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