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
;