152 lines
5.8 KiB
C++
152 lines
5.8 KiB
C++
// * jcapistd.c
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// *
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// * Copyright (C) 1994-1995, 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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#define JPEG_INTERNALS
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#include "JINCLUDE.h"
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#include "JPEGLIB.h"
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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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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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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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// * 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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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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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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// * Alternate entry point to write raw data.
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// * Processes exactly one iMCU row per call, unless suspended.
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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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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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