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)
45 #include "radiant_jpeglib.h"
46 #include "jpeg6/jerror.h"
49 #include "ifilesystem.h"
53 typedef unsigned char byte;
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)
79 my_src_ptr src = (my_src_ptr) cinfo->src;
81 /* We reset the empty-input-file flag for each image,
82 * but we don't clear the input buffer.
83 * This is correct behavior for reading a series of images from one source.
85 src->start_of_file = TRUE;
90 * Fill the input buffer --- called whenever buffer is emptied.
92 * In typical applications, this should read fresh data into the buffer
93 * (ignoring the current state of next_input_byte & bytes_in_buffer),
94 * reset the pointer & count to the start of the buffer, and return TRUE
95 * indicating that the buffer has been reloaded. It is not necessary to
96 * fill the buffer entirely, only to obtain at least one more byte.
98 * There is no such thing as an EOF return. If the end of the file has been
99 * reached, the routine has a choice of ERREXIT() or inserting fake data into
100 * the buffer. In most cases, generating a warning message and inserting a
101 * fake EOI marker is the best course of action --- this will allow the
102 * decompressor to output however much of the image is there. However,
103 * the resulting error message is misleading if the real problem is an empty
104 * input file, so we handle that case specially.
106 * In applications that need to be able to suspend compression due to input
107 * not being available yet, a FALSE return indicates that no more data can be
108 * obtained right now, but more may be forthcoming later. In this situation,
109 * the decompressor will return to its caller (with an indication of the
110 * number of scanlines it has read, if any). The application should resume
111 * decompression after it has loaded more data into the input buffer. Note
112 * that there are substantial restrictions on the use of suspension --- see
115 * When suspending, the decompressor will back up to a convenient restart point
116 * (typically the start of the current MCU). next_input_byte & bytes_in_buffer
117 * indicate where the restart point will be if the current call returns FALSE.
118 * Data beyond this point must be rescanned after resumption, so move it to
119 * the front of the buffer rather than discarding it.
122 static boolean my_fill_input_buffer (j_decompress_ptr cinfo)
124 my_src_ptr src = (my_src_ptr) cinfo->src;
127 if (src->src_size > INPUT_BUF_SIZE)
128 nbytes = INPUT_BUF_SIZE;
130 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);
139 WARNMS(cinfo, JWRN_JPEG_EOF);
140 /* Insert a fake EOI marker */
141 src->buffer[0] = (JOCTET) 0xFF;
142 src->buffer[1] = (JOCTET) JPEG_EOI;
146 src->pub.next_input_byte = src->buffer;
147 src->pub.bytes_in_buffer = nbytes;
148 src->start_of_file = FALSE;
155 * Skip data --- used to skip over a potentially large amount of
156 * uninteresting data (such as an APPn marker).
158 * Writers of suspendable-input applications must note that skip_input_data
159 * is not granted the right to give a suspension return. If the skip extends
160 * beyond the data currently in the buffer, the buffer can be marked empty so
161 * that the next read will cause a fill_input_buffer call that can suspend.
162 * Arranging for additional bytes to be discarded before reloading the input
163 * buffer is the application writer's problem.
166 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.
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)
208 /* no work necessary here */
213 * Prepare for input from a stdio stream.
214 * The caller must have already opened the stream, and is responsible
215 * for closing it after finishing decompression.
218 static void jpeg_buffer_src (j_decompress_ptr cinfo, void* buffer, int bufsize)
222 /* The source object and input buffer are made permanent so that a series
223 * of JPEG images can be read from the same file by calling jpeg_stdio_src
224 * only before the first one. (If we discarded the buffer at the end of
225 * one image, we'd likely lose the start of the next one.)
226 * This makes it unsafe to use this manager and a different source
227 * manager serially with the same JPEG object. Caveat programmer.
229 if (cinfo->src == NULL) { /* first time for this JPEG object? */
230 cinfo->src = (struct jpeg_source_mgr *)
231 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
232 sizeof (my_source_mgr));
233 src = (my_src_ptr) cinfo->src;
234 src->buffer = (JOCTET *)
235 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
236 INPUT_BUF_SIZE * sizeof (JOCTET));
239 src = (my_src_ptr) cinfo->src;
240 src->pub.init_source = my_init_source;
241 src->pub.fill_input_buffer = my_fill_input_buffer;
242 src->pub.skip_input_data = my_skip_input_data;
243 src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
244 src->pub.term_source = my_term_source;
245 src->src_buffer = (JOCTET *)buffer;
246 src->src_size = bufsize;
247 src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
248 src->pub.next_input_byte = NULL; /* until buffer loaded */
251 // =============================================================================
253 static char errormsg[JMSG_LENGTH_MAX];
255 typedef struct my_jpeg_error_mgr
257 struct jpeg_error_mgr pub; // "public" fields
258 jmp_buf setjmp_buffer; // for return to caller
261 static void my_jpeg_error_exit (j_common_ptr cinfo)
263 my_jpeg_error_mgr* myerr = (bt_jpeg_error_mgr*) cinfo->err;
265 (*cinfo->err->format_message) (cinfo, errormsg);
267 longjmp (myerr->setjmp_buffer, 1);
271 static void j_putRGBScanline (unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row)
273 int offset = row * widthPix * 4;
276 for (count = 0; count < widthPix; count++)
278 unsigned char iRed, iBlu, iGrn;
279 unsigned char *oRed, *oBlu, *oGrn, *oAlp;
281 iRed = *(jpegline + count * 3 + 0);
282 iGrn = *(jpegline + count * 3 + 1);
283 iBlu = *(jpegline + count * 3 + 2);
285 oRed = outBuf + offset + count * 4 + 0;
286 oGrn = outBuf + offset + count * 4 + 1;
287 oBlu = outBuf + offset + count * 4 + 2;
288 oAlp = outBuf + offset + count * 4 + 3;
298 static void j_putRGBAScanline (unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row)
300 int offset = row * widthPix * 4;
303 for (count = 0; count < widthPix; count++)
305 unsigned char iRed, iBlu, iGrn, iAlp;
306 unsigned char *oRed, *oBlu, *oGrn, *oAlp;
308 iRed = *(jpegline + count * 4 + 0);
309 iGrn = *(jpegline + count * 4 + 1);
310 iBlu = *(jpegline + count * 4 + 2);
311 iAlp = *(jpegline + count * 4 + 3);
313 oRed = outBuf + offset + count * 4 + 0;
314 oGrn = outBuf + offset + count * 4 + 1;
315 oBlu = outBuf + offset + count * 4 + 2;
316 oAlp = outBuf + offset + count * 4 + 3;
322 //!\todo fix jpeglib, it leaves alpha channel uninitialised
331 // stash a gray scanline
332 static void j_putGrayScanlineToRGB (unsigned char* jpegline, int widthPix, unsigned char* outBuf, int row)
334 int offset = row * widthPix * 4;
337 for (count = 0; count < widthPix; count++)
340 unsigned char *oRed, *oBlu, *oGrn, *oAlp;
342 // get our grayscale value
343 iGray = *(jpegline + count);
345 oRed = outBuf + offset + count * 4;
346 oGrn = outBuf + offset + count * 4 + 1;
347 oBlu = outBuf + offset + count * 4 + 2;
348 oAlp = outBuf + offset + count * 4 + 3;
357 static Image* LoadJPGBuff_(const void *src_buffer, int src_size)
359 struct jpeg_decompress_struct cinfo;
360 struct my_jpeg_error_mgr jerr;
362 cinfo.err = jpeg_std_error (&jerr.pub);
363 jerr.pub.error_exit = my_jpeg_error_exit;
365 if (setjmp (jerr.setjmp_buffer)) //< TODO: use c++ exceptions instead of setjmp/longjmp to handle errors
367 globalErrorStream() << "WARNING: JPEG library error: " << errormsg << "\n";
368 jpeg_destroy_decompress (&cinfo);
372 jpeg_create_decompress (&cinfo);
373 jpeg_buffer_src (&cinfo, const_cast<void*>(src_buffer), src_size);
374 jpeg_read_header (&cinfo, TRUE);
375 jpeg_start_decompress (&cinfo);
377 int row_stride = cinfo.output_width * cinfo.output_components;
379 RGBAImage* image = new RGBAImage(cinfo.output_width, cinfo.output_height);
381 JSAMPARRAY 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, image->getRGBAPixels(), cinfo.output_scanline-1);
389 else if (cinfo.out_color_components == 3)
390 j_putRGBScanline (buffer[0], cinfo.output_width, image->getRGBAPixels(), cinfo.output_scanline-1);
391 else if (cinfo.out_color_components == 1)
392 j_putGrayScanlineToRGB (buffer[0], cinfo.output_width, image->getRGBAPixels(), cinfo.output_scanline-1);
395 jpeg_finish_decompress (&cinfo);
396 jpeg_destroy_decompress (&cinfo);
401 Image* LoadJPG(ArchiveFile& file)
403 ScopedArchiveBuffer buffer(file);
404 return LoadJPGBuff_(buffer.buffer, static_cast<int>(buffer.length));