/* | |
* jdapistd.c | |
* | |
* Copyright (C) 1994-1996, 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 "standard" API routines that are | |
* used in the normal full-decompression case. They are not used by a | |
* transcoding-only application. Note that if an application links in | |
* jpeg_start_decompress, it will end up linking in the entire decompressor. | |
* We thus must separate this file from jdapimin.c to avoid linking the | |
* whole decompression library into a transcoder. | |
*/ | |
#define JPEG_INTERNALS | |
#include "jinclude.h" | |
#include "jpeglib.h" | |
/* Forward declarations */ | |
LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo)); | |
/* | |
* 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. | |
* | |
* Returns FALSE if suspended. The return value need be inspected only if | |
* a suspending data source is used. | |
*/ | |
GLOBAL(boolean) | |
jpeg_start_decompress (j_decompress_ptr cinfo) | |
{ | |
if (cinfo->global_state == DSTATE_READY) { | |
/* First call: initialize master control, select active modules */ | |
jinit_master_decompress(cinfo); | |
if (cinfo->buffered_image) { | |
/* No more work here; expecting jpeg_start_output next */ | |
cinfo->global_state = DSTATE_BUFIMAGE; | |
return TRUE; | |
} | |
cinfo->global_state = DSTATE_PRELOAD; | |
} | |
if (cinfo->global_state == DSTATE_PRELOAD) { | |
/* If file has multiple scans, absorb them all into the coef buffer */ | |
if (cinfo->inputctl->has_multiple_scans) { | |
#ifdef D_MULTISCAN_FILES_SUPPORTED | |
for (;;) { | |
int retcode; | |
/* Call progress monitor hook if present */ | |
if (cinfo->progress != NULL) | |
(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); | |
/* Absorb some more input */ | |
retcode = (*cinfo->inputctl->consume_input) (cinfo); | |
if (retcode == JPEG_SUSPENDED) | |
return FALSE; | |
if (retcode == JPEG_REACHED_EOI) | |
break; | |
/* Advance progress counter if appropriate */ | |
if (cinfo->progress != NULL && | |
(retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) { | |
if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) { | |
/* jdmaster underestimated number of scans; ratchet up one scan */ | |
cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows; | |
} | |
} | |
} | |
#else | |
ERREXIT(cinfo, JERR_NOT_COMPILED); | |
#endif /* D_MULTISCAN_FILES_SUPPORTED */ | |
} | |
cinfo->output_scan_number = cinfo->input_scan_number; | |
} else if (cinfo->global_state != DSTATE_PRESCAN) | |
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); | |
/* Perform any dummy output passes, and set up for the final pass */ | |
return output_pass_setup(cinfo); | |
} | |
/* | |
* Set up for an output pass, and perform any dummy pass(es) needed. | |
* Common subroutine for jpeg_start_decompress and jpeg_start_output. | |
* Entry: global_state = DSTATE_PRESCAN only if previously suspended. | |
* Exit: If done, returns TRUE and sets global_state for proper output mode. | |
* If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN. | |
*/ | |
LOCAL(boolean) | |
output_pass_setup (j_decompress_ptr cinfo) | |
{ | |
if (cinfo->global_state != DSTATE_PRESCAN) { | |
/* First call: do pass setup */ | |
(*cinfo->master->prepare_for_output_pass) (cinfo); | |
cinfo->output_scanline = 0; | |
cinfo->global_state = DSTATE_PRESCAN; | |
} | |
/* Loop over any required dummy passes */ | |
while (cinfo->master->is_dummy_pass) { | |
#ifdef QUANT_2PASS_SUPPORTED | |
/* Crank through the dummy pass */ | |
while (cinfo->output_scanline < cinfo->output_height) { | |
JDIMENSION last_scanline; | |
/* 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 */ | |
last_scanline = cinfo->output_scanline; | |
(*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL, | |
&cinfo->output_scanline, (JDIMENSION) 0); | |
if (cinfo->output_scanline == last_scanline) | |
return FALSE; /* No progress made, must suspend */ | |
} | |
/* Finish up dummy pass, and set up for another one */ | |
(*cinfo->master->finish_output_pass) (cinfo); | |
(*cinfo->master->prepare_for_output_pass) (cinfo); | |
cinfo->output_scanline = 0; | |
#else | |
ERREXIT(cinfo, JERR_NOT_COMPILED); | |
#endif /* QUANT_2PASS_SUPPORTED */ | |
} | |
/* Ready for application to drive output pass through | |
* jpeg_read_scanlines or jpeg_read_raw_data. | |
*/ | |
cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING; | |
return TRUE; | |
} | |
/* | |
* 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); | |
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); | |
} | |
/* 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 iMCU row per call, unless suspended. | |
*/ | |
GLOBAL(JDIMENSION) | |
jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data, | |
JDIMENSION max_lines) | |
{ | |
JDIMENSION lines_per_iMCU_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 iMCU row can be returned. */ | |
lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_v_scaled_size; | |
if (max_lines < lines_per_iMCU_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 iMCU row. */ | |
cinfo->output_scanline += lines_per_iMCU_row; | |
return lines_per_iMCU_row; | |
} | |
/* Additional entry points for buffered-image mode. */ | |
#ifdef D_MULTISCAN_FILES_SUPPORTED | |
/* | |
* Initialize for an output pass in buffered-image mode. | |
*/ | |
GLOBAL(boolean) | |
jpeg_start_output (j_decompress_ptr cinfo, int scan_number) | |
{ | |
if (cinfo->global_state != DSTATE_BUFIMAGE && | |
cinfo->global_state != DSTATE_PRESCAN) | |
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); | |
/* Limit scan number to valid range */ | |
if (scan_number <= 0) | |
scan_number = 1; | |
if (cinfo->inputctl->eoi_reached && | |
scan_number > cinfo->input_scan_number) | |
scan_number = cinfo->input_scan_number; | |
cinfo->output_scan_number = scan_number; | |
/* Perform any dummy output passes, and set up for the real pass */ | |
return output_pass_setup(cinfo); | |
} | |
/* | |
* Finish up after an output pass in buffered-image mode. | |
* | |
* Returns FALSE if suspended. The return value need be inspected only if | |
* a suspending data source is used. | |
*/ | |
GLOBAL(boolean) | |
jpeg_finish_output (j_decompress_ptr cinfo) | |
{ | |
if ((cinfo->global_state == DSTATE_SCANNING || | |
cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) { | |
/* Terminate this pass. */ | |
/* We do not require the whole pass to have been completed. */ | |
(*cinfo->master->finish_output_pass) (cinfo); | |
cinfo->global_state = DSTATE_BUFPOST; | |
} else if (cinfo->global_state != DSTATE_BUFPOST) { | |
/* BUFPOST = repeat call after a suspension, anything else is error */ | |
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); | |
} | |
/* Read markers looking for SOS or EOI */ | |
while (cinfo->input_scan_number <= cinfo->output_scan_number && | |
! cinfo->inputctl->eoi_reached) { | |
if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) | |
return FALSE; /* Suspend, come back later */ | |
} | |
cinfo->global_state = DSTATE_BUFIMAGE; | |
return TRUE; | |
} | |
#endif /* D_MULTISCAN_FILES_SUPPORTED */ |