jdapimin.c (12637B)
1 /* 2 * jdapimin.c 3 * 4 * Copyright (C) 1994-1998, 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 "minimum" API routines that may be 10 * needed in either the normal full-decompression case or the 11 * transcoding-only case. 12 * 13 * Most of the routines intended to be called directly by an application 14 * are in this file or in jdapistd.c. But also see jcomapi.c for routines 15 * shared by compression and decompression, and jdtrans.c for the transcoding 16 * case. 17 */ 18 19 #define JPEG_INTERNALS 20 #include "jinclude.h" 21 #include "jpeglib.h" 22 23 24 /* 25 * Initialization of a JPEG decompression object. 26 * The error manager must already be set up (in case memory manager fails). 27 */ 28 29 GLOBAL(void) 30 jpeg_CreateDecompress (j_decompress_ptr cinfo, int version, size_t structsize) 31 { 32 int i; 33 34 /* Guard against version mismatches between library and caller. */ 35 cinfo->mem = NULL; /* so jpeg_destroy knows mem mgr not called */ 36 if (version != JPEG_LIB_VERSION) 37 ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version); 38 if (structsize != SIZEOF(struct jpeg_decompress_struct)) 39 ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE, 40 (int) SIZEOF(struct jpeg_decompress_struct), (int) structsize); 41 42 /* For debugging purposes, we zero the whole master structure. 43 * But the application has already set the err pointer, and may have set 44 * client_data, so we have to save and restore those fields. 45 * Note: if application hasn't set client_data, tools like Purify may 46 * complain here. 47 */ 48 { 49 struct jpeg_error_mgr * err = cinfo->err; 50 void * client_data = cinfo->client_data; /* ignore Purify complaint here */ 51 MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct)); 52 cinfo->err = err; 53 cinfo->client_data = client_data; 54 } 55 cinfo->is_decompressor = TRUE; 56 57 /* Initialize a memory manager instance for this object */ 58 jinit_memory_mgr((j_common_ptr) cinfo); 59 60 /* Zero out pointers to permanent structures. */ 61 cinfo->progress = NULL; 62 cinfo->src = NULL; 63 64 for (i = 0; i < NUM_QUANT_TBLS; i++) 65 cinfo->quant_tbl_ptrs[i] = NULL; 66 67 for (i = 0; i < NUM_HUFF_TBLS; i++) { 68 cinfo->dc_huff_tbl_ptrs[i] = NULL; 69 cinfo->ac_huff_tbl_ptrs[i] = NULL; 70 } 71 72 /* Initialize marker processor so application can override methods 73 * for COM, APPn markers before calling jpeg_read_header. 74 */ 75 cinfo->marker_list = NULL; 76 jinit_marker_reader(cinfo); 77 78 /* And initialize the overall input controller. */ 79 jinit_input_controller(cinfo); 80 81 /* OK, I'm ready */ 82 cinfo->global_state = DSTATE_START; 83 } 84 85 86 /* 87 * Destruction of a JPEG decompression object 88 */ 89 90 GLOBAL(void) 91 jpeg_destroy_decompress (j_decompress_ptr cinfo) 92 { 93 jpeg_destroy((j_common_ptr) cinfo); /* use common routine */ 94 } 95 96 97 /* 98 * Abort processing of a JPEG decompression operation, 99 * but don't destroy the object itself. 100 */ 101 102 GLOBAL(void) 103 jpeg_abort_decompress (j_decompress_ptr cinfo) 104 { 105 jpeg_abort((j_common_ptr) cinfo); /* use common routine */ 106 } 107 108 109 /* 110 * Set default decompression parameters. 111 */ 112 113 LOCAL(void) 114 default_decompress_parms (j_decompress_ptr cinfo) 115 { 116 /* Guess the input colorspace, and set output colorspace accordingly. */ 117 /* (Wish JPEG committee had provided a real way to specify this...) */ 118 /* Note application may override our guesses. */ 119 switch (cinfo->num_components) { 120 case 1: 121 cinfo->jpeg_color_space = JCS_GRAYSCALE; 122 cinfo->out_color_space = JCS_GRAYSCALE; 123 break; 124 125 case 3: 126 if (cinfo->saw_JFIF_marker) { 127 cinfo->jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */ 128 } else if (cinfo->saw_Adobe_marker) { 129 switch (cinfo->Adobe_transform) { 130 case 0: 131 cinfo->jpeg_color_space = JCS_RGB; 132 break; 133 case 1: 134 cinfo->jpeg_color_space = JCS_YCbCr; 135 break; 136 default: 137 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform); 138 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */ 139 break; 140 } 141 } else { 142 /* Saw no special markers, try to guess from the component IDs */ 143 int cid0 = cinfo->comp_info[0].component_id; 144 int cid1 = cinfo->comp_info[1].component_id; 145 int cid2 = cinfo->comp_info[2].component_id; 146 147 if (cid0 == 1 && cid1 == 2 && cid2 == 3) 148 cinfo->jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */ 149 else if (cid0 == 82 && cid1 == 71 && cid2 == 66) 150 cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */ 151 else { 152 TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2); 153 cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */ 154 } 155 } 156 /* Always guess RGB is proper output colorspace. */ 157 cinfo->out_color_space = JCS_RGB; 158 break; 159 160 case 4: 161 if (cinfo->saw_Adobe_marker) { 162 switch (cinfo->Adobe_transform) { 163 case 0: 164 cinfo->jpeg_color_space = JCS_CMYK; 165 break; 166 case 2: 167 cinfo->jpeg_color_space = JCS_YCCK; 168 break; 169 default: 170 WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform); 171 cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */ 172 break; 173 } 174 } else { 175 /* No special markers, assume straight CMYK. */ 176 cinfo->jpeg_color_space = JCS_CMYK; 177 } 178 cinfo->out_color_space = JCS_CMYK; 179 break; 180 181 default: 182 cinfo->jpeg_color_space = JCS_UNKNOWN; 183 cinfo->out_color_space = JCS_UNKNOWN; 184 break; 185 } 186 187 /* Set defaults for other decompression parameters. */ 188 cinfo->scale_num = 1; /* 1:1 scaling */ 189 cinfo->scale_denom = 1; 190 cinfo->output_gamma = 1.0; 191 cinfo->buffered_image = FALSE; 192 cinfo->raw_data_out = FALSE; 193 cinfo->dct_method = JDCT_DEFAULT; 194 cinfo->do_fancy_upsampling = TRUE; 195 cinfo->do_block_smoothing = TRUE; 196 cinfo->quantize_colors = FALSE; 197 /* We set these in case application only sets quantize_colors. */ 198 cinfo->dither_mode = JDITHER_FS; 199 #ifdef QUANT_2PASS_SUPPORTED 200 cinfo->two_pass_quantize = TRUE; 201 #else 202 cinfo->two_pass_quantize = FALSE; 203 #endif 204 cinfo->desired_number_of_colors = 256; 205 cinfo->colormap = NULL; 206 /* Initialize for no mode change in buffered-image mode. */ 207 cinfo->enable_1pass_quant = FALSE; 208 cinfo->enable_external_quant = FALSE; 209 cinfo->enable_2pass_quant = FALSE; 210 } 211 212 213 /* 214 * Decompression startup: read start of JPEG datastream to see what's there. 215 * Need only initialize JPEG object and supply a data source before calling. 216 * 217 * This routine will read as far as the first SOS marker (ie, actual start of 218 * compressed data), and will save all tables and parameters in the JPEG 219 * object. It will also initialize the decompression parameters to default 220 * values, and finally return JPEG_HEADER_OK. On return, the application may 221 * adjust the decompression parameters and then call jpeg_start_decompress. 222 * (Or, if the application only wanted to determine the image parameters, 223 * the data need not be decompressed. In that case, call jpeg_abort or 224 * jpeg_destroy to release any temporary space.) 225 * If an abbreviated (tables only) datastream is presented, the routine will 226 * return JPEG_HEADER_TABLES_ONLY upon reaching EOI. The application may then 227 * re-use the JPEG object to read the abbreviated image datastream(s). 228 * It is unnecessary (but OK) to call jpeg_abort in this case. 229 * The JPEG_SUSPENDED return code only occurs if the data source module 230 * requests suspension of the decompressor. In this case the application 231 * should load more source data and then re-call jpeg_read_header to resume 232 * processing. 233 * If a non-suspending data source is used and require_image is TRUE, then the 234 * return code need not be inspected since only JPEG_HEADER_OK is possible. 235 * 236 * This routine is now just a front end to jpeg_consume_input, with some 237 * extra error checking. 238 */ 239 240 GLOBAL(int) 241 jpeg_read_header (j_decompress_ptr cinfo, boolean require_image) 242 { 243 int retcode; 244 245 if (cinfo->global_state != DSTATE_START && 246 cinfo->global_state != DSTATE_INHEADER) 247 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 248 249 retcode = jpeg_consume_input(cinfo); 250 251 switch (retcode) { 252 case JPEG_REACHED_SOS: 253 retcode = JPEG_HEADER_OK; 254 break; 255 case JPEG_REACHED_EOI: 256 if (require_image) /* Complain if application wanted an image */ 257 ERREXIT(cinfo, JERR_NO_IMAGE); 258 /* Reset to start state; it would be safer to require the application to 259 * call jpeg_abort, but we can't change it now for compatibility reasons. 260 * A side effect is to free any temporary memory (there shouldn't be any). 261 */ 262 jpeg_abort((j_common_ptr) cinfo); /* sets state = DSTATE_START */ 263 retcode = JPEG_HEADER_TABLES_ONLY; 264 break; 265 case JPEG_SUSPENDED: 266 /* no work */ 267 break; 268 } 269 270 return retcode; 271 } 272 273 274 /* 275 * Consume data in advance of what the decompressor requires. 276 * This can be called at any time once the decompressor object has 277 * been created and a data source has been set up. 278 * 279 * This routine is essentially a state machine that handles a couple 280 * of critical state-transition actions, namely initial setup and 281 * transition from header scanning to ready-for-start_decompress. 282 * All the actual input is done via the input controller's consume_input 283 * method. 284 */ 285 286 GLOBAL(int) 287 jpeg_consume_input (j_decompress_ptr cinfo) 288 { 289 int retcode = JPEG_SUSPENDED; 290 291 /* NB: every possible DSTATE value should be listed in this switch */ 292 switch (cinfo->global_state) { 293 case DSTATE_START: 294 /* Start-of-datastream actions: reset appropriate modules */ 295 (*cinfo->inputctl->reset_input_controller) (cinfo); 296 /* Initialize application's data source module */ 297 (*cinfo->src->init_source) (cinfo); 298 cinfo->global_state = DSTATE_INHEADER; 299 /*FALLTHROUGH*/ 300 case DSTATE_INHEADER: 301 retcode = (*cinfo->inputctl->consume_input) (cinfo); 302 if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */ 303 /* Set up default parameters based on header data */ 304 default_decompress_parms(cinfo); 305 /* Set global state: ready for start_decompress */ 306 cinfo->global_state = DSTATE_READY; 307 } 308 break; 309 case DSTATE_READY: 310 /* Can't advance past first SOS until start_decompress is called */ 311 retcode = JPEG_REACHED_SOS; 312 break; 313 case DSTATE_PRELOAD: 314 case DSTATE_PRESCAN: 315 case DSTATE_SCANNING: 316 case DSTATE_RAW_OK: 317 case DSTATE_BUFIMAGE: 318 case DSTATE_BUFPOST: 319 case DSTATE_STOPPING: 320 retcode = (*cinfo->inputctl->consume_input) (cinfo); 321 break; 322 default: 323 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 324 } 325 return retcode; 326 } 327 328 329 /* 330 * Have we finished reading the input file? 331 */ 332 333 GLOBAL(boolean) 334 jpeg_input_complete (j_decompress_ptr cinfo) 335 { 336 /* Check for valid jpeg object */ 337 if (cinfo->global_state < DSTATE_START || 338 cinfo->global_state > DSTATE_STOPPING) 339 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 340 return cinfo->inputctl->eoi_reached; 341 } 342 343 344 /* 345 * Is there more than one scan? 346 */ 347 348 GLOBAL(boolean) 349 jpeg_has_multiple_scans (j_decompress_ptr cinfo) 350 { 351 /* Only valid after jpeg_read_header completes */ 352 if (cinfo->global_state < DSTATE_READY || 353 cinfo->global_state > DSTATE_STOPPING) 354 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 355 return cinfo->inputctl->has_multiple_scans; 356 } 357 358 359 /* 360 * Finish JPEG decompression. 361 * 362 * This will normally just verify the file trailer and release temp storage. 363 * 364 * Returns FALSE if suspended. The return value need be inspected only if 365 * a suspending data source is used. 366 */ 367 368 GLOBAL(boolean) 369 jpeg_finish_decompress (j_decompress_ptr cinfo) 370 { 371 if ((cinfo->global_state == DSTATE_SCANNING || 372 cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) { 373 /* Terminate final pass of non-buffered mode */ 374 if (cinfo->output_scanline < cinfo->output_height) 375 ERREXIT(cinfo, JERR_TOO_LITTLE_DATA); 376 (*cinfo->master->finish_output_pass) (cinfo); 377 cinfo->global_state = DSTATE_STOPPING; 378 } else if (cinfo->global_state == DSTATE_BUFIMAGE) { 379 /* Finishing after a buffered-image operation */ 380 cinfo->global_state = DSTATE_STOPPING; 381 } else if (cinfo->global_state != DSTATE_STOPPING) { 382 /* STOPPING = repeat call after a suspension, anything else is error */ 383 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 384 } 385 /* Read until EOI */ 386 while (! cinfo->inputctl->eoi_reached) { 387 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) 388 return FALSE; /* Suspend, come back later */ 389 } 390 /* Do final cleanup */ 391 (*cinfo->src->term_source) (cinfo); 392 /* We can use jpeg_abort to release memory and reset global_state */ 393 jpeg_abort((j_common_ptr) cinfo); 394 return TRUE; 395 }