4
* Copyright (C) 1994-1996, Thomas G. Lane.
5
* Modified 2009 by Guido Vollbeding.
6
* This file is part of the Independent JPEG Group's software.
7
* For conditions of distribution and use, see the accompanying README file.
9
* This file contains compression data destination routines for the case of
10
* emitting JPEG data to memory or to a file (or any stdio stream).
11
* While these routines are sufficient for most applications,
12
* some will want to use a different destination manager.
13
* IMPORTANT: we assume that fwrite() will correctly transcribe an array of
14
* JOCTETs into 8-bit-wide elements on external storage. If char is wider
15
* than 8 bits on your machine, you may need to do some tweaking.
18
/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
23
#ifndef HAVE_STDLIB_H /* <stdlib.h> should declare malloc(),free() */
24
extern void * malloc JPP((size_t size));
25
extern void free JPP((void *ptr));
29
/* Expanded data destination object for stdio output */
32
struct jpeg_destination_mgr pub; /* public fields */
34
FILE * outfile; /* target stream */
35
JOCTET * buffer; /* start of buffer */
38
typedef my_destination_mgr * my_dest_ptr;
40
#define OUTPUT_BUF_SIZE 4096 /* choose an efficiently fwrite'able size */
43
/* Expanded data destination object for memory output */
46
struct jpeg_destination_mgr pub; /* public fields */
48
unsigned char ** outbuffer; /* target buffer */
49
unsigned long * outsize;
50
unsigned char * newbuffer; /* newly allocated buffer */
51
JOCTET * buffer; /* start of buffer */
53
} my_mem_destination_mgr;
55
typedef my_mem_destination_mgr * my_mem_dest_ptr;
59
* Initialize destination --- called by jpeg_start_compress
60
* before any data is actually written.
64
init_destination (j_compress_ptr cinfo)
66
my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
68
/* Allocate the output buffer --- it will be released when done with image */
69
dest->buffer = (JOCTET *)
70
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
71
OUTPUT_BUF_SIZE * SIZEOF(JOCTET));
73
dest->pub.next_output_byte = dest->buffer;
74
dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
78
init_mem_destination (j_compress_ptr cinfo)
80
/* no work necessary here */
85
* Empty the output buffer --- called whenever buffer fills up.
87
* In typical applications, this should write the entire output buffer
88
* (ignoring the current state of next_output_byte & free_in_buffer),
89
* reset the pointer & count to the start of the buffer, and return TRUE
90
* indicating that the buffer has been dumped.
92
* In applications that need to be able to suspend compression due to output
93
* overrun, a FALSE return indicates that the buffer cannot be emptied now.
94
* In this situation, the compressor will return to its caller (possibly with
95
* an indication that it has not accepted all the supplied scanlines). The
96
* application should resume compression after it has made more room in the
97
* output buffer. Note that there are substantial restrictions on the use of
98
* suspension --- see the documentation.
100
* When suspending, the compressor will back up to a convenient restart point
101
* (typically the start of the current MCU). next_output_byte & free_in_buffer
102
* indicate where the restart point will be if the current call returns FALSE.
103
* Data beyond this point will be regenerated after resumption, so do not
104
* write it out when emptying the buffer externally.
108
empty_output_buffer (j_compress_ptr cinfo)
110
my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
112
if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE) !=
113
(size_t) OUTPUT_BUF_SIZE)
114
ERREXIT(cinfo, JERR_FILE_WRITE);
116
dest->pub.next_output_byte = dest->buffer;
117
dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
123
empty_mem_output_buffer (j_compress_ptr cinfo)
127
my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
129
/* Try to allocate new buffer with double size */
130
nextsize = dest->bufsize * 2;
131
nextbuffer = malloc(nextsize);
133
if (nextbuffer == NULL)
134
ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
136
MEMCOPY(nextbuffer, dest->buffer, dest->bufsize);
138
if (dest->newbuffer != NULL)
139
free(dest->newbuffer);
141
dest->newbuffer = nextbuffer;
143
dest->pub.next_output_byte = nextbuffer + dest->bufsize;
144
dest->pub.free_in_buffer = dest->bufsize;
146
dest->buffer = nextbuffer;
147
dest->bufsize = nextsize;
154
* Terminate destination --- called by jpeg_finish_compress
155
* after all data has been written. Usually needs to flush buffer.
157
* NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
158
* application must deal with any cleanup that should happen even
163
term_destination (j_compress_ptr cinfo)
165
my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
166
size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;
168
/* Write any data remaining in the buffer */
170
if (JFWRITE(dest->outfile, dest->buffer, datacount) != datacount)
171
ERREXIT(cinfo, JERR_FILE_WRITE);
173
fflush(dest->outfile);
174
/* Make sure we wrote the output file OK */
175
if (ferror(dest->outfile))
176
ERREXIT(cinfo, JERR_FILE_WRITE);
180
term_mem_destination (j_compress_ptr cinfo)
182
my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
184
*dest->outbuffer = dest->buffer;
185
*dest->outsize = dest->bufsize - dest->pub.free_in_buffer;
190
* Prepare for output to a stdio stream.
191
* The caller must have already opened the stream, and is responsible
192
* for closing it after finishing compression.
196
jpeg_stdio_dest (j_compress_ptr cinfo, FILE * outfile)
200
/* The destination object is made permanent so that multiple JPEG images
201
* can be written to the same file without re-executing jpeg_stdio_dest.
202
* This makes it dangerous to use this manager and a different destination
203
* manager serially with the same JPEG object, because their private object
204
* sizes may be different. Caveat programmer.
206
if (cinfo->dest == NULL) { /* first time for this JPEG object? */
207
cinfo->dest = (struct jpeg_destination_mgr *)
208
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
209
SIZEOF(my_destination_mgr));
212
dest = (my_dest_ptr) cinfo->dest;
213
dest->pub.init_destination = init_destination;
214
dest->pub.empty_output_buffer = empty_output_buffer;
215
dest->pub.term_destination = term_destination;
216
dest->outfile = outfile;
221
* Prepare for output to a memory buffer.
222
* The caller may supply an own initial buffer with appropriate size.
223
* Otherwise, or when the actual data output exceeds the given size,
224
* the library adapts the buffer size as necessary.
225
* The standard library functions malloc/free are used for allocating
226
* larger memory, so the buffer is available to the application after
227
* finishing compression, and then the application is responsible for
228
* freeing the requested memory.
232
jpeg_mem_dest (j_compress_ptr cinfo,
233
unsigned char ** outbuffer, unsigned long * outsize)
235
my_mem_dest_ptr dest;
237
if (outbuffer == NULL || outsize == NULL) /* sanity check */
238
ERREXIT(cinfo, JERR_BUFFER_SIZE);
240
/* The destination object is made permanent so that multiple JPEG images
241
* can be written to the same buffer without re-executing jpeg_mem_dest.
243
if (cinfo->dest == NULL) { /* first time for this JPEG object? */
244
cinfo->dest = (struct jpeg_destination_mgr *)
245
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
246
SIZEOF(my_mem_destination_mgr));
249
dest = (my_mem_dest_ptr) cinfo->dest;
250
dest->pub.init_destination = init_mem_destination;
251
dest->pub.empty_output_buffer = empty_mem_output_buffer;
252
dest->pub.term_destination = term_mem_destination;
253
dest->outbuffer = outbuffer;
254
dest->outsize = outsize;
255
dest->newbuffer = NULL;
257
if (*outbuffer == NULL || *outsize == 0) {
258
/* Allocate initial buffer */
259
dest->newbuffer = *outbuffer = malloc(OUTPUT_BUF_SIZE);
260
if (dest->newbuffer == NULL)
261
ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
262
*outsize = OUTPUT_BUF_SIZE;
265
dest->pub.next_output_byte = dest->buffer = *outbuffer;
266
dest->pub.free_in_buffer = dest->bufsize = *outsize;