1 /* 2 * jdapistd.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 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 { 40 if (cinfo->global_state == DSTATE_READY) { 41 /* First call: initialize master control, select active modules */ 42 jinit_master_decompress(cinfo); 43 if (cinfo->buffered_image) { 44 /* No more work here; expecting jpeg_start_output next */ 45 cinfo->global_state = DSTATE_BUFIMAGE; 46 return TRUE; 47 } 48 cinfo->global_state = DSTATE_PRELOAD; 49 } 50 if (cinfo->global_state == DSTATE_PRELOAD) { 51 /* If file has multiple scans, absorb them all into the coef buffer */ 52 if (cinfo->inputctl->has_multiple_scans) { 53 #ifdef D_MULTISCAN_FILES_SUPPORTED 54 for (;;) { 55 int retcode; 56 /* Call progress monitor hook if present */ 57 if (cinfo->progress != NULL) 58 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 59 /* Absorb some more input */ 60 retcode = (*cinfo->inputctl->consume_input) (cinfo); 61 if (retcode == JPEG_SUSPENDED) 62 return FALSE; 63 if (retcode == JPEG_REACHED_EOI) 64 break; 65 /* Advance progress counter if appropriate */ 66 if (cinfo->progress != NULL && 67 (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) { 68 if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) { 69 /* jdmaster underestimated number of scans; ratchet up one scan */ 70 cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows; 71 } 72 } 73 } 74 #else 75 ERREXIT(cinfo, JERR_NOT_COMPILED); 76 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 77 } 78 cinfo->output_scan_number = cinfo->input_scan_number; 79 } else if (cinfo->global_state != DSTATE_PRESCAN) 80 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 81 /* Perform any dummy output passes, and set up for the final pass */ 82 return output_pass_setup(cinfo); 83 } 84 85 /* 86 * Tile decompression initialization. 87 * jpeg_read_header must be completed before calling this. 88 */ 89 90 GLOBAL(boolean) 91 jpeg_start_tile_decompress (j_decompress_ptr cinfo) 92 { 93 if (cinfo->global_state == DSTATE_READY) { 94 /* First call: initialize master control, select active modules */ 95 cinfo->tile_decode = TRUE; 96 jinit_master_decompress(cinfo); 97 if (cinfo->buffered_image) { 98 cinfo->global_state = DSTATE_BUFIMAGE; 99 return TRUE; 100 } 101 cinfo->global_state = DSTATE_PRELOAD; 102 } 103 if (cinfo->global_state == DSTATE_PRELOAD) { 104 cinfo->output_scan_number = cinfo->input_scan_number; 105 } else if (cinfo->global_state != DSTATE_PRESCAN) 106 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 107 /* Perform any dummy output passes, and set up for the final pass */ 108 return output_pass_setup(cinfo); 109 } 110 111 112 /* 113 * Set up for an output pass, and perform any dummy pass(es) needed. 114 * Common subroutine for jpeg_start_decompress and jpeg_start_output. 115 * Entry: global_state = DSTATE_PRESCAN only if previously suspended. 116 * Exit: If done, returns TRUE and sets global_state for proper output mode. 117 * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN. 118 */ 119 120 LOCAL(boolean) 121 output_pass_setup (j_decompress_ptr cinfo) 122 { 123 if (cinfo->global_state != DSTATE_PRESCAN) { 124 /* First call: do pass setup */ 125 (*cinfo->master->prepare_for_output_pass) (cinfo); 126 cinfo->output_scanline = 0; 127 cinfo->global_state = DSTATE_PRESCAN; 128 } 129 /* Loop over any required dummy passes */ 130 while (cinfo->master->is_dummy_pass) { 131 #ifdef QUANT_2PASS_SUPPORTED 132 /* Crank through the dummy pass */ 133 while (cinfo->output_scanline < cinfo->output_height) { 134 JDIMENSION last_scanline; 135 /* Call progress monitor hook if present */ 136 if (cinfo->progress != NULL) { 137 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 138 cinfo->progress->pass_limit = (long) cinfo->output_height; 139 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 140 } 141 /* Process some data */ 142 last_scanline = cinfo->output_scanline; 143 (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL, 144 &cinfo->output_scanline, (JDIMENSION) 0); 145 if (cinfo->output_scanline == last_scanline) 146 return FALSE; /* No progress made, must suspend */ 147 } 148 /* Finish up dummy pass, and set up for another one */ 149 (*cinfo->master->finish_output_pass) (cinfo); 150 (*cinfo->master->prepare_for_output_pass) (cinfo); 151 cinfo->output_scanline = 0; 152 #else 153 ERREXIT(cinfo, JERR_NOT_COMPILED); 154 #endif /* QUANT_2PASS_SUPPORTED */ 155 } 156 /* Ready for application to drive output pass through 157 * jpeg_read_scanlines or jpeg_read_raw_data. 158 */ 159 cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING; 160 return TRUE; 161 } 162 163 164 /* 165 * Read some scanlines of data from the JPEG decompressor. 166 * 167 * The return value will be the number of lines actually read. 168 * This may be less than the number requested in several cases, 169 * including bottom of image, data source suspension, and operating 170 * modes that emit multiple scanlines at a time. 171 * 172 * Note: we warn about excess calls to jpeg_read_scanlines() since 173 * this likely signals an application programmer error. However, 174 * an oversize buffer (max_lines > scanlines remaining) is not an error. 175 */ 176 177 GLOBAL(JDIMENSION) 178 jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines, 179 JDIMENSION max_lines) 180 { 181 JDIMENSION row_ctr; 182 183 if (cinfo->global_state != DSTATE_SCANNING) 184 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 185 if (cinfo->output_scanline >= cinfo->output_height) { 186 WARNMS(cinfo, JWRN_TOO_MUCH_DATA); 187 return 0; 188 } 189 190 /* Call progress monitor hook if present */ 191 if (cinfo->progress != NULL) { 192 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 193 cinfo->progress->pass_limit = (long) cinfo->output_height; 194 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 195 } 196 197 /* Process some data */ 198 row_ctr = 0; 199 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines); 200 cinfo->output_scanline += row_ctr; 201 return row_ctr; 202 } 203 /* 204 * Initialize the jpeg decoder to decompressing a rectangle with size of (width, height) 205 * and its upper-left corner located at (start_x, start_y). 206 * Align start_x and start_y to multiplies of iMCU width and height, respectively. 207 * Also, the new reader position and sampled image size will be returned in 208 * (start_x, start_y) and (width, height), respectively. 209 */ 210 211 GLOBAL(void) 212 jpeg_init_read_tile_scanline(j_decompress_ptr cinfo, huffman_index *index, 213 int *start_x, int *start_y, int *width, int *height) 214 { 215 // Calculates the boundary of iMCU 216 int lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE; 217 int lines_per_iMCU_col = cinfo->max_h_samp_factor * DCTSIZE; 218 int row_offset = *start_y / lines_per_iMCU_row; 219 int col_left_boundary = ((*start_x / lines_per_iMCU_col) 220 / index->MCU_sample_size) * index->MCU_sample_size; 221 int col_right_boundary = 222 jdiv_round_up(*start_x + *width, lines_per_iMCU_col); 223 224 cinfo->coef->MCU_columns_to_skip = 225 *start_x / lines_per_iMCU_col - col_left_boundary; 226 227 *height = (*start_y - row_offset * lines_per_iMCU_row) + *height; 228 *start_x = col_left_boundary * lines_per_iMCU_col; 229 *start_y = row_offset * lines_per_iMCU_row; 230 cinfo->image_width = jmin(cinfo->original_image_width, 231 col_right_boundary * lines_per_iMCU_col) - 232 col_left_boundary * lines_per_iMCU_col; 233 cinfo->input_iMCU_row = row_offset; 234 cinfo->output_iMCU_row = row_offset; 235 236 // Updates JPEG decoder parameter 237 jinit_color_deconverter(cinfo); 238 jpeg_calc_output_dimensions(cinfo); 239 jinit_upsampler(cinfo); 240 (*cinfo->master->prepare_for_output_pass) (cinfo); 241 if (cinfo->progressive_mode) 242 (*cinfo->entropy->start_pass) (cinfo); 243 else 244 jpeg_decompress_per_scan_setup(cinfo); 245 246 int sample_size = DCTSIZE / cinfo->min_DCT_scaled_size; 247 248 *height = jdiv_round_up(*height, sample_size); 249 *width = cinfo->output_width; 250 cinfo->output_scanline = lines_per_iMCU_row * row_offset / sample_size; 251 cinfo->inputctl->consume_input = cinfo->coef->consume_data; 252 cinfo->inputctl->consume_input_build_huffman_index = 253 cinfo->coef->consume_data_build_huffman_index; 254 cinfo->entropy->index = index; 255 cinfo->input_iMCU_row = row_offset; 256 cinfo->output_iMCU_row = row_offset; 257 cinfo->coef->MCU_column_left_boundary = col_left_boundary; 258 cinfo->coef->MCU_column_right_boundary = col_right_boundary; 259 cinfo->coef->column_left_boundary = 260 col_left_boundary / index->MCU_sample_size; 261 cinfo->coef->column_right_boundary = 262 jdiv_round_up(col_right_boundary, index->MCU_sample_size); 263 } 264 265 /* 266 * Read a scanline from the current position. 267 * 268 * Return the number of lines actually read. 269 */ 270 271 GLOBAL(JDIMENSION) 272 jpeg_read_tile_scanline (j_decompress_ptr cinfo, huffman_index *index, 273 JSAMPARRAY scanlines) 274 { 275 // Calculates the boundary of iMCU 276 int lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE; 277 int lines_per_iMCU_col = cinfo->max_h_samp_factor * DCTSIZE; 278 int sample_size = DCTSIZE / cinfo->min_DCT_scaled_size; 279 JDIMENSION row_ctr = 0; 280 281 if (cinfo->progressive_mode) { 282 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, 1); 283 } else { 284 if (cinfo->output_scanline % (lines_per_iMCU_row / sample_size) == 0) { 285 // Set the read head to the next iMCU row 286 int iMCU_row_offset = cinfo->output_scanline / 287 (lines_per_iMCU_row / sample_size); 288 int offset_data_col_position = cinfo->coef->MCU_column_left_boundary / 289 index->MCU_sample_size; 290 huffman_offset_data offset_data = 291 index->scan[0].offset[iMCU_row_offset][offset_data_col_position]; 292 (*cinfo->entropy->configure_huffman_decoder) (cinfo, offset_data); 293 } 294 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, 1); 295 } 296 297 cinfo->output_scanline += row_ctr; 298 return row_ctr; 299 } 300 301 /* 302 * Alternate entry point to read raw data. 303 * Processes exactly one iMCU row per call, unless suspended. 304 */ 305 306 GLOBAL(JDIMENSION) 307 jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data, 308 JDIMENSION max_lines) 309 { 310 JDIMENSION lines_per_iMCU_row; 311 312 if (cinfo->global_state != DSTATE_RAW_OK) 313 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 314 if (cinfo->output_scanline >= cinfo->output_height) { 315 WARNMS(cinfo, JWRN_TOO_MUCH_DATA); 316 return 0; 317 } 318 319 /* Call progress monitor hook if present */ 320 if (cinfo->progress != NULL) { 321 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 322 cinfo->progress->pass_limit = (long) cinfo->output_height; 323 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 324 } 325 326 /* Verify that at least one iMCU row can be returned. */ 327 lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size; 328 if (max_lines < lines_per_iMCU_row) 329 ERREXIT(cinfo, JERR_BUFFER_SIZE); 330 331 /* Decompress directly into user's buffer. */ 332 if (! (*cinfo->coef->decompress_data) (cinfo, data)) 333 return 0; /* suspension forced, can do nothing more */ 334 335 /* OK, we processed one iMCU row. */ 336 cinfo->output_scanline += lines_per_iMCU_row; 337 return lines_per_iMCU_row; 338 } 339 340 341 /* Additional entry points for buffered-image mode. */ 342 343 #ifdef D_MULTISCAN_FILES_SUPPORTED 344 345 /* 346 * Initialize for an output pass in buffered-image mode. 347 */ 348 349 GLOBAL(boolean) 350 jpeg_start_output (j_decompress_ptr cinfo, int scan_number) 351 { 352 if (cinfo->global_state != DSTATE_BUFIMAGE && 353 cinfo->global_state != DSTATE_PRESCAN) 354 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 355 /* Limit scan number to valid range */ 356 if (scan_number <= 0) 357 scan_number = 1; 358 if (cinfo->inputctl->eoi_reached && 359 scan_number > cinfo->input_scan_number) 360 scan_number = cinfo->input_scan_number; 361 cinfo->output_scan_number = scan_number; 362 /* Perform any dummy output passes, and set up for the real pass */ 363 return output_pass_setup(cinfo); 364 } 365 366 367 /* 368 * Finish up after an output pass in buffered-image mode. 369 * 370 * Returns FALSE if suspended. The return value need be inspected only if 371 * a suspending data source is used. 372 */ 373 374 GLOBAL(boolean) 375 jpeg_finish_output (j_decompress_ptr cinfo) 376 { 377 if ((cinfo->global_state == DSTATE_SCANNING || 378 cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) { 379 /* Terminate this pass. */ 380 /* We do not require the whole pass to have been completed. */ 381 (*cinfo->master->finish_output_pass) (cinfo); 382 cinfo->global_state = DSTATE_BUFPOST; 383 } else if (cinfo->global_state != DSTATE_BUFPOST) { 384 /* BUFPOST = repeat call after a suspension, anything else is error */ 385 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 386 } 387 /* Read markers looking for SOS or EOI */ 388 while (cinfo->input_scan_number <= cinfo->output_scan_number && 389 ! cinfo->inputctl->eoi_reached) { 390 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) 391 return FALSE; /* Suspend, come back later */ 392 } 393 cinfo->global_state = DSTATE_BUFIMAGE; 394 return TRUE; 395 } 396 397 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 398
