media/libjpeg/jcapistd.c

   1 /*
   2  * jcapistd.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.ijg
   7  * file.
   8  *
   9  * This file contains application interface code for the compression half
  10  * of the JPEG library.  These are the "standard" API routines that are
  11  * used in the normal full-compression case.  They are not used by a
  12  * transcoding-only application.  Note that if an application links in
  13  * jpeg_start_compress, it will end up linking in the entire compressor.
  14  * We thus must separate this file from jcapimin.c to avoid linking the
  15  * whole compression library into a transcoder.
  16  */
  17
  18 #define JPEG_INTERNALS
  19 #include "jinclude.h"
  20 #include "jpeglib.h"
  21
  22
  23 /*
  24  * Compression initialization.
  25  * Before calling this, all parameters and a data destination must be set up.
  26  *
  27  * We require a write_all_tables parameter as a failsafe check when writing
  28  * multiple datastreams from the same compression object.  Since prior runs
  29  * will have left all the tables marked sent_table=TRUE, a subsequent run
  30  * would emit an abbreviated stream (no tables) by default.  This may be what
  31  * is wanted, but for safety's sake it should not be the default behavior:
  32  * programmers should have to make a deliberate choice to emit abbreviated
  33  * images.  Therefore the documentation and examples should encourage people
  34  * to pass write_all_tables=TRUE; then it will take active thought to do the
  35  * wrong thing.
  36  */
  37
  38 GLOBAL(void)
  39 jpeg_start_compress(j_compress_ptr cinfo, boolean write_all_tables)
  40 {
  41   if (cinfo->global_state != CSTATE_START)
  42     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  43
  44   if (write_all_tables)
  45     jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */
  46
  47   /* (Re)initialize error mgr and destination modules */
  48   (*cinfo->err->reset_error_mgr) ((j_common_ptr)cinfo);
  49   (*cinfo->dest->init_destination) (cinfo);
  50   /* Perform master selection of active modules */
  51   jinit_compress_master(cinfo);
  52   /* Set up for the first pass */
  53   (*cinfo->master->prepare_for_pass) (cinfo);
  54   /* Ready for application to drive first pass through jpeg_write_scanlines
  55    * or jpeg_write_raw_data.
  56    */
  57   cinfo->next_scanline = 0;
  58   cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING);
  59 }
  60
  61
  62 /*
  63  * Write some scanlines of data to the JPEG compressor.
  64  *
  65  * The return value will be the number of lines actually written.
  66  * This should be less than the supplied num_lines only in case that
  67  * the data destination module has requested suspension of the compressor,
  68  * or if more than image_height scanlines are passed in.
  69  *
  70  * Note: we warn about excess calls to jpeg_write_scanlines() since
  71  * this likely signals an application programmer error.  However,
  72  * excess scanlines passed in the last valid call are *silently* ignored,
  73  * so that the application need not adjust num_lines for end-of-image
  74  * when using a multiple-scanline buffer.
  75  */
  76
  77 GLOBAL(JDIMENSION)
  78 jpeg_write_scanlines(j_compress_ptr cinfo, JSAMPARRAY scanlines,
  79                      JDIMENSION num_lines)
  80 {
  81   JDIMENSION row_ctr, rows_left;
  82
  83   if (cinfo->global_state != CSTATE_SCANNING)
  84     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  85   if (cinfo->next_scanline >= cinfo->image_height)
  86     WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
  87
  88   /* Call progress monitor hook if present */
  89   if (cinfo->progress != NULL) {
  90     cinfo->progress->pass_counter = (long)cinfo->next_scanline;
  91     cinfo->progress->pass_limit = (long)cinfo->image_height;
  92     (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo);
  93   }
  94
  95   /* Give master control module another chance if this is first call to
  96    * jpeg_write_scanlines.  This lets output of the frame/scan headers be
  97    * delayed so that application can write COM, etc, markers between
  98    * jpeg_start_compress and jpeg_write_scanlines.
  99    */
 100   if (cinfo->master->call_pass_startup)
 101     (*cinfo->master->pass_startup) (cinfo);
 102
 103   /* Ignore any extra scanlines at bottom of image. */
 104   rows_left = cinfo->image_height - cinfo->next_scanline;
 105   if (num_lines > rows_left)
 106     num_lines = rows_left;
 107
 108   row_ctr = 0;
 109   (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines);
 110   cinfo->next_scanline += row_ctr;
 111   return row_ctr;
 112 }
 113
 114
 115 /*
 116  * Alternate entry point to write raw data.
 117  * Processes exactly one iMCU row per call, unless suspended.
 118  */
 119
 120 GLOBAL(JDIMENSION)
 121 jpeg_write_raw_data(j_compress_ptr cinfo, JSAMPIMAGE data,
 122                     JDIMENSION num_lines)
 123 {
 124   JDIMENSION lines_per_iMCU_row;
 125
 126   if (cinfo->global_state != CSTATE_RAW_OK)
 127     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 128   if (cinfo->next_scanline >= cinfo->image_height) {
 129     WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
 130     return 0;
 131   }
 132
 133   /* Call progress monitor hook if present */
 134   if (cinfo->progress != NULL) {
 135     cinfo->progress->pass_counter = (long)cinfo->next_scanline;
 136     cinfo->progress->pass_limit = (long)cinfo->image_height;
 137     (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo);
 138   }
 139
 140   /* Give master control module another chance if this is first call to
 141    * jpeg_write_raw_data.  This lets output of the frame/scan headers be
 142    * delayed so that application can write COM, etc, markers between
 143    * jpeg_start_compress and jpeg_write_raw_data.
 144    */
 145   if (cinfo->master->call_pass_startup)
 146     (*cinfo->master->pass_startup) (cinfo);
 147
 148   /* Verify that at least one iMCU row has been passed. */
 149   lines_per_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE;
 150   if (num_lines < lines_per_iMCU_row)
 151     ERREXIT(cinfo, JERR_BUFFER_SIZE);
 152
 153   /* Directly compress the row. */
 154   if (!(*cinfo->coef->compress_data) (cinfo, data)) {
 155     /* If compressor did not consume the whole row, suspend processing. */
 156     return 0;
 157   }
 158
 159   /* OK, we processed one iMCU row. */
 160   cinfo->next_scanline += lines_per_iMCU_row;
 161   return lines_per_iMCU_row;
 162 }