michael@0: /*
michael@0:  * jdapimin.c
michael@0:  *
michael@0:  * Copyright (C) 1994-1998, Thomas G. Lane.
michael@0:  * This file is part of the Independent JPEG Group's software.
michael@0:  * For conditions of distribution and use, see the accompanying README file.
michael@0:  *
michael@0:  * This file contains application interface code for the decompression half
michael@0:  * of the JPEG library.  These are the "minimum" API routines that may be
michael@0:  * needed in either the normal full-decompression case or the
michael@0:  * transcoding-only case.
michael@0:  *
michael@0:  * Most of the routines intended to be called directly by an application
michael@0:  * are in this file or in jdapistd.c.  But also see jcomapi.c for routines
michael@0:  * shared by compression and decompression, and jdtrans.c for the transcoding
michael@0:  * case.
michael@0:  */
michael@0: 
michael@0: #define JPEG_INTERNALS
michael@0: #include "jinclude.h"
michael@0: #include "jpeglib.h"
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Initialization of a JPEG decompression object.
michael@0:  * The error manager must already be set up (in case memory manager fails).
michael@0:  */
michael@0: 
michael@0: GLOBAL(void)
michael@0: jpeg_CreateDecompress (j_decompress_ptr cinfo, int version, size_t structsize)
michael@0: {
michael@0:   int i;
michael@0: 
michael@0:   /* Guard against version mismatches between library and caller. */
michael@0:   cinfo->mem = NULL;		/* so jpeg_destroy knows mem mgr not called */
michael@0:   if (version != JPEG_LIB_VERSION)
michael@0:     ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
michael@0:   if (structsize != SIZEOF(struct jpeg_decompress_struct))
michael@0:     ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE, 
michael@0: 	     (int) SIZEOF(struct jpeg_decompress_struct), (int) structsize);
michael@0: 
michael@0:   /* For debugging purposes, we zero the whole master structure.
michael@0:    * But the application has already set the err pointer, and may have set
michael@0:    * client_data, so we have to save and restore those fields.
michael@0:    * Note: if application hasn't set client_data, tools like Purify may
michael@0:    * complain here.
michael@0:    */
michael@0:   {
michael@0:     struct jpeg_error_mgr * err = cinfo->err;
michael@0:     void * client_data = cinfo->client_data; /* ignore Purify complaint here */
michael@0:     MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));
michael@0:     cinfo->err = err;
michael@0:     cinfo->client_data = client_data;
michael@0:   }
michael@0:   cinfo->is_decompressor = TRUE;
michael@0: 
michael@0:   /* Initialize a memory manager instance for this object */
michael@0:   jinit_memory_mgr((j_common_ptr) cinfo);
michael@0: 
michael@0:   /* Zero out pointers to permanent structures. */
michael@0:   cinfo->progress = NULL;
michael@0:   cinfo->src = NULL;
michael@0: 
michael@0:   for (i = 0; i < NUM_QUANT_TBLS; i++)
michael@0:     cinfo->quant_tbl_ptrs[i] = NULL;
michael@0: 
michael@0:   for (i = 0; i < NUM_HUFF_TBLS; i++) {
michael@0:     cinfo->dc_huff_tbl_ptrs[i] = NULL;
michael@0:     cinfo->ac_huff_tbl_ptrs[i] = NULL;
michael@0:   }
michael@0: 
michael@0:   /* Initialize marker processor so application can override methods
michael@0:    * for COM, APPn markers before calling jpeg_read_header.
michael@0:    */
michael@0:   cinfo->marker_list = NULL;
michael@0:   jinit_marker_reader(cinfo);
michael@0: 
michael@0:   /* And initialize the overall input controller. */
michael@0:   jinit_input_controller(cinfo);
michael@0: 
michael@0:   /* OK, I'm ready */
michael@0:   cinfo->global_state = DSTATE_START;
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Destruction of a JPEG decompression object
michael@0:  */
michael@0: 
michael@0: GLOBAL(void)
michael@0: jpeg_destroy_decompress (j_decompress_ptr cinfo)
michael@0: {
michael@0:   jpeg_destroy((j_common_ptr) cinfo); /* use common routine */
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Abort processing of a JPEG decompression operation,
michael@0:  * but don't destroy the object itself.
michael@0:  */
michael@0: 
michael@0: GLOBAL(void)
michael@0: jpeg_abort_decompress (j_decompress_ptr cinfo)
michael@0: {
michael@0:   jpeg_abort((j_common_ptr) cinfo); /* use common routine */
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Set default decompression parameters.
michael@0:  */
michael@0: 
michael@0: LOCAL(void)
michael@0: default_decompress_parms (j_decompress_ptr cinfo)
michael@0: {
michael@0:   /* Guess the input colorspace, and set output colorspace accordingly. */
michael@0:   /* (Wish JPEG committee had provided a real way to specify this...) */
michael@0:   /* Note application may override our guesses. */
michael@0:   switch (cinfo->num_components) {
michael@0:   case 1:
michael@0:     cinfo->jpeg_color_space = JCS_GRAYSCALE;
michael@0:     cinfo->out_color_space = JCS_GRAYSCALE;
michael@0:     break;
michael@0:     
michael@0:   case 3:
michael@0:     if (cinfo->saw_JFIF_marker) {
michael@0:       cinfo->jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */
michael@0:     } else if (cinfo->saw_Adobe_marker) {
michael@0:       switch (cinfo->Adobe_transform) {
michael@0:       case 0:
michael@0: 	cinfo->jpeg_color_space = JCS_RGB;
michael@0: 	break;
michael@0:       case 1:
michael@0: 	cinfo->jpeg_color_space = JCS_YCbCr;
michael@0: 	break;
michael@0:       default:
michael@0: 	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
michael@0: 	cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
michael@0: 	break;
michael@0:       }
michael@0:     } else {
michael@0:       /* Saw no special markers, try to guess from the component IDs */
michael@0:       int cid0 = cinfo->comp_info[0].component_id;
michael@0:       int cid1 = cinfo->comp_info[1].component_id;
michael@0:       int cid2 = cinfo->comp_info[2].component_id;
michael@0: 
michael@0:       if (cid0 == 1 && cid1 == 2 && cid2 == 3)
michael@0: 	cinfo->jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */
michael@0:       else if (cid0 == 82 && cid1 == 71 && cid2 == 66)
michael@0: 	cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */
michael@0:       else {
michael@0: 	TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
michael@0: 	cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
michael@0:       }
michael@0:     }
michael@0:     /* Always guess RGB is proper output colorspace. */
michael@0:     cinfo->out_color_space = JCS_RGB;
michael@0:     break;
michael@0:     
michael@0:   case 4:
michael@0:     if (cinfo->saw_Adobe_marker) {
michael@0:       switch (cinfo->Adobe_transform) {
michael@0:       case 0:
michael@0: 	cinfo->jpeg_color_space = JCS_CMYK;
michael@0: 	break;
michael@0:       case 2:
michael@0: 	cinfo->jpeg_color_space = JCS_YCCK;
michael@0: 	break;
michael@0:       default:
michael@0: 	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
michael@0: 	cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */
michael@0: 	break;
michael@0:       }
michael@0:     } else {
michael@0:       /* No special markers, assume straight CMYK. */
michael@0:       cinfo->jpeg_color_space = JCS_CMYK;
michael@0:     }
michael@0:     cinfo->out_color_space = JCS_CMYK;
michael@0:     break;
michael@0:     
michael@0:   default:
michael@0:     cinfo->jpeg_color_space = JCS_UNKNOWN;
michael@0:     cinfo->out_color_space = JCS_UNKNOWN;
michael@0:     break;
michael@0:   }
michael@0: 
michael@0:   /* Set defaults for other decompression parameters. */
michael@0:   cinfo->scale_num = 1;		/* 1:1 scaling */
michael@0:   cinfo->scale_denom = 1;
michael@0:   cinfo->output_gamma = 1.0;
michael@0:   cinfo->buffered_image = FALSE;
michael@0:   cinfo->raw_data_out = FALSE;
michael@0:   cinfo->dct_method = JDCT_DEFAULT;
michael@0:   cinfo->do_fancy_upsampling = TRUE;
michael@0:   cinfo->do_block_smoothing = TRUE;
michael@0:   cinfo->quantize_colors = FALSE;
michael@0:   /* We set these in case application only sets quantize_colors. */
michael@0:   cinfo->dither_mode = JDITHER_FS;
michael@0: #ifdef QUANT_2PASS_SUPPORTED
michael@0:   cinfo->two_pass_quantize = TRUE;
michael@0: #else
michael@0:   cinfo->two_pass_quantize = FALSE;
michael@0: #endif
michael@0:   cinfo->desired_number_of_colors = 256;
michael@0:   cinfo->colormap = NULL;
michael@0:   /* Initialize for no mode change in buffered-image mode. */
michael@0:   cinfo->enable_1pass_quant = FALSE;
michael@0:   cinfo->enable_external_quant = FALSE;
michael@0:   cinfo->enable_2pass_quant = FALSE;
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Decompression startup: read start of JPEG datastream to see what's there.
michael@0:  * Need only initialize JPEG object and supply a data source before calling.
michael@0:  *
michael@0:  * This routine will read as far as the first SOS marker (ie, actual start of
michael@0:  * compressed data), and will save all tables and parameters in the JPEG
michael@0:  * object.  It will also initialize the decompression parameters to default
michael@0:  * values, and finally return JPEG_HEADER_OK.  On return, the application may
michael@0:  * adjust the decompression parameters and then call jpeg_start_decompress.
michael@0:  * (Or, if the application only wanted to determine the image parameters,
michael@0:  * the data need not be decompressed.  In that case, call jpeg_abort or
michael@0:  * jpeg_destroy to release any temporary space.)
michael@0:  * If an abbreviated (tables only) datastream is presented, the routine will
michael@0:  * return JPEG_HEADER_TABLES_ONLY upon reaching EOI.  The application may then
michael@0:  * re-use the JPEG object to read the abbreviated image datastream(s).
michael@0:  * It is unnecessary (but OK) to call jpeg_abort in this case.
michael@0:  * The JPEG_SUSPENDED return code only occurs if the data source module
michael@0:  * requests suspension of the decompressor.  In this case the application
michael@0:  * should load more source data and then re-call jpeg_read_header to resume
michael@0:  * processing.
michael@0:  * If a non-suspending data source is used and require_image is TRUE, then the
michael@0:  * return code need not be inspected since only JPEG_HEADER_OK is possible.
michael@0:  *
michael@0:  * This routine is now just a front end to jpeg_consume_input, with some
michael@0:  * extra error checking.
michael@0:  */
michael@0: 
michael@0: GLOBAL(int)
michael@0: jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)
michael@0: {
michael@0:   int retcode;
michael@0: 
michael@0:   if (cinfo->global_state != DSTATE_START &&
michael@0:       cinfo->global_state != DSTATE_INHEADER)
michael@0:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
michael@0: 
michael@0:   retcode = jpeg_consume_input(cinfo);
michael@0: 
michael@0:   switch (retcode) {
michael@0:   case JPEG_REACHED_SOS:
michael@0:     retcode = JPEG_HEADER_OK;
michael@0:     break;
michael@0:   case JPEG_REACHED_EOI:
michael@0:     if (require_image)		/* Complain if application wanted an image */
michael@0:       ERREXIT(cinfo, JERR_NO_IMAGE);
michael@0:     /* Reset to start state; it would be safer to require the application to
michael@0:      * call jpeg_abort, but we can't change it now for compatibility reasons.
michael@0:      * A side effect is to free any temporary memory (there shouldn't be any).
michael@0:      */
michael@0:     jpeg_abort((j_common_ptr) cinfo); /* sets state = DSTATE_START */
michael@0:     retcode = JPEG_HEADER_TABLES_ONLY;
michael@0:     break;
michael@0:   case JPEG_SUSPENDED:
michael@0:     /* no work */
michael@0:     break;
michael@0:   }
michael@0: 
michael@0:   return retcode;
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Consume data in advance of what the decompressor requires.
michael@0:  * This can be called at any time once the decompressor object has
michael@0:  * been created and a data source has been set up.
michael@0:  *
michael@0:  * This routine is essentially a state machine that handles a couple
michael@0:  * of critical state-transition actions, namely initial setup and
michael@0:  * transition from header scanning to ready-for-start_decompress.
michael@0:  * All the actual input is done via the input controller's consume_input
michael@0:  * method.
michael@0:  */
michael@0: 
michael@0: GLOBAL(int)
michael@0: jpeg_consume_input (j_decompress_ptr cinfo)
michael@0: {
michael@0:   int retcode = JPEG_SUSPENDED;
michael@0: 
michael@0:   /* NB: every possible DSTATE value should be listed in this switch */
michael@0:   switch (cinfo->global_state) {
michael@0:   case DSTATE_START:
michael@0:     /* Start-of-datastream actions: reset appropriate modules */
michael@0:     (*cinfo->inputctl->reset_input_controller) (cinfo);
michael@0:     /* Initialize application's data source module */
michael@0:     (*cinfo->src->init_source) (cinfo);
michael@0:     cinfo->global_state = DSTATE_INHEADER;
michael@0:     /*FALLTHROUGH*/
michael@0:   case DSTATE_INHEADER:
michael@0:     retcode = (*cinfo->inputctl->consume_input) (cinfo);
michael@0:     if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */
michael@0:       /* Set up default parameters based on header data */
michael@0:       default_decompress_parms(cinfo);
michael@0:       /* Set global state: ready for start_decompress */
michael@0:       cinfo->global_state = DSTATE_READY;
michael@0:     }
michael@0:     break;
michael@0:   case DSTATE_READY:
michael@0:     /* Can't advance past first SOS until start_decompress is called */
michael@0:     retcode = JPEG_REACHED_SOS;
michael@0:     break;
michael@0:   case DSTATE_PRELOAD:
michael@0:   case DSTATE_PRESCAN:
michael@0:   case DSTATE_SCANNING:
michael@0:   case DSTATE_RAW_OK:
michael@0:   case DSTATE_BUFIMAGE:
michael@0:   case DSTATE_BUFPOST:
michael@0:   case DSTATE_STOPPING:
michael@0:     retcode = (*cinfo->inputctl->consume_input) (cinfo);
michael@0:     break;
michael@0:   default:
michael@0:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
michael@0:   }
michael@0:   return retcode;
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Have we finished reading the input file?
michael@0:  */
michael@0: 
michael@0: GLOBAL(boolean)
michael@0: jpeg_input_complete (j_decompress_ptr cinfo)
michael@0: {
michael@0:   /* Check for valid jpeg object */
michael@0:   if (cinfo->global_state < DSTATE_START ||
michael@0:       cinfo->global_state > DSTATE_STOPPING)
michael@0:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
michael@0:   return cinfo->inputctl->eoi_reached;
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Is there more than one scan?
michael@0:  */
michael@0: 
michael@0: GLOBAL(boolean)
michael@0: jpeg_has_multiple_scans (j_decompress_ptr cinfo)
michael@0: {
michael@0:   /* Only valid after jpeg_read_header completes */
michael@0:   if (cinfo->global_state < DSTATE_READY ||
michael@0:       cinfo->global_state > DSTATE_STOPPING)
michael@0:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
michael@0:   return cinfo->inputctl->has_multiple_scans;
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Finish JPEG decompression.
michael@0:  *
michael@0:  * This will normally just verify the file trailer and release temp storage.
michael@0:  *
michael@0:  * Returns FALSE if suspended.  The return value need be inspected only if
michael@0:  * a suspending data source is used.
michael@0:  */
michael@0: 
michael@0: GLOBAL(boolean)
michael@0: jpeg_finish_decompress (j_decompress_ptr cinfo)
michael@0: {
michael@0:   if ((cinfo->global_state == DSTATE_SCANNING ||
michael@0:        cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) {
michael@0:     /* Terminate final pass of non-buffered mode */
michael@0:     if (cinfo->output_scanline < cinfo->output_height)
michael@0:       ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
michael@0:     (*cinfo->master->finish_output_pass) (cinfo);
michael@0:     cinfo->global_state = DSTATE_STOPPING;
michael@0:   } else if (cinfo->global_state == DSTATE_BUFIMAGE) {
michael@0:     /* Finishing after a buffered-image operation */
michael@0:     cinfo->global_state = DSTATE_STOPPING;
michael@0:   } else if (cinfo->global_state != DSTATE_STOPPING) {
michael@0:     /* STOPPING = repeat call after a suspension, anything else is error */
michael@0:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
michael@0:   }
michael@0:   /* Read until EOI */
michael@0:   while (! cinfo->inputctl->eoi_reached) {
michael@0:     if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
michael@0:       return FALSE;		/* Suspend, come back later */
michael@0:   }
michael@0:   /* Do final cleanup */
michael@0:   (*cinfo->src->term_source) (cinfo);
michael@0:   /* We can use jpeg_abort to release memory and reset global_state */
michael@0:   jpeg_abort((j_common_ptr) cinfo);
michael@0:   return TRUE;
michael@0: }