1/* 2 * reserved comment block 3 * DO NOT REMOVE OR ALTER! 4 */ 5/* 6 * jcapistd.c 7 * 8 * Copyright (C) 1994-1996, Thomas G. Lane. 9 * This file is part of the Independent JPEG Group's software. 10 * For conditions of distribution and use, see the accompanying README file. 11 * 12 * This file contains application interface code for the compression half 13 * of the JPEG library. These are the "standard" API routines that are 14 * used in the normal full-compression case. They are not used by a 15 * transcoding-only application. Note that if an application links in 16 * jpeg_start_compress, it will end up linking in the entire compressor. 17 * We thus must separate this file from jcapimin.c to avoid linking the 18 * whole compression library into a transcoder. 19 */ 20 21#define JPEG_INTERNALS 22#include "jinclude.h" 23#include "jpeglib.h" 24 25 26/* 27 * Compression initialization. 28 * Before calling this, all parameters and a data destination must be set up. 29 * 30 * We require a write_all_tables parameter as a failsafe check when writing 31 * multiple datastreams from the same compression object. Since prior runs 32 * will have left all the tables marked sent_table=TRUE, a subsequent run 33 * would emit an abbreviated stream (no tables) by default. This may be what 34 * is wanted, but for safety's sake it should not be the default behavior: 35 * programmers should have to make a deliberate choice to emit abbreviated 36 * images. Therefore the documentation and examples should encourage people 37 * to pass write_all_tables=TRUE; then it will take active thought to do the 38 * wrong thing. 39 */ 40 41GLOBAL(void) 42jpeg_start_compress (j_compress_ptr cinfo, boolean write_all_tables) 43{ 44 if (cinfo->global_state != CSTATE_START) 45 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 46 47 if (write_all_tables) 48 jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */ 49 50 /* (Re)initialize error mgr and destination modules */ 51 (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo); 52 (*cinfo->dest->init_destination) (cinfo); 53 /* Perform master selection of active modules */ 54 jinit_compress_master(cinfo); 55 /* Set up for the first pass */ 56 (*cinfo->master->prepare_for_pass) (cinfo); 57 /* Ready for application to drive first pass through jpeg_write_scanlines 58 * or jpeg_write_raw_data. 59 */ 60 cinfo->next_scanline = 0; 61 cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING); 62} 63 64 65/* 66 * Write some scanlines of data to the JPEG compressor. 67 * 68 * The return value will be the number of lines actually written. 69 * This should be less than the supplied num_lines only in case that 70 * the data destination module has requested suspension of the compressor, 71 * or if more than image_height scanlines are passed in. 72 * 73 * Note: we warn about excess calls to jpeg_write_scanlines() since 74 * this likely signals an application programmer error. However, 75 * excess scanlines passed in the last valid call are *silently* ignored, 76 * so that the application need not adjust num_lines for end-of-image 77 * when using a multiple-scanline buffer. 78 */ 79 80GLOBAL(JDIMENSION) 81jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines, 82 JDIMENSION num_lines) 83{ 84 JDIMENSION row_ctr, rows_left; 85 86 if (cinfo->global_state != CSTATE_SCANNING) 87 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 88 if (cinfo->next_scanline >= cinfo->image_height) 89 WARNMS(cinfo, JWRN_TOO_MUCH_DATA); 90 91 /* Call progress monitor hook if present */ 92 if (cinfo->progress != NULL) { 93 cinfo->progress->pass_counter = (long) cinfo->next_scanline; 94 cinfo->progress->pass_limit = (long) cinfo->image_height; 95 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 96 } 97 98 /* Give master control module another chance if this is first call to 99 * jpeg_write_scanlines. This lets output of the frame/scan headers be 100 * delayed so that application can write COM, etc, markers between 101 * jpeg_start_compress and jpeg_write_scanlines. 102 */ 103 if (cinfo->master->call_pass_startup) 104 (*cinfo->master->pass_startup) (cinfo); 105 106 /* Ignore any extra scanlines at bottom of image. */ 107 rows_left = cinfo->image_height - cinfo->next_scanline; 108 if (num_lines > rows_left) 109 num_lines = rows_left; 110 111 row_ctr = 0; 112 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines); 113 cinfo->next_scanline += row_ctr; 114 return row_ctr; 115} 116 117 118/* 119 * Alternate entry point to write raw data. 120 * Processes exactly one iMCU row per call, unless suspended. 121 */ 122 123GLOBAL(JDIMENSION) 124jpeg_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data, 125 JDIMENSION num_lines) 126{ 127 JDIMENSION lines_per_iMCU_row; 128 129 if (cinfo->global_state != CSTATE_RAW_OK) 130 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 131 if (cinfo->next_scanline >= cinfo->image_height) { 132 WARNMS(cinfo, JWRN_TOO_MUCH_DATA); 133 return 0; 134 } 135 136 /* Call progress monitor hook if present */ 137 if (cinfo->progress != NULL) { 138 cinfo->progress->pass_counter = (long) cinfo->next_scanline; 139 cinfo->progress->pass_limit = (long) cinfo->image_height; 140 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 141 } 142 143 /* Give master control module another chance if this is first call to 144 * jpeg_write_raw_data. This lets output of the frame/scan headers be 145 * delayed so that application can write COM, etc, markers between 146 * jpeg_start_compress and jpeg_write_raw_data. 147 */ 148 if (cinfo->master->call_pass_startup) 149 (*cinfo->master->pass_startup) (cinfo); 150 151 /* Verify that at least one iMCU row has been passed. */ 152 lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE; 153 if (num_lines < lines_per_iMCU_row) 154 ERREXIT(cinfo, JERR_BUFFER_SIZE); 155 156 /* Directly compress the row. */ 157 if (! (*cinfo->coef->compress_data) (cinfo, data)) { 158 /* If compressor did not consume the whole row, suspend processing. */ 159 return 0; 160 } 161 162 /* OK, we processed one iMCU row. */ 163 cinfo->next_scanline += lines_per_iMCU_row; 164 return lines_per_iMCU_row; 165} 166