jdapistd.cpp (10522B)
1 /* 2 * jdapistd.c 3 * 4 * Copyright (C) 1994-1995, 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 decompression half 9 * of the JPEG library. These are the "standard" API routines that are 10 * used in the normal full-decompression case. They are not used by a 11 * transcoding-only application. Note that if an application links in 12 * jpeg_start_decompress, it will end up linking in the entire decompressor. 13 * We thus must separate this file from jdapimin.c to avoid linking the 14 * whole decompression library into a transcoder. 15 */ 16 17 #define JPEG_INTERNALS 18 #include "jinclude.h" 19 #include "jpeglib.h" 20 21 22 /* Forward declarations */ 23 LOCAL boolean output_pass_setup JPP( (j_decompress_ptr cinfo) ); 24 25 26 /* 27 * Decompression initialization. 28 * jpeg_read_header must be completed before calling this. 29 * 30 * If a multipass operating mode was selected, this will do all but the 31 * last pass, and thus may take a great deal of time. 32 * 33 * Returns FALSE if suspended. The return value need be inspected only if 34 * a suspending data source is used. 35 */ 36 37 GLOBAL boolean 38 jpeg_start_decompress( j_decompress_ptr cinfo ) { 39 if ( cinfo->global_state == DSTATE_READY ) { 40 /* First call: initialize master control, select active modules */ 41 jinit_master_decompress( cinfo ); 42 if ( cinfo->buffered_image ) { 43 /* No more work here; expecting jpeg_start_output next */ 44 cinfo->global_state = DSTATE_BUFIMAGE; 45 return TRUE; 46 } 47 cinfo->global_state = DSTATE_PRELOAD; 48 } 49 if ( cinfo->global_state == DSTATE_PRELOAD ) { 50 /* If file has multiple scans, absorb them all into the coef buffer */ 51 if ( cinfo->inputctl->has_multiple_scans ) { 52 #ifdef D_MULTISCAN_FILES_SUPPORTED 53 for (;; ) { 54 int retcode; 55 /* Call progress monitor hook if present */ 56 if ( cinfo->progress != NULL ) { 57 ( *cinfo->progress->progress_monitor )( (j_common_ptr) cinfo ); 58 } 59 /* Absorb some more input */ 60 retcode = ( *cinfo->inputctl->consume_input )( cinfo ); 61 if ( retcode == JPEG_SUSPENDED ) { 62 return FALSE; 63 } 64 if ( retcode == JPEG_REACHED_EOI ) { 65 break; 66 } 67 /* Advance progress counter if appropriate */ 68 if ( ( cinfo->progress != NULL ) && 69 ( ( retcode == JPEG_ROW_COMPLETED ) || ( retcode == JPEG_REACHED_SOS ) ) ) { 70 if ( ++cinfo->progress->pass_counter >= cinfo->progress->pass_limit ) { 71 /* jdmaster underestimated number of scans; ratchet up one scan */ 72 cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows; 73 } 74 } 75 } 76 #else 77 ERREXIT( cinfo, JERR_NOT_COMPILED ); 78 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 79 } 80 cinfo->output_scan_number = cinfo->input_scan_number; 81 } else if ( cinfo->global_state != DSTATE_PRESCAN ) { 82 ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state ); 83 } 84 /* Perform any dummy output passes, and set up for the final pass */ 85 return output_pass_setup( cinfo ); 86 } 87 88 89 /* 90 * Set up for an output pass, and perform any dummy pass(es) needed. 91 * Common subroutine for jpeg_start_decompress and jpeg_start_output. 92 * Entry: global_state = DSTATE_PRESCAN only if previously suspended. 93 * Exit: If done, returns TRUE and sets global_state for proper output mode. 94 * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN. 95 */ 96 97 LOCAL boolean 98 output_pass_setup( j_decompress_ptr cinfo ) { 99 if ( cinfo->global_state != DSTATE_PRESCAN ) { 100 /* First call: do pass setup */ 101 ( *cinfo->master->prepare_for_output_pass )( cinfo ); 102 cinfo->output_scanline = 0; 103 cinfo->global_state = DSTATE_PRESCAN; 104 } 105 /* Loop over any required dummy passes */ 106 while ( cinfo->master->is_dummy_pass ) { 107 #ifdef QUANT_2PASS_SUPPORTED 108 /* Crank through the dummy pass */ 109 while ( cinfo->output_scanline < cinfo->output_height ) { 110 JDIMENSION last_scanline; 111 /* Call progress monitor hook if present */ 112 if ( cinfo->progress != NULL ) { 113 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 114 cinfo->progress->pass_limit = (long) cinfo->output_height; 115 ( *cinfo->progress->progress_monitor )( (j_common_ptr) cinfo ); 116 } 117 /* Process some data */ 118 last_scanline = cinfo->output_scanline; 119 ( *cinfo->main->process_data )( cinfo, (JSAMPARRAY) NULL, 120 &cinfo->output_scanline, (JDIMENSION) 0 ); 121 if ( cinfo->output_scanline == last_scanline ) { 122 return FALSE; 123 } /* No progress made, must suspend */ 124 } 125 /* Finish up dummy pass, and set up for another one */ 126 ( *cinfo->master->finish_output_pass )( cinfo ); 127 ( *cinfo->master->prepare_for_output_pass )( cinfo ); 128 cinfo->output_scanline = 0; 129 #else 130 ERREXIT( cinfo, JERR_NOT_COMPILED ); 131 #endif /* QUANT_2PASS_SUPPORTED */ 132 } 133 /* Ready for application to drive output pass through 134 * jpeg_read_scanlines or jpeg_read_raw_data. 135 */ 136 cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING; 137 return TRUE; 138 } 139 140 141 /* 142 * Read some scanlines of data from the JPEG decompressor. 143 * 144 * The return value will be the number of lines actually read. 145 * This may be less than the number requested in several cases, 146 * including bottom of image, data source suspension, and operating 147 * modes that emit multiple scanlines at a time. 148 * 149 * Note: we warn about excess calls to jpeg_read_scanlines() since 150 * this likely signals an application programmer error. However, 151 * an oversize buffer (max_lines > scanlines remaining) is not an error. 152 */ 153 154 GLOBAL JDIMENSION 155 jpeg_read_scanlines( j_decompress_ptr cinfo, JSAMPARRAY scanlines, 156 JDIMENSION max_lines ) { 157 JDIMENSION row_ctr; 158 159 if ( cinfo->global_state != DSTATE_SCANNING ) { 160 ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state ); 161 } 162 if ( cinfo->output_scanline >= cinfo->output_height ) { 163 WARNMS( cinfo, JWRN_TOO_MUCH_DATA ); 164 return 0; 165 } 166 167 /* Call progress monitor hook if present */ 168 if ( cinfo->progress != NULL ) { 169 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 170 cinfo->progress->pass_limit = (long) cinfo->output_height; 171 ( *cinfo->progress->progress_monitor )( (j_common_ptr) cinfo ); 172 } 173 174 /* Process some data */ 175 row_ctr = 0; 176 ( *cinfo->main->process_data )( cinfo, scanlines, &row_ctr, max_lines ); 177 cinfo->output_scanline += row_ctr; 178 return row_ctr; 179 } 180 181 182 /* 183 * Alternate entry point to read raw data. 184 * Processes exactly one iMCU row per call, unless suspended. 185 */ 186 187 GLOBAL JDIMENSION 188 jpeg_read_raw_data( j_decompress_ptr cinfo, JSAMPIMAGE data, 189 JDIMENSION max_lines ) { 190 JDIMENSION lines_per_iMCU_row; 191 192 if ( cinfo->global_state != DSTATE_RAW_OK ) { 193 ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state ); 194 } 195 if ( cinfo->output_scanline >= cinfo->output_height ) { 196 WARNMS( cinfo, JWRN_TOO_MUCH_DATA ); 197 return 0; 198 } 199 200 /* Call progress monitor hook if present */ 201 if ( cinfo->progress != NULL ) { 202 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 203 cinfo->progress->pass_limit = (long) cinfo->output_height; 204 ( *cinfo->progress->progress_monitor )( (j_common_ptr) cinfo ); 205 } 206 207 /* Verify that at least one iMCU row can be returned. */ 208 lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size; 209 if ( max_lines < lines_per_iMCU_row ) { 210 ERREXIT( cinfo, JERR_BUFFER_SIZE ); 211 } 212 213 /* Decompress directly into user's buffer. */ 214 if ( !( *cinfo->coef->decompress_data )( cinfo, data ) ) { 215 return 0; 216 } /* suspension forced, can do nothing more */ 217 218 /* OK, we processed one iMCU row. */ 219 cinfo->output_scanline += lines_per_iMCU_row; 220 return lines_per_iMCU_row; 221 } 222 223 224 /* Additional entry points for buffered-image mode. */ 225 226 #ifdef D_MULTISCAN_FILES_SUPPORTED 227 228 /* 229 * Initialize for an output pass in buffered-image mode. 230 */ 231 232 GLOBAL boolean 233 jpeg_start_output( j_decompress_ptr cinfo, int scan_number ) { 234 if ( ( cinfo->global_state != DSTATE_BUFIMAGE ) && 235 ( cinfo->global_state != DSTATE_PRESCAN ) ) { 236 ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state ); 237 } 238 /* Limit scan number to valid range */ 239 if ( scan_number <= 0 ) { 240 scan_number = 1; 241 } 242 if ( ( cinfo->inputctl->eoi_reached ) && 243 ( scan_number > cinfo->input_scan_number ) ) { 244 scan_number = cinfo->input_scan_number; 245 } 246 cinfo->output_scan_number = scan_number; 247 /* Perform any dummy output passes, and set up for the real pass */ 248 return output_pass_setup( cinfo ); 249 } 250 251 252 /* 253 * Finish up after an output pass in buffered-image mode. 254 * 255 * Returns FALSE if suspended. The return value need be inspected only if 256 * a suspending data source is used. 257 */ 258 259 GLOBAL boolean 260 jpeg_finish_output( j_decompress_ptr cinfo ) { 261 if ( ( ( cinfo->global_state == DSTATE_SCANNING ) || 262 ( cinfo->global_state == DSTATE_RAW_OK ) && cinfo->buffered_image ) ) { 263 /* Terminate this pass. */ 264 /* We do not require the whole pass to have been completed. */ 265 ( *cinfo->master->finish_output_pass )( cinfo ); 266 cinfo->global_state = DSTATE_BUFPOST; 267 } else if ( cinfo->global_state != DSTATE_BUFPOST ) { 268 /* BUFPOST = repeat call after a suspension, anything else is error */ 269 ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state ); 270 } 271 /* Read markers looking for SOS or EOI */ 272 while ( cinfo->input_scan_number <= cinfo->output_scan_number && 273 !cinfo->inputctl->eoi_reached ) { 274 if ( ( *cinfo->inputctl->consume_input )( cinfo ) == JPEG_SUSPENDED ) { 275 return FALSE; 276 } /* Suspend, come back later */ 277 } 278 cinfo->global_state = DSTATE_BUFIMAGE; 279 return TRUE; 280 } 281 282 #endif /* D_MULTISCAN_FILES_SUPPORTED */