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161 lines
5.7 KiB
161 lines
5.7 KiB
/* |
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* jcapistd.c |
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* |
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* Copyright (C) 1994-1996, 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 compression 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-compression 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_compress, it will end up linking in the entire compressor. |
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* We thus must separate this file from jcapimin.c to avoid linking the |
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* whole compression 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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/* |
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* Compression initialization. |
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* Before calling this, all parameters and a data destination must be set up. |
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* |
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* We require a write_all_tables parameter as a failsafe check when writing |
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* multiple datastreams from the same compression object. Since prior runs |
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* will have left all the tables marked sent_table=TRUE, a subsequent run |
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* would emit an abbreviated stream (no tables) by default. This may be what |
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* is wanted, but for safety's sake it should not be the default behavior: |
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* programmers should have to make a deliberate choice to emit abbreviated |
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* images. Therefore the documentation and examples should encourage people |
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* to pass write_all_tables=TRUE; then it will take active thought to do the |
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* wrong thing. |
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*/ |
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GLOBAL(void) |
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jpeg_start_compress (j_compress_ptr cinfo, boolean write_all_tables) |
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{ |
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if (cinfo->global_state != CSTATE_START) |
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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if (write_all_tables) |
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jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */ |
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/* (Re)initialize error mgr and destination modules */ |
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(*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo); |
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(*cinfo->dest->init_destination) (cinfo); |
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/* Perform master selection of active modules */ |
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jinit_compress_master(cinfo); |
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/* Set up for the first pass */ |
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(*cinfo->master->prepare_for_pass) (cinfo); |
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/* Ready for application to drive first pass through jpeg_write_scanlines |
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* or jpeg_write_raw_data. |
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*/ |
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cinfo->next_scanline = 0; |
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cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING); |
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} |
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/* |
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* Write some scanlines of data to the JPEG compressor. |
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* |
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* The return value will be the number of lines actually written. |
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* This should be less than the supplied num_lines only in case that |
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* the data destination module has requested suspension of the compressor, |
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* or if more than image_height scanlines are passed in. |
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* |
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* Note: we warn about excess calls to jpeg_write_scanlines() since |
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* this likely signals an application programmer error. However, |
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* excess scanlines passed in the last valid call are *silently* ignored, |
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* so that the application need not adjust num_lines for end-of-image |
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* when using a multiple-scanline buffer. |
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*/ |
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GLOBAL(JDIMENSION) |
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jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines, |
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JDIMENSION num_lines) |
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{ |
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JDIMENSION row_ctr, rows_left; |
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if (cinfo->global_state != CSTATE_SCANNING) |
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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if (cinfo->next_scanline >= cinfo->image_height) |
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WARNMS(cinfo, JWRN_TOO_MUCH_DATA); |
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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->next_scanline; |
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cinfo->progress->pass_limit = (long) cinfo->image_height; |
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(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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} |
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/* Give master control module another chance if this is first call to |
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* jpeg_write_scanlines. This lets output of the frame/scan headers be |
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* delayed so that application can write COM, etc, markers between |
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* jpeg_start_compress and jpeg_write_scanlines. |
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*/ |
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if (cinfo->master->call_pass_startup) |
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(*cinfo->master->pass_startup) (cinfo); |
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/* Ignore any extra scanlines at bottom of image. */ |
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rows_left = cinfo->image_height - cinfo->next_scanline; |
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if (num_lines > rows_left) |
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num_lines = rows_left; |
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row_ctr = 0; |
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(*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines); |
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cinfo->next_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 write 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_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data, |
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JDIMENSION num_lines) |
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{ |
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JDIMENSION lines_per_iMCU_row; |
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if (cinfo->global_state != CSTATE_RAW_OK) |
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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if (cinfo->next_scanline >= cinfo->image_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->next_scanline; |
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cinfo->progress->pass_limit = (long) cinfo->image_height; |
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(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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} |
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/* Give master control module another chance if this is first call to |
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* jpeg_write_raw_data. This lets output of the frame/scan headers be |
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* delayed so that application can write COM, etc, markers between |
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* jpeg_start_compress and jpeg_write_raw_data. |
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*/ |
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if (cinfo->master->call_pass_startup) |
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(*cinfo->master->pass_startup) (cinfo); |
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/* Verify that at least one iMCU row has been passed. */ |
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lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE; |
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if (num_lines < lines_per_iMCU_row) |
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ERREXIT(cinfo, JERR_BUFFER_SIZE); |
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/* Directly compress the row. */ |
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if (! (*cinfo->coef->compress_data) (cinfo, data)) { |
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/* If compressor did not consume the whole row, suspend processing. */ |
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return 0; |
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} |
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/* OK, we processed one iMCU row. */ |
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cinfo->next_scanline += lines_per_iMCU_row; |
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return lines_per_iMCU_row; |
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}
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