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_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 */