1 /* 2 * jdapistd.c 3 * 4 * This file was part of the Independent JPEG Group's software: 5 * Copyright (C) 1994-1996, Thomas G. Lane. 6 * libjpeg-turbo Modifications: 7 * Copyright (C) 2010, D. R. Commander. 8 * For conditions of distribution and use, see the accompanying README file. 9 * 10 * This file contains application interface code for the decompression half 11 * of the JPEG library. These are the "standard" API routines that are 12 * used in the normal full-decompression case. They are not used by a 13 * transcoding-only application. Note that if an application links in 14 * jpeg_start_decompress, it will end up linking in the entire decompressor. 15 * We thus must separate this file from jdapimin.c to avoid linking the 16 * whole decompression library into a transcoder. 17 */ 18 19 #define JPEG_INTERNALS 20 #include "jinclude.h" 21 #include "jpeglib.h" 22 #include "jpegcomp.h" 23 24 25 /* Forward declarations */ 26 LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo)); 27 28 29 /* 30 * Decompression initialization. 31 * jpeg_read_header must be completed before calling this. 32 * 33 * If a multipass operating mode was selected, this will do all but the 34 * last pass, and thus may take a great deal of time. 35 * 36 * Returns FALSE if suspended. The return value need be inspected only if 37 * a suspending data source is used. 38 */ 39 40 GLOBAL(boolean) 41 jpeg_start_decompress (j_decompress_ptr cinfo) 42 { 43 if (cinfo->global_state == DSTATE_READY) { 44 /* First call: initialize master control, select active modules */ 45 jinit_master_decompress(cinfo); 46 if (cinfo->buffered_image) { 47 /* No more work here; expecting jpeg_start_output next */ 48 cinfo->global_state = DSTATE_BUFIMAGE; 49 return TRUE; 50 } 51 cinfo->global_state = DSTATE_PRELOAD; 52 } 53 if (cinfo->global_state == DSTATE_PRELOAD) { 54 /* If file has multiple scans, absorb them all into the coef buffer */ 55 if (cinfo->inputctl->has_multiple_scans) { 56 #ifdef D_MULTISCAN_FILES_SUPPORTED 57 for (;;) { 58 int retcode; 59 /* Call progress monitor hook if present */ 60 if (cinfo->progress != NULL) 61 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 62 /* Absorb some more input */ 63 retcode = (*cinfo->inputctl->consume_input) (cinfo); 64 if (retcode == JPEG_SUSPENDED) 65 return FALSE; 66 if (retcode == JPEG_REACHED_EOI) 67 break; 68 /* Advance progress counter if appropriate */ 69 if (cinfo->progress != NULL && 70 (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) { 71 if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) { 72 /* jdmaster underestimated number of scans; ratchet up one scan */ 73 cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows; 74 } 75 } 76 } 77 #else 78 ERREXIT(cinfo, JERR_NOT_COMPILED); 79 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 80 } 81 cinfo->output_scan_number = cinfo->input_scan_number; 82 } else if (cinfo->global_state != DSTATE_PRESCAN) 83 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 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 { 100 if (cinfo->global_state != DSTATE_PRESCAN) { 101 /* First call: do pass setup */ 102 (*cinfo->master->prepare_for_output_pass) (cinfo); 103 cinfo->output_scanline = 0; 104 cinfo->global_state = DSTATE_PRESCAN; 105 } 106 /* Loop over any required dummy passes */ 107 while (cinfo->master->is_dummy_pass) { 108 #ifdef QUANT_2PASS_SUPPORTED 109 /* Crank through the dummy pass */ 110 while (cinfo->output_scanline < cinfo->output_height) { 111 JDIMENSION last_scanline; 112 /* Call progress monitor hook if present */ 113 if (cinfo->progress != NULL) { 114 cinfo->progress->pass_counter = (long) cinfo->output_scanline; 115 cinfo->progress->pass_limit = (long) cinfo->output_height; 116 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); 117 } 118 /* Process some data */ 119 last_scanline = cinfo->output_scanline; 120 (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL, 121 &cinfo->output_scanline, (JDIMENSION) 0); 122 if (cinfo->output_scanline == last_scanline) 123 return FALSE; /* 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 { 158 JDIMENSION row_ctr; 159 160 if (cinfo->global_state != DSTATE_SCANNING) 161 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 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 { 191 JDIMENSION lines_per_iMCU_row; 192 193 if (cinfo->global_state != DSTATE_RAW_OK) 194 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 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 /* Decompress directly into user's buffer. */ 213 if (! (*cinfo->coef->decompress_data) (cinfo, data)) 214 return 0; /* suspension forced, can do nothing more */ 215 216 /* OK, we processed one iMCU row. */ 217 cinfo->output_scanline += lines_per_iMCU_row; 218 return lines_per_iMCU_row; 219 } 220 221 222 /* Additional entry points for buffered-image mode. */ 223 224 #ifdef D_MULTISCAN_FILES_SUPPORTED 225 226 /* 227 * Initialize for an output pass in buffered-image mode. 228 */ 229 230 GLOBAL(boolean) 231 jpeg_start_output (j_decompress_ptr cinfo, int scan_number) 232 { 233 if (cinfo->global_state != DSTATE_BUFIMAGE && 234 cinfo->global_state != DSTATE_PRESCAN) 235 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 236 /* Limit scan number to valid range */ 237 if (scan_number <= 0) 238 scan_number = 1; 239 if (cinfo->inputctl->eoi_reached && 240 scan_number > cinfo->input_scan_number) 241 scan_number = cinfo->input_scan_number; 242 cinfo->output_scan_number = scan_number; 243 /* Perform any dummy output passes, and set up for the real pass */ 244 return output_pass_setup(cinfo); 245 } 246 247 248 /* 249 * Finish up after an output pass in buffered-image mode. 250 * 251 * Returns FALSE if suspended. The return value need be inspected only if 252 * a suspending data source is used. 253 */ 254 255 GLOBAL(boolean) 256 jpeg_finish_output (j_decompress_ptr cinfo) 257 { 258 if ((cinfo->global_state == DSTATE_SCANNING || 259 cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) { 260 /* Terminate this pass. */ 261 /* We do not require the whole pass to have been completed. */ 262 (*cinfo->master->finish_output_pass) (cinfo); 263 cinfo->global_state = DSTATE_BUFPOST; 264 } else if (cinfo->global_state != DSTATE_BUFPOST) { 265 /* BUFPOST = repeat call after a suspension, anything else is error */ 266 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 267 } 268 /* Read markers looking for SOS or EOI */ 269 while (cinfo->input_scan_number <= cinfo->output_scan_number && 270 ! cinfo->inputctl->eoi_reached) { 271 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) 272 return FALSE; /* Suspend, come back later */ 273 } 274 cinfo->global_state = DSTATE_BUFIMAGE; 275 return TRUE; 276 } 277 278 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 279
