2 Copyright (c) 2001, Loki software, inc.
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32 // Functions to load JPEG files from a buffer, based on jdatasrc.c
34 // Leonardo Zide (leo@lokigames.com)
38 // Ugly hack so that INT32 is defined before jmorecfg.h is parsed.
55 /* Expanded data source object for stdio input */
58 struct jpeg_source_mgr pub; /* public fields */
63 JOCTET * buffer; /* start of buffer */
64 boolean start_of_file; /* have we gotten any data yet? */
67 typedef my_source_mgr * my_src_ptr;
69 #define INPUT_BUF_SIZE 4096 /* choose an efficiently fread'able size */
73 * Initialize source --- called by jpeg_read_header
74 * before any data is actually read.
77 static void my_init_source( j_decompress_ptr cinfo ){
78 my_src_ptr src = (my_src_ptr) cinfo->src;
80 /* We reset the empty-input-file flag for each image,
81 * but we don't clear the input buffer.
82 * This is correct behavior for reading a series of images from one source.
84 src->start_of_file = TRUE;
89 * Fill the input buffer --- called whenever buffer is emptied.
91 * In typical applications, this should read fresh data into the buffer
92 * (ignoring the current state of next_input_byte & bytes_in_buffer),
93 * reset the pointer & count to the start of the buffer, and return TRUE
94 * indicating that the buffer has been reloaded. It is not necessary to
95 * fill the buffer entirely, only to obtain at least one more byte.
97 * There is no such thing as an EOF return. If the end of the file has been
98 * reached, the routine has a choice of ERREXIT() or inserting fake data into
99 * the buffer. In most cases, generating a warning message and inserting a
100 * fake EOI marker is the best course of action --- this will allow the
101 * decompressor to output however much of the image is there. However,
102 * the resulting error message is misleading if the real problem is an empty
103 * input file, so we handle that case specially.
105 * In applications that need to be able to suspend compression due to input
106 * not being available yet, a FALSE return indicates that no more data can be
107 * obtained right now, but more may be forthcoming later. In this situation,
108 * the decompressor will return to its caller (with an indication of the
109 * number of scanlines it has read, if any). The application should resume
110 * decompression after it has loaded more data into the input buffer. Note
111 * that there are substantial restrictions on the use of suspension --- see
114 * When suspending, the decompressor will back up to a convenient restart point
115 * (typically the start of the current MCU). next_input_byte & bytes_in_buffer
116 * indicate where the restart point will be if the current call returns FALSE.
117 * Data beyond this point must be rescanned after resumption, so move it to
118 * the front of the buffer rather than discarding it.
121 static boolean my_fill_input_buffer( j_decompress_ptr cinfo ){
122 my_src_ptr src = (my_src_ptr) cinfo->src;
125 if ( src->src_size > INPUT_BUF_SIZE ) {
126 nbytes = INPUT_BUF_SIZE;
129 nbytes = src->src_size;
132 memcpy( src->buffer, src->src_buffer, nbytes );
133 src->src_buffer += nbytes;
134 src->src_size -= nbytes;
137 if ( src->start_of_file ) { /* Treat empty input file as fatal error */
138 ERREXIT( cinfo, JERR_INPUT_EMPTY );
140 WARNMS( cinfo, JWRN_JPEG_EOF );
141 /* Insert a fake EOI marker */
142 src->buffer[0] = (JOCTET) 0xFF;
143 src->buffer[1] = (JOCTET) JPEG_EOI;
147 src->pub.next_input_byte = src->buffer;
148 src->pub.bytes_in_buffer = nbytes;
149 src->start_of_file = FALSE;
156 * Skip data --- used to skip over a potentially large amount of
157 * uninteresting data (such as an APPn marker).
159 * Writers of suspendable-input applications must note that skip_input_data
160 * is not granted the right to give a suspension return. If the skip extends
161 * beyond the data currently in the buffer, the buffer can be marked empty so
162 * that the next read will cause a fill_input_buffer call that can suspend.
163 * Arranging for additional bytes to be discarded before reloading the input
164 * buffer is the application writer's problem.
167 static void my_skip_input_data( j_decompress_ptr cinfo, long num_bytes ){
168 my_src_ptr src = (my_src_ptr) cinfo->src;
170 /* Just a dumb implementation for now. Could use fseek() except
171 * it doesn't work on pipes. Not clear that being smart is worth
172 * any trouble anyway --- large skips are infrequent.
174 if ( num_bytes > 0 ) {
175 while ( num_bytes > (long) src->pub.bytes_in_buffer ) {
176 num_bytes -= (long) src->pub.bytes_in_buffer;
177 (void) my_fill_input_buffer( cinfo );
178 /* note we assume that fill_input_buffer will never return FALSE,
179 * so suspension need not be handled.
182 src->pub.next_input_byte += (size_t) num_bytes;
183 src->pub.bytes_in_buffer -= (size_t) num_bytes;
189 * An additional method that can be provided by data source modules is the
190 * resync_to_restart method for error recovery in the presence of RST markers.
191 * For the moment, this source module just uses the default resync method
192 * provided by the JPEG library. That method assumes that no backtracking
198 * Terminate source --- called by jpeg_finish_decompress
199 * after all data has been read. Often a no-op.
201 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
202 * application must deal with any cleanup that should happen even
206 static void my_term_source( j_decompress_ptr cinfo ){
207 /* no work necessary here */
212 * Prepare for input from a stdio stream.
213 * The caller must have already opened the stream, and is responsible
214 * for closing it after finishing decompression.
217 static void jpeg_buffer_src( j_decompress_ptr cinfo, void* buffer, int bufsize ){
220 /* The source object and input buffer are made permanent so that a series
221 * of JPEG images can be read from the same file by calling jpeg_stdio_src
222 * only before the first one. (If we discarded the buffer at the end of
223 * one image, we'd likely lose the start of the next one.)
224 * This makes it unsafe to use this manager and a different source
225 * manager serially with the same JPEG object. Caveat programmer.
227 if ( cinfo->src == NULL ) { /* first time for this JPEG object? */
228 cinfo->src = (struct jpeg_source_mgr *)
229 ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_PERMANENT,
230 sizeof( my_source_mgr ) );
231 src = (my_src_ptr) cinfo->src;
232 src->buffer = (JOCTET *)
233 ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_PERMANENT,
234 INPUT_BUF_SIZE * sizeof( JOCTET ) );
237 src = (my_src_ptr) cinfo->src;
238 src->pub.init_source = my_init_source;
239 src->pub.fill_input_buffer = my_fill_input_buffer;
240 src->pub.skip_input_data = my_skip_input_data;
241 src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
242 src->pub.term_source = my_term_source;
243 src->src_buffer = (JOCTET *)buffer;
244 src->src_size = bufsize;
245 src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
246 src->pub.next_input_byte = NULL; /* until buffer loaded */
249 // =============================================================================
251 static char errormsg[JMSG_LENGTH_MAX];
253 typedef struct my_jpeg_error_mgr
255 struct jpeg_error_mgr pub; // "public" fields
256 jmp_buf setjmp_buffer; // for return to caller
259 static void my_jpeg_error_exit( j_common_ptr cinfo ){
260 my_jpeg_error_mgr* myerr = (bt_jpeg_error_mgr*) cinfo->err;
262 ( *cinfo->err->format_message )( cinfo, errormsg );
264 longjmp( myerr->setjmp_buffer, 1 );
268 static void j_putRGBScanline( unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row ){
269 int offset = row * widthPix * 4;
272 for ( count = 0; count < widthPix; count++ )
274 unsigned char iRed, iBlu, iGrn;
275 unsigned char *oRed, *oBlu, *oGrn, *oAlp;
277 iRed = *( jpegline + count * 3 + 0 );
278 iGrn = *( jpegline + count * 3 + 1 );
279 iBlu = *( jpegline + count * 3 + 2 );
281 oRed = outBuf + offset + count * 4 + 0;
282 oGrn = outBuf + offset + count * 4 + 1;
283 oBlu = outBuf + offset + count * 4 + 2;
284 oAlp = outBuf + offset + count * 4 + 3;
294 static void j_putRGBAScanline( unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row ){
295 int offset = row * widthPix * 4;
298 for ( count = 0; count < widthPix; count++ )
300 unsigned char iRed, iBlu, iGrn, iAlp;
301 unsigned char *oRed, *oBlu, *oGrn, *oAlp;
303 iRed = *( jpegline + count * 4 + 0 );
304 iGrn = *( jpegline + count * 4 + 1 );
305 iBlu = *( jpegline + count * 4 + 2 );
306 iAlp = *( jpegline + count * 4 + 3 );
308 oRed = outBuf + offset + count * 4 + 0;
309 oGrn = outBuf + offset + count * 4 + 1;
310 oBlu = outBuf + offset + count * 4 + 2;
311 oAlp = outBuf + offset + count * 4 + 3;
316 // ydnar: see bug 900
317 *oAlp = 255; //% iAlp;
321 // stash a gray scanline
322 static void j_putGrayScanlineToRGB( unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row ){
323 int offset = row * widthPix * 4;
326 for ( count = 0; count < widthPix; count++ )
329 unsigned char *oRed, *oBlu, *oGrn, *oAlp;
331 // get our grayscale value
332 iGray = *( jpegline + count );
334 oRed = outBuf + offset + count * 4;
335 oGrn = outBuf + offset + count * 4 + 1;
336 oBlu = outBuf + offset + count * 4 + 2;
337 oAlp = outBuf + offset + count * 4 + 3;
346 static int LoadJPGBuff( void *src_buffer, int src_size, unsigned char **pic, int *width, int *height ) {
347 struct jpeg_decompress_struct cinfo;
348 struct my_jpeg_error_mgr jerr;
350 int row_stride, size;
352 cinfo.err = jpeg_std_error( &jerr.pub );
353 jerr.pub.error_exit = my_jpeg_error_exit;
355 if ( setjmp( jerr.setjmp_buffer ) ) {
356 *pic = (unsigned char*)errormsg;
357 jpeg_destroy_decompress( &cinfo );
361 jpeg_create_decompress( &cinfo );
362 jpeg_buffer_src( &cinfo, src_buffer, src_size );
363 jpeg_read_header( &cinfo, TRUE );
364 jpeg_start_decompress( &cinfo );
366 row_stride = cinfo.output_width * cinfo.output_components;
368 size = cinfo.output_width * cinfo.output_height * 4;
369 *width = cinfo.output_width;
370 *height = cinfo.output_height;
371 *pic = (unsigned char*) ( g_malloc( size + 1 ) );
372 memset( *pic, 0, size + 1 );
374 buffer = ( *cinfo.mem->alloc_sarray )( ( j_common_ptr ) & cinfo, JPOOL_IMAGE, row_stride, 1 );
376 while ( cinfo.output_scanline < cinfo.output_height )
378 jpeg_read_scanlines( &cinfo, buffer, 1 );
380 if ( cinfo.out_color_components == 4 ) {
381 j_putRGBAScanline( buffer[0], cinfo.output_width, *pic, cinfo.output_scanline - 1 );
383 else if ( cinfo.out_color_components == 3 ) {
384 j_putRGBScanline( buffer[0], cinfo.output_width, *pic, cinfo.output_scanline - 1 );
386 else if ( cinfo.out_color_components == 1 ) {
387 j_putGrayScanlineToRGB( buffer[0], cinfo.output_width, *pic, cinfo.output_scanline - 1 );
391 jpeg_finish_decompress( &cinfo );
392 jpeg_destroy_decompress( &cinfo );
397 void LoadJPG( const char *filename, unsigned char **pic, int *width, int *height ) {
398 unsigned char *fbuffer = NULL;
399 int nLen = vfsLoadFile( (char *)filename, (void **)&fbuffer, 0 );
404 if ( LoadJPGBuff( fbuffer, nLen, pic, width, height ) != 0 ) {
405 g_FuncTable.m_pfnSysPrintf( "WARNING: JPEG library failed to load %s because %s\n", filename, *pic );
409 vfsFreeFile( fbuffer );