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