1 /*

     2  * reserved comment block

     3  * DO NOT REMOVE OR ALTER!

     4  */

     5 /*

     6  * jdapistd.c

     7  *

     8  * Copyright (C) 1994-1996, 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 GLOBAL(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 GLOBAL(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 GLOBAL(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_DCT_scaled_size;

   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->coef->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 GLOBAL(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 GLOBAL(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 */