPPORTED

     jinit_arith_encoder(cinfo);

 #else

     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);

 #endif

   } else {

     if (cinfo->progressive_mode) {

 #ifdef C_PROGRESSIVE_SUPPORTED

       jinit_phuff_encoder(cinfo);

 #else

       ERREXIT(cinfo, JERR_NOT_COMPILED);

 #endif

     } else

       jinit_huff_encoder(cinfo);

   }

   /* We need a special coefficient buffer controller. */

   transencode_coef_controller(cinfo, coef_arrays);

   jinit_marker_writer(cinfo);

   /* We can now tell the memory manager to allocate virtual arrays. */

   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);

   /* Write the datastream header (SOI, JFIF) immediately.

    * Frame and scan headers are postponed till later.

    * This lets application insert special markers after the SOI.

    */

   (*cinfo->marker->write_file_header) (cinfo);

 }

 /*

  * The rest of this file is a special implementation of the coefficient

  * buffer controller.  This is similar to jccoefct.c, but it handles only

  * output from presupplied virtual arrays.  Furthermore, we generate any

  * dummy padding blocks on-the-fly rather than expecting them to be present

  * in the arrays.

  */

 /* Private buffer controller object */

 typedef struct {

   struct jpeg_c_coef_controller pub; /* public fields */

   JDIMENSION iMCU_row_num;	/* iMCU row # within image */

   JDIMENSION mcu_ctr;		/* counts MCUs processed in current row */

   int MCU_vert_offset;		/* counts MCU rows within iMCU row */

   int MCU_rows_per_iMCU_row;	/* number of such rows needed */

   /* Virtual block array for each component. */

   jvirt_barray_ptr * whole_image;

   /* Workspace for constructing dummy blocks at right/bottom edges. */

   JBLOCKROW dummy_buffer[C_MAX_BLOCKS_IN_MCU];

 } my_coef_controller;

 typedef my_coef_controller * my_coef_ptr;

 LOCAL(void)

 start_iMCU_row (j_compress_ptr cinfo)

 /* Reset within-iMCU-row counters for a new row */

 {

   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

   /* In an interleaved scan, an MCU row is the same as an iMCU row.

    * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.

    * But at the bottom of the image, process only what's left.

    */

   if (cinfo->comps_in_scan > 1) {

     coef->MCU_rows_per_iMCU_row = 1;

   } else {

     if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1))

       coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;

     else

       coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;

   }

   coef->mcu_ctr = 0;

   coef->MCU_vert_offset = 0;

 }

 /*

  * Initialize for a processing pass.

  */

 METHODDEF(void)

 start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode)

 {

   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

   if (pass_mode != JBUF_CRANK_DEST)

     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

   coef->iMCU_row_num = 0;

   start_iMCU_row(cinfo);

 }

 /*

  * Process some data.

  * We process the equivalent of one fully interleaved MCU row ("iMCU" row)

  * per call, ie, v_samp_factor block rows for each component in the scan.

  * The data is obtained from the virtual arrays and fed to the entropy coder.

  * Returns TRUE if the iMCU row is completed, FALSE if suspended.

  *

  * NB: input_buf is ignored; it is likely to be a NULL pointer.

  */

 METHODDEF(boolean)

 compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)

 {

   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

   JDIMENSION MCU_col_num;	/* index of current MCU within row */

   JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;

   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;

   int blkn, ci, xindex, yindex, yoffset, blockcnt;

   JDIMENSION start_col;

   JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];

   JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];

   JBLOCKROW buffer_ptr;

   jpeg_component_info *compptr;

   /* Align the virtual buffers for the components used in this scan. */

   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {

     compptr = cinfo->cur_comp_info[ci];

     buffer[ci] = (*cinfo->mem->access_virt_barray)

       ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],

        coef->iMCU_row_num * compptr->v_samp_factor,

        (JDIMENSION) compptr->v_samp_factor, FALSE);

   }

   /* Loop to process one whole iMCU row */

   for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;

        yoffset++) {

     for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;

 	 MCU_col_num++) {

       /* Construct list of pointers to DCT blocks belonging to this MCU */

       blkn = 0;			/* index of current DCT block within MCU */

       for (ci = 0; ci < cinfo->comps_in_scan; ci++) {

 	compptr = cinfo->cur_comp_info[ci];

 	start_col = MCU_col_num * compptr->MCU_width;

 	blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width

 						: compptr->last_col_width;

 	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {

 	  if (coef->iMCU_row_num < last_iMCU_row ||

 	      yindex+yoffset < compptr->last_row_height) {

 	    /* Fill in pointers to real blocks in this row */

 	    buffer_ptr = buffer[ci][yindex+yoffset] + start_col;

 	    for (xindex = 0; xindex < blockcnt; xindex++)

 	      MCU_buffer[blkn++] = buffer_ptr++;

 	  } else {

 	    /* At bottom of image, need a whole row of dummy blocks */

 	    xindex = 0;

 	  }

 	  /* Fill in any dummy blocks needed in this row.

 	   * Dummy blocks are filled in the same way as in jccoefct.c:

 	   * all zeroes in the AC entries, DC entries equal to previous

 	   * block's DC value.  The init routine has already zeroed the

 	   * AC entries, so we need only set the DC entries correctly.

 	   */

 	  for (; xindex < compptr->MCU_width; xindex++) {

 	    MCU_buffer[blkn] = coef->dummy_buffer[blkn];

 	    MCU_buffer[blkn][0][0] = MCU_buffer[blkn-1][0][0];

 	    blkn++;

 	  }

 	}

       }

       /* Try to write the MCU. */

       if (! (*cinfo->entropy->encode_mcu) (cinfo, MCU_buffer)) {

 	/* Suspension forced; update state counters and exit */

 	coef->MCU_vert_offset = yoffset;

 	coef->mcu_ctr = MCU_col_num;

 	return FALSE;

       }

     }

     /* Completed an MCU row, but perhaps not an iMCU row */

     coef->mcu_ctr = 0;

   }

   /* Completed the iMCU row, advance counters for next one */

   coef->iMCU_row_num++;

   start_iMCU_row(cinfo);

   return TRUE;

 }

 /*

  * Initialize coefficient buffer controller.

  *

  * Each passed coefficient array must be the right size for that

  * coefficient: width_in_blocks wide and height_in_blocks high,

  * with unitheight at least v_samp_factor.

  */

 LOCAL(void)

 transencode_coef_controller (j_compress_ptr cinfo,

 			     jvirt_barray_ptr * coef_arrays)

 {

   my_coef_ptr coef;

   JBLOCKROW buffer;

   int i;

   coef = (my_coef_ptr)

     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

 				SIZEOF(my_coef_controller));

   cinfo->coef = (struct jpeg_c_coef_controller *) coef;

   coef->pub.start_pass = start_pass_coef;

   coef->pub.compress_data = compress_output;

   /* Save pointer to virtual arrays */

   coef->whole_image = coef_arrays;

   /* Allocate and pre-zero space for dummy DCT blocks. */

   buffer = (JBLOCKROW)

     (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,

 				C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));

   jzero_far((void FAR *) buffer, C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));

   for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {

     coef->dummy_buffer[i] = buffer + i;

   }

 }