4 * Copyright (C) 2001, Dorian Goldstein, Thomas G. Lane.
6 * This file contains compression data destination routines for the case of
7 * This file is identicle with IJG's built in destination file manager in
8 * every respect but 1... instead fo emmiting data to a file
9 * it facilitates definition of a callback function.
12 /* this is not a core library module, so it doesn't define JPEG_INTERNALS */
18 /* Expanded data destination object for stdio output */
21 struct jpeg_destination_mgr pub; /* public fields */
23 JOCTET * outbuff; // target output buffer
24 JOCTET * buffer; // start of internal buffer
25 UINT16 size_outbuff; // current size of target output buffer
26 JMETHOD (void, flush_output_buffer_callback, (JOCTET *outbuf, JOCTET* buffer, size_t size));
29 typedef my_destination_mgr * my_dest_ptr;
31 #define OUTPUT_BUF_SIZE 4096 /* choose an efficiently fwrite'able size */
35 * Initialize destination --- called by jpeg_start_compress
36 * before any data is actually written.
40 init_destination (j_compress_ptr cinfo)
42 my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
44 /* Allocate the output buffer --- it will be released when done with image */
45 dest->buffer = (JOCTET *)
46 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
47 OUTPUT_BUF_SIZE * SIZEOF(JOCTET));
49 dest->pub.next_output_byte = dest->buffer;
50 dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
55 * Empty the output buffer --- called whenever buffer fills up.
57 * In typical applications, this should write the entire output buffer
58 * (ignoring the current state of next_output_byte & free_in_buffer),
59 * reset the pointer & count to the start of the buffer, and return TRUE
60 * indicating that the buffer has been dumped.
62 * In applications that need to be able to suspend compression due to output
63 * overrun, a FALSE return indicates that the buffer cannot be emptied now.
64 * In this situation, the compressor will return to its caller (possibly with
65 * an indication that it has not accepted all the supplied scanlines). The
66 * application should resume compression after it has made more room in the
67 * output buffer. Note that there are substantial restrictions on the use of
68 * suspension --- see the documentation.
70 * When suspending, the compressor will back up to a convenient restart point
71 * (typically the start of the current MCU). next_output_byte & free_in_buffer
72 * indicate where the restart point will be if the current call returns FALSE.
73 * Data beyond this point will be regenerated after resumption, so do not
74 * write it out when emptying the buffer externally.
78 empty_output_buffer (j_compress_ptr cinfo)
80 my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
82 // DG Temp if (dest->flush_output_buffer_callback == NULL) {
83 // DG Temp if (dest->outbuff) {
84 // DG Temp MEMCOPY(dest->outbuff + dest->size_outbuff, dest->buffer, OUTPUT_BUF_SIZE);
85 // DG Temp dest->size_outbuff += OUTPUT_BUF_SIZE;
88 // DG Temp (*dest->flush_output_buffer_callback)(dest->buffer, OUTPUT_BUF_SIZE);
91 (*dest->flush_output_buffer_callback)(dest->outbuff, dest->buffer, OUTPUT_BUF_SIZE);
94 dest->pub.next_output_byte = dest->buffer;
95 dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
102 * Terminate destination --- called by jpeg_finish_compress
103 * after all data has been written. Usually needs to flush buffer.
105 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
106 * application must deal with any cleanup that should happen even
111 term_destination (j_compress_ptr cinfo)
113 my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
114 size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;
116 /* Write any data remaining in the buffer */
118 // DG Temp if (dest->flush_output_buffer_callback == NULL) {
119 // DG Temp if (dest->outbuff) {
120 // DG Temp MEMCOPY(dest->outbuff + dest->size_outbuff, dest->buffer, datacount);
121 // DG Temp dest->size_outbuff += datacount;
124 // DG Temp (*dest->flush_output_buffer_callback)(dest->buffer, datacount);
127 (*dest->flush_output_buffer_callback)(dest->outbuff, dest->buffer, datacount);
133 * Prepare for output to a stdio stream.
134 * The caller must have already opened the stream, and is responsible
135 * for closing it after finishing compression.
139 jpeg_buffer_dest (j_compress_ptr cinfo, JOCTET* outbuff, void* flush_output_buffer_callback)
143 /* The destination object is made permanent so that multiple JPEG images
144 * can be written to the same file without re-executing jpeg_stdio_dest.
145 * This makes it dangerous to use this manager and a different destination
146 * manager serially with the same JPEG object, because their private object
147 * sizes may be different. Caveat programmer.
149 if (cinfo->dest == NULL) { /* first time for this JPEG object? */
150 cinfo->dest = (struct jpeg_destination_mgr *)
151 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
152 SIZEOF(my_destination_mgr));
155 dest = (my_dest_ptr) cinfo->dest;
156 dest->pub.init_destination = init_destination;
157 dest->pub.empty_output_buffer = empty_output_buffer;
158 dest->pub.term_destination = term_destination;
160 dest->outbuff = outbuff;
161 dest->size_outbuff = 0;
162 dest->flush_output_buffer_callback = flush_output_buffer_callback;
163 //(*dest->flush_output_buffer_callback)(-1 , -1);
167 jpeg_buffer_size_dest (j_compress_ptr cinfo)
169 my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
171 return dest->size_outbuff;