1 |
#ifndef lint |
2 |
static const char RCSid[] = "$Id: bmpfile.c,v 2.6 2004/03/27 16:33:31 greg Exp $"; |
3 |
#endif |
4 |
/* |
5 |
* Windows and OS/2 BMP file support |
6 |
*/ |
7 |
|
8 |
#include <stdio.h> |
9 |
#include <stdlib.h> |
10 |
#include <string.h> |
11 |
#include "bmpfile.h" |
12 |
|
13 |
/* get corresponding error message */ |
14 |
const char * |
15 |
BMPerrorMessage(int ec) |
16 |
{ |
17 |
switch (ec) { |
18 |
case BIR_OK: |
19 |
return "No error"; |
20 |
case BIR_EOF: |
21 |
return "End of BMP image"; |
22 |
case BIR_TRUNCATED: |
23 |
return "Truncated BMP image"; |
24 |
case BIR_UNSUPPORTED: |
25 |
return "Unsupported BMP feature"; |
26 |
case BIR_RLERROR: |
27 |
return "BMP runlength encoding error"; |
28 |
case BIR_SEEKERR: |
29 |
return "BMP seek error"; |
30 |
} |
31 |
return "Unknown BMP error"; |
32 |
} |
33 |
|
34 |
/* check than header is sensible */ |
35 |
static int |
36 |
BMPheaderOK(const BMPHeader *hdr) |
37 |
{ |
38 |
if (!hdr) |
39 |
return 0; |
40 |
if ((hdr->width <= 0) | (hdr->height <= 0)) |
41 |
return 0; |
42 |
switch (hdr->bpp) { /* check compression */ |
43 |
case 1: |
44 |
case 24: |
45 |
if (hdr->compr != BI_UNCOMPR) |
46 |
return 0; |
47 |
break; |
48 |
case 16: |
49 |
case 32: |
50 |
if ((hdr->compr != BI_UNCOMPR) & (hdr->compr != BI_BITFIELDS)) |
51 |
return 0; |
52 |
break; |
53 |
case 4: |
54 |
if ((hdr->compr != BI_UNCOMPR) & (hdr->compr != BI_RLE4)) |
55 |
return 0; |
56 |
break; |
57 |
case 8: |
58 |
if ((hdr->compr != BI_UNCOMPR) & (hdr->compr != BI_RLE8)) |
59 |
return 0; |
60 |
break; |
61 |
default: |
62 |
return 0; |
63 |
} |
64 |
if (hdr->compr == BI_BITFIELDS && (BMPbitField(hdr)[0] & |
65 |
BMPbitField(hdr)[1] & BMPbitField(hdr)[2])) |
66 |
return 0; |
67 |
if ((hdr->nColors < 0) | (hdr->impColors < 0)) |
68 |
return 0; |
69 |
if (hdr->impColors > hdr->nColors) |
70 |
return 0; |
71 |
if (hdr->nColors > BMPpalLen(hdr)) |
72 |
return 0; |
73 |
return 1; |
74 |
} |
75 |
|
76 |
/* compute uncompressed scan size */ |
77 |
#define getScanSiz(h) ( ((((h)->bpp*(h)->width+7) >>3) + 3) & ~03 ) |
78 |
|
79 |
/* get next byte from reader */ |
80 |
#define rdbyte(c,br) ((br)->fpos += (c=(*(br)->cget)((br)->c_data))!=EOF, c) |
81 |
|
82 |
/* read n bytes */ |
83 |
static int |
84 |
rdbytes(char *bp, uint32 n, BMPReader *br) |
85 |
{ |
86 |
int c; |
87 |
|
88 |
while (n--) { |
89 |
if (rdbyte(c, br) == EOF) |
90 |
return BIR_TRUNCATED; |
91 |
*bp++ = c; |
92 |
} |
93 |
return BIR_OK; |
94 |
} |
95 |
|
96 |
/* read 32-bit integer in littlendian order */ |
97 |
static int32 |
98 |
rdint32(BMPReader *br) |
99 |
{ |
100 |
int32 i; |
101 |
int c; |
102 |
|
103 |
i = rdbyte(c, br); |
104 |
i |= rdbyte(c, br) << 8; |
105 |
i |= rdbyte(c, br) << 16; |
106 |
i |= rdbyte(c, br) << 24; |
107 |
return i; /* -1 on EOF */ |
108 |
} |
109 |
|
110 |
/* read 16-bit unsigned integer in littlendian order */ |
111 |
static int |
112 |
rduint16(BMPReader *br) |
113 |
{ |
114 |
int i; |
115 |
int c; |
116 |
|
117 |
i = rdbyte(c, br); |
118 |
i |= rdbyte(c, br) << 8; |
119 |
return i; /* -1 on EOF */ |
120 |
} |
121 |
|
122 |
/* seek on reader or return 0 (BIR_OK) on success */ |
123 |
static int |
124 |
rdseek(uint32 pos, BMPReader *br) |
125 |
{ |
126 |
if (pos == br->fpos) |
127 |
return BIR_OK; |
128 |
if (br->seek == NULL || (*br->seek)(pos, br->c_data) != 0) |
129 |
return BIR_SEEKERR; |
130 |
br->fpos = pos; |
131 |
return BIR_OK; |
132 |
} |
133 |
|
134 |
/* open BMP stream for reading and get first scanline */ |
135 |
BMPReader * |
136 |
BMPopenReader(int (*cget)(void *), int (*seek)(uint32, void *), void *c_data) |
137 |
{ |
138 |
BMPReader *br; |
139 |
uint32 bmPos, hdrSiz; |
140 |
int palLen; |
141 |
|
142 |
if (cget == NULL) |
143 |
return NULL; |
144 |
int magic[2]; /* check magic number */ |
145 |
magic[0] = (*cget)(c_data); |
146 |
if (magic[0] != 'B') |
147 |
return NULL; |
148 |
magic[1] = (*cget)(c_data); |
149 |
if (magic[1] != 'M' && magic[1] != 'A') |
150 |
return NULL; |
151 |
br = (BMPReader *)calloc(1, sizeof(BMPReader)); |
152 |
if (br == NULL) |
153 |
return NULL; |
154 |
br->cget = cget; |
155 |
br->seek = seek; |
156 |
br->c_data = c_data; |
157 |
br->hdr = (BMPHeader *)malloc(sizeof(BMPHeader)); |
158 |
if (br->hdr == NULL) |
159 |
goto err; |
160 |
br->fpos = 2; |
161 |
/* read & verify file header */ |
162 |
(void)rdint32(br); /* file size */ |
163 |
(void)rdint32(br); /* reserved word */ |
164 |
bmPos = rdint32(br); /* offset to bitmap */ |
165 |
hdrSiz = 2 + 3*4 + rdint32(br); /* header size */ |
166 |
if (hdrSiz < 2 + 6*4 + 2*2 + 6*4) |
167 |
goto err; |
168 |
br->hdr->width = rdint32(br); /* bitmap width */ |
169 |
br->hdr->height = rdint32(br); /* bitmap height */ |
170 |
if (((br->hdr->width <= 0) | (br->hdr->height == 0))) |
171 |
goto err; |
172 |
if ((br->hdr->yIsDown = br->hdr->height < 0)) |
173 |
br->hdr->height = -br->hdr->height; |
174 |
if (rduint16(br) != 1) /* number of planes */ |
175 |
goto err; |
176 |
br->hdr->bpp = rduint16(br); /* bits per pixel */ |
177 |
br->hdr->compr = rdint32(br); /* compression mode */ |
178 |
(void)rdint32(br); /* bitmap size */ |
179 |
br->hdr->hRes = rdint32(br); /* horizontal resolution */ |
180 |
br->hdr->vRes = rdint32(br); /* vertical resolution */ |
181 |
br->hdr->nColors = rdint32(br); /* # colors used */ |
182 |
br->hdr->impColors = rdint32(br); /* # important colors */ |
183 |
if (br->hdr->impColors < 0) |
184 |
goto err; /* catch premature EOF */ |
185 |
if (!BMPheaderOK(br->hdr)) |
186 |
goto err; |
187 |
palLen = BMPpalLen(br->hdr); |
188 |
if (br->hdr->bpp <= 8) { /* normalize color counts */ |
189 |
if (br->hdr->nColors <= 0) |
190 |
br->hdr->nColors = palLen; |
191 |
if (br->hdr->impColors <= 0) |
192 |
br->hdr->impColors = br->hdr->nColors; |
193 |
} |
194 |
/* extend header */ |
195 |
if (bmPos < hdrSiz + sizeof(RGBquad)*palLen) |
196 |
goto err; |
197 |
br->hdr->infoSiz = bmPos - (hdrSiz + sizeof(RGBquad)*palLen); |
198 |
if (palLen > 0 || br->hdr->infoSiz > 0) { |
199 |
br->hdr = (BMPHeader *)realloc((void *)br->hdr, |
200 |
sizeof(BMPHeader) + |
201 |
sizeof(RGBquad)*palLen + |
202 |
br->hdr->infoSiz); |
203 |
if (br->hdr == NULL) |
204 |
goto err; |
205 |
} |
206 |
/* read colors or fields */ |
207 |
if (br->hdr->compr == BI_BITFIELDS) { |
208 |
BMPbitField(br->hdr)[0] = (uint32)rdint32(br); |
209 |
BMPbitField(br->hdr)[1] = (uint32)rdint32(br); |
210 |
BMPbitField(br->hdr)[2] = (uint32)rdint32(br); |
211 |
} else if (rdbytes((char *)br->hdr->palette, |
212 |
sizeof(RGBquad)*palLen, br) != BIR_OK) |
213 |
goto err; |
214 |
/* read add'l information */ |
215 |
if (rdbytes(BMPinfo(br->hdr), br->hdr->infoSiz, br) != BIR_OK) |
216 |
goto err; |
217 |
/* read first scanline */ |
218 |
br->scanline = (uint8 *)calloc(getScanSiz(br->hdr), sizeof(uint8)); |
219 |
if (br->scanline == NULL) |
220 |
goto err; |
221 |
br->yscan = -1; |
222 |
if (seek != NULL && ((br->hdr->compr == BI_RLE8) | |
223 |
(br->hdr->compr == BI_RLE4))) { |
224 |
BMPReader *newbr = (BMPReader *)realloc((void *)br, |
225 |
sizeof(BMPReader) + |
226 |
sizeof(br->scanpos[0]) * |
227 |
br->hdr->height); |
228 |
if (newbr == NULL) |
229 |
goto err; |
230 |
br = newbr; |
231 |
memset((void *)(br->scanpos + 1), 0, |
232 |
sizeof(br->scanpos[0])*br->hdr->height); |
233 |
} |
234 |
br->scanpos[0] = br->fpos; |
235 |
if (BMPreadScanline(br) != BIR_OK) |
236 |
goto err; |
237 |
return br; |
238 |
err: |
239 |
if (br->hdr != NULL) |
240 |
free((void *)br->hdr); |
241 |
if (br->scanline != NULL) |
242 |
free((void *)br->scanline); |
243 |
free((void *)br); |
244 |
return NULL; |
245 |
} |
246 |
|
247 |
/* determine if image is grayscale */ |
248 |
int |
249 |
BMPisGrayscale(const BMPHeader *hdr) |
250 |
{ |
251 |
const RGBquad *rgbp; |
252 |
int n; |
253 |
|
254 |
if (hdr == NULL) |
255 |
return -1; |
256 |
if (hdr->bpp > 8) /* assume they had a reason for it */ |
257 |
return 0; |
258 |
for (rgbp = hdr->palette, n = hdr->nColors; n-- > 0; rgbp++) |
259 |
if (((rgbp->r != rgbp->g) | (rgbp->g != rgbp->b))) |
260 |
return 0; |
261 |
return 1; /* all colors neutral in map */ |
262 |
} |
263 |
|
264 |
/* read and decode next BMP scanline */ |
265 |
int |
266 |
BMPreadScanline(BMPReader *br) |
267 |
{ |
268 |
int n; |
269 |
int8 *sp; |
270 |
|
271 |
if (br->yscan + 1 >= br->hdr->height) |
272 |
return BIR_EOF; |
273 |
br->yscan++; /* prepare to read */ |
274 |
n = getScanSiz(br->hdr); /* reading uncompressed data? */ |
275 |
if (br->hdr->compr == BI_UNCOMPR || br->hdr->compr == BI_BITFIELDS) |
276 |
return rdbytes((char *)br->scanline, n, br); |
277 |
/* |
278 |
* RLE/RLE8 Decoding |
279 |
* |
280 |
* Certain aspects of this scheme are completely insane, so |
281 |
* we don't support them. Fortunately, they rarely appear. |
282 |
* One is the mid-file EOD (0x0001) and another is the ill-conceived |
283 |
* "delta" (0x0002), which is like a "goto" statement for bitmaps. |
284 |
* Whoever thought this up should be shot, then told why |
285 |
* it's impossible to support such a scheme in any reasonable way. |
286 |
* Also, RLE4 mode allows runs to stop halfway through a byte, |
287 |
* which is likewise uncodeable, so we don't even try. |
288 |
* Finally, the scanline break is ambiguous -- we assume here that |
289 |
* it is required at the end of each scanline, though I haven't |
290 |
* found anywhere this is written. Otherwise, we would read to |
291 |
* the end of the scanline, assuming the next bit of data belongs |
292 |
* the following scan. If a break follows the last pixel, as it |
293 |
* seems to in the files I've tested out of Photoshop, you end up |
294 |
* painting every other line black. Also, I assume any skipped |
295 |
* pixels are painted with color 0, which is often black. Nowhere |
296 |
* is it specified what we should assume for missing pixels. This |
297 |
* is undoubtedly the most brain-dead format I've ever encountered. |
298 |
*/ |
299 |
sp = br->scanline; |
300 |
while (n > 0) { |
301 |
int skipOdd, len, val; |
302 |
|
303 |
if (rdbyte(len, br) == EOF) |
304 |
return BIR_TRUNCATED; |
305 |
if (len > 0) { /* got a run */ |
306 |
if (br->hdr->compr == BI_RLE4) { |
307 |
if (len & 1) |
308 |
return BIR_UNSUPPORTED; |
309 |
len >>= 1; |
310 |
} |
311 |
if (len > n) |
312 |
return BIR_RLERROR; |
313 |
if (rdbyte(val, br) == EOF) |
314 |
return BIR_TRUNCATED; |
315 |
n -= len; |
316 |
while (len--) |
317 |
*sp++ = val; |
318 |
continue; |
319 |
} |
320 |
switch (rdbyte(len, br)) { |
321 |
case EOF: |
322 |
return BIR_TRUNCATED; |
323 |
case 0: /* end of line */ |
324 |
while (n--) |
325 |
*sp++ = 0; |
326 |
/* leaves n == -1 as flag for test after loop */ |
327 |
continue; |
328 |
case 1: /* end of bitmap */ |
329 |
case 2: /* delta */ |
330 |
return BIR_UNSUPPORTED; |
331 |
} |
332 |
/* absolute mode */ |
333 |
if (br->hdr->compr == BI_RLE4) { |
334 |
if (len & 1) |
335 |
return BIR_UNSUPPORTED; |
336 |
len >>= 1; |
337 |
} |
338 |
skipOdd = len & 1; |
339 |
if (len > n) |
340 |
return BIR_RLERROR; |
341 |
n -= len; |
342 |
while (len--) { |
343 |
if (rdbyte(val, br) == EOF) |
344 |
return BIR_TRUNCATED; |
345 |
*sp++ = val; |
346 |
} |
347 |
if (skipOdd && rdbyte(val, br) == EOF) |
348 |
return BIR_TRUNCATED; |
349 |
} |
350 |
/* verify break at end of line */ |
351 |
if (!n && (rdbyte(n, br) != 0 || (rdbyte(n, br) != 0 && |
352 |
(n != 1 || br->yscan != br->hdr->height-1)))) |
353 |
return BIR_RLERROR; |
354 |
if (br->seek != NULL) /* record next scanline position */ |
355 |
br->scanpos[br->yscan + 1] = br->fpos; |
356 |
return BIR_OK; |
357 |
} |
358 |
|
359 |
/* read a specific scanline */ |
360 |
int |
361 |
BMPseekScanline(int y, BMPReader *br) |
362 |
{ |
363 |
int rv; |
364 |
/* check arguments */ |
365 |
if (br == NULL) |
366 |
return BIR_EOF; |
367 |
if (y < 0) |
368 |
return BIR_SEEKERR; |
369 |
if (y >= br->hdr->height) |
370 |
return BIR_EOF; |
371 |
/* already read? */ |
372 |
if (y == br->yscan) |
373 |
return BIR_OK; |
374 |
/* shall we seek? */ |
375 |
if (y != br->yscan + 1 && br->seek != NULL) { |
376 |
int yseek; |
377 |
uint32 seekp; |
378 |
if (br->hdr->compr == BI_UNCOMPR || |
379 |
br->hdr->compr == BI_BITFIELDS) { |
380 |
yseek = y; |
381 |
seekp = br->scanpos[0] + y*getScanSiz(br->hdr); |
382 |
} else { |
383 |
yseek = br->yscan + 1; |
384 |
while (yseek < y && br->scanpos[yseek+1] != 0) |
385 |
++yseek; |
386 |
if (y < yseek && br->scanpos[yseek=y] == 0) |
387 |
return BIR_SEEKERR; |
388 |
seekp = br->scanpos[yseek]; |
389 |
} |
390 |
if ((rv = rdseek(seekp, br)) != BIR_OK) |
391 |
return rv; |
392 |
br->yscan = yseek - 1; |
393 |
} else if (y < br->yscan) /* else we can't back up */ |
394 |
return BIR_SEEKERR; |
395 |
/* read until we get there */ |
396 |
while (br->yscan < y) |
397 |
if ((rv = BMPreadScanline(br)) != BIR_OK) |
398 |
return rv; |
399 |
return BIR_OK; |
400 |
} |
401 |
|
402 |
/* get ith pixel from last scanline */ |
403 |
RGBquad |
404 |
BMPdecodePixel(int i, const BMPReader *br) |
405 |
{ |
406 |
static const uint32 std16mask[3] = {0x7c00, 0x3e0, 0x1f}; |
407 |
static const RGBquad black = {0, 0, 0, 0}; |
408 |
const uint32 *mask; |
409 |
const uint8 *pp; |
410 |
uint32 pval, v; |
411 |
RGBquad cval; |
412 |
|
413 |
if (((br == NULL) | (i < 0)) || i >= br->hdr->width) |
414 |
return black; |
415 |
|
416 |
cval.padding = 0; |
417 |
|
418 |
switch (br->hdr->bpp) { |
419 |
case 24: |
420 |
pp = br->scanline + 3*i; |
421 |
cval.b = *pp++; |
422 |
cval.g = *pp++; |
423 |
cval.r = *pp; |
424 |
return cval; |
425 |
case 32: |
426 |
if (br->hdr->compr == BI_UNCOMPR) |
427 |
return ((RGBquad *)br->scanline)[i]; |
428 |
/* convert bit fields */ |
429 |
pp = br->scanline + 4*i; |
430 |
pval = *pp++; |
431 |
pval |= *pp++ << 8; |
432 |
pval |= *pp++ << 16; |
433 |
pval |= *pp << 24; |
434 |
mask = BMPbitField(br->hdr); |
435 |
v = pval & mask[0]; |
436 |
while (v & ~0xff) v >>= 8; |
437 |
cval.r = v; |
438 |
v = pval & mask[1]; |
439 |
while (v & ~0xff) v >>= 8; |
440 |
cval.g = v; |
441 |
v = pval & mask[2]; |
442 |
while (v & ~0xff) v >>= 8; |
443 |
cval.b = v; |
444 |
return cval; |
445 |
case 8: |
446 |
return br->hdr->palette[br->scanline[i]]; |
447 |
case 1: |
448 |
return br->hdr->palette[br->scanline[i>>3]>>((7-i)&7) & 1]; |
449 |
case 4: |
450 |
return br->hdr->palette[br->scanline[i>>1]>>(i&1?4:0) & 0xf]; |
451 |
case 16: |
452 |
pp = br->scanline + 2*i; |
453 |
pval = *pp++; |
454 |
pval |= *pp++ << 8; |
455 |
mask = std16mask; |
456 |
if (br->hdr->compr == BI_BITFIELDS) |
457 |
mask = BMPbitField(br->hdr); |
458 |
cval.r = ((pval & mask[0]) << 8) / (mask[0] + 1); |
459 |
cval.g = ((pval & mask[1]) << 8) / (mask[1] + 1); |
460 |
cval.b = ((pval & mask[2]) << 8) / (mask[2] + 1); |
461 |
return cval; |
462 |
} |
463 |
return black; /* should never happen */ |
464 |
} |
465 |
|
466 |
/* free BMP reader resources */ |
467 |
void |
468 |
BMPfreeReader(BMPReader *br) |
469 |
{ |
470 |
if (br == NULL) |
471 |
return; |
472 |
free((void *)br->hdr); |
473 |
free((void *)br->scanline); |
474 |
free((void *)br); |
475 |
} |
476 |
|
477 |
/* stdio getc() callback */ |
478 |
int |
479 |
stdio_getc(void *p) |
480 |
{ |
481 |
if (!p) |
482 |
return EOF; |
483 |
return getc((FILE *)p); |
484 |
} |
485 |
|
486 |
/* stdio putc() callback */ |
487 |
void |
488 |
stdio_putc(int c, void *p) |
489 |
{ |
490 |
if (p) |
491 |
putc(c, (FILE *)p); |
492 |
} |
493 |
|
494 |
/* stdio fseek() callback */ |
495 |
int |
496 |
stdio_fseek(uint32 pos, void *p) |
497 |
{ |
498 |
if (!p) |
499 |
return -1; |
500 |
return fseek((FILE *)p, (long)pos, 0); |
501 |
} |
502 |
|
503 |
/* allocate uncompressed (24-bit) RGB header */ |
504 |
BMPHeader * |
505 |
BMPtruecolorHeader(int xr, int yr, int infolen) |
506 |
{ |
507 |
BMPHeader *hdr; |
508 |
|
509 |
if (xr <= 0 || yr <= 0 || infolen < 0) |
510 |
return NULL; |
511 |
hdr = (BMPHeader *)malloc(sizeof(BMPHeader) - sizeof(hdr->palette) + |
512 |
infolen); |
513 |
if (hdr == NULL) |
514 |
return NULL; |
515 |
hdr->width = xr; |
516 |
hdr->height = yr; |
517 |
hdr->yIsDown = 0; /* default to upwards order */ |
518 |
hdr->bpp = 24; |
519 |
hdr->compr = BI_UNCOMPR; |
520 |
hdr->hRes = hdr->vRes = 2835; /* default to 72 ppi */ |
521 |
hdr->nColors = hdr->impColors = 0; |
522 |
hdr->infoSiz = infolen; |
523 |
return hdr; |
524 |
} |
525 |
|
526 |
/* allocate color-mapped header (defaults to minimal grayscale) */ |
527 |
BMPHeader * |
528 |
BMPmappedHeader(int xr, int yr, int infolen, int ncolors) |
529 |
{ |
530 |
int n; |
531 |
BMPHeader *hdr; |
532 |
|
533 |
if (xr <= 0 || yr <= 0 || infolen < 0 || ncolors < 2) |
534 |
return NULL; |
535 |
if (ncolors <= 2) |
536 |
n = 1; |
537 |
else if (ncolors <= 16) |
538 |
n = 4; |
539 |
else if (ncolors <= 256) |
540 |
n = 8; |
541 |
else |
542 |
return NULL; |
543 |
hdr = (BMPHeader *)malloc(sizeof(BMPHeader) + |
544 |
sizeof(RGBquad)*(1<<n) - |
545 |
sizeof(hdr->palette) + |
546 |
infolen); |
547 |
if (hdr == NULL) |
548 |
return NULL; |
549 |
hdr->width = xr; |
550 |
hdr->height = yr; |
551 |
hdr->yIsDown = 0; /* default to upwards order */ |
552 |
hdr->bpp = n; |
553 |
hdr->compr = BI_UNCOMPR; /* compression needs seek */ |
554 |
hdr->hRes = hdr->vRes = 2835; /* default to 72 ppi */ |
555 |
hdr->nColors = ncolors; |
556 |
hdr->impColors = 0; /* says all colors important */ |
557 |
hdr->infoSiz = infolen; |
558 |
memset((void *)hdr->palette, 0, sizeof(RGBquad)*(1<<n) + infolen); |
559 |
for (n = ncolors; n--; ) |
560 |
hdr->palette[n].r = hdr->palette[n].g = |
561 |
hdr->palette[n].b = n*255/(ncolors-1); |
562 |
return hdr; |
563 |
} |
564 |
|
565 |
/* put byte to writer */ |
566 |
#define wrbyte(c,bw) ( (*(bw)->cput)(c,(bw)->c_data), \ |
567 |
++(bw)->fpos > (bw)->flen ? \ |
568 |
((bw)->flen = (bw)->fpos) : \ |
569 |
(bw)->fpos ) |
570 |
|
571 |
/* write out a string of bytes */ |
572 |
static void |
573 |
wrbytes(char *bp, uint32 n, BMPWriter *bw) |
574 |
{ |
575 |
while (n--) |
576 |
wrbyte(*bp++, bw); |
577 |
} |
578 |
|
579 |
/* write 32-bit integer in littlendian order */ |
580 |
static void |
581 |
wrint32(int32 i, BMPWriter *bw) |
582 |
{ |
583 |
wrbyte(i& 0xff, bw); |
584 |
wrbyte(i>>8 & 0xff, bw); |
585 |
wrbyte(i>>16 & 0xff, bw); |
586 |
wrbyte(i>>24 & 0xff, bw); |
587 |
} |
588 |
|
589 |
/* write 16-bit unsigned integer in littlendian order */ |
590 |
static void |
591 |
wruint16(uint16 ui, BMPWriter *bw) |
592 |
{ |
593 |
wrbyte(ui & 0xff, bw); |
594 |
wrbyte(ui>>8 & 0xff, bw); |
595 |
} |
596 |
|
597 |
/* seek to the specified file position, returning 0 (BIR_OK) on success */ |
598 |
static int |
599 |
wrseek(uint32 pos, BMPWriter *bw) |
600 |
{ |
601 |
if (pos == bw->fpos) |
602 |
return BIR_OK; |
603 |
if (bw->seek == NULL) { |
604 |
if (pos < bw->fpos) |
605 |
return BIR_SEEKERR; |
606 |
while (bw->fpos < pos) |
607 |
wrbyte(0, bw); |
608 |
return BIR_OK; |
609 |
} |
610 |
if ((*bw->seek)(pos, bw->c_data) != 0) |
611 |
return BIR_SEEKERR; |
612 |
bw->fpos = pos; |
613 |
if (pos > bw->flen) |
614 |
bw->flen = pos; |
615 |
return BIR_OK; |
616 |
} |
617 |
|
618 |
/* open BMP stream for writing */ |
619 |
BMPWriter * |
620 |
BMPopenWriter(void (*cput)(int, void *), int (*seek)(uint32, void *), |
621 |
void *c_data, BMPHeader *hdr) |
622 |
{ |
623 |
BMPWriter *bw; |
624 |
uint32 hdrSiz, palSiz, scanSiz, bmSiz; |
625 |
/* check arguments */ |
626 |
if (cput == NULL) |
627 |
return NULL; |
628 |
if (!BMPheaderOK(hdr)) |
629 |
return NULL; |
630 |
if ((hdr->bpp == 16) | (hdr->compr == BI_RLE4)) |
631 |
return NULL; /* unsupported */ |
632 |
/* no seek means we may have the wrong file length, but most app's don't care |
633 |
if (seek == NULL && ((hdr->compr == BI_RLE8) | (hdr->compr == BI_RLE4))) |
634 |
return NULL; |
635 |
*/ |
636 |
/* compute sizes */ |
637 |
hdrSiz = 2 + 6*4 + 2*2 + 6*4; |
638 |
if (hdr->compr == BI_BITFIELDS) |
639 |
hdrSiz += sizeof(uint32)*3; |
640 |
palSiz = sizeof(RGBquad)*BMPpalLen(hdr); |
641 |
scanSiz = getScanSiz(hdr); |
642 |
bmSiz = hdr->height*scanSiz; /* wrong if compressed */ |
643 |
/* initialize writer */ |
644 |
bw = (BMPWriter *)malloc(sizeof(BMPWriter)); |
645 |
if (bw == NULL) |
646 |
return NULL; |
647 |
bw->hdr = hdr; |
648 |
bw->yscan = 0; |
649 |
bw->scanline = (uint8 *)calloc(scanSiz, sizeof(uint8)); |
650 |
if (bw->scanline == NULL) { |
651 |
free((void *)bw); |
652 |
return NULL; |
653 |
} |
654 |
bw->fbmp = hdrSiz + palSiz + hdr->infoSiz; |
655 |
bw->fpos = bw->flen = 0; |
656 |
bw->cput = cput; |
657 |
bw->seek = seek; |
658 |
bw->c_data = c_data; |
659 |
/* write out header */ |
660 |
wrbyte('B', bw); wrbyte('M', bw); /* magic number */ |
661 |
wrint32(bw->fbmp + bmSiz, bw); /* file size */ |
662 |
wrint32(0, bw); /* reserved word */ |
663 |
wrint32(bw->fbmp, bw); /* offset to bitmap */ |
664 |
wrint32(hdrSiz - bw->fpos, bw); /* info header size */ |
665 |
wrint32(hdr->width, bw); /* bitmap width */ |
666 |
if (hdr->yIsDown) /* bitmap height */ |
667 |
wrint32(-hdr->height, bw); |
668 |
else |
669 |
wrint32(hdr->height, bw); |
670 |
wruint16(1, bw); /* number of planes */ |
671 |
wruint16(hdr->bpp, bw); /* bits per pixel */ |
672 |
wrint32(hdr->compr, bw); /* compression mode */ |
673 |
wrint32(bmSiz, bw); /* bitmap size */ |
674 |
wrint32(hdr->hRes, bw); /* horizontal resolution */ |
675 |
wrint32(hdr->vRes, bw); /* vertical resolution */ |
676 |
wrint32(hdr->nColors, bw); /* # colors used */ |
677 |
wrint32(hdr->impColors, bw); /* # important colors */ |
678 |
/* write out color palette */ |
679 |
wrbytes((char *)hdr->palette, palSiz, bw); |
680 |
/* write add'l information */ |
681 |
wrbytes(BMPinfo(hdr), hdr->infoSiz, bw); |
682 |
#ifndef NDEBUG |
683 |
if (bw->fpos != bw->fbmp) { |
684 |
fputs("Coding error 1 in BMPopenWriter\n", stderr); |
685 |
exit(1); |
686 |
} |
687 |
#endif |
688 |
return bw; |
689 |
} |
690 |
|
691 |
/* find position of next run of 5 or more identical bytes, or 255 if none */ |
692 |
static int |
693 |
findNextRun(const int8 *bp, int len) |
694 |
{ |
695 |
int pos, cnt; |
696 |
/* look for run */ |
697 |
for (pos = 0; (len > 0) & (pos < 255); pos++, bp++, len--) { |
698 |
if (len < 5) /* no hope left? */ |
699 |
continue; |
700 |
cnt = 1; /* else let's try it */ |
701 |
while (bp[cnt] == bp[0]) |
702 |
if (++cnt >= 5) |
703 |
return pos; /* long enough */ |
704 |
} |
705 |
return pos; /* didn't find any */ |
706 |
} |
707 |
|
708 |
/* write the current scanline */ |
709 |
int |
710 |
BMPwriteScanline(BMPWriter *bw) |
711 |
{ |
712 |
const int8 *sp; |
713 |
int n; |
714 |
|
715 |
if (bw->yscan >= bw->hdr->height) |
716 |
return BIR_EOF; |
717 |
/* writing uncompressed? */ |
718 |
if (bw->hdr->compr == BI_UNCOMPR || bw->hdr->compr == BI_BITFIELDS) { |
719 |
uint32 scanSiz = getScanSiz(bw->hdr); |
720 |
uint32 slpos = bw->fbmp + bw->yscan*scanSiz; |
721 |
if (wrseek(slpos, bw) != BIR_OK) |
722 |
return BIR_SEEKERR; |
723 |
wrbytes((char *)bw->scanline, scanSiz, bw); |
724 |
bw->yscan++; |
725 |
return BIR_OK; |
726 |
} |
727 |
/* |
728 |
* RLE8 Encoding |
729 |
* |
730 |
* See the notes in BMPreadScanline() on this encoding. Needless |
731 |
* to say, we avoid the nuttier aspects of this specification. |
732 |
* We also assume that every scanline ends in a line break |
733 |
* (0x0000) except for the last, which ends in a bitmap break |
734 |
* (0x0001). We don't support RLE4 at all; it's too awkward. |
735 |
*/ |
736 |
sp = bw->scanline; |
737 |
n = bw->hdr->width; |
738 |
while (n > 0) { |
739 |
int cnt, val; |
740 |
|
741 |
cnt = findNextRun(sp, n); /* 0-255 < n */ |
742 |
if (cnt >= 3) { /* output non-run */ |
743 |
int skipOdd = cnt & 1; |
744 |
wrbyte(0, bw); |
745 |
wrbyte(cnt, bw); |
746 |
n -= cnt; |
747 |
while (cnt--) |
748 |
wrbyte(*sp++, bw); |
749 |
if (skipOdd) |
750 |
wrbyte(0, bw); |
751 |
} |
752 |
if (n <= 0) /* was that it? */ |
753 |
break; |
754 |
val = *sp; /* output run */ |
755 |
for (cnt = 1; cnt < 255; cnt++) |
756 |
if ((!--n) | (*++sp != val)) |
757 |
break; |
758 |
wrbyte(cnt, bw); |
759 |
wrbyte(val, bw); |
760 |
} |
761 |
bw->yscan++; /* write line break or EOD */ |
762 |
if (bw->yscan == bw->hdr->height) { |
763 |
wrbyte(0, bw); wrbyte(1, bw); /* end of bitmap marker */ |
764 |
if (bw->seek == NULL || (*bw->seek)(2, bw->c_data) != 0) |
765 |
return BIR_OK; /* no one may care */ |
766 |
bw->fpos = 2; |
767 |
wrint32(bw->flen-bw->fbmp, bw); /* correct bitmap length */ |
768 |
} else { |
769 |
wrbyte(0, bw); wrbyte(0, bw); /* end of line marker */ |
770 |
} |
771 |
return BIR_OK; |
772 |
} |
773 |
|
774 |
/* free BMP writer resources */ |
775 |
void |
776 |
BMPfreeWriter(BMPWriter *bw) |
777 |
{ |
778 |
if (bw == NULL) |
779 |
return; |
780 |
free((void *)bw->hdr); |
781 |
free((void *)bw->scanline); |
782 |
free((void *)bw); |
783 |
} |