quicktime/jdatadst.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include "jpeg.h"
   4 #include "jpeglib.h"
   5 #include "jerror.h"
   6
   7
   8 /* Expanded data destination object for stdio output */
   9
  10 typedef struct {
  11   struct jpeg_destination_mgr pub; /* public fields */
  12
  13   JOCTET *buffer;               /* Pointer to buffer */
  14   mjpa_compress_engine *engine;
  15 } my_destination_mgr;
  16
  17 typedef my_destination_mgr *my_dest_ptr;
  18
  19
  20 /*
  21  * Initialize destination --- called by jpeg_start_compress
  22  * before any data is actually written.
  23  */
  24
  25 METHODDEF(void)
  26 init_destination (j_compress_ptr cinfo)
  27 {
  28   my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
  29
  30 /* Set the pointer to the preallocated buffer */
  31   dest->buffer = dest->engine->output_buffer;
  32
  33   dest->pub.next_output_byte = dest->buffer;
  34   dest->pub.free_in_buffer = dest->engine->output_allocated;
  35 }
  36
  37
  38 /*
  39  * Empty the output buffer --- called whenever buffer fills up.
  40  *
  41  * In typical applications, this should write the entire output buffer
  42  * (ignoring the current state of next_output_byte & free_in_buffer),
  43  * reset the pointer & count to the start of the buffer, and return TRUE
  44  * indicating that the buffer has been dumped.
  45  *
  46  * In applications that need to be able to suspend compression due to output
  47  * overrun, a FALSE return indicates that the buffer cannot be emptied now.
  48  * In this situation, the compressor will return to its caller (possibly with
  49  * an indication that it has not accepted all the supplied scanlines).  The
  50  * application should resume compression after it has made more room in the
  51  * output buffer.  Note that there are substantial restrictions on the use of
  52  * suspension --- see the documentation.
  53  *
  54  * When suspending, the compressor will back up to a convenient restart point
  55  * (typically the start of the current MCU). next_output_byte & free_in_buffer
  56  * indicate where the restart point will be if the current call returns FALSE.
  57  * Data beyond this point will be regenerated after resumption, so do not
  58  * write it out when emptying the buffer externally.
  59  */
  60
  61 METHODDEF(boolean)
  62 empty_output_buffer (j_compress_ptr cinfo)
  63 {
  64 /* Allocate a bigger buffer. */
  65         my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
  66         char *new_buffer;
  67         int new_size, i;
  68         int offset = dest->engine->output_allocated;
  69
  70         new_size = dest->engine->output_allocated * 2;
  71         new_buffer = malloc(new_size);
  72         for(i = 0; i < offset; i++)
  73                 new_buffer[i] = dest->engine->output_buffer[i];
  74         free(dest->engine->output_buffer);
  75         dest->engine->output_buffer = new_buffer;
  76         dest->engine->output_allocated = new_size;
  77         dest->buffer = dest->engine->output_buffer;
  78
  79         dest->pub.next_output_byte = dest->buffer + offset;
  80         dest->pub.free_in_buffer = dest->engine->output_allocated - offset;
  81
  82         return TRUE;
  83 }
  84
  85
  86 /*
  87  * Terminate destination --- called by jpeg_finish_compress
  88  * after all data has been written.  Usually needs to flush buffer.
  89  *
  90  * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
  91  * application must deal with any cleanup that should happen even
  92  * for error exit.
  93  */
  94
  95 METHODDEF(void)
  96 term_destination (j_compress_ptr cinfo)
  97 {
  98 /* Just get the length */
  99         my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
 100         dest->engine->output_size = dest->engine->output_allocated - dest->pub.free_in_buffer;
 101 }
 102
 103
 104 /*
 105  * Prepare for output to a stdio stream.
 106  * The caller must have already opened the stream, and is responsible
 107  * for closing it after finishing compression.
 108  */
 109
 110 GLOBAL(void)
 111 jpeg_buffer_dest (j_compress_ptr cinfo, mjpa_compress_engine *engine)
 112 {
 113   my_dest_ptr dest;
 114
 115   /* The destination object is made permanent so that multiple JPEG images
 116    * can be written to the same file without re-executing jpeg_stdio_dest.
 117    * This makes it dangerous to use this manager and a different destination
 118    * manager serially with the same JPEG object, because their private object
 119    * sizes may be different.  Caveat programmer.
 120    */
 121   if (cinfo->dest == NULL) {    /* first time for this JPEG object? */
 122     cinfo->dest = (struct jpeg_destination_mgr *)
 123       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
 124                                   sizeof(my_destination_mgr));
 125   }
 126
 127   dest = (my_dest_ptr) cinfo->dest;
 128   dest->pub.init_destination = init_destination;
 129   dest->pub.empty_output_buffer = empty_output_buffer;
 130   dest->pub.term_destination = term_destination;
 131   dest->engine = engine;
 132 }