1/*
2 * jdatadst.c
3 *
4 * Copyright (C) 1994-1996, Thomas G. Lane.
5 * Modified 2009-2012 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.
8 *
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.
16 */
17
18/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
19#include "jinclude.h"
20#include "jpeglib.h"
21#include "jerror.h"
22
23#ifndef HAVE_STDLIB_H /* <stdlib.h> should declare malloc(),free() */
24extern void * malloc JPP((size_t size));
25extern void free JPP((void *ptr));
26#endif
27
28
29/* Expanded data destination object for stdio output */
30
31typedef struct {
32 struct jpeg_destination_mgr pub; /* public fields */
33
34 FILE * outfile; /* target stream */
35 JOCTET * buffer; /* start of buffer */
36} my_destination_mgr;
37
38typedef my_destination_mgr * my_dest_ptr;
39
40#define OUTPUT_BUF_SIZE 4096 /* choose an efficiently fwrite'able size */
41
42
43/* Expanded data destination object for memory output */
44
45typedef struct {
46 struct jpeg_destination_mgr pub; /* public fields */
47
48 unsigned char ** outbuffer; /* target buffer */
49 unsigned long * outsize;
50 unsigned char * newbuffer; /* newly allocated buffer */
51 JOCTET * buffer; /* start of buffer */
52 size_t bufsize;
53} my_mem_destination_mgr;
54
55typedef my_mem_destination_mgr * my_mem_dest_ptr;
56
57
58/*
59 * Initialize destination --- called by jpeg_start_compress
60 * before any data is actually written.
61 */
62
63METHODDEF(void)
64init_destination (j_compress_ptr cinfo)
65{
66 my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
67
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));
72
73 dest->pub.next_output_byte = dest->buffer;
74 dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
75}
76
77METHODDEF(void)
78init_mem_destination (j_compress_ptr cinfo)
79{
80 /* no work necessary here */
81}
82
83
84/*
85 * Empty the output buffer --- called whenever buffer fills up.
86 *
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.
91 *
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.
99 *
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.
105 */
106
107METHODDEF(boolean)
108empty_output_buffer (j_compress_ptr cinfo)
109{
110 my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
111
112 if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE) !=
113 (size_t) OUTPUT_BUF_SIZE)
114 ERREXIT(cinfo, JERR_FILE_WRITE);
115
116 dest->pub.next_output_byte = dest->buffer;
117 dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
118
119 return TRUE;
120}
121
122METHODDEF(boolean)
123empty_mem_output_buffer (j_compress_ptr cinfo)
124{
125 size_t nextsize;
126 JOCTET * nextbuffer;
127 my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
128
129 /* Try to allocate new buffer with double size */
130 nextsize = dest->bufsize * 2;
131 nextbuffer = (JOCTET *) malloc(nextsize);
132
133 if (nextbuffer == NULL)
134 ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
135
136 MEMCOPY(nextbuffer, dest->buffer, dest->bufsize);
137
138 if (dest->newbuffer != NULL)
139 free(dest->newbuffer);
140
141 dest->newbuffer = nextbuffer;
142
143 dest->pub.next_output_byte = nextbuffer + dest->bufsize;
144 dest->pub.free_in_buffer = dest->bufsize;
145
146 dest->buffer = nextbuffer;
147 dest->bufsize = nextsize;
148
149 return TRUE;
150}
151
152
153/*
154 * Terminate destination --- called by jpeg_finish_compress
155 * after all data has been written. Usually needs to flush buffer.
156 *
157 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
158 * application must deal with any cleanup that should happen even
159 * for error exit.
160 */
161
162METHODDEF(void)
163term_destination (j_compress_ptr cinfo)
164{
165 my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
166 size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;
167
168 /* Write any data remaining in the buffer */
169 if (datacount > 0) {
170 if (JFWRITE(dest->outfile, dest->buffer, datacount) != datacount)
171 ERREXIT(cinfo, JERR_FILE_WRITE);
172 }
173 fflush(dest->outfile);
174 /* Make sure we wrote the output file OK */
175 if (ferror(dest->outfile))
176 ERREXIT(cinfo, JERR_FILE_WRITE);
177}
178
179METHODDEF(void)
180term_mem_destination (j_compress_ptr cinfo)
181{
182 my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
183
184 *dest->outbuffer = dest->buffer;
185 *dest->outsize = dest->bufsize - dest->pub.free_in_buffer;
186}
187
188
189/*
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.
193 */
194
195GLOBAL(void)
196jpeg_stdio_dest (j_compress_ptr cinfo, FILE * outfile)
197{
198 my_dest_ptr dest;
199
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.
205 */
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));
210 }
211
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;
217}
218
219
220/*
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.
229 * Note: An initial buffer supplied by the caller is expected to be
230 * managed by the application. The library does not free such buffer
231 * when allocating a larger buffer.
232 */
233
234GLOBAL(void)
235jpeg_mem_dest (j_compress_ptr cinfo,
236 unsigned char ** outbuffer, unsigned long * outsize)
237{
238 my_mem_dest_ptr dest;
239
240 if (outbuffer == NULL || outsize == NULL) /* sanity check */
241 ERREXIT(cinfo, JERR_BUFFER_SIZE);
242
243 /* The destination object is made permanent so that multiple JPEG images
244 * can be written to the same buffer without re-executing jpeg_mem_dest.
245 */
246 if (cinfo->dest == NULL) { /* first time for this JPEG object? */
247 cinfo->dest = (struct jpeg_destination_mgr *)
248 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
249 SIZEOF(my_mem_destination_mgr));
250 }
251
252 dest = (my_mem_dest_ptr) cinfo->dest;
253 dest->pub.init_destination = init_mem_destination;
254 dest->pub.empty_output_buffer = empty_mem_output_buffer;
255 dest->pub.term_destination = term_mem_destination;
256 dest->outbuffer = outbuffer;
257 dest->outsize = outsize;
258 dest->newbuffer = NULL;
259
260 if (*outbuffer == NULL || *outsize == 0) {
261 /* Allocate initial buffer */
262 dest->newbuffer = *outbuffer = (unsigned char *) malloc(OUTPUT_BUF_SIZE);
263 if (dest->newbuffer == NULL)
264 ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
265 *outsize = OUTPUT_BUF_SIZE;
266 }
267
268 dest->pub.next_output_byte = dest->buffer = *outbuffer;
269 dest->pub.free_in_buffer = dest->bufsize = *outsize;
270}
271