1 line
11 KiB
C
1 line
11 KiB
C
/*
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* jdapi.c
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*
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* Copyright (C) 1994, 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 of
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* the JPEG library. Most of the routines intended to be called directly by
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* an application are in this file. But also see jcomapi.c for routines
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* shared by compression and decompression.
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*/
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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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/*
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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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*/
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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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{
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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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cinfo->sample_range_limit = NULL;
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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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*/
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cinfo->marker = NULL;
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jinit_marker_reader(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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/*
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* Destruction of a JPEG decompression object
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*/
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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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/*
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* Set default decompression parameters.
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*/
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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->quantize_colors = FALSE;
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/* We set these in case application only sets quantize_colors. */
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cinfo->two_pass_quantize = TRUE;
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cinfo->use_dithering = TRUE;
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cinfo->desired_number_of_colors = 256;
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cinfo->colormap = NULL;
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cinfo->do_block_smoothing = FALSE;
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cinfo->do_fancy_upsampling = TRUE;
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}
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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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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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/* First-time actions: reset appropriate modules */
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(*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
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(*cinfo->marker->reset_marker_reader) (cinfo);
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(*cinfo->src->init_source) (cinfo);
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cinfo->global_state = DSTATE_INHEADER;
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} else if (cinfo->global_state != DSTATE_INHEADER) {
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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}
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retcode = (*cinfo->marker->read_markers) (cinfo);
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switch (retcode) {
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case JPEG_HEADER_OK: /* 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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break;
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case JPEG_HEADER_TABLES_ONLY: /* Found EOI before any SOS */
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if (cinfo->marker->saw_SOF)
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ERREXIT(cinfo, JERR_SOF_NO_SOS);
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if (require_image) /* Complain if application wants an image */
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ERREXIT(cinfo, JERR_NO_IMAGE);
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/* We need not do any cleanup since only permanent storage (for DQT, DHT)
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* has been allocated.
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*/
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/* Set global state: ready for a new datastream */
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cinfo->global_state = DSTATE_START;
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break;
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case JPEG_SUSPENDED: /* Had to suspend before end of headers */
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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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/*
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* Decompression initialization.
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* jpeg_read_header must be completed before calling this.
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*
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* If a multipass operating mode was selected, this will do all but the
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* last pass, and thus may take a great deal of time.
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*/
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GLOBAL void
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jpeg_start_decompress (j_decompress_ptr cinfo)
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{
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JDIMENSION row_ctr;
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if (cinfo->global_state != DSTATE_READY)
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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/* Perform master selection of active modules */
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jinit_master_decompress(cinfo);
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/* Do all but the final (output) pass, and set up for that one. */
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for (;;) {
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(*cinfo->master->prepare_for_pass) (cinfo);
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if (cinfo->master->is_last_pass)
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break;
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/* loop counting here needs reworked for multiple-source-scan case??? */
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cinfo->output_scanline = 0;
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while (cinfo->output_scanline < cinfo->output_height) {
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row_ctr = 0;
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(*cinfo->main->process_data) (cinfo, NULL, &row_ctr, (JDIMENSION) 0);
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if (row_ctr == 0) /* check for failure to make progress */
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ERREXIT(cinfo, JERR_CANT_SUSPEND);
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cinfo->output_scanline += row_ctr;
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}
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(*cinfo->master->finish_pass) (cinfo);
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}
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/* Ready for application to drive last pass through jpeg_read_scanlines */
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cinfo->output_scanline = 0;
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cinfo->global_state = DSTATE_SCANNING;
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}
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/*
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* Read some scanlines of data from the JPEG decompressor.
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*
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* The return value will be the number of lines actually read.
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* This may be less than the number requested in several cases,
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* including bottom of image, data source suspension, and operating
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* modes that emit multiple scanlines at a time.
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*/
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GLOBAL JDIMENSION
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jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
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JDIMENSION max_lines)
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{
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JDIMENSION row_ctr;
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if (cinfo->global_state != DSTATE_SCANNING)
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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row_ctr = 0;
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(*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
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cinfo->output_scanline += row_ctr;
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return row_ctr;
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}
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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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*/
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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->output_scanline == cinfo->output_height) {
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/* Terminate final pass */
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(*cinfo->master->finish_pass) (cinfo);
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cinfo->global_state = DSTATE_STOPPING;
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} else if (cinfo->global_state != DSTATE_STOPPING) {
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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}
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/* Check for EOI in source file, unless master control already read it */
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if (! cinfo->master->eoi_processed) {
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switch ((*cinfo->marker->read_markers) (cinfo)) {
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case JPEG_HEADER_OK: /* Found SOS!? */
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ERREXIT(cinfo, JERR_EOI_EXPECTED);
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break;
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case JPEG_HEADER_TABLES_ONLY: /* Found EOI, A-OK */
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break;
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case JPEG_SUSPENDED: /* Suspend, come back later */
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return FALSE;
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}
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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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/*
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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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*/
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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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