4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1994-1996, Thomas G. Lane.
6 * Modified 2009-2012 by Guido Vollbeding.
7 * libjpeg-turbo Modifications:
8 * Copyright (C) 2011, D. R. Commander.
9 * For conditions of distribution and use, see the accompanying README file.
11 * This file contains compression data destination routines for the case of
12 * emitting JPEG data to memory or to a file (or any stdio stream).
13 * While these routines are sufficient for most applications,
14 * some will want to use a different destination manager.
15 * IMPORTANT: we assume that fwrite() will correctly transcribe an array of
16 * JOCTETs into 8-bit-wide elements on external storage. If char is wider
17 * than 8 bits on your machine, you may need to do some tweaking.
20 /* this is not a core library module, so it doesn't define JPEG_INTERNALS */
25 #ifndef HAVE_STDLIB_H /* <stdlib.h> should declare malloc(),free() */
26 extern void * malloc JPP((size_t size));
27 extern void free JPP((void *ptr));
31 #define OUTPUT_BUF_SIZE 4096 /* choose an efficiently fwrite'able size */
34 /* Expanded data destination object for memory output */
37 struct jpeg_destination_mgr pub; /* public fields */
39 unsigned char ** outbuffer; /* target buffer */
40 unsigned long * outsize;
41 unsigned char * newbuffer; /* newly allocated buffer */
42 JOCTET * buffer; /* start of buffer */
45 } my_mem_destination_mgr;
47 typedef my_mem_destination_mgr * my_mem_dest_ptr;
51 * Initialize destination --- called by jpeg_start_compress
52 * before any data is actually written.
56 init_mem_destination (j_compress_ptr cinfo)
58 /* no work necessary here */
63 * Empty the output buffer --- called whenever buffer fills up.
65 * In typical applications, this should write the entire output buffer
66 * (ignoring the current state of next_output_byte & free_in_buffer),
67 * reset the pointer & count to the start of the buffer, and return TRUE
68 * indicating that the buffer has been dumped.
70 * In applications that need to be able to suspend compression due to output
71 * overrun, a FALSE return indicates that the buffer cannot be emptied now.
72 * In this situation, the compressor will return to its caller (possibly with
73 * an indication that it has not accepted all the supplied scanlines). The
74 * application should resume compression after it has made more room in the
75 * output buffer. Note that there are substantial restrictions on the use of
76 * suspension --- see the documentation.
78 * When suspending, the compressor will back up to a convenient restart point
79 * (typically the start of the current MCU). next_output_byte & free_in_buffer
80 * indicate where the restart point will be if the current call returns FALSE.
81 * Data beyond this point will be regenerated after resumption, so do not
82 * write it out when emptying the buffer externally.
86 empty_mem_output_buffer (j_compress_ptr cinfo)
90 my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
92 if (!dest->alloc) ERREXIT(cinfo, JERR_BUFFER_SIZE);
94 /* Try to allocate new buffer with double size */
95 nextsize = dest->bufsize * 2;
96 nextbuffer = (JOCTET *) malloc(nextsize);
98 if (nextbuffer == NULL)
99 ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
101 MEMCOPY(nextbuffer, dest->buffer, dest->bufsize);
103 if (dest->newbuffer != NULL)
104 free(dest->newbuffer);
106 dest->newbuffer = nextbuffer;
108 dest->pub.next_output_byte = nextbuffer + dest->bufsize;
109 dest->pub.free_in_buffer = dest->bufsize;
111 dest->buffer = nextbuffer;
112 dest->bufsize = nextsize;
119 * Terminate destination --- called by jpeg_finish_compress
120 * after all data has been written. Usually needs to flush buffer.
122 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
123 * application must deal with any cleanup that should happen even
128 term_mem_destination (j_compress_ptr cinfo)
130 my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
132 if(dest->alloc) *dest->outbuffer = dest->buffer;
133 *dest->outsize = (unsigned long)(dest->bufsize - dest->pub.free_in_buffer);
138 * Prepare for output to a memory buffer.
139 * The caller may supply an own initial buffer with appropriate size.
140 * Otherwise, or when the actual data output exceeds the given size,
141 * the library adapts the buffer size as necessary.
142 * The standard library functions malloc/free are used for allocating
143 * larger memory, so the buffer is available to the application after
144 * finishing compression, and then the application is responsible for
145 * freeing the requested memory.
149 jpeg_mem_dest_tj (j_compress_ptr cinfo,
150 unsigned char ** outbuffer, unsigned long * outsize,
153 my_mem_dest_ptr dest;
155 if (outbuffer == NULL || outsize == NULL) /* sanity check */
156 ERREXIT(cinfo, JERR_BUFFER_SIZE);
158 /* The destination object is made permanent so that multiple JPEG images
159 * can be written to the same buffer without re-executing jpeg_mem_dest.
161 if (cinfo->dest == NULL) { /* first time for this JPEG object? */
162 cinfo->dest = (struct jpeg_destination_mgr *)
163 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
164 SIZEOF(my_mem_destination_mgr));
165 dest = (my_mem_dest_ptr) cinfo->dest;
166 dest->newbuffer = NULL;
169 dest = (my_mem_dest_ptr) cinfo->dest;
170 dest->pub.init_destination = init_mem_destination;
171 dest->pub.empty_output_buffer = empty_mem_output_buffer;
172 dest->pub.term_destination = term_mem_destination;
173 dest->outbuffer = outbuffer;
174 dest->outsize = outsize;
177 if (*outbuffer == NULL || *outsize == 0) {
179 /* Allocate initial buffer */
180 dest->newbuffer = *outbuffer = (unsigned char *) malloc(OUTPUT_BUF_SIZE);
181 if (dest->newbuffer == NULL)
182 ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
183 *outsize = OUTPUT_BUF_SIZE;
185 else ERREXIT(cinfo, JERR_BUFFER_SIZE);
188 dest->pub.next_output_byte = dest->buffer = *outbuffer;
189 dest->pub.free_in_buffer = dest->bufsize = *outsize;