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276 lines
9.2 KiB
276 lines
9.2 KiB
/* |
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* jdapistd.c |
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* |
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* Copyright (C) 1994-1996, Thomas G. Lane. |
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* Modified 2002-2013 by Guido Vollbeding. |
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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 "standard" API routines that are |
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* used in the normal full-decompression case. They are not used by a |
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* transcoding-only application. Note that if an application links in |
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* jpeg_start_decompress, it will end up linking in the entire decompressor. |
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* We thus must separate this file from jdapimin.c to avoid linking the |
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* whole decompression library into a transcoder. |
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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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/* Forward declarations */ |
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LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo)); |
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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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* 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_start_decompress (j_decompress_ptr cinfo) |
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{ |
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if (cinfo->global_state == DSTATE_READY) { |
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/* First call: initialize master control, select active modules */ |
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jinit_master_decompress(cinfo); |
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if (cinfo->buffered_image) { |
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/* No more work here; expecting jpeg_start_output next */ |
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cinfo->global_state = DSTATE_BUFIMAGE; |
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return TRUE; |
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} |
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cinfo->global_state = DSTATE_PRELOAD; |
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} |
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if (cinfo->global_state == DSTATE_PRELOAD) { |
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/* If file has multiple scans, absorb them all into the coef buffer */ |
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if (cinfo->inputctl->has_multiple_scans) { |
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#ifdef D_MULTISCAN_FILES_SUPPORTED |
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for (;;) { |
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int retcode; |
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/* Call progress monitor hook if present */ |
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if (cinfo->progress != NULL) |
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(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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/* Absorb some more input */ |
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retcode = (*cinfo->inputctl->consume_input) (cinfo); |
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if (retcode == JPEG_SUSPENDED) |
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return FALSE; |
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if (retcode == JPEG_REACHED_EOI) |
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break; |
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/* Advance progress counter if appropriate */ |
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if (cinfo->progress != NULL && |
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(retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) { |
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if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) { |
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/* jdmaster underestimated number of scans; ratchet up one scan */ |
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cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows; |
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} |
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} |
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} |
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#else |
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ERREXIT(cinfo, JERR_NOT_COMPILED); |
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#endif /* D_MULTISCAN_FILES_SUPPORTED */ |
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} |
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cinfo->output_scan_number = cinfo->input_scan_number; |
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} else if (cinfo->global_state != DSTATE_PRESCAN) |
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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/* Perform any dummy output passes, and set up for the final pass */ |
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return output_pass_setup(cinfo); |
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} |
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/* |
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* Set up for an output pass, and perform any dummy pass(es) needed. |
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* Common subroutine for jpeg_start_decompress and jpeg_start_output. |
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* Entry: global_state = DSTATE_PRESCAN only if previously suspended. |
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* Exit: If done, returns TRUE and sets global_state for proper output mode. |
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* If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN. |
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*/ |
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LOCAL(boolean) |
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output_pass_setup (j_decompress_ptr cinfo) |
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{ |
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if (cinfo->global_state != DSTATE_PRESCAN) { |
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/* First call: do pass setup */ |
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(*cinfo->master->prepare_for_output_pass) (cinfo); |
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cinfo->output_scanline = 0; |
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cinfo->global_state = DSTATE_PRESCAN; |
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} |
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/* Loop over any required dummy passes */ |
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while (cinfo->master->is_dummy_pass) { |
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#ifdef QUANT_2PASS_SUPPORTED |
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/* Crank through the dummy pass */ |
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while (cinfo->output_scanline < cinfo->output_height) { |
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JDIMENSION last_scanline; |
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/* Call progress monitor hook if present */ |
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if (cinfo->progress != NULL) { |
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cinfo->progress->pass_counter = (long) cinfo->output_scanline; |
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cinfo->progress->pass_limit = (long) cinfo->output_height; |
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(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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} |
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/* Process some data */ |
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last_scanline = cinfo->output_scanline; |
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(*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL, |
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&cinfo->output_scanline, (JDIMENSION) 0); |
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if (cinfo->output_scanline == last_scanline) |
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return FALSE; /* No progress made, must suspend */ |
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} |
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/* Finish up dummy pass, and set up for another one */ |
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(*cinfo->master->finish_output_pass) (cinfo); |
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(*cinfo->master->prepare_for_output_pass) (cinfo); |
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cinfo->output_scanline = 0; |
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#else |
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ERREXIT(cinfo, JERR_NOT_COMPILED); |
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#endif /* QUANT_2PASS_SUPPORTED */ |
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} |
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/* Ready for application to drive output pass through |
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* jpeg_read_scanlines or jpeg_read_raw_data. |
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*/ |
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cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING; |
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return TRUE; |
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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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* Note: we warn about excess calls to jpeg_read_scanlines() since |
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* this likely signals an application programmer error. However, |
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* an oversize buffer (max_lines > scanlines remaining) is not an error. |
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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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if (cinfo->output_scanline >= cinfo->output_height) { |
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WARNMS(cinfo, JWRN_TOO_MUCH_DATA); |
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return 0; |
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} |
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/* Call progress monitor hook if present */ |
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if (cinfo->progress != NULL) { |
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cinfo->progress->pass_counter = (long) cinfo->output_scanline; |
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cinfo->progress->pass_limit = (long) cinfo->output_height; |
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(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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} |
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/* Process some data */ |
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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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* Alternate entry point to read raw data. |
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* Processes exactly one iMCU row per call, unless suspended. |
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*/ |
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GLOBAL(JDIMENSION) |
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jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data, |
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JDIMENSION max_lines) |
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{ |
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JDIMENSION lines_per_iMCU_row; |
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if (cinfo->global_state != DSTATE_RAW_OK) |
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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if (cinfo->output_scanline >= cinfo->output_height) { |
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WARNMS(cinfo, JWRN_TOO_MUCH_DATA); |
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return 0; |
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} |
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/* Call progress monitor hook if present */ |
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if (cinfo->progress != NULL) { |
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cinfo->progress->pass_counter = (long) cinfo->output_scanline; |
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cinfo->progress->pass_limit = (long) cinfo->output_height; |
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(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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} |
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/* Verify that at least one iMCU row can be returned. */ |
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lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_v_scaled_size; |
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if (max_lines < lines_per_iMCU_row) |
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ERREXIT(cinfo, JERR_BUFFER_SIZE); |
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/* Decompress directly into user's buffer. */ |
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if (! (*cinfo->coef->decompress_data) (cinfo, data)) |
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return 0; /* suspension forced, can do nothing more */ |
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/* OK, we processed one iMCU row. */ |
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cinfo->output_scanline += lines_per_iMCU_row; |
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return lines_per_iMCU_row; |
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} |
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/* Additional entry points for buffered-image mode. */ |
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#ifdef D_MULTISCAN_FILES_SUPPORTED |
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/* |
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* Initialize for an output pass in buffered-image mode. |
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*/ |
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GLOBAL(boolean) |
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jpeg_start_output (j_decompress_ptr cinfo, int scan_number) |
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{ |
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if (cinfo->global_state != DSTATE_BUFIMAGE && |
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cinfo->global_state != DSTATE_PRESCAN) |
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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/* Limit scan number to valid range */ |
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if (scan_number <= 0) |
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scan_number = 1; |
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if (cinfo->inputctl->eoi_reached && |
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scan_number > cinfo->input_scan_number) |
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scan_number = cinfo->input_scan_number; |
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cinfo->output_scan_number = scan_number; |
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/* Perform any dummy output passes, and set up for the real pass */ |
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return output_pass_setup(cinfo); |
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} |
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/* |
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* Finish up after an output pass in buffered-image mode. |
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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_output (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 this pass. */ |
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/* We do not require the whole pass to have been completed. */ |
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(*cinfo->master->finish_output_pass) (cinfo); |
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cinfo->global_state = DSTATE_BUFPOST; |
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} else if (cinfo->global_state != DSTATE_BUFPOST) { |
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/* BUFPOST = 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 markers looking for SOS or EOI */ |
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while (cinfo->input_scan_number <= cinfo->output_scan_number && |
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! 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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cinfo->global_state = DSTATE_BUFIMAGE; |
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return TRUE; |
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} |
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#endif /* D_MULTISCAN_FILES_SUPPORTED */
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