compiler/libjpeg/main/jcapistd.c

   1 /*
   2     $Id$
   3 */
   4
   5 /*
   6  * jcapistd.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 compression half
  13  * of the JPEG library.  These are the "standard" API routines that are
  14  * used in the normal full-compression case.  They are not used by a
  15  * transcoding-only application.  Note that if an application links in
  16  * jpeg_start_compress, it will end up linking in the entire compressor.
  17  * We thus must separate this file from jcapimin.c to avoid linking the
  18  * whole compression library into a transcoder.
  19  */
  20
  21 #define JPEG_INTERNALS
  22 #include "jinclude.h"
  23 #include "jpeglib.h"
  24
  25
  26 /*
  27  * Compression initialization.
  28  * Before calling this, all parameters and a data destination must be set up.
  29  *
  30  * We require a write_all_tables parameter as a failsafe check when writing
  31  * multiple datastreams from the same compression object.  Since prior runs
  32  * will have left all the tables marked sent_table=TRUE, a subsequent run
  33  * would emit an abbreviated stream (no tables) by default.  This may be what
  34  * is wanted, but for safety's sake it should not be the default behavior:
  35  * programmers should have to make a deliberate choice to emit abbreviated
  36  * images.  Therefore the documentation and examples should encourage people
  37  * to pass write_all_tables=TRUE; then it will take active thought to do the
  38  * wrong thing.
  39  */
  40
  41 JGLOBAL(void)
  42 jpeg_start_compress (j_compress_ptr cinfo, boolean write_all_tables)
  43 {
  44   if (cinfo->global_state != CSTATE_START)
  45     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  46
  47   if (write_all_tables)
  48     jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */
  49
  50   /* (Re)initialize error mgr and destination modules */
  51   (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
  52   (*cinfo->dest->init_destination) (cinfo);
  53   /* Perform master selection of active modules */
  54   jinit_compress_master(cinfo);
  55   /* Set up for the first pass */
  56   (*cinfo->master->prepare_for_pass) (cinfo);
  57   /* Ready for application to drive first pass through jpeg_write_scanlines
  58    * or jpeg_write_raw_data.
  59    */
  60   cinfo->next_scanline = 0;
  61   cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING);
  62 }
  63
  64
  65 /*
  66  * Write some scanlines of data to the JPEG compressor.
  67  *
  68  * The return value will be the number of lines actually written.
  69  * This should be less than the supplied num_lines only in case that
  70  * the data destination module has requested suspension of the compressor,
  71  * or if more than image_height scanlines are passed in.
  72  *
  73  * Note: we warn about excess calls to jpeg_write_scanlines() since
  74  * this likely signals an application programmer error.  However,
  75  * excess scanlines passed in the last valid call are *silently* ignored,
  76  * so that the application need not adjust num_lines for end-of-image
  77  * when using a multiple-scanline buffer.
  78  */
  79
  80 JGLOBAL(JDIMENSION)
  81 jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines,
  82                       JDIMENSION num_lines)
  83 {
  84   JDIMENSION row_ctr, rows_left;
  85
  86   if (cinfo->global_state != CSTATE_SCANNING)
  87     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  88   if (cinfo->next_scanline >= cinfo->image_height)
  89     WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
  90
  91   /* Call progress monitor hook if present */
  92   if (cinfo->progress != NULL) {
  93     cinfo->progress->pass_counter = (long) cinfo->next_scanline;
  94     cinfo->progress->pass_limit = (long) cinfo->image_height;
  95     (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
  96   }
  97
  98   /* Give master control module another chance if this is first call to
  99    * jpeg_write_scanlines.  This lets output of the frame/scan headers be
 100    * delayed so that application can write COM, etc, markers between
 101    * jpeg_start_compress and jpeg_write_scanlines.
 102    */
 103   if (cinfo->master->call_pass_startup)
 104     (*cinfo->master->pass_startup) (cinfo);
 105
 106   /* Ignore any extra scanlines at bottom of image. */
 107   rows_left = cinfo->image_height - cinfo->next_scanline;
 108   if (num_lines > rows_left)
 109     num_lines = rows_left;
 110
 111   row_ctr = 0;
 112   (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines);
 113   cinfo->next_scanline += row_ctr;
 114   return row_ctr;
 115 }
 116
 117
 118 /*
 119  * Alternate entry point to write raw data.
 120  * Processes exactly one iMCU row per call, unless suspended.
 121  */
 122
 123 JGLOBAL(JDIMENSION)
 124 jpeg_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data,
 125                      JDIMENSION num_lines)
 126 {
 127   JDIMENSION lines_per_iMCU_row;
 128
 129   if (cinfo->global_state != CSTATE_RAW_OK)
 130     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 131   if (cinfo->next_scanline >= cinfo->image_height) {
 132     WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
 133     return 0;
 134   }
 135
 136   /* Call progress monitor hook if present */
 137   if (cinfo->progress != NULL) {
 138     cinfo->progress->pass_counter = (long) cinfo->next_scanline;
 139     cinfo->progress->pass_limit = (long) cinfo->image_height;
 140     (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
 141   }
 142
 143   /* Give master control module another chance if this is first call to
 144    * jpeg_write_raw_data.  This lets output of the frame/scan headers be
 145    * delayed so that application can write COM, etc, markers between
 146    * jpeg_start_compress and jpeg_write_raw_data.
 147    */
 148   if (cinfo->master->call_pass_startup)
 149     (*cinfo->master->pass_startup) (cinfo);
 150
 151   /* Verify that at least one iMCU row has been passed. */
 152   lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->data_unit;
 153   if (num_lines < lines_per_iMCU_row)
 154     ERREXIT(cinfo, JERR_BUFFER_SIZE);
 155
 156   /* Directly compress the row. */
 157   if (! (*cinfo->codec->compress_data) (cinfo, data)) {
 158     /* If compressor did not consume the whole row, suspend processing. */
 159     return 0;
 160   }
 161
 162   /* OK, we processed one iMCU row. */
 163   cinfo->next_scanline += lines_per_iMCU_row;
 164   return lines_per_iMCU_row;
 165 }