385 lines
12 KiB
C++
385 lines
12 KiB
C++
// * jdapimin.c
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// *
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// * Copyright (C) 1994-1995, Thomas G. Lane.
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// * This file is part of the Independent JPEG Group's software.
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// * For conditions of distribution and use, see the accompanying README file.
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// *
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// * This file contains application interface code for the decompression half
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// * of the JPEG library. These are the "minimum" API routines that may be
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// * needed in either the normal full-decompression case or the
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// * transcoding-only case.
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// *
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// * Most of the routines intended to be called directly by an application
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// * are in this file or in jdapistd.c. But also see jcomapi.c for routines
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// * shared by compression and decompression, and jdtrans.c for the transcoding
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// * case.
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#ifdef _MSC_VER
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#pragma warning(push)
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#pragma warning(disable: 4127)
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#endif
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#define JPEG_INTERNALS
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#include "JINCLUDE.h"
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#include "JPEGLIB.h"
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// * Initialization of a JPEG decompression object.
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// * The error manager must already be set up (in case memory manager fails).
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GLOBAL void
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jpeg_create_decompress (j_decompress_ptr cinfo)
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{
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int i;
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// For debugging purposes, zero the whole master structure.
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// * But error manager pointer is already there, so save and restore it.
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{
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struct jpeg_error_mgr * err = cinfo->err;
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MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));
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cinfo->err = err;
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}
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cinfo->is_decompressor = TRUE;
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// Initialize a memory manager instance for this object
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jinit_memory_mgr((j_common_ptr) cinfo);
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// Zero out pointers to permanent structures.
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cinfo->progress = NULL;
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cinfo->src = NULL;
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for (i = 0; i < NUM_QUANT_TBLS; i++)
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cinfo->quant_tbl_ptrs[i] = NULL;
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for (i = 0; i < NUM_HUFF_TBLS; i++) {
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cinfo->dc_huff_tbl_ptrs[i] = NULL;
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cinfo->ac_huff_tbl_ptrs[i] = NULL;
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}
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// Initialize marker processor so application can override methods
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// * for COM, APPn markers before calling jpeg_read_header.
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jinit_marker_reader(cinfo);
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// And initialize the overall input controller.
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jinit_input_controller(cinfo);
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// OK, I'm ready
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cinfo->global_state = DSTATE_START;
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}
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// * Destruction of a JPEG decompression object
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GLOBAL void
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jpeg_destroy_decompress (j_decompress_ptr cinfo)
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{
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jpeg_destroy((j_common_ptr) cinfo); // use common routine
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}
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// * Abort processing of a JPEG decompression operation,
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// * but don't destroy the object itself.
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GLOBAL void
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jpeg_abort_decompress (j_decompress_ptr cinfo)
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{
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jpeg_abort((j_common_ptr) cinfo); // use common routine
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}
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// * Install a special processing method for COM or APPn markers.
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GLOBAL void
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jpeg_set_marker_processor (j_decompress_ptr cinfo, int marker_code,
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jpeg_marker_parser_method routine)
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{
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if (marker_code == JPEG_COM)
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cinfo->marker->process_COM = routine;
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else if (marker_code >= JPEG_APP0 && marker_code <= JPEG_APP0+15)
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cinfo->marker->process_APPn[marker_code-JPEG_APP0] = routine;
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else
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ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);
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}
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// * Set default decompression parameters.
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LOCAL void
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default_decompress_parms (j_decompress_ptr cinfo)
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{
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// Guess the input colorspace, and set output colorspace accordingly.
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// (Wish JPEG committee had provided a real way to specify this...)
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// Note application may override our guesses.
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switch (cinfo->num_components) {
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case 1:
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cinfo->jpeg_color_space = JCS_GRAYSCALE;
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cinfo->out_color_space = JCS_GRAYSCALE;
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break;
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case 3:
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if (cinfo->saw_JFIF_marker) {
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cinfo->jpeg_color_space = JCS_YCbCr; // JFIF implies YCbCr
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} else if (cinfo->saw_Adobe_marker) {
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switch (cinfo->Adobe_transform) {
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case 0:
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cinfo->jpeg_color_space = JCS_RGB;
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break;
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case 1:
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cinfo->jpeg_color_space = JCS_YCbCr;
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break;
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default:
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WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
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cinfo->jpeg_color_space = JCS_YCbCr; // assume it's YCbCr
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break;
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}
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} else {
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// Saw no special markers, try to guess from the component IDs
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int cid0 = cinfo->comp_info[0].component_id;
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int cid1 = cinfo->comp_info[1].component_id;
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int cid2 = cinfo->comp_info[2].component_id;
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if (cid0 == 1 && cid1 == 2 && cid2 == 3)
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cinfo->jpeg_color_space = JCS_YCbCr; // assume JFIF w/out marker
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else if (cid0 == 82 && cid1 == 71 && cid2 == 66)
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cinfo->jpeg_color_space = JCS_RGB; // ASCII 'R', 'G', 'B'
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else {
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TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
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cinfo->jpeg_color_space = JCS_YCbCr; // assume it's YCbCr
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}
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}
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// Always guess RGB is proper output colorspace.
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cinfo->out_color_space = JCS_RGB;
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break;
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case 4:
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if (cinfo->saw_Adobe_marker) {
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switch (cinfo->Adobe_transform) {
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case 0:
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cinfo->jpeg_color_space = JCS_CMYK;
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break;
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case 2:
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cinfo->jpeg_color_space = JCS_YCCK;
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break;
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default:
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WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
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cinfo->jpeg_color_space = JCS_YCCK; // assume it's YCCK
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break;
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}
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} else {
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// No special markers, assume straight CMYK.
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cinfo->jpeg_color_space = JCS_CMYK;
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}
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cinfo->out_color_space = JCS_CMYK;
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break;
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default:
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cinfo->jpeg_color_space = JCS_UNKNOWN;
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cinfo->out_color_space = JCS_UNKNOWN;
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break;
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}
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// Set defaults for other decompression parameters.
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cinfo->scale_num = 1; // 1:1 scaling
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cinfo->scale_denom = 1;
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cinfo->output_gamma = 1.0;
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cinfo->buffered_image = FALSE;
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cinfo->raw_data_out = FALSE;
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cinfo->dct_method = JDCT_DEFAULT;
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cinfo->do_fancy_upsampling = TRUE;
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cinfo->do_block_smoothing = TRUE;
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cinfo->quantize_colors = FALSE;
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// We set these in case application only sets quantize_colors.
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cinfo->dither_mode = JDITHER_FS;
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#ifdef QUANT_2PASS_SUPPORTED
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cinfo->two_pass_quantize = TRUE;
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#else
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cinfo->two_pass_quantize = FALSE;
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#endif
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cinfo->desired_number_of_colors = 256;
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cinfo->colormap = NULL;
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// Initialize for no mode change in buffered-image mode.
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cinfo->enable_1pass_quant = FALSE;
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cinfo->enable_external_quant = FALSE;
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cinfo->enable_2pass_quant = FALSE;
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}
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// * Decompression startup: read start of JPEG datastream to see what's there.
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// * Need only initialize JPEG object and supply a data source before calling.
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// *
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// * This routine will read as far as the first SOS marker (ie, actual start of
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// * compressed data), and will save all tables and parameters in the JPEG
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// * object. It will also initialize the decompression parameters to default
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// * values, and finally return JPEG_HEADER_OK. On return, the application may
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// * adjust the decompression parameters and then call jpeg_start_decompress.
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// * (Or, if the application only wanted to determine the image parameters,
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// * the data need not be decompressed. In that case, call jpeg_abort or
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// * jpeg_destroy to release any temporary space.)
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// * If an abbreviated (tables only) datastream is presented, the routine will
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// * return JPEG_HEADER_TABLES_ONLY upon reaching EOI. The application may then
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// * re-use the JPEG object to read the abbreviated image datastream(s).
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// * It is unnecessary (but OK) to call jpeg_abort in this case.
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// * The JPEG_SUSPENDED return code only occurs if the data source module
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// * requests suspension of the decompressor. In this case the application
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// * should load more source data and then re-call jpeg_read_header to resume
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// * processing.
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// * If a non-suspending data source is used and require_image is TRUE, then the
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// * return code need not be inspected since only JPEG_HEADER_OK is possible.
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// *
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// * This routine is now just a front end to jpeg_consume_input, with some
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// * extra error checking.
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GLOBAL int
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jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)
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{
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int retcode;
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if (cinfo->global_state != DSTATE_START &&
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cinfo->global_state != DSTATE_INHEADER)
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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retcode = jpeg_consume_input(cinfo);
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switch (retcode) {
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case JPEG_REACHED_SOS:
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retcode = JPEG_HEADER_OK;
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break;
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case JPEG_REACHED_EOI:
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if (require_image) // Complain if application wanted an image
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ERREXIT(cinfo, JERR_NO_IMAGE);
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// Reset to start state; it would be safer to require the application to
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// * call jpeg_abort, but we can't change it now for compatibility reasons.
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// * A side effect is to free any temporary memory (there shouldn't be any).
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jpeg_abort((j_common_ptr) cinfo); // sets state = DSTATE_START
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retcode = JPEG_HEADER_TABLES_ONLY;
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break;
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case JPEG_SUSPENDED:
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// no work
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break;
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}
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return retcode;
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}
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// * Consume data in advance of what the decompressor requires.
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// * This can be called at any time once the decompressor object has
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// * been created and a data source has been set up.
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// *
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// * This routine is essentially a state machine that handles a couple
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// * of critical state-transition actions, namely initial setup and
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// * transition from header scanning to ready-for-start_decompress.
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// * All the actual input is done via the input controller's consume_input
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// * method.
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GLOBAL int
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jpeg_consume_input (j_decompress_ptr cinfo)
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{
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int retcode = JPEG_SUSPENDED;
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// NB: every possible DSTATE value should be listed in this switch
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switch (cinfo->global_state) {
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case DSTATE_START:
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// Start-of-datastream actions: reset appropriate modules
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(*cinfo->inputctl->reset_input_controller) (cinfo);
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// Initialize application's data source module
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(*cinfo->src->init_source) (cinfo);
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cinfo->global_state = DSTATE_INHEADER;
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//FALLTHROUGH
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case DSTATE_INHEADER:
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retcode = (*cinfo->inputctl->consume_input) (cinfo);
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if (retcode == JPEG_REACHED_SOS) { // Found SOS, prepare to decompress
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// Set up default parameters based on header data
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default_decompress_parms(cinfo);
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// Set global state: ready for start_decompress
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cinfo->global_state = DSTATE_READY;
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}
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break;
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case DSTATE_READY:
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// Can't advance past first SOS until start_decompress is called
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retcode = JPEG_REACHED_SOS;
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break;
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case DSTATE_PRELOAD:
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case DSTATE_PRESCAN:
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case DSTATE_SCANNING:
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case DSTATE_RAW_OK:
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case DSTATE_BUFIMAGE:
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case DSTATE_BUFPOST:
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case DSTATE_STOPPING:
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retcode = (*cinfo->inputctl->consume_input) (cinfo);
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break;
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default:
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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}
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return retcode;
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}
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// * Have we finished reading the input file?
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GLOBAL boolean
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jpeg_input_complete (j_decompress_ptr cinfo)
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{
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// Check for valid jpeg object
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if (cinfo->global_state < DSTATE_START ||
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cinfo->global_state > DSTATE_STOPPING)
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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return cinfo->inputctl->eoi_reached;
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}
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// * Is there more than one scan?
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GLOBAL boolean
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jpeg_has_multiple_scans (j_decompress_ptr cinfo)
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{
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// Only valid after jpeg_read_header completes
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if (cinfo->global_state < DSTATE_READY ||
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cinfo->global_state > DSTATE_STOPPING)
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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return cinfo->inputctl->has_multiple_scans;
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}
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// * Finish JPEG decompression.
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// *
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// * This will normally just verify the file trailer and release temp storage.
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// *
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// * Returns FALSE if suspended. The return value need be inspected only if
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// * a suspending data source is used.
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GLOBAL boolean
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jpeg_finish_decompress (j_decompress_ptr cinfo)
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{
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if ((cinfo->global_state == DSTATE_SCANNING ||
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cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) {
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// Terminate final pass of non-buffered mode
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if (cinfo->output_scanline < cinfo->output_height)
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ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
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(*cinfo->master->finish_output_pass) (cinfo);
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cinfo->global_state = DSTATE_STOPPING;
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} else if (cinfo->global_state == DSTATE_BUFIMAGE) {
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// Finishing after a buffered-image operation
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cinfo->global_state = DSTATE_STOPPING;
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} else if (cinfo->global_state != DSTATE_STOPPING) {
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// STOPPING = repeat call after a suspension, anything else is error
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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}
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// Read until EOI
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while (! cinfo->inputctl->eoi_reached) {
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if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
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return FALSE; // Suspend, come back later
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}
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// Do final cleanup
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(*cinfo->src->term_source) (cinfo);
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// We can use jpeg_abort to release memory and reset global_state
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jpeg_abort((j_common_ptr) cinfo);
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return TRUE;
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}
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#ifdef _MSC_VER
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#pragma warning(pop)
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#endif
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