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)
47 #include "radiant_jpeglib.h"
48 #include "jpeg6/jerror.h"
54 /* Expanded data source object for stdio input */
57 struct jpeg_source_mgr pub; /* public fields */
62 JOCTET * buffer; /* start of buffer */
63 boolean start_of_file; /* have we gotten any data yet? */
66 typedef my_source_mgr * my_src_ptr;
68 #define INPUT_BUF_SIZE 4096 /* choose an efficiently fread'able size */
72 * Initialize source --- called by jpeg_read_header
73 * before any data is actually read.
76 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)
123 my_src_ptr src = (my_src_ptr) cinfo->src;
126 if (src->src_size > INPUT_BUF_SIZE)
127 nbytes = INPUT_BUF_SIZE;
129 nbytes = src->src_size;
131 memcpy (src->buffer, src->src_buffer, nbytes);
132 src->src_buffer += nbytes;
133 src->src_size -= nbytes;
136 if (src->start_of_file) /* Treat empty input file as fatal error */
137 ERREXIT(cinfo, JERR_INPUT_EMPTY);
138 WARNMS(cinfo, JWRN_JPEG_EOF);
139 /* Insert a fake EOI marker */
140 src->buffer[0] = (JOCTET) 0xFF;
141 src->buffer[1] = (JOCTET) JPEG_EOI;
145 src->pub.next_input_byte = src->buffer;
146 src->pub.bytes_in_buffer = nbytes;
147 src->start_of_file = FALSE;
154 * Skip data --- used to skip over a potentially large amount of
155 * uninteresting data (such as an APPn marker).
157 * Writers of suspendable-input applications must note that skip_input_data
158 * is not granted the right to give a suspension return. If the skip extends
159 * beyond the data currently in the buffer, the buffer can be marked empty so
160 * that the next read will cause a fill_input_buffer call that can suspend.
161 * Arranging for additional bytes to be discarded before reloading the input
162 * buffer is the application writer's problem.
165 static void my_skip_input_data (j_decompress_ptr cinfo, long num_bytes)
167 my_src_ptr src = (my_src_ptr) cinfo->src;
169 /* Just a dumb implementation for now. Could use fseek() except
170 * it doesn't work on pipes. Not clear that being smart is worth
171 * any trouble anyway --- large skips are infrequent.
174 while (num_bytes > (long) src->pub.bytes_in_buffer) {
175 num_bytes -= (long) src->pub.bytes_in_buffer;
176 (void) my_fill_input_buffer(cinfo);
177 /* note we assume that fill_input_buffer will never return FALSE,
178 * so suspension need not be handled.
181 src->pub.next_input_byte += (size_t) num_bytes;
182 src->pub.bytes_in_buffer -= (size_t) num_bytes;
188 * An additional method that can be provided by data source modules is the
189 * resync_to_restart method for error recovery in the presence of RST markers.
190 * For the moment, this source module just uses the default resync method
191 * provided by the JPEG library. That method assumes that no backtracking
197 * Terminate source --- called by jpeg_finish_decompress
198 * after all data has been read. Often a no-op.
200 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
201 * application must deal with any cleanup that should happen even
205 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)
221 /* The source object and input buffer are made permanent so that a series
222 * of JPEG images can be read from the same file by calling jpeg_stdio_src
223 * only before the first one. (If we discarded the buffer at the end of
224 * one image, we'd likely lose the start of the next one.)
225 * This makes it unsafe to use this manager and a different source
226 * manager serially with the same JPEG object. Caveat programmer.
228 if (cinfo->src == NULL) { /* first time for this JPEG object? */
229 cinfo->src = (struct jpeg_source_mgr *)
230 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
231 sizeof (my_source_mgr));
232 src = (my_src_ptr) cinfo->src;
233 src->buffer = (JOCTET *)
234 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
235 INPUT_BUF_SIZE * sizeof (JOCTET));
238 src = (my_src_ptr) cinfo->src;
239 src->pub.init_source = my_init_source;
240 src->pub.fill_input_buffer = my_fill_input_buffer;
241 src->pub.skip_input_data = my_skip_input_data;
242 src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
243 src->pub.term_source = my_term_source;
244 src->src_buffer = (JOCTET *)buffer;
245 src->src_size = bufsize;
246 src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
247 src->pub.next_input_byte = NULL; /* until buffer loaded */
250 // =============================================================================
252 static char errormsg[JMSG_LENGTH_MAX];
254 typedef struct my_jpeg_error_mgr
256 struct jpeg_error_mgr pub; // "public" fields
257 jmp_buf setjmp_buffer; // for return to caller
260 static void my_jpeg_error_exit (j_common_ptr cinfo)
262 my_jpeg_error_mgr* myerr = (bt_jpeg_error_mgr*) cinfo->err;
264 (*cinfo->err->format_message) (cinfo, errormsg);
266 longjmp (myerr->setjmp_buffer, 1);
270 static void j_putRGBScanline (unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row)
272 int offset = row * widthPix * 4;
275 for (count = 0; count < widthPix; count++)
277 unsigned char iRed, iBlu, iGrn;
278 unsigned char *oRed, *oBlu, *oGrn, *oAlp;
280 iRed = *(jpegline + count * 3 + 0);
281 iGrn = *(jpegline + count * 3 + 1);
282 iBlu = *(jpegline + count * 3 + 2);
284 oRed = outBuf + offset + count * 4 + 0;
285 oGrn = outBuf + offset + count * 4 + 1;
286 oBlu = outBuf + offset + count * 4 + 2;
287 oAlp = outBuf + offset + count * 4 + 3;
297 static void j_putRGBAScanline (unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row)
299 int offset = row * widthPix * 4;
302 for (count = 0; count < widthPix; count++)
304 unsigned char iRed, iBlu, iGrn, iAlp;
305 unsigned char *oRed, *oBlu, *oGrn, *oAlp;
307 iRed = *(jpegline + count * 4 + 0);
308 iGrn = *(jpegline + count * 4 + 1);
309 iBlu = *(jpegline + count * 4 + 2);
310 iAlp = *(jpegline + count * 4 + 3);
312 oRed = outBuf + offset + count * 4 + 0;
313 oGrn = outBuf + offset + count * 4 + 1;
314 oBlu = outBuf + offset + count * 4 + 2;
315 oAlp = outBuf + offset + count * 4 + 3;
320 // ydnar: see bug 900
321 *oAlp = 255; //% iAlp;
325 // stash a gray scanline
326 static void j_putGrayScanlineToRGB (unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row)
328 int offset = row * widthPix * 4;
331 for (count = 0; count < widthPix; count++)
334 unsigned char *oRed, *oBlu, *oGrn, *oAlp;
336 // get our grayscale value
337 iGray = *(jpegline + count);
339 oRed = outBuf + offset + count * 4;
340 oGrn = outBuf + offset + count * 4 + 1;
341 oBlu = outBuf + offset + count * 4 + 2;
342 oAlp = outBuf + offset + count * 4 + 3;
351 static int _LoadJPGBuff (void *src_buffer, int src_size, unsigned char **pic, int *width, int *height)
353 struct jpeg_decompress_struct cinfo;
354 struct my_jpeg_error_mgr jerr;
356 int row_stride, size;
358 cinfo.err = jpeg_std_error (&jerr.pub);
359 jerr.pub.error_exit = my_jpeg_error_exit;
361 if (setjmp (jerr.setjmp_buffer))
363 *pic = (unsigned char*)errormsg;
364 jpeg_destroy_decompress (&cinfo);
368 jpeg_create_decompress (&cinfo);
369 jpeg_buffer_src (&cinfo, src_buffer, src_size);
370 jpeg_read_header (&cinfo, TRUE);
371 jpeg_start_decompress (&cinfo);
373 row_stride = cinfo.output_width * cinfo.output_components;
375 size = cinfo.output_width * cinfo.output_height * 4;
376 *width = cinfo.output_width;
377 *height = cinfo.output_height;
378 *pic = (unsigned char*) (g_malloc (size+1));
379 memset (*pic, 0, size+1);
381 buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);
383 while (cinfo.output_scanline < cinfo.output_height)
385 jpeg_read_scanlines (&cinfo, buffer, 1);
387 if (cinfo.out_color_components == 4)
388 j_putRGBAScanline (buffer[0], cinfo.output_width, *pic, cinfo.output_scanline-1);
389 else if (cinfo.out_color_components == 3)
390 j_putRGBScanline (buffer[0], cinfo.output_width, *pic, cinfo.output_scanline-1);
391 else if (cinfo.out_color_components == 1)
392 j_putGrayScanlineToRGB (buffer[0], cinfo.output_width, *pic, cinfo.output_scanline-1);
395 jpeg_finish_decompress (&cinfo);
396 jpeg_destroy_decompress (&cinfo);
401 void LoadJPG (const char *filename, unsigned char **pic, int *width, int *height)
403 unsigned char *fbuffer = NULL;
404 int nLen = vfsLoadFile ((char *)filename, (void **)&fbuffer, 0 );
408 if (_LoadJPGBuff (fbuffer, nLen, pic, width, height) != 0)
410 g_FuncTable.m_pfnSysPrintf( "WARNING: JPEG library failed to load %s because %s\n", filename, *pic );
414 vfsFreeFile (fbuffer);