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b59bf2db JS |
1 | ///////////////////////////////////////////////////////////////////////////// |
2 | // Name: imaggif.cpp | |
3 | // Purpose: wxGIFHandler | |
4 | // Author: Guillermo Rodriguez Garcia | |
5 | // wxWindows adaptation by Vaclav Slavik | |
6 | // Licence: wxWindows licence | |
7 | ///////////////////////////////////////////////////////////////////////////// | |
8 | ||
9 | #ifdef __GNUG__ | |
10 | #pragma implementation "imaggif.h" | |
11 | #endif | |
12 | ||
13 | // For compilers that support precompilation, includes "wx.h". | |
14 | #include <wx/wxprec.h> | |
15 | ||
16 | #ifdef __BORLANDC__ | |
17 | #pragma hdrstop | |
18 | #endif | |
19 | ||
20 | #include <wx/wx.h> | |
21 | ||
22 | #include <wx/image.h> | |
23 | #include <wx/wfstream.h> | |
24 | #include <wx/module.h> | |
25 | ||
26 | #include <wx/imaggif.h> | |
27 | ||
28 | /* | |
29 | ||
30 | FOLLOWING CODE IS BY G.R.G. : | |
31 | (except wxInputStream stuff) | |
32 | ||
33 | */ | |
34 | ||
35 | /************************************************************************ | |
e207152c | 36 | READGIF.H - Reads a GIF file |
b59bf2db JS |
37 | ------------------------------------------------------------------------ |
38 | Guillermo Rodriguez Garcia | |
39 | <guille@iies.es> | |
40 | ||
99cc0158 | 41 | Version: 2.1 |
b59bf2db JS |
42 | *************************************************************************/ |
43 | ||
e207152c | 44 | |
b59bf2db JS |
45 | typedef struct |
46 | { | |
47 | int w; /* width */ | |
48 | int h; /* height */ | |
99cc0158 | 49 | int transparent; /* transparent color (-1 = none) */ |
b59bf2db JS |
50 | unsigned char *p; /* bitmap */ |
51 | unsigned char *pal; /* palette */ | |
52 | } IMAGEN; | |
53 | ||
54 | ||
e207152c | 55 | |
b59bf2db | 56 | /************************************************************************ |
e207152c | 57 | READGIF.C - Reads a GIF file |
b59bf2db JS |
58 | ------------------------------------------------------------------------ |
59 | Guillermo Rodriguez Garcia | |
60 | <guille@iies.es> | |
61 | ||
99cc0158 | 62 | Version: 2.1 |
b59bf2db JS |
63 | *************************************************************************/ |
64 | ||
65 | ||
b59bf2db JS |
66 | #include <stdlib.h> |
67 | #include <string.h> | |
68 | ||
69 | ||
70 | /* error codes */ | |
71 | #define E_OK 0 /* everything was OK */ | |
72 | #define E_ARCHIVO -1 /* error opening file */ | |
73 | #define E_FORMATO -2 /* error in gif header */ | |
74 | #define E_MEMORIA -3 /* error allocating memory */ | |
75 | ||
76 | ||
77 | /* This class binding is by VS, so all bugs in it are mine ;-) */ | |
78 | ||
79 | class gifDecoder | |
80 | { | |
81 | private: | |
82 | /* globals */ | |
83 | int restbits; /* remaining valid bits */ | |
84 | unsigned int restbyte; /* remaining bytes in this block */ | |
85 | unsigned int lastbyte; /* last byte read */ | |
86 | ||
53b7ce7e | 87 | wxInputStream *f; /* input file */ |
b59bf2db | 88 | |
e207152c VS |
89 | public: |
90 | gifDecoder(wxInputStream *s) { f = s; } | |
91 | int getcode(int bits); | |
92 | int dgif(IMAGEN *img, int interl, int bits); | |
93 | int readgif(IMAGEN *img); | |
b59bf2db JS |
94 | }; |
95 | ||
96 | ||
b59bf2db JS |
97 | |
98 | /* getcode: | |
99 | * Reads the next code from the file, with size 'bits' | |
b59bf2db JS |
100 | */ |
101 | int gifDecoder::getcode(int bits) | |
102 | { | |
103 | unsigned int mask; /* bit mask */ | |
104 | unsigned int code; /* code (result) */ | |
105 | ||
106 | ||
107 | /* get remaining bits from last byte read */ | |
108 | mask = (1 << bits) - 1; | |
109 | code = (lastbyte >> (8 - restbits)) & mask; | |
110 | ||
e207152c | 111 | /* keep reading new bytes while needed */ |
b59bf2db JS |
112 | while (bits > restbits) |
113 | { | |
114 | /* if no bytes left in this block, read the next block */ | |
115 | if (restbyte == 0) | |
e207152c | 116 | restbyte = (unsigned char)f->GetC(); |
b59bf2db JS |
117 | |
118 | /* read next byte and isolate the bits we need */ | |
e207152c | 119 | lastbyte = (unsigned char)f->GetC(); |
b59bf2db JS |
120 | mask = (1 << (bits - restbits)) - 1; |
121 | code = code + ((lastbyte & mask) << restbits); | |
122 | restbyte--; | |
123 | ||
124 | /* adjust total number of bits extracted from the buffer */ | |
125 | restbits = restbits + 8; | |
126 | } | |
e207152c | 127 | |
b59bf2db JS |
128 | /* find number of bits reamining for next code */ |
129 | restbits = (restbits - bits); | |
130 | ||
131 | return code; | |
132 | } | |
133 | ||
53b7ce7e | 134 | |
e207152c | 135 | |
b59bf2db JS |
136 | /* dgif: |
137 | * GIF decoding function. The initial code size (aka root size) | |
138 | * is 'bits'. Supports interlaced images (interl == 1). | |
139 | */ | |
140 | int gifDecoder::dgif(IMAGEN *img, int interl, int bits) | |
141 | { | |
142 | int ab_prefix[4096]; /* alphabet (prefixes) */ | |
143 | int ab_tail[4096]; /* alphabet (tails) */ | |
144 | int stack[4096]; /* decompression stack */ | |
145 | ||
146 | int ab_clr; /* clear code */ | |
147 | int ab_fin; /* end of info code */ | |
148 | int ab_bits; /* actual symbol width, in bits */ | |
149 | int ab_free; /* first free position in alphabet */ | |
150 | int ab_max; /* last possible character in alphabet */ | |
151 | int pass; /* pass number in interlaced images */ | |
152 | int pos; /* index into decompresion stack */ | |
153 | int x, y; /* position in image buffer */ | |
154 | ||
155 | int code, readcode, lastcode, abcabca; | |
156 | ||
157 | /* these won't change */ | |
158 | ab_clr = (1 << bits); | |
159 | ab_fin = (1 << bits) + 1; | |
160 | ||
161 | /* these will change through the decompression proccess */ | |
162 | ab_bits = bits + 1; | |
163 | ab_free = (1 << bits) + 2; | |
164 | ab_max = (1 << ab_bits) - 1; | |
165 | lastcode = -1; | |
166 | abcabca = -1; | |
167 | pass = 1; | |
168 | pos = x = y = 0; | |
169 | ||
170 | /* reset static globals */ | |
171 | restbits = 0; | |
172 | restbyte = 0; | |
173 | lastbyte = 0; | |
174 | ||
175 | do | |
176 | { | |
177 | /* get next code */ | |
178 | readcode = code = getcode(ab_bits); | |
179 | ||
180 | /* end of image? */ | |
181 | if (code == ab_fin) break; | |
182 | ||
183 | /* reset alphabet? */ | |
184 | if (code == ab_clr) | |
185 | { | |
186 | /* reset main variables */ | |
187 | ab_bits = bits + 1; | |
188 | ab_free = (1 << bits) + 2; | |
189 | ab_max = (1 << ab_bits) - 1; | |
190 | lastcode = -1; | |
191 | abcabca = -1; | |
192 | ||
193 | /* skip to next code */ | |
194 | continue; | |
195 | } | |
196 | ||
197 | /* unknown code: special case (like in ABCABCA) */ | |
198 | if (code >= ab_free) | |
199 | { | |
200 | code = lastcode; /* take last string */ | |
201 | stack[pos++] = abcabca; /* add first character */ | |
202 | } | |
203 | ||
204 | /* build the string for this code in the stack */ | |
205 | while (code > ab_clr) | |
206 | { | |
207 | stack[pos++] = ab_tail[code]; | |
208 | code = ab_prefix[code]; | |
209 | } | |
210 | stack[pos] = code; /* push last code into the stack */ | |
211 | abcabca = code; /* save for special case */ | |
212 | ||
213 | /* make new entry in alphabet (only if NOT just cleared) */ | |
214 | if (lastcode != -1) | |
215 | { | |
216 | ab_prefix[ab_free] = lastcode; | |
217 | ab_tail[ab_free] = code; | |
218 | ab_free++; | |
219 | ||
220 | if ((ab_free > ab_max) && (ab_bits < 12)) | |
221 | { | |
222 | ab_bits++; | |
223 | ab_max = (1 << ab_bits) - 1; | |
224 | } | |
225 | } | |
226 | ||
227 | /* dump stack data to the buffer */ | |
228 | while (pos >= 0) | |
229 | { | |
230 | (img->p)[x + (y * (img->w))] = (char)stack[pos--]; | |
231 | ||
232 | if (++x >= (img->w)) | |
233 | { | |
234 | x = 0; | |
235 | ||
236 | if (interl) | |
237 | { | |
238 | /* support for interlaced images */ | |
239 | switch (pass) | |
240 | { | |
241 | case 1: y += 8; break; | |
242 | case 2: y += 8; break; | |
243 | case 3: y += 4; break; | |
244 | case 4: y += 2; break; | |
245 | } | |
246 | if (y >= (img->h)) | |
247 | { | |
248 | switch (++pass) | |
249 | { | |
250 | case 2: y = 4; break; | |
251 | case 3: y = 2; break; | |
252 | case 4: y = 1; break; | |
253 | } | |
254 | } | |
255 | } | |
256 | else | |
257 | { | |
258 | /* non-interlaced */ | |
259 | y++; | |
260 | } | |
261 | } | |
262 | } | |
263 | ||
264 | pos = 0; | |
265 | lastcode = readcode; | |
266 | } | |
267 | while (code != ab_fin); | |
268 | ||
269 | return 0; | |
270 | } | |
271 | ||
e207152c VS |
272 | |
273 | ||
b59bf2db JS |
274 | /* readgif: |
275 | * Reads a GIF image from the file with filename 'nombre' in the | |
276 | * IMAGEN structure pointed by 'img'. Can read GIFs with any bit | |
277 | * size (color depth), but the output image is always expanded | |
278 | * to 8 bits per pixel. Also, the image palette always contains | |
279 | * 256 colors, although some of them may be unused. Returns E_OK | |
280 | * (== 0) on success, or an error code if something fails. Error | |
281 | * codes are E_ARCHIVO, E_FORMATO, E_MEMORIA (see above). | |
282 | */ | |
283 | int gifDecoder::readgif(IMAGEN *img) | |
284 | { | |
285 | int size, ncolors, bits, interl, i; | |
286 | unsigned char pal[768]; | |
287 | unsigned char buf[16]; | |
288 | ||
e207152c | 289 | |
b59bf2db | 290 | /* read header and logical screen descriptor block (LSDB) */ |
e207152c | 291 | f->Read(buf, 13); |
b59bf2db JS |
292 | |
293 | /* check GIF signature */ | |
294 | if (memcmp(buf, "GIF", 3) != 0) return E_FORMATO; | |
295 | ||
296 | /* load global color map if available */ | |
297 | if ((buf[10] & 0x80) == 0x80) | |
298 | { | |
299 | ncolors = 2 << (buf[10] & 0x07); | |
e207152c | 300 | f->Read(pal, 3 * ncolors); |
b59bf2db JS |
301 | } |
302 | ||
99cc0158 VS |
303 | /* assume no transparent color */ |
304 | img->transparent = -1; | |
b59bf2db | 305 | |
99cc0158 | 306 | /* skip most extensions */ |
e207152c | 307 | while (((unsigned char)f->GetC()) == 0x21) /* separator */ |
99cc0158 | 308 | { |
e207152c | 309 | if (((unsigned char)f->GetC()) == 0xF9) /* graphic control ext. */ |
99cc0158 | 310 | { |
99cc0158 | 311 | f->Read(buf, 6); |
e207152c | 312 | if (buf[1] & 0x01) |
99cc0158 | 313 | img->transparent = buf[4]; |
99cc0158 VS |
314 | } |
315 | else | |
e207152c | 316 | while ((i = (unsigned char)f->GetC()) != 0) /* byte count */ |
99cc0158 | 317 | f->SeekI(i, wxFromCurrent); |
b59bf2db JS |
318 | } |
319 | ||
320 | /* read image descriptor block (IDB) */ | |
e207152c | 321 | f->Read(buf, 9); |
b59bf2db | 322 | img->w = buf[4] + 256 * buf[5]; |
b59bf2db JS |
323 | img->h = buf[6] + 256 * buf[7]; |
324 | size = img->w * img->h; | |
325 | interl = ((buf[8] & 0x40)? 1 : 0); | |
326 | ||
327 | /* load local color map if available */ | |
328 | if ((buf[8] & 0x80) == 0x80) | |
329 | { | |
330 | ncolors = 2 << (buf[8] & 0x07); | |
e207152c | 331 | f->Read(pal, 3 * ncolors); |
b59bf2db JS |
332 | } |
333 | ||
334 | /* get initial code size from first byte in raster data */ | |
e207152c | 335 | bits = (unsigned char)f->GetC(); |
b59bf2db JS |
336 | |
337 | /* allocate memory for image and palette */ | |
338 | if ((img->p = (unsigned char*) malloc(size)) == NULL) return E_MEMORIA; | |
339 | if ((img->pal = (unsigned char*) malloc(768)) == NULL) return E_MEMORIA; | |
340 | ||
341 | /* shift palette to fit VGA 6-bit format */ | |
342 | for (i = 0; i < 768; i++) | |
e207152c | 343 | (img->pal)[i] = (unsigned char)pal[i]; /* >> 2 not in wxWin */ |
b59bf2db JS |
344 | |
345 | /* decode GIF */ | |
346 | dgif(img, interl, bits); | |
347 | ||
348 | /* finish successfully :-) */ | |
349 | return E_OK; | |
350 | } | |
351 | ||
e207152c VS |
352 | |
353 | ||
b59bf2db JS |
354 | /* |
355 | ||
356 | FOLLOWING CODE IS BY V.S. : | |
357 | ||
358 | */ | |
359 | ||
360 | //----------------------------------------------------------------------------- | |
361 | // wxGIFHandler | |
362 | //----------------------------------------------------------------------------- | |
363 | ||
364 | IMPLEMENT_DYNAMIC_CLASS(wxGIFHandler,wxImageHandler) | |
365 | ||
366 | bool wxGIFHandler::LoadFile( wxImage *image, wxInputStream& stream ) | |
367 | { | |
368 | unsigned char *ptr, *src, *pal; | |
b59bf2db JS |
369 | IMAGEN igif; |
370 | int i; | |
371 | gifDecoder *decod; | |
372 | ||
373 | image->Destroy(); | |
374 | ||
53b7ce7e | 375 | decod = new gifDecoder(&stream); |
b59bf2db | 376 | |
e207152c | 377 | if (decod->readgif(&igif) != E_OK) { |
3e473156 | 378 | wxLogDebug(_T("Error reading GIF")); |
b59bf2db JS |
379 | delete decod; |
380 | return FALSE; | |
381 | } | |
b59bf2db JS |
382 | delete decod; |
383 | ||
384 | image->Create(igif.w, igif.h); | |
385 | if (!image->Ok()) { | |
386 | free(igif.pal); | |
387 | free(igif.p); | |
388 | return FALSE; | |
389 | } | |
b59bf2db JS |
390 | |
391 | ptr = image->GetData(); | |
392 | src = igif.p; | |
393 | pal = igif.pal; | |
e207152c VS |
394 | |
395 | if (igif.transparent != -1) { | |
396 | for (i = 0; i < 256; i++) | |
397 | if ((pal[3 * i + 0] == 255) && (pal[3 * i + 1] == 0) && (pal[3 * i + 2] == 255)) pal[3 * i + 2] = 254; | |
398 | pal[3 * (igif.transparent) + 0] = 255, | |
399 | pal[3 * (igif.transparent) + 1] = 0, | |
400 | pal[3 * (igif.transparent) + 2] = 255; | |
401 | image->SetMaskColour(255, 0, 255); | |
402 | } | |
403 | else image->SetMask(FALSE); | |
404 | ||
b59bf2db JS |
405 | for (i = 0; i < igif.w * igif.h; i++, src++) { |
406 | *(ptr++) = pal[3 * (*src) + 0]; | |
407 | *(ptr++) = pal[3 * (*src) + 1]; | |
408 | *(ptr++) = pal[3 * (*src) + 2]; | |
409 | } | |
410 | ||
411 | free(igif.pal); | |
412 | free(igif.p); | |
413 | return TRUE; | |
414 | } | |
415 | ||
416 | bool wxGIFHandler::SaveFile( wxImage *image, wxOutputStream& stream ) | |
417 | { | |
3e473156 | 418 | wxLogDebug(_T("wxGIFHandler is read-only!!")); |
b59bf2db JS |
419 | return FALSE; |
420 | } | |
421 | ||
b59bf2db | 422 | |
99cc0158 VS |
423 | |
424 | ||
425 | ||
426 |