www.pudn.com > Cimage.zip > JDAPI.C
/*
* jdapi.c
*
* Copyright (C) 1994, 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. Most of the routines intended to be called directly by
* an application are in this file. But also see jcomapi.c for routines
* shared by compression and decompression.
*/
#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_create_decompress (j_decompress_ptr cinfo)
{
int i;
/* For debugging purposes, zero the whole master structure.
* But error manager pointer is already there, so save and restore it.
*/
{
struct jpeg_error_mgr * err = cinfo->err;
MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));
cinfo->err = err;
}
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;
}
cinfo->sample_range_limit = NULL;
/* Initialize marker processor so application can override methods
* for COM, APPn markers before calling jpeg_read_header.
*/
cinfo->marker = NULL;
jinit_marker_reader(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 */
}
/*
* Install a special processing method for COM or APPn markers.
*/
GLOBAL void
jpeg_set_marker_processor (j_decompress_ptr cinfo, int marker_code,
jpeg_marker_parser_method routine)
{
if (marker_code == JPEG_COM)
cinfo->marker->process_COM = routine;
else if (marker_code >= JPEG_APP0 && marker_code <= JPEG_APP0+15)
cinfo->marker->process_APPn[marker_code-JPEG_APP0] = routine;
else
ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);
}
/*
* 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->raw_data_out = FALSE;
cinfo->quantize_colors = FALSE;
/* We set these in case application only sets quantize_colors. */
cinfo->two_pass_quantize = TRUE;
cinfo->dither_mode = JDITHER_FS;
cinfo->desired_number_of_colors = 256;
cinfo->colormap = NULL;
/* DCT algorithm preference */
cinfo->dct_method = JDCT_DEFAULT;
cinfo->do_fancy_upsampling = TRUE;
}
/*
* 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.
*/
GLOBAL int
jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)
{
int retcode;
if (cinfo->global_state == DSTATE_START) {
/* First-time actions: reset appropriate modules */
(*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
(*cinfo->marker->reset_marker_reader) (cinfo);
(*cinfo->src->init_source) (cinfo);
cinfo->global_state = DSTATE_INHEADER;
} else if (cinfo->global_state != DSTATE_INHEADER) {
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
}
retcode = (*cinfo->marker->read_markers) (cinfo);
switch (retcode) {
case JPEG_HEADER_OK: /* 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 JPEG_HEADER_TABLES_ONLY: /* Found EOI before any SOS */
if (cinfo->marker->saw_SOF)
ERREXIT(cinfo, JERR_SOF_NO_SOS);
if (require_image) /* Complain if application wants an image */
ERREXIT(cinfo, JERR_NO_IMAGE);
/* We need not do any cleanup since only permanent storage (for DQT, DHT)
* has been allocated.
*/
/* Set global state: ready for a new datastream */
cinfo->global_state = DSTATE_START;
break;
case JPEG_SUSPENDED: /* Had to suspend before end of headers */
/* no work */
break;
}
return retcode;
}
/*
* Decompression initialization.
* jpeg_read_header must be completed before calling this.
*
* If a multipass operating mode was selected, this will do all but the
* last pass, and thus may take a great deal of time.
*/
GLOBAL void
jpeg_start_decompress (j_decompress_ptr cinfo)
{
JDIMENSION chunk_ctr, last_chunk_ctr;
if (cinfo->global_state != DSTATE_READY)
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
/* Perform master selection of active modules */
jinit_master_decompress(cinfo);
/* Do all but the final (output) pass, and set up for that one. */
for (;;) {
(*cinfo->master->prepare_for_pass) (cinfo);
if (cinfo->master->is_last_pass)
break;
chunk_ctr = 0;
while (chunk_ctr < cinfo->main->num_chunks) {
/* Call progress monitor hook if present */
if (cinfo->progress != NULL) {
cinfo->progress->pass_counter = (long) chunk_ctr;
cinfo->progress->pass_limit = (long) cinfo->main->num_chunks;
(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
}
/* Process some data */
last_chunk_ctr = chunk_ctr;
(*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
&chunk_ctr, (JDIMENSION) 0);
if (chunk_ctr == last_chunk_ctr) /* check for failure to make progress */
ERREXIT(cinfo, JERR_CANT_SUSPEND);
}
(*cinfo->master->finish_pass) (cinfo);
}
/* Ready for application to drive last pass through jpeg_read_scanlines
* or jpeg_read_raw_data.
*/
cinfo->output_scanline = 0;
cinfo->global_state = (cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING);
}
/*
* Read some scanlines of data from the JPEG decompressor.
*
* The return value will be the number of lines actually read.
* This may be less than the number requested in several cases,
* including bottom of image, data source suspension, and operating
* modes that emit multiple scanlines at a time.
*
* Note: we warn about excess calls to jpeg_read_scanlines() since
* this likely signals an application programmer error. However,
* an oversize buffer (max_lines > scanlines remaining) is not an error.
*/
GLOBAL JDIMENSION
jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
JDIMENSION max_lines)
{
JDIMENSION row_ctr;
if (cinfo->global_state != DSTATE_SCANNING)
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
if (cinfo->output_scanline >= cinfo->output_height)
WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
/* Call progress monitor hook if present */
if (cinfo->progress != NULL) {
cinfo->progress->pass_counter = (long) cinfo->output_scanline;
cinfo->progress->pass_limit = (long) cinfo->output_height;
(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
}
/* Process some data */
row_ctr = 0;
(*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
cinfo->output_scanline += row_ctr;
return row_ctr;
}
/*
* Alternate entry point to read raw data.
* Processes exactly one MCU row per call.
*/
GLOBAL JDIMENSION
jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
JDIMENSION max_lines)
{
JDIMENSION lines_per_MCU_row;
if (cinfo->global_state != DSTATE_RAW_OK)
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
if (cinfo->output_scanline >= cinfo->output_height) {
WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
return 0;
}
/* Call progress monitor hook if present */
if (cinfo->progress != NULL) {
cinfo->progress->pass_counter = (long) cinfo->output_scanline;
cinfo->progress->pass_limit = (long) cinfo->output_height;
(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
}
/* Verify that at least one MCU row can be returned. */
lines_per_MCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size;
if (max_lines < lines_per_MCU_row)
ERREXIT(cinfo, JERR_BUFFER_SIZE);
/* Decompress directly into user's buffer. */
if (! (*cinfo->coef->decompress_data) (cinfo, data))
return 0; /* suspension forced, can do nothing more */
/* OK, we processed one MCU row. */
cinfo->output_scanline += lines_per_MCU_row;
return lines_per_MCU_row;
}
/*
* 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) {
/* Terminate final pass */
if (cinfo->output_scanline < cinfo->output_height)
ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
(*cinfo->master->finish_pass) (cinfo);
cinfo->global_state = DSTATE_STOPPING;
} else if (cinfo->global_state != DSTATE_STOPPING) {
/* Repeat call after a suspension? */
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
}
/* Check for EOI in source file, unless master control already read it */
if (! cinfo->master->eoi_processed) {
switch ((*cinfo->marker->read_markers) (cinfo)) {
case JPEG_HEADER_OK: /* Found SOS!? */
ERREXIT(cinfo, JERR_EOI_EXPECTED);
break;
case JPEG_HEADER_TABLES_ONLY: /* Found EOI, A-OK */
break;
case JPEG_SUSPENDED: /* Suspend, come back later */
return FALSE;
}
}
/* 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;
}
/*
* 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 */
}