1 /* 2 * jdapistd.c 3 * 4 * Copyright (C) 1994-1996, Thomas G. Lane. 5 * Modified 2002-2013 by Guido Vollbeding. 6 * This file is part of the Independent JPEG Group's software. 7 * For conditions of distribution and use, see the accompanying README file. 8 * 9 * This file contains application interface code for the decompression half 10 * of the JPEG library. These are the "standard" API routines that are 11 * used in the normal full-decompression case. They are not used by a 12 * transcoding-only application. Note that if an application links in 13 * jpeg_start_decompress, it will end up linking in the entire decompressor. 14 * We thus must separate this file from jdapimin.c to avoid linking the 15 * whole decompression library into a transcoder. 16 */ 17 18 #define JPEG_INTERNALS 19 #include "jinclude.h" 20 #include "jpeglib.h" 21 22 23 /* Forward declarations */ 24 LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo)); 25 26 27 /* 28 * Decompression initialization. 29 * jpeg_read_header must be completed before calling this. 30 * 31 * If a multipass operating mode was selected, this will do all but the 32 * last pass, and thus may take a great deal of time. 33 * 34 * Returns FALSE if suspended. The return value need be inspected only if 35 * a suspending data source is used. 36 */ 37 38 GLOBAL(boolean) 39 jpeg_start_decompress (j_decompress_ptr cinfo) 40 { 41 if (cinfo->global_state == DSTATE_READY) { 42 /* First call: initialize master control, select active modules */ 43 jinit_master_decompress(cinfo); 44 if (cinfo->buffered_image) { 45 /* No more work here; expecting jpeg_start_output next */ 46 cinfo->global_state = DSTATE_BUFIMAGE; 47 return TRUE; 48 } 49 cinfo->global_state = DSTATE_PRELOAD; 50 } 51 if (cinfo->global_state == DSTATE_PRELOAD) { 52 /* If file has multiple scans, absorb them all into the coef buffer */ 53 if (cinfo->inputctl->has_multiple_scans) { 54 #ifdef D_MULTISCAN_FILES_SUPPORTED 55 for (;;) { 56 int retcode; 57 /* Call progress monitor hook if present */ 58 if (cinfo->progress != NULL) 59 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 60 /* Absorb some more input */ 61 retcode = (*cinfo->inputctl->consume_input) (cinfo); 62 if (retcode == JPEG_SUSPENDED) 63 return FALSE; 64 if (retcode == JPEG_REACHED_EOI) 65 break; 66 /* Advance progress counter if appropriate */ 67 if (cinfo->progress != NULL && 68 (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) { 69 if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) { 70 /* jdmaster underestimated number of scans; ratchet up one scan */ 71 cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows; 72 } 73 } 74 } 75 #else 76 ERREXIT(cinfo, JERR_NOT_COMPILED); 77 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 78 } 79 cinfo->output_scan_number = cinfo->input_scan_number; 80 } else if (cinfo->global_state != DSTATE_PRESCAN) 81 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 82 /* Perform any dummy output passes, and set up for the final pass */ 83 return output_pass_setup(cinfo); 84 } 85 86 87 /* 88 * Set up for an output pass, and perform any dummy pass(es) needed. 89 * Common subroutine for jpeg_start_decompress and jpeg_start_output. 90 * Entry: global_state = DSTATE_PRESCAN only if previously suspended. 91 * Exit: If done, returns TRUE and sets global_state for proper output mode. 92 * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN. 93 */ 94 95 LOCAL(boolean) 96 output_pass_setup (j_decompress_ptr cinfo) 97 { 98 if (cinfo->global_state != DSTATE_PRESCAN) { 99 /* First call: do pass setup */ 100 (*cinfo->master->prepare_for_output_pass) (cinfo); 101 cinfo->output_scanline = 0; 102 cinfo->global_state = DSTATE_PRESCAN; 103 } 104 /* Loop over any required dummy passes */ 105 while (cinfo->master->is_dummy_pass) { 106 #ifdef QUANT_2PASS_SUPPORTED 107 /* Crank through the dummy pass */ 108 while (cinfo->output_scanline < cinfo->output_height) { 109 JDIMENSION last_scanline; 110 /* Call progress monitor hook if present */ 111 if (cinfo->progress != NULL) { 112 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 113 cinfo->progress->pass_limit = (long) cinfo->output_height; 114 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 115 } 116 /* Process some data */ 117 last_scanline = cinfo->output_scanline; 118 (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL, 119 &cinfo->output_scanline, (JDIMENSION) 0); 120 if (cinfo->output_scanline == last_scanline) 121 return FALSE; /* No progress made, must suspend */ 122 } 123 /* Finish up dummy pass, and set up for another one */ 124 (*cinfo->master->finish_output_pass) (cinfo); 125 (*cinfo->master->prepare_for_output_pass) (cinfo); 126 cinfo->output_scanline = 0; 127 #else 128 ERREXIT(cinfo, JERR_NOT_COMPILED); 129 #endif /* QUANT_2PASS_SUPPORTED */ 130 } 131 /* Ready for application to drive output pass through 132 * jpeg_read_scanlines or jpeg_read_raw_data. 133 */ 134 cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING; 135 return TRUE; 136 } 137 138 139 /* 140 * Read some scanlines of data from the JPEG decompressor. 141 * 142 * The return value will be the number of lines actually read. 143 * This may be less than the number requested in several cases, 144 * including bottom of image, data source suspension, and operating 145 * modes that emit multiple scanlines at a time. 146 * 147 * Note: we warn about excess calls to jpeg_read_scanlines() since 148 * this likely signals an application programmer error. However, 149 * an oversize buffer (max_lines > scanlines remaining) is not an error. 150 */ 151 152 GLOBAL(JDIMENSION) 153 jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines, 154 JDIMENSION max_lines) 155 { 156 JDIMENSION row_ctr; 157 158 if (cinfo->global_state != DSTATE_SCANNING) 159 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 160 if (cinfo->output_scanline >= cinfo->output_height) { 161 WARNMS(cinfo, JWRN_TOO_MUCH_DATA); 162 return 0; 163 } 164 165 /* Call progress monitor hook if present */ 166 if (cinfo->progress != NULL) { 167 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 168 cinfo->progress->pass_limit = (long) cinfo->output_height; 169 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 170 } 171 172 /* Process some data */ 173 row_ctr = 0; 174 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines); 175 cinfo->output_scanline += row_ctr; 176 return row_ctr; 177 } 178 179 180 /* 181 * Alternate entry point to read raw data. 182 * Processes exactly one iMCU row per call, unless suspended. 183 */ 184 185 GLOBAL(JDIMENSION) 186 jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data, 187 JDIMENSION max_lines) 188 { 189 JDIMENSION lines_per_iMCU_row; 190 191 if (cinfo->global_state != DSTATE_RAW_OK) 192 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 193 if (cinfo->output_scanline >= cinfo->output_height) { 194 WARNMS(cinfo, JWRN_TOO_MUCH_DATA); 195 return 0; 196 } 197 198 /* Call progress monitor hook if present */ 199 if (cinfo->progress != NULL) { 200 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 201 cinfo->progress->pass_limit = (long) cinfo->output_height; 202 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 203 } 204 205 /* Verify that at least one iMCU row can be returned. */ 206 lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_v_scaled_size; 207 if (max_lines < lines_per_iMCU_row) 208 ERREXIT(cinfo, JERR_BUFFER_SIZE); 209 210 /* Decompress directly into user's buffer. */ 211 if (! (*cinfo->coef->decompress_data) (cinfo, data)) 212 return 0; /* suspension forced, can do nothing more */ 213 214 /* OK, we processed one iMCU row. */ 215 cinfo->output_scanline += lines_per_iMCU_row; 216 return lines_per_iMCU_row; 217 } 218 219 220 /* Additional entry points for buffered-image mode. */ 221 222 #ifdef D_MULTISCAN_FILES_SUPPORTED 223 224 /* 225 * Initialize for an output pass in buffered-image mode. 226 */ 227 228 GLOBAL(boolean) 229 jpeg_start_output (j_decompress_ptr cinfo, int scan_number) 230 { 231 if (cinfo->global_state != DSTATE_BUFIMAGE && 232 cinfo->global_state != DSTATE_PRESCAN) 233 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 234 /* Limit scan number to valid range */ 235 if (scan_number <= 0) 236 scan_number = 1; 237 if (cinfo->inputctl->eoi_reached && 238 scan_number > cinfo->input_scan_number) 239 scan_number = cinfo->input_scan_number; 240 cinfo->output_scan_number = scan_number; 241 /* Perform any dummy output passes, and set up for the real pass */ 242 return output_pass_setup(cinfo); 243 } 244 245 246 /* 247 * Finish up after an output pass in buffered-image mode. 248 * 249 * Returns FALSE if suspended. The return value need be inspected only if 250 * a suspending data source is used. 251 */ 252 253 GLOBAL(boolean) 254 jpeg_finish_output (j_decompress_ptr cinfo) 255 { 256 if ((cinfo->global_state == DSTATE_SCANNING || 257 cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) { 258 /* Terminate this pass. */ 259 /* We do not require the whole pass to have been completed. */ 260 (*cinfo->master->finish_output_pass) (cinfo); 261 cinfo->global_state = DSTATE_BUFPOST; 262 } else if (cinfo->global_state != DSTATE_BUFPOST) { 263 /* BUFPOST = repeat call after a suspension, anything else is error */ 264 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 265 } 266 /* Read markers looking for SOS or EOI */ 267 while (cinfo->input_scan_number <= cinfo->output_scan_number && 268 ! cinfo->inputctl->eoi_reached) { 269 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) 270 return FALSE; /* Suspend, come back later */ 271 } 272 cinfo->global_state = DSTATE_BUFIMAGE; 273 return TRUE; 274 } 275 276 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 277