src/jpeg/jdapimin.c

   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 }