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Quelle jcapistd.c Sprache: C |
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/*
* reserved comment block * DO NOT REMOVE OR ALTER! */ /* * jcapistd.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 compression half * of the JPEG library. These are the "standard" API routines that are * used in the normal full-compression case. They are not used by a * transcoding-only application. Note that if an application links in * jpeg_start_compress, it will end up linking in the entire compressor. * We thus must separate this file from jcapimin.c to avoid linking the * whole compression library into a transcoder. */ #define JPEG_INTERNALS #include "jinclude.h" #include "jpeglib.h" /* * Compression initialization. * Before calling this, all parameters and a data destination must be set up. * * We require a write_all_tables parameter as a failsafe check when writing * multiple datastreams from the same compression object. Since prior runs * will have left all the tables marked sent_table=TRUE, a subsequent run * would emit an abbreviated stream (no tables) by default. This may be what * is wanted, but for safety's sake it should not be the default behavior: * programmers should have to make a deliberate choice to emit abbreviated * images. Therefore the documentation and examples should encourage people * to pass write_all_tables=TRUE; then it will take active thought to do the * wrong thing. */ GLOBAL(void) jpeg_start_compress (j_compress_ptr cinfo, boolean write_all_tables) { if (cinfo->global_state != CSTATE_START) ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); if (write_all_tables) jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */ /* (Re)initialize error mgr and destination modules */ (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo); (*cinfo->dest->init_destination) (cinfo); /* Perform master selection of active modules */ jinit_compress_master(cinfo); /* Set up for the first pass */ (*cinfo->master->prepare_for_pass) (cinfo); /* Ready for application to drive first pass through jpeg_write_scanlines * or jpeg_write_raw_data. */ cinfo->next_scanline = 0; cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING); } /* * Write some scanlines of data to the JPEG compressor. * * The return value will be the number of lines actually written. * This should be less than the supplied num_lines only in case that * the data destination module has requested suspension of the compressor, * or if more than image_height scanlines are passed in. * * Note: we warn about excess calls to jpeg_write_scanlines() since * this likely signals an application programmer error. However, * excess scanlines passed in the last valid call are *silently* ignored, * so that the application need not adjust num_lines for end-of-image * when using a multiple-scanline buffer. */ GLOBAL(JDIMENSION) jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines, JDIMENSION num_lines) { JDIMENSION row_ctr, rows_left; if (cinfo->global_state != CSTATE_SCANNING) ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); if (cinfo->next_scanline >= cinfo->image_height) WARNMS(cinfo, JWRN_TOO_MUCH_DATA); /* Call progress monitor hook if present */ if (cinfo->progress != NULL) { cinfo->progress->pass_counter = (long) cinfo->next_scanline; cinfo->progress->pass_limit = (long) cinfo->image_height; (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); } /* Give master control module another chance if this is first call to * jpeg_write_scanlines. This lets output of the frame/scan headers be * delayed so that application can write COM, etc, markers between * jpeg_start_compress and jpeg_write_scanlines. */ if (cinfo->master->call_pass_startup) (*cinfo->master->pass_startup) (cinfo); /* Ignore any extra scanlines at bottom of image. */ rows_left = cinfo->image_height - cinfo->next_scanline; if (num_lines > rows_left) num_lines = rows_left; row_ctr = 0; (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines); cinfo->next_scanline += row_ctr; return row_ctr; } /* * Alternate entry point to write raw data. * Processes exactly one iMCU row per call, unless suspended. */ GLOBAL(JDIMENSION) jpeg_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data, JDIMENSION num_lines) { JDIMENSION lines_per_iMCU_row; if (cinfo->global_state != CSTATE_RAW_OK) ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); if (cinfo->next_scanline >= cinfo->image_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->next_scanline; cinfo->progress->pass_limit = (long) cinfo->image_height; (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); } /* Give master control module another chance if this is first call to * jpeg_write_raw_data. This lets output of the frame/scan headers be * delayed so that application can write COM, etc, markers between * jpeg_start_compress and jpeg_write_raw_data. */ if (cinfo->master->call_pass_startup) (*cinfo->master->pass_startup) (cinfo); /* Verify that at least one iMCU row has been passed. */ lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE; if (num_lines < lines_per_iMCU_row) ERREXIT(cinfo, JERR_BUFFER_SIZE); /* Directly compress the row. */ if (! (*cinfo->coef->compress_data) (cinfo, data)) { /* If compressor did not consume the whole row, suspend processing. */ return 0; } /* OK, we processed one iMCU row. */ cinfo->next_scanline += lines_per_iMCU_row; return lines_per_iMCU_row; } ¤ Dauer der Verarbeitung: 0.2 Sekunden (vorverarbeitet) ¤*© Formatika GbR, Deutschland |
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2026-03-28