jdapistd.c (9348B)
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 /* 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 94 LOCAL(boolean) 95 output_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 */ 150 151 GLOBAL(JDIMENSION) 152 jpeg_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 } 177 178 179 /* 180 * Alternate entry point to read raw data. 181 * Processes exactly one iMCU row per call, unless suspended. 182 */ 183 184 GLOBAL(JDIMENSION) 185 jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data, 186 JDIMENSION max_lines) 187 { 188 JDIMENSION lines_per_iMCU_row; 189 190 if (cinfo->global_state != DSTATE_RAW_OK) 191 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 192 if (cinfo->output_scanline >= cinfo->output_height) { 193 WARNMS(cinfo, JWRN_TOO_MUCH_DATA); 194 return 0; 195 } 196 197 /* Call progress monitor hook if present */ 198 if (cinfo->progress != NULL) { 199 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 200 cinfo->progress->pass_limit = (long) cinfo->output_height; 201 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 202 } 203 204 /* Verify that at least one iMCU row can be returned. */ 205 lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size; 206 if (max_lines < lines_per_iMCU_row) 207 ERREXIT(cinfo, JERR_BUFFER_SIZE); 208 209 /* Decompress directly into user's buffer. */ 210 if (! (*cinfo->coef->decompress_data) (cinfo, data)) 211 return 0; /* suspension forced, can do nothing more */ 212 213 /* OK, we processed one iMCU row. */ 214 cinfo->output_scanline += lines_per_iMCU_row; 215 return lines_per_iMCU_row; 216 } 217 218 219 /* Additional entry points for buffered-image mode. */ 220 221 #ifdef D_MULTISCAN_FILES_SUPPORTED 222 223 /* 224 * Initialize for an output pass in buffered-image mode. 225 */ 226 227 GLOBAL(boolean) 228 jpeg_start_output (j_decompress_ptr cinfo, int scan_number) 229 { 230 if (cinfo->global_state != DSTATE_BUFIMAGE && 231 cinfo->global_state != DSTATE_PRESCAN) 232 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 233 /* Limit scan number to valid range */ 234 if (scan_number <= 0) 235 scan_number = 1; 236 if (cinfo->inputctl->eoi_reached && 237 scan_number > cinfo->input_scan_number) 238 scan_number = cinfo->input_scan_number; 239 cinfo->output_scan_number = scan_number; 240 /* Perform any dummy output passes, and set up for the real pass */ 241 return output_pass_setup(cinfo); 242 } 243 244 245 /* 246 * Finish up after an output pass in buffered-image mode. 247 * 248 * Returns FALSE if suspended. The return value need be inspected only if 249 * a suspending data source is used. 250 */ 251 252 GLOBAL(boolean) 253 jpeg_finish_output (j_decompress_ptr cinfo) 254 { 255 if ((cinfo->global_state == DSTATE_SCANNING || 256 cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) { 257 /* Terminate this pass. */ 258 /* We do not require the whole pass to have been completed. */ 259 (*cinfo->master->finish_output_pass) (cinfo); 260 cinfo->global_state = DSTATE_BUFPOST; 261 } else if (cinfo->global_state != DSTATE_BUFPOST) { 262 /* BUFPOST = repeat call after a suspension, anything else is error */ 263 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 264 } 265 /* Read markers looking for SOS or EOI */ 266 while (cinfo->input_scan_number <= cinfo->output_scan_number && 267 ! cinfo->inputctl->eoi_reached) { 268 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) 269 return FALSE; /* Suspend, come back later */ 270 } 271 cinfo->global_state = DSTATE_BUFIMAGE; 272 return TRUE; 273 } 274 275 #endif /* D_MULTISCAN_FILES_SUPPORTED */