The Tor Browser / file revision

 /*

  * jdapimin.c

  *

  * Copyright (C) 1994-1998, Thomas G. Lane.

  * 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 application interface code for the decompression half

  * of the JPEG library.  These are the "minimum" API routines that may be

  * needed in either the normal full-decompression case or the

  * transcoding-only case.

  *

  * Most of the routines intended to be called directly by an application

  * are in this file or in jdapistd.c.  But also see jcomapi.c for routines

  * shared by compression and decompression, and jdtrans.c for the transcoding

  * case.

  */

 #define JPEG_INTERNALS

 #include "jinclude.h"

 #include "jpeglib.h"

 /*

  * Initialization of a JPEG decompression object.

  * The error manager must already be set up (in case memory manager fails).

  */

 GLOBAL(void)

 jpeg_CreateDecompress (j_decompress_ptr cinfo, int version, size_t structsize)

 {

   int i;

   /* Guard against version mismatches between library and caller. */

   cinfo->mem = NULL;		/* so jpeg_destroy knows mem mgr not called */

   if (version != JPEG_LIB_VERSION)

     ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);

   if (structsize != SIZEOF(struct jpeg_decompress_struct))

     ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE, 

 	     (int) SIZEOF(struct jpeg_decompress_struct), (int) structsize);

   /* For debugging purposes, we zero the whole master structure.

    * But the application has already set the err pointer, and may have set

    * client_data, so we have to save and restore those fields.

    * Note: if application hasn't set client_data, tools like Purify may

    * complain here.

    */

   {

     struct jpeg_error_mgr * err = cinfo->err;

     void * client_data = cinfo->client_data; /* ignore Purify complaint here */

     MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));

     cinfo->err = err;

     cinfo->client_data = client_data;

   }

   cinfo->is_decompressor = TRUE;

   /* Initialize a memory manager instance for this object */

   jinit_memory_mgr((j_common_ptr) cinfo);

   /* Zero out pointers to permanent structures. */

   cinfo->progress = NULL;

   cinfo->src = NULL;

   for (i = 0; i < NUM_QUANT_TBLS; i++)

     cinfo->quant_tbl_ptrs[i] = NULL;

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

     cinfo->dc_huff_tbl_ptrs[i] = NULL;

     cinfo->ac_huff_tbl_ptrs[i] = NULL;

   }

   /* Initialize marker processor so application can override methods

    * for COM, APPn markers before calling jpeg_read_header.

    */

   cinfo->marker_list = NULL;

   jinit_marker_reader(cinfo);

   /* And initialize the overall input controller. */

   jinit_input_controller(cinfo);

   /* OK, I'm ready */

   cinfo->global_state = DSTATE_START;

 }

 /*

  * Destruction of a JPEG decompression object

  */

 GLOBAL(void)

 jpeg_destroy_decompress (j_decompress_ptr cinfo)

 {

   jpeg_destroy((j_common_ptr) cinfo); /* use common routine */

 }

 /*

  * Abort processing of a JPEG decompression operation,

  * but don't destroy the object itself.

  */

 GLOBAL(void)

 jpeg_abort_decompress (j_decompress_ptr cinfo)

 {

   jpeg_abort((j_common_ptr) cinfo); /* use common routine */

 }

 /*

  * Set default decompression parameters.

  */

 LOCAL(void)

 default_decompress_parms (j_decompress_ptr cinfo)

 {

   /* Guess the input colorspace, and set output colorspace accordingly. */

   /* (Wish JPEG committee had provided a real way to specify this...) */

   /* Note application may override our guesses. */

   switch (cinfo->num_components) {

   case 1:

     cinfo->jpeg_color_space = JCS_GRAYSCALE;

     cinfo->out_color_space = JCS_GRAYSCALE;

     break;

   case 3:

     if (cinfo->saw_JFIF_marker) {

       cinfo->jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */

     } else if (cinfo->saw_Adobe_marker) {

       switch (cinfo->Adobe_transform) {

       case 0:

 	cinfo->jpeg_color_space = JCS_RGB;

 	break;

       case 1:

 	cinfo->jpeg_color_space = JCS_YCbCr;

 	break;

       default:

 	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);

 	cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */

 	break;

       }

     } else {

       /* Saw no special markers, try to guess from the component IDs */

       int cid0 = cinfo->comp_info[0].component_id;

       int cid1 = cinfo->comp_info[1].component_id;

       int cid2 = cinfo->comp_info[2].component_id;

       if (cid0 == 1 && cid1 == 2 && cid2 == 3)

 	cinfo->jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */

       else if (cid0 == 82 && cid1 == 71 && cid2 == 66)

 	cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */

       else {

 	TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);

 	cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */

       }

     }

     /* Always guess RGB is proper output colorspace. */

     cinfo->out_color_space = JCS_RGB;

     break;

   case 4:

     if (cinfo->saw_Adobe_marker) {

       switch (cinfo->Adobe_transform) {

       case 0:

 	cinfo->jpeg_color_space = JCS_CMYK;

 	break;

       case 2:

 	cinfo->jpeg_color_space = JCS_YCCK;

 	break;

       default:

 	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);

 	cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */

 	break;

       }

     } else {

       /* No special markers, assume straight CMYK. */

       cinfo->jpeg_color_space = JCS_CMYK;

     }

     cinfo->out_color_space = JCS_CMYK;

     break;

   default:

     cinfo->jpeg_color_space = JCS_UNKNOWN;

     cinfo->out_color_space = JCS_UNKNOWN;

     break;

   }

   /* Set defaults for other decompression parameters. */

   cinfo->scale_num = 1;		/* 1:1 scaling */

   cinfo->scale_denom = 1;

   cinfo->output_gamma = 1.0;

   cinfo->buffered_image = FALSE;

   cinfo->raw_data_out = FALSE;

   cinfo->dct_method = JDCT_DEFAULT;

   cinfo->do_fancy_upsampling = TRUE;

   cinfo->do_block_smoothing = TRUE;

   cinfo->quantize_colors = FALSE;

   /* We set these in case application only sets quantize_colors. */

   cinfo->dither_mode = JDITHER_FS;

 #ifdef QUANT_2PASS_SUPPORTED

   cinfo->two_pass_quantize = TRUE;

 #else

   cinfo->two_pass_quantize = FALSE;

 #endif

   cinfo->desired_number_of_colors = 256;

   cinfo->colormap = NULL;

   /* Initialize for no mode change in buffered-image mode. */

   cinfo->enable_1pass_quant = FALSE;

   cinfo->enable_external_quant = FALSE;

   cinfo->enable_2pass_quant = FALSE;

 }

 /*

  * Decompression startup: read start of JPEG datastream to see what's there.

  * Need only initialize JPEG object and supply a data source before calling.

  *

  * This routine will read as far as the first SOS marker (ie, actual start of

  * compressed data), and will save all tables and parameters in the JPEG

  * object.  It will also initialize the decompression parameters to default

  * values, and finally return JPEG_HEADER_OK.  On return, the application may

  * adjust the decompression parameters and then call jpeg_start_decompress.

  * (Or, if the application only wanted to determine the image parameters,

  * the data need not be decompressed.  In that case, call jpeg_abort or

  * jpeg_destroy to release any temporary space.)

  * If an abbreviated (tables only) datastream is presented, the routine will

  * return JPEG_HEADER_TABLES_ONLY upon reaching EOI.  The application may then

  * re-use the JPEG object to read the abbreviated image datastream(s).

  * It is unnecessary (but OK) to call jpeg_abort in this case.

  * The JPEG_SUSPENDED return code only occurs if the data source module

  * requests suspension of the decompressor.  In this case the application

  * should load more source data and then re-call jpeg_read_header to resume

  * processing.

  * If a non-suspending data source is used and require_image is TRUE, then the

  * return code need not be inspected since only JPEG_HEADER_OK is possible.

  *

  * This routine is now just a front end to jpeg_consume_input, with some

  * extra error checking.

  */

 GLOBAL(int)

 jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)

 {

   int retcode;

   if (cinfo->global_state != DSTATE_START &&

       cinfo->global_state != DSTATE_INHEADER)

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

   retcode = jpeg_consume_input(cinfo);

   switch (retcode) {

   case JPEG_REACHED_SOS:

     retcode = JPEG_HEADER_OK;

     break;

   case JPEG_REACHED_EOI:

     if (require_image)		/* Complain if application wanted an image */

       ERREXIT(cinfo, JERR_NO_IMAGE);

     /* Reset to start state; it would be safer to require the application to

      * call jpeg_abort, but we can't change it now for compatibility reasons.

      * A side effect is to free any temporary memory (there shouldn't be any).

      */

     jpeg_abort((j_common_ptr) cinfo); /* sets state = DSTATE_START */

     retcode = JPEG_HEADER_TABLES_ONLY;

     break;

   case JPEG_SUSPENDED:

     /* no work */

     break;

   }

   return retcode;

 }

 /*

  * Consume data in advance of what the decompressor requires.

  * This can be called at any time once the decompressor object has

  * been created and a data source has been set up.

  *

  * This routine is essentially a state machine that handles a couple

  * of critical state-transition actions, namely initial setup and

  * transition from header scanning to ready-for-start_decompress.

  * All the actual input is done via the input controller's consume_input

  * method.

  */

 GLOBAL(int)

 jpeg_consume_input (j_decompress_ptr cinfo)

 {

   int retcode = JPEG_SUSPENDED;

   /* NB: every possible DSTATE value should be listed in this switch */

   switch (cinfo->global_state) {

   case DSTATE_START:

     /* Start-of-datastream actions: reset appropriate modules */

     (*cinfo->inputctl->reset_input_controller) (cinfo);

     /* Initialize application's data source module */

     (*cinfo->src->init_source) (cinfo);

     cinfo->global_state = DSTATE_INHEADER;

     /*FALLTHROUGH*/

   case DSTATE_INHEADER:

     retcode = (*cinfo->inputctl->consume_input) (cinfo);

     if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */

       /* Set up default parameters based on header data */

       default_decompress_parms(cinfo);

       /* Set global state: ready for start_decompress */

       cinfo->global_state = DSTATE_READY;

     }

     break;

   case DSTATE_READY:

     /* Can't advance past first SOS until start_decompress is called */

     retcode = JPEG_REACHED_SOS;

     break;

   case DSTATE_PRELOAD:

   case DSTATE_PRESCAN:

   case DSTATE_SCANNING:

   case DSTATE_RAW_OK:

   case DSTATE_BUFIMAGE:

   case DSTATE_BUFPOST:

   case DSTATE_STOPPING:

     retcode = (*cinfo->inputctl->consume_input) (cinfo);

     break;

   default:

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

   }

   return retcode;

 }

 /*

  * Have we finished reading the input file?

  */

 GLOBAL(boolean)

 jpeg_input_complete (j_decompress_ptr cinfo)

 {

   /* Check for valid jpeg object */

   if (cinfo->global_state < DSTATE_START ||

       cinfo->global_state > DSTATE_STOPPING)

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

   return cinfo->inputctl->eoi_reached;

 }

 /*

  * Is there more than one scan?

  */

 GLOBAL(boolean)

 jpeg_has_multiple_scans (j_decompress_ptr cinfo)

 {

   /* Only valid after jpeg_read_header completes */

   if (cinfo->global_state < DSTATE_READY ||

       cinfo->global_state > DSTATE_STOPPING)

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

   return cinfo->inputctl->has_multiple_scans;

 }

 /*

  * Finish JPEG decompression.

  *

  * This will normally just verify the file trailer and release temp storage.

  *

  * Returns FALSE if suspended.  The return value need be inspected only if

  * a suspending data source is used.

  */

 GLOBAL(boolean)

 jpeg_finish_decompress (j_decompress_ptr cinfo)

 {

   if ((cinfo->global_state == DSTATE_SCANNING ||

        cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) {

     /* Terminate final pass of non-buffered mode */

     if (cinfo->output_scanline < cinfo->output_height)

       ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);

     (*cinfo->master->finish_output_pass) (cinfo);

     cinfo->global_state = DSTATE_STOPPING;

   } else if (cinfo->global_state == DSTATE_BUFIMAGE) {

     /* Finishing after a buffered-image operation */

     cinfo->global_state = DSTATE_STOPPING;

   } else if (cinfo->global_state != DSTATE_STOPPING) {

     /* STOPPING = repeat call after a suspension, anything else is error */

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

   }

   /* Read until EOI */

   while (! cinfo->inputctl->eoi_reached) {

     if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)

       return FALSE;		/* Suspend, come back later */

   }

   /* Do final cleanup */

   (*cinfo->src->term_source) (cinfo);

   /* We can use jpeg_abort to release memory and reset global_state */

   jpeg_abort((j_common_ptr) cinfo);

   return TRUE;

 }