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