jdapistd.c revision 3147fbe7688fc353e6ae03825a37cf101a4ee01d
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 */ 23LOCAL(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 37GLOBAL(boolean) 38jpeg_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/* 87 * Set up for an output pass, and perform any dummy pass(es) needed. 88 * Common subroutine for jpeg_start_decompress and jpeg_start_output. 89 * Entry: global_state = DSTATE_PRESCAN only if previously suspended. 90 * Exit: If done, returns TRUE and sets global_state for proper output mode. 91 * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN. 92 */ 93 94LOCAL(boolean) 95output_pass_setup (j_decompress_ptr cinfo) 96{ 97 if (cinfo->global_state != DSTATE_PRESCAN) { 98 /* First call: do pass setup */ 99 (*cinfo->master->prepare_for_output_pass) (cinfo); 100 cinfo->output_scanline = 0; 101 cinfo->global_state = DSTATE_PRESCAN; 102 } 103 /* Loop over any required dummy passes */ 104 while (cinfo->master->is_dummy_pass) { 105#ifdef QUANT_2PASS_SUPPORTED 106 /* Crank through the dummy pass */ 107 while (cinfo->output_scanline < cinfo->output_height) { 108 JDIMENSION last_scanline; 109 /* Call progress monitor hook if present */ 110 if (cinfo->progress != NULL) { 111 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 112 cinfo->progress->pass_limit = (long) cinfo->output_height; 113 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 114 } 115 /* Process some data */ 116 last_scanline = cinfo->output_scanline; 117 (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL, 118 &cinfo->output_scanline, (JDIMENSION) 0); 119 if (cinfo->output_scanline == last_scanline) 120 return FALSE; /* No progress made, must suspend */ 121 } 122 /* Finish up dummy pass, and set up for another one */ 123 (*cinfo->master->finish_output_pass) (cinfo); 124 (*cinfo->master->prepare_for_output_pass) (cinfo); 125 cinfo->output_scanline = 0; 126#else 127 ERREXIT(cinfo, JERR_NOT_COMPILED); 128#endif /* QUANT_2PASS_SUPPORTED */ 129 } 130 /* Ready for application to drive output pass through 131 * jpeg_read_scanlines or jpeg_read_raw_data. 132 */ 133 cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING; 134 return TRUE; 135} 136 137 138/* 139 * Read some scanlines of data from the JPEG decompressor. 140 * 141 * The return value will be the number of lines actually read. 142 * This may be less than the number requested in several cases, 143 * including bottom of image, data source suspension, and operating 144 * modes that emit multiple scanlines at a time. 145 * 146 * Note: we warn about excess calls to jpeg_read_scanlines() since 147 * this likely signals an application programmer error. However, 148 * an oversize buffer (max_lines > scanlines remaining) is not an error. 149 */ 150 151GLOBAL(JDIMENSION) 152jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines, 153 JDIMENSION max_lines) 154{ 155 JDIMENSION row_ctr; 156 157 if (cinfo->global_state != DSTATE_SCANNING) 158 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 159 if (cinfo->output_scanline >= cinfo->output_height) { 160 WARNMS(cinfo, JWRN_TOO_MUCH_DATA); 161 return 0; 162 } 163 164 /* Call progress monitor hook if present */ 165 if (cinfo->progress != NULL) { 166 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 167 cinfo->progress->pass_limit = (long) cinfo->output_height; 168 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 169 } 170 171 /* Process some data */ 172 row_ctr = 0; 173 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines); 174 cinfo->output_scanline += row_ctr; 175 return row_ctr; 176} 177/* 178 * Initialize the jpeg decoder to decompressing a rectangle with size of (width, height) 179 * and its upper-left corner located at (start_x, start_y). 180 * Align start_x and start_y to multiplies of iMCU width and height, respectively. 181 * Also, the new reader position will be returned in (start_x, start_y). 182 */ 183 184GLOBAL(void) 185jpeg_init_read_tile_scanline(j_decompress_ptr cinfo, huffman_index *index, 186 int *start_x, int *start_y, int *width, int *height) 187{ 188 // Calculates the boundary of iMCU 189 int lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE; 190 int lines_per_iMCU_col = cinfo->max_h_samp_factor * DCTSIZE; 191 int row_offset = *start_y / lines_per_iMCU_row; 192 int col_left_boundary = ((*start_x / lines_per_iMCU_col) / index->MCU_sample_size) 193 * index->MCU_sample_size; 194 int col_right_boundary = (*start_x + *width + lines_per_iMCU_col - 1) / lines_per_iMCU_col; 195 196 *height = (*start_y - row_offset * lines_per_iMCU_row) + *height; 197 *start_x = col_left_boundary * lines_per_iMCU_col; 198 *start_y = row_offset * lines_per_iMCU_row; 199 cinfo->image_width = (col_right_boundary - col_left_boundary) * lines_per_iMCU_col; 200 cinfo->input_iMCU_row = row_offset; 201 cinfo->output_iMCU_row = row_offset; 202 203 // Updates JPEG decoder parameter 204 jinit_color_deconverter(cinfo); 205 jpeg_calc_output_dimensions(cinfo); 206 jinit_upsampler(cinfo); 207 jpeg_decompress_per_scan_setup(cinfo); 208 cinfo->MCUs_per_row = col_right_boundary - col_left_boundary; 209 210 int sampleSize = cinfo->image_width / cinfo->output_width; 211 *height /= sampleSize; 212 *width = cinfo->output_width; 213 cinfo->output_scanline = lines_per_iMCU_row * row_offset / sampleSize; 214 (*cinfo->master->prepare_for_output_pass) (cinfo); 215} 216 217/* 218 * Read a scanline from the current position. 219 * 220 * Return the number of lines actually read. 221 */ 222 223GLOBAL(JDIMENSION) 224jpeg_read_tile_scanline (j_decompress_ptr cinfo, huffman_index *index, 225 JSAMPARRAY scanlines, int start_x, int start_y, int width, int height) 226{ 227 // Calculates the boundary of iMCU 228 int lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE; 229 int lines_per_iMCU_col = cinfo->max_h_samp_factor * DCTSIZE; 230 int col_left_boundary = ((start_x / lines_per_iMCU_col) / index->MCU_sample_size) 231 * index->MCU_sample_size; 232 int sampleSize = cinfo->image_width / cinfo->output_width; 233 234 if (cinfo->output_scanline % (lines_per_iMCU_row / sampleSize) == 0) { 235 // Set the read head to the next iMCU row 236 cinfo->unread_marker = 0; 237 int iMCU_row_offset = cinfo->output_scanline / (lines_per_iMCU_row / sampleSize); 238 int offset_data_col_position = col_left_boundary / index->MCU_sample_size; 239 huffman_offset_data *offset_data = 240 &index->scan[0].offset[iMCU_row_offset][offset_data_col_position]; 241 242 jpeg_configure_huffman_decoder(cinfo, 243 offset_data->bitstream_offset, offset_data->prev_dc); 244 } 245 246 int row_ctr = jpeg_read_scanlines(cinfo, scanlines, 1); // Read one line 247 return row_ctr; 248} 249 250 251/* 252 * Alternate entry point to read raw data. 253 * Processes exactly one iMCU row per call, unless suspended. 254 */ 255 256GLOBAL(JDIMENSION) 257jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data, 258 JDIMENSION max_lines) 259{ 260 JDIMENSION lines_per_iMCU_row; 261 262 if (cinfo->global_state != DSTATE_RAW_OK) 263 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 264 if (cinfo->output_scanline >= cinfo->output_height) { 265 WARNMS(cinfo, JWRN_TOO_MUCH_DATA); 266 return 0; 267 } 268 269 /* Call progress monitor hook if present */ 270 if (cinfo->progress != NULL) { 271 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 272 cinfo->progress->pass_limit = (long) cinfo->output_height; 273 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 274 } 275 276 /* Verify that at least one iMCU row can be returned. */ 277 lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size; 278 if (max_lines < lines_per_iMCU_row) 279 ERREXIT(cinfo, JERR_BUFFER_SIZE); 280 281 /* Decompress directly into user's buffer. */ 282 if (! (*cinfo->coef->decompress_data) (cinfo, data)) 283 return 0; /* suspension forced, can do nothing more */ 284 285 /* OK, we processed one iMCU row. */ 286 cinfo->output_scanline += lines_per_iMCU_row; 287 return lines_per_iMCU_row; 288} 289 290 291/* Additional entry points for buffered-image mode. */ 292 293#ifdef D_MULTISCAN_FILES_SUPPORTED 294 295/* 296 * Initialize for an output pass in buffered-image mode. 297 */ 298 299GLOBAL(boolean) 300jpeg_start_output (j_decompress_ptr cinfo, int scan_number) 301{ 302 if (cinfo->global_state != DSTATE_BUFIMAGE && 303 cinfo->global_state != DSTATE_PRESCAN) 304 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 305 /* Limit scan number to valid range */ 306 if (scan_number <= 0) 307 scan_number = 1; 308 if (cinfo->inputctl->eoi_reached && 309 scan_number > cinfo->input_scan_number) 310 scan_number = cinfo->input_scan_number; 311 cinfo->output_scan_number = scan_number; 312 /* Perform any dummy output passes, and set up for the real pass */ 313 return output_pass_setup(cinfo); 314} 315 316 317/* 318 * Finish up after an output pass in buffered-image mode. 319 * 320 * Returns FALSE if suspended. The return value need be inspected only if 321 * a suspending data source is used. 322 */ 323 324GLOBAL(boolean) 325jpeg_finish_output (j_decompress_ptr cinfo) 326{ 327 if ((cinfo->global_state == DSTATE_SCANNING || 328 cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) { 329 /* Terminate this pass. */ 330 /* We do not require the whole pass to have been completed. */ 331 (*cinfo->master->finish_output_pass) (cinfo); 332 cinfo->global_state = DSTATE_BUFPOST; 333 } else if (cinfo->global_state != DSTATE_BUFPOST) { 334 /* BUFPOST = repeat call after a suspension, anything else is error */ 335 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 336 } 337 /* Read markers looking for SOS or EOI */ 338 while (cinfo->input_scan_number <= cinfo->output_scan_number && 339 ! cinfo->inputctl->eoi_reached) { 340 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) 341 return FALSE; /* Suspend, come back later */ 342 } 343 cinfo->global_state = DSTATE_BUFIMAGE; 344 return TRUE; 345} 346 347#endif /* D_MULTISCAN_FILES_SUPPORTED */ 348