Subversion Repositories AndroidProjects

Rev

Details | Last modification | View Log | RSS feed

Rev Author Line No. Line
244 chris 1 
/*
2 
 * jdatadst.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 compression data destination routines for the case of
9 
 * emitting JPEG data to a file (or any stdio stream).  While these routines
10 
 * are sufficient for most applications, some will want to use a different
11 
 * destination manager.
12 
 * IMPORTANT: we assume that fwrite() will correctly transcribe an array of
13 
 * JOCTETs into 8-bit-wide elements on external storage.  If char is wider
14 
 * than 8 bits on your machine, you may need to do some tweaking.
15 
 */
16 
 
17 
/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
18 
#include "jinclude.h"
19 
#include "jpeglib.h"
20 
#include "jerror.h"
21 
 
22 
 
23 
/* Expanded data destination object for stdio output */
24 
 
25 
typedef struct {
26 
  struct jpeg_destination_mgr pub; /* public fields */
27 
 
28 
  FILE * outfile;               /* target stream */
29 
  JOCTET * buffer;              /* start of buffer */
30 
} my_destination_mgr;
31 
 
32 
typedef my_destination_mgr * my_dest_ptr;
33 
 
34 
#define OUTPUT_BUF_SIZE  4096   /* choose an efficiently fwrite'able size */
35 
 
36 
 
37 
/*
38 
 * Initialize destination --- called by jpeg_start_compress
39 
 * before any data is actually written.
40 
 */
41 
 
42 
METHODDEF(void)
43 
init_destination (j_compress_ptr cinfo)
44 
{
45 
  my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
46 
 
47 
  /* Allocate the output buffer --- it will be released when done with image */
48 
  dest->buffer = (JOCTET *)
49 
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
50 
                                  OUTPUT_BUF_SIZE * SIZEOF(JOCTET));
51 
 
52 
  dest->pub.next_output_byte = dest->buffer;
53 
  dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
54 
}
55 
 
56 
 
57 
/*
58 
 * Empty the output buffer --- called whenever buffer fills up.
59 
 *
60 
 * In typical applications, this should write the entire output buffer
61 
 * (ignoring the current state of next_output_byte & free_in_buffer),
62 
 * reset the pointer & count to the start of the buffer, and return TRUE
63 
 * indicating that the buffer has been dumped.
64 
 *
65 
 * In applications that need to be able to suspend compression due to output
66 
 * overrun, a FALSE return indicates that the buffer cannot be emptied now.
67 
 * In this situation, the compressor will return to its caller (possibly with
68 
 * an indication that it has not accepted all the supplied scanlines).  The
69 
 * application should resume compression after it has made more room in the
70 
 * output buffer.  Note that there are substantial restrictions on the use of
71 
 * suspension --- see the documentation.
72 
 *
73 
 * When suspending, the compressor will back up to a convenient restart point
74 
 * (typically the start of the current MCU). next_output_byte & free_in_buffer
75 
 * indicate where the restart point will be if the current call returns FALSE.
76 
 * Data beyond this point will be regenerated after resumption, so do not
77 
 * write it out when emptying the buffer externally.
78 
 */
79 
 
80 
METHODDEF(boolean)
81 
empty_output_buffer (j_compress_ptr cinfo)
82 
{
83 
  my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
84 
 
85 
  if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE) !=
86 
      (size_t) OUTPUT_BUF_SIZE)
87 
    ERREXIT(cinfo, JERR_FILE_WRITE);
88 
 
89 
  dest->pub.next_output_byte = dest->buffer;
90 
  dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
91 
 
92 
  return TRUE;
93 
}
94 
 
95 
 
96 
/*
97 
 * Terminate destination --- called by jpeg_finish_compress
98 
 * after all data has been written.  Usually needs to flush buffer.
99 
 *
100 
 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
101 
 * application must deal with any cleanup that should happen even
102 
 * for error exit.
103 
 */
104 
 
105 
METHODDEF(void)
106 
term_destination (j_compress_ptr cinfo)
107 
{
108 
  my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
109 
  size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;
110 
 
111 
  /* Write any data remaining in the buffer */
112 
  if (datacount > 0) {
113 
    if (JFWRITE(dest->outfile, dest->buffer, datacount) != datacount)
114 
      ERREXIT(cinfo, JERR_FILE_WRITE);
115 
  }
116 
  fflush(dest->outfile);
117 
  /* Make sure we wrote the output file OK */
118 
  if (ferror(dest->outfile))
119 
    ERREXIT(cinfo, JERR_FILE_WRITE);
120 
}
121 
 
122 
 
123 
/*
124 
 * Prepare for output to a stdio stream.
125 
 * The caller must have already opened the stream, and is responsible
126 
 * for closing it after finishing compression.
127 
 */
128 
 
129 
GLOBAL(void)
130 
jpeg_stdio_dest (j_compress_ptr cinfo, FILE * outfile)
131 
{
132 
  my_dest_ptr dest;
133 
 
134 
  /* The destination object is made permanent so that multiple JPEG images
135 
   * can be written to the same file without re-executing jpeg_stdio_dest.
136 
   * This makes it dangerous to use this manager and a different destination
137 
   * manager serially with the same JPEG object, because their private object
138 
   * sizes may be different.  Caveat programmer.
139 
   */
140 
  if (cinfo->dest == NULL) {    /* first time for this JPEG object? */
141 
    cinfo->dest = (struct jpeg_destination_mgr *)
142 
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
143 
                                  SIZEOF(my_destination_mgr));
144 
  }
145 
 
146 
  dest = (my_dest_ptr) cinfo->dest;
147 
  dest->pub.init_destination = init_destination;
148 
  dest->pub.empty_output_buffer = empty_output_buffer;
149 
  dest->pub.term_destination = term_destination;
150 
  dest->outfile = outfile;
151 
}