compiler/libjpeg/main/jdapistd.c

   1 /*
   2     $Id$
   3 */
   4
   5 /*
   6  * jdapistd.c
   7  *
   8  * Copyright (C) 1994-1998, Thomas G. Lane.
   9  * This file is part of the Independent JPEG Group's software.
  10  * For conditions of distribution and use, see the accompanying README file.
  11  *
  12  * This file contains application interface code for the decompression half
  13  * of the JPEG library.  These are the "standard" API routines that are
  14  * used in the normal full-decompression case.  They are not used by a
  15  * transcoding-only application.  Note that if an application links in
  16  * jpeg_start_decompress, it will end up linking in the entire decompressor.
  17  * We thus must separate this file from jdapimin.c to avoid linking the
  18  * whole decompression library into a transcoder.
  19  */
  20
  21 #define JPEG_INTERNALS
  22 #include "jinclude.h"
  23 #include "jpeglib.h"
  24
  25
  26 /* Forward declarations */
  27 LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo));
  28
  29
  30 /*
  31  * Decompression initialization.
  32  * jpeg_read_header must be completed before calling this.
  33  *
  34  * If a multipass operating mode was selected, this will do all but the
  35  * last pass, and thus may take a great deal of time.
  36  *
  37  * Returns FALSE if suspended.  The return value need be inspected only if
  38  * a suspending data source is used.
  39  */
  40
  41 JGLOBAL(boolean)
  42 jpeg_start_decompress (j_decompress_ptr cinfo)
  43 {
  44   if (cinfo->global_state == DSTATE_READY) {
  45     /* First call: initialize master control, select active modules */
  46     jinit_master_decompress(cinfo);
  47     if (cinfo->buffered_image) {
  48       /* No more work here; expecting jpeg_start_output next */
  49       cinfo->global_state = DSTATE_BUFIMAGE;
  50       return TRUE;
  51     }
  52     cinfo->global_state = DSTATE_PRELOAD;
  53   }
  54   if (cinfo->global_state == DSTATE_PRELOAD) {
  55     /* If file has multiple scans, absorb them all into the coef buffer */
  56     if (cinfo->inputctl->has_multiple_scans) {
  57 #ifdef D_MULTISCAN_FILES_SUPPORTED
  58       for (;;) {
  59         int retcode;
  60         /* Call progress monitor hook if present */
  61         if (cinfo->progress != NULL)
  62           (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
  63         /* Absorb some more input */
  64         retcode = (*cinfo->inputctl->consume_input) (cinfo);
  65         if (retcode == JPEG_SUSPENDED)
  66           return FALSE;
  67         if (retcode == JPEG_REACHED_EOI)
  68           break;
  69         /* Advance progress counter if appropriate */
  70         if (cinfo->progress != NULL &&
  71             (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
  72           if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
  73             /* jdmaster underestimated number of scans; ratchet up one scan */
  74             cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
  75           }
  76         }
  77       }
  78 #else
  79       ERREXIT(cinfo, JERR_NOT_COMPILED);
  80 #endif /* D_MULTISCAN_FILES_SUPPORTED */
  81     }
  82     cinfo->output_scan_number = cinfo->input_scan_number;
  83   } else if (cinfo->global_state != DSTATE_PRESCAN)
  84     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  85   /* Perform any dummy output passes, and set up for the final pass */
  86   return output_pass_setup(cinfo);
  87 }
  88
  89
  90 /*
  91  * Set up for an output pass, and perform any dummy pass(es) needed.
  92  * Common subroutine for jpeg_start_decompress and jpeg_start_output.
  93  * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
  94  * Exit: If done, returns TRUE and sets global_state for proper output mode.
  95  *       If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
  96  */
  97
  98 LOCAL(boolean)
  99 output_pass_setup (j_decompress_ptr cinfo)
 100 {
 101   if (cinfo->global_state != DSTATE_PRESCAN) {
 102     /* First call: do pass setup */
 103     (*cinfo->master->prepare_for_output_pass) (cinfo);
 104     cinfo->output_scanline = 0;
 105     cinfo->global_state = DSTATE_PRESCAN;
 106   }
 107   /* Loop over any required dummy passes */
 108   while (cinfo->master->is_dummy_pass) {
 109 #ifdef QUANT_2PASS_SUPPORTED
 110     /* Crank through the dummy pass */
 111     while (cinfo->output_scanline < cinfo->output_height) {
 112       JDIMENSION last_scanline;
 113       /* Call progress monitor hook if present */
 114       if (cinfo->progress != NULL) {
 115         cinfo->progress->pass_counter = (long) cinfo->output_scanline;
 116         cinfo->progress->pass_limit = (long) cinfo->output_height;
 117         (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
 118       }
 119       /* Process some data */
 120       last_scanline = cinfo->output_scanline;
 121       (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
 122                                     &cinfo->output_scanline, (JDIMENSION) 0);
 123       if (cinfo->output_scanline == last_scanline)
 124         return FALSE;           /* No progress made, must suspend */
 125     }
 126     /* Finish up dummy pass, and set up for another one */
 127     (*cinfo->master->finish_output_pass) (cinfo);
 128     (*cinfo->master->prepare_for_output_pass) (cinfo);
 129     cinfo->output_scanline = 0;
 130 #else
 131     ERREXIT(cinfo, JERR_NOT_COMPILED);
 132 #endif /* QUANT_2PASS_SUPPORTED */
 133   }
 134   /* Ready for application to drive output pass through
 135    * jpeg_read_scanlines or jpeg_read_raw_data.
 136    */
 137   cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
 138   return TRUE;
 139 }
 140
 141
 142 /*
 143  * Read some scanlines of data from the JPEG decompressor.
 144  *
 145  * The return value will be the number of lines actually read.
 146  * This may be less than the number requested in several cases,
 147  * including bottom of image, data source suspension, and operating
 148  * modes that emit multiple scanlines at a time.
 149  *
 150  * Note: we warn about excess calls to jpeg_read_scanlines() since
 151  * this likely signals an application programmer error.  However,
 152  * an oversize buffer (max_lines > scanlines remaining) is not an error.
 153  */
 154
 155 JGLOBAL(JDIMENSION)
 156 jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
 157                      JDIMENSION max_lines)
 158 {
 159   JDIMENSION row_ctr;
 160
 161   if (cinfo->global_state != DSTATE_SCANNING)
 162     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 163   if (cinfo->output_scanline >= cinfo->output_height) {
 164     WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
 165     return 0;
 166   }
 167
 168   /* Call progress monitor hook if present */
 169   if (cinfo->progress != NULL) {
 170     cinfo->progress->pass_counter = (long) cinfo->output_scanline;
 171     cinfo->progress->pass_limit = (long) cinfo->output_height;
 172     (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
 173   }
 174
 175   /* Process some data */
 176   row_ctr = 0;
 177   (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
 178   cinfo->output_scanline += row_ctr;
 179   return row_ctr;
 180 }
 181
 182
 183 /*
 184  * Alternate entry point to read raw data.
 185  * Processes exactly one iMCU row per call, unless suspended.
 186  */
 187
 188 JGLOBAL(JDIMENSION)
 189 jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
 190                     JDIMENSION max_lines)
 191 {
 192   JDIMENSION lines_per_iMCU_row;
 193
 194   if (cinfo->global_state != DSTATE_RAW_OK)
 195     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 196   if (cinfo->output_scanline >= cinfo->output_height) {
 197     WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
 198     return 0;
 199   }
 200
 201   /* Call progress monitor hook if present */
 202   if (cinfo->progress != NULL) {
 203     cinfo->progress->pass_counter = (long) cinfo->output_scanline;
 204     cinfo->progress->pass_limit = (long) cinfo->output_height;
 205     (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
 206   }
 207
 208   /* Verify that at least one iMCU row can be returned. */
 209   lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_codec_data_unit;
 210   if (max_lines < lines_per_iMCU_row)
 211     ERREXIT(cinfo, JERR_BUFFER_SIZE);
 212
 213   /* Decompress directly into user's buffer. */
 214   if (! (*cinfo->codec->decompress_data) (cinfo, data))
 215     return 0;                   /* suspension forced, can do nothing more */
 216
 217   /* OK, we processed one iMCU row. */
 218   cinfo->output_scanline += lines_per_iMCU_row;
 219   return lines_per_iMCU_row;
 220 }
 221
 222
 223 /* Additional entry points for buffered-image mode. */
 224
 225 #ifdef D_MULTISCAN_FILES_SUPPORTED
 226
 227 /*
 228  * Initialize for an output pass in buffered-image mode.
 229  */
 230
 231 JGLOBAL(boolean)
 232 jpeg_start_output (j_decompress_ptr cinfo, int scan_number)
 233 {
 234   if (cinfo->global_state != DSTATE_BUFIMAGE &&
 235       cinfo->global_state != DSTATE_PRESCAN)
 236     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 237   /* Limit scan number to valid range */
 238   if (scan_number <= 0)
 239     scan_number = 1;
 240   if (cinfo->inputctl->eoi_reached &&
 241       scan_number > cinfo->input_scan_number)
 242     scan_number = cinfo->input_scan_number;
 243   cinfo->output_scan_number = scan_number;
 244   /* Perform any dummy output passes, and set up for the real pass */
 245   return output_pass_setup(cinfo);
 246 }
 247
 248
 249 /*
 250  * Finish up after an output pass in buffered-image mode.
 251  *
 252  * Returns FALSE if suspended.  The return value need be inspected only if
 253  * a suspending data source is used.
 254  */
 255
 256 JGLOBAL(boolean)
 257 jpeg_finish_output (j_decompress_ptr cinfo)
 258 {
 259   if ((cinfo->global_state == DSTATE_SCANNING ||
 260        cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) {
 261     /* Terminate this pass. */
 262     /* We do not require the whole pass to have been completed. */
 263     (*cinfo->master->finish_output_pass) (cinfo);
 264     cinfo->global_state = DSTATE_BUFPOST;
 265   } else if (cinfo->global_state != DSTATE_BUFPOST) {
 266     /* BUFPOST = repeat call after a suspension, anything else is error */
 267     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 268   }
 269   /* Read markers looking for SOS or EOI */
 270   while (cinfo->input_scan_number <= cinfo->output_scan_number &&
 271          ! cinfo->inputctl->eoi_reached) {
 272     if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
 273       return FALSE;             /* Suspend, come back later */
 274   }
 275   cinfo->global_state = DSTATE_BUFIMAGE;
 276   return TRUE;
 277 }
 278
 279 #endif /* D_MULTISCAN_FILES_SUPPORTED */