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)
44 #include "radiant_jpeglib.h"
45 #include "jpeg6/jerror.h"
50 /* Expanded data source object for stdio input */
53 struct jpeg_source_mgr pub; /* public fields */
58 JOCTET * buffer; /* start of buffer */
59 boolean start_of_file; /* have we gotten any data yet? */
62 typedef my_source_mgr * my_src_ptr;
64 #define INPUT_BUF_SIZE 4096 /* choose an efficiently fread'able size */
68 * Initialize source --- called by jpeg_read_header
69 * before any data is actually read.
72 static void my_init_source (j_decompress_ptr cinfo)
74 my_src_ptr src = (my_src_ptr) cinfo->src;
76 /* We reset the empty-input-file flag for each image,
77 * but we don't clear the input buffer.
78 * This is correct behavior for reading a series of images from one source.
80 src->start_of_file = TRUE;
85 * Fill the input buffer --- called whenever buffer is emptied.
87 * In typical applications, this should read fresh data into the buffer
88 * (ignoring the current state of next_input_byte & bytes_in_buffer),
89 * reset the pointer & count to the start of the buffer, and return TRUE
90 * indicating that the buffer has been reloaded. It is not necessary to
91 * fill the buffer entirely, only to obtain at least one more byte.
93 * There is no such thing as an EOF return. If the end of the file has been
94 * reached, the routine has a choice of ERREXIT() or inserting fake data into
95 * the buffer. In most cases, generating a warning message and inserting a
96 * fake EOI marker is the best course of action --- this will allow the
97 * decompressor to output however much of the image is there. However,
98 * the resulting error message is misleading if the real problem is an empty
99 * input file, so we handle that case specially.
101 * In applications that need to be able to suspend compression due to input
102 * not being available yet, a FALSE return indicates that no more data can be
103 * obtained right now, but more may be forthcoming later. In this situation,
104 * the decompressor will return to its caller (with an indication of the
105 * number of scanlines it has read, if any). The application should resume
106 * decompression after it has loaded more data into the input buffer. Note
107 * that there are substantial restrictions on the use of suspension --- see
110 * When suspending, the decompressor will back up to a convenient restart point
111 * (typically the start of the current MCU). next_input_byte & bytes_in_buffer
112 * indicate where the restart point will be if the current call returns FALSE.
113 * Data beyond this point must be rescanned after resumption, so move it to
114 * the front of the buffer rather than discarding it.
117 static boolean my_fill_input_buffer (j_decompress_ptr cinfo)
119 my_src_ptr src = (my_src_ptr) cinfo->src;
122 if (src->src_size > INPUT_BUF_SIZE)
123 nbytes = INPUT_BUF_SIZE;
125 nbytes = src->src_size;
127 memcpy (src->buffer, src->src_buffer, nbytes);
128 src->src_buffer += nbytes;
129 src->src_size -= nbytes;
132 if (src->start_of_file) /* Treat empty input file as fatal error */
133 ERREXIT(cinfo, JERR_INPUT_EMPTY);
134 WARNMS(cinfo, JWRN_JPEG_EOF);
135 /* Insert a fake EOI marker */
136 src->buffer[0] = (JOCTET) 0xFF;
137 src->buffer[1] = (JOCTET) JPEG_EOI;
141 src->pub.next_input_byte = src->buffer;
142 src->pub.bytes_in_buffer = nbytes;
143 src->start_of_file = FALSE;
150 * Skip data --- used to skip over a potentially large amount of
151 * uninteresting data (such as an APPn marker).
153 * Writers of suspendable-input applications must note that skip_input_data
154 * is not granted the right to give a suspension return. If the skip extends
155 * beyond the data currently in the buffer, the buffer can be marked empty so
156 * that the next read will cause a fill_input_buffer call that can suspend.
157 * Arranging for additional bytes to be discarded before reloading the input
158 * buffer is the application writer's problem.
161 static void my_skip_input_data (j_decompress_ptr cinfo, long num_bytes)
163 my_src_ptr src = (my_src_ptr) cinfo->src;
165 /* Just a dumb implementation for now. Could use fseek() except
166 * it doesn't work on pipes. Not clear that being smart is worth
167 * any trouble anyway --- large skips are infrequent.
170 while (num_bytes > (long) src->pub.bytes_in_buffer) {
171 num_bytes -= (long) src->pub.bytes_in_buffer;
172 (void) my_fill_input_buffer(cinfo);
173 /* note we assume that fill_input_buffer will never return FALSE,
174 * so suspension need not be handled.
177 src->pub.next_input_byte += (size_t) num_bytes;
178 src->pub.bytes_in_buffer -= (size_t) num_bytes;
184 * An additional method that can be provided by data source modules is the
185 * resync_to_restart method for error recovery in the presence of RST markers.
186 * For the moment, this source module just uses the default resync method
187 * provided by the JPEG library. That method assumes that no backtracking
193 * Terminate source --- called by jpeg_finish_decompress
194 * after all data has been read. Often a no-op.
196 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
197 * application must deal with any cleanup that should happen even
201 static void my_term_source (j_decompress_ptr cinfo)
203 /* no work necessary here */
208 * Prepare for input from a stdio stream.
209 * The caller must have already opened the stream, and is responsible
210 * for closing it after finishing decompression.
213 static void jpeg_buffer_src (j_decompress_ptr cinfo, void* buffer, int bufsize)
217 /* The source object and input buffer are made permanent so that a series
218 * of JPEG images can be read from the same file by calling jpeg_stdio_src
219 * only before the first one. (If we discarded the buffer at the end of
220 * one image, we'd likely lose the start of the next one.)
221 * This makes it unsafe to use this manager and a different source
222 * manager serially with the same JPEG object. Caveat programmer.
224 if (cinfo->src == NULL) { /* first time for this JPEG object? */
225 cinfo->src = (struct jpeg_source_mgr *)
226 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
227 sizeof (my_source_mgr));
228 src = (my_src_ptr) cinfo->src;
229 src->buffer = (JOCTET *)
230 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
231 INPUT_BUF_SIZE * sizeof (JOCTET));
234 src = (my_src_ptr) cinfo->src;
235 src->pub.init_source = my_init_source;
236 src->pub.fill_input_buffer = my_fill_input_buffer;
237 src->pub.skip_input_data = my_skip_input_data;
238 src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
239 src->pub.term_source = my_term_source;
240 src->src_buffer = (JOCTET *)buffer;
241 src->src_size = bufsize;
242 src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
243 src->pub.next_input_byte = NULL; /* until buffer loaded */
246 // =============================================================================
248 static char errormsg[JMSG_LENGTH_MAX];
250 typedef struct my_jpeg_error_mgr
252 struct jpeg_error_mgr pub; // "public" fields
253 jmp_buf setjmp_buffer; // for return to caller
256 static void my_jpeg_error_exit (j_common_ptr cinfo)
258 my_jpeg_error_mgr* myerr = (bt_jpeg_error_mgr*) cinfo->err;
260 (*cinfo->err->format_message) (cinfo, errormsg);
262 longjmp (myerr->setjmp_buffer, 1);
266 static void j_putRGBScanline (unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row)
268 int offset = row * widthPix * 4;
271 for (count = 0; count < widthPix; count++)
273 unsigned char iRed, iBlu, iGrn;
274 unsigned char *oRed, *oBlu, *oGrn, *oAlp;
276 iRed = *(jpegline + count * 3 + 0);
277 iGrn = *(jpegline + count * 3 + 1);
278 iBlu = *(jpegline + count * 3 + 2);
280 oRed = outBuf + offset + count * 4 + 0;
281 oGrn = outBuf + offset + count * 4 + 1;
282 oBlu = outBuf + offset + count * 4 + 2;
283 oAlp = outBuf + offset + count * 4 + 3;
293 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)
324 int offset = row * widthPix * 4;
327 for (count = 0; count < widthPix; count++)
330 unsigned char *oRed, *oBlu, *oGrn, *oAlp;
332 // get our grayscale value
333 iGray = *(jpegline + count);
335 oRed = outBuf + offset + count * 4;
336 oGrn = outBuf + offset + count * 4 + 1;
337 oBlu = outBuf + offset + count * 4 + 2;
338 oAlp = outBuf + offset + count * 4 + 3;
347 static int _LoadJPGBuff (void *src_buffer, int src_size, unsigned char **pic, int *width, int *height)
349 struct jpeg_decompress_struct cinfo;
350 struct my_jpeg_error_mgr jerr;
352 int row_stride, size;
354 cinfo.err = jpeg_std_error (&jerr.pub);
355 jerr.pub.error_exit = my_jpeg_error_exit;
357 if (setjmp (jerr.setjmp_buffer))
359 *pic = (unsigned char*)errormsg;
360 jpeg_destroy_decompress (&cinfo);
364 jpeg_create_decompress (&cinfo);
365 jpeg_buffer_src (&cinfo, src_buffer, src_size);
366 jpeg_read_header (&cinfo, TRUE);
367 jpeg_start_decompress (&cinfo);
369 row_stride = cinfo.output_width * cinfo.output_components;
371 size = cinfo.output_width * cinfo.output_height * 4;
372 *width = cinfo.output_width;
373 *height = cinfo.output_height;
374 *pic = (unsigned char*) (g_malloc (size+1));
375 memset (*pic, 0, size+1);
377 buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);
379 while (cinfo.output_scanline < cinfo.output_height)
381 jpeg_read_scanlines (&cinfo, buffer, 1);
383 if (cinfo.out_color_components == 4)
384 j_putRGBAScanline (buffer[0], cinfo.output_width, *pic, cinfo.output_scanline-1);
385 else if (cinfo.out_color_components == 3)
386 j_putRGBScanline (buffer[0], cinfo.output_width, *pic, cinfo.output_scanline-1);
387 else if (cinfo.out_color_components == 1)
388 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)
399 unsigned char *fbuffer = NULL;
400 int nLen = vfsLoadFile ((char *)filename, (void **)&fbuffer, 0 );
404 if (_LoadJPGBuff (fbuffer, nLen, pic, width, height) != 0)
406 g_FuncTable.m_pfnSysPrintf( "WARNING: JPEG library failed to load %s because %s\n", filename, *pic );
410 vfsFreeFile (fbuffer);