| 1 |
#ifndef lint |
| 2 |
static const char RCSid[] = "$Id: bmpfile.c,v 2.21 2021/10/04 23:04:59 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 |
#ifdef getc_unlocked /* avoid horrendous overhead of flockfile */ |
| 14 |
#undef getc |
| 15 |
#undef putc |
| 16 |
#define getc getc_unlocked |
| 17 |
#define putc putc_unlocked |
| 18 |
#endif |
| 19 |
|
| 20 |
/* Get corresponding error message */ |
| 21 |
const char * |
| 22 |
BMPerrorMessage(int ec) |
| 23 |
{ |
| 24 |
switch (ec) { |
| 25 |
case BIR_OK: |
| 26 |
return "No error"; |
| 27 |
case BIR_EOF: |
| 28 |
return "End of BMP image"; |
| 29 |
case BIR_TRUNCATED: |
| 30 |
return "Truncated BMP image"; |
| 31 |
case BIR_UNSUPPORTED: |
| 32 |
return "Unsupported BMP feature"; |
| 33 |
case BIR_RLERROR: |
| 34 |
return "BMP runlength encoding error"; |
| 35 |
case BIR_SEEKERR: |
| 36 |
return "BMP seek error"; |
| 37 |
} |
| 38 |
return "Unknown BMP error"; |
| 39 |
} |
| 40 |
|
| 41 |
/* Check that header is sensible */ |
| 42 |
static int |
| 43 |
BMPheaderOK(const BMPHeader *hdr) |
| 44 |
{ |
| 45 |
if (!hdr) |
| 46 |
return 0; |
| 47 |
if ((hdr->width <= 0) | (hdr->height <= 0)) |
| 48 |
return 0; |
| 49 |
switch (hdr->bpp) { /* check compression */ |
| 50 |
case 1: |
| 51 |
case 24: |
| 52 |
if (hdr->compr != BI_UNCOMPR) |
| 53 |
return 0; |
| 54 |
break; |
| 55 |
case 16: |
| 56 |
case 32: |
| 57 |
if ((hdr->compr != BI_UNCOMPR) & (hdr->compr != BI_BITFIELDS)) |
| 58 |
return 0; |
| 59 |
break; |
| 60 |
case 4: |
| 61 |
if ((hdr->compr != BI_UNCOMPR) & (hdr->compr != BI_RLE4)) |
| 62 |
return 0; |
| 63 |
break; |
| 64 |
case 8: |
| 65 |
if ((hdr->compr != BI_UNCOMPR) & (hdr->compr != BI_RLE8)) |
| 66 |
return 0; |
| 67 |
break; |
| 68 |
default: |
| 69 |
return 0; |
| 70 |
} |
| 71 |
if (hdr->compr == BI_BITFIELDS && (BMPbitField(hdr)[0] & |
| 72 |
BMPbitField(hdr)[1] & BMPbitField(hdr)[2])) |
| 73 |
return 0; |
| 74 |
if (hdr->bpp > 8) { |
| 75 |
if (hdr->nColors != 0) |
| 76 |
return 0; |
| 77 |
} else { |
| 78 |
if ((hdr->nColors < 0) | (hdr->nColors > 1<<hdr->bpp)) |
| 79 |
return 0; |
| 80 |
if ((hdr->impColors < 0) | (hdr->impColors > hdr->nColors)) |
| 81 |
return 0; |
| 82 |
} |
| 83 |
return 1; |
| 84 |
} |
| 85 |
|
| 86 |
/* compute uncompressed scan size */ |
| 87 |
#define getScanSiz(h) ( ((((h)->bpp*(h)->width+7) >>3) + 3) & ~03 ) |
| 88 |
|
| 89 |
/* get next byte from reader */ |
| 90 |
#define rdbyte(c,br) ((br)->fpos += (c=(*(br)->cget)((br)->c_data))!=EOF, c) |
| 91 |
|
| 92 |
/* Read n bytes */ |
| 93 |
static int |
| 94 |
rdbytes(char *bp, uint32 n, BMPReader *br) |
| 95 |
{ |
| 96 |
int c; |
| 97 |
|
| 98 |
while (n--) { |
| 99 |
if (rdbyte(c, br) == EOF) |
| 100 |
return BIR_TRUNCATED; |
| 101 |
*bp++ = c; |
| 102 |
} |
| 103 |
return BIR_OK; |
| 104 |
} |
| 105 |
|
| 106 |
/* Read 32-bit integer in littlendian order */ |
| 107 |
static int32 |
| 108 |
rdint32(BMPReader *br) |
| 109 |
{ |
| 110 |
int32 i; |
| 111 |
int c; |
| 112 |
|
| 113 |
i = rdbyte(c, br); |
| 114 |
i |= rdbyte(c, br) << 8; |
| 115 |
i |= rdbyte(c, br) << 16; |
| 116 |
i |= rdbyte(c, br) << 24; |
| 117 |
return i; /* -1 on EOF */ |
| 118 |
} |
| 119 |
|
| 120 |
/* Read 16-bit unsigned integer in littlendian order */ |
| 121 |
static int |
| 122 |
rduint16(BMPReader *br) |
| 123 |
{ |
| 124 |
int i; |
| 125 |
int c; |
| 126 |
|
| 127 |
i = rdbyte(c, br); |
| 128 |
i |= rdbyte(c, br) << 8; |
| 129 |
return i; /* -1 on EOF */ |
| 130 |
} |
| 131 |
|
| 132 |
/* Seek on reader or return 0 (BIR_OK) on success */ |
| 133 |
static int |
| 134 |
rdseek(uint32 pos, BMPReader *br) |
| 135 |
{ |
| 136 |
if (pos == br->fpos) |
| 137 |
return BIR_OK; |
| 138 |
if (br->seek == NULL || (*br->seek)(pos, br->c_data) != 0) |
| 139 |
return BIR_SEEKERR; |
| 140 |
br->fpos = pos; |
| 141 |
return BIR_OK; |
| 142 |
} |
| 143 |
|
| 144 |
/* Open BMP stream for reading and get first scanline */ |
| 145 |
BMPReader * |
| 146 |
BMPopenReader(int (*cget)(void *), int (*seek)(uint32, void *), void *c_data) |
| 147 |
{ |
| 148 |
BMPReader *br; |
| 149 |
uint32 bmPos, hdrSiz, palSiz; |
| 150 |
int magic[2]; /* check magic number */ |
| 151 |
|
| 152 |
if (cget == NULL) |
| 153 |
return NULL; |
| 154 |
if (cget == &stdio_getc && c_data == NULL) |
| 155 |
return NULL; /* stdio error condition */ |
| 156 |
magic[0] = (*cget)(c_data); |
| 157 |
if (magic[0] != 'B') |
| 158 |
return NULL; |
| 159 |
magic[1] = (*cget)(c_data); |
| 160 |
if (magic[1] != 'M' && magic[1] != 'A') |
| 161 |
return NULL; |
| 162 |
br = (BMPReader *)calloc(1, sizeof(BMPReader)); |
| 163 |
if (br == NULL) |
| 164 |
return NULL; |
| 165 |
br->cget = cget; |
| 166 |
br->seek = seek; |
| 167 |
br->c_data = c_data; |
| 168 |
br->hdr = (BMPHeader *)malloc(sizeof(BMPHeader)); |
| 169 |
if (br->hdr == NULL) |
| 170 |
goto err; |
| 171 |
br->fpos = 2; |
| 172 |
/* read & verify file header */ |
| 173 |
(void)rdint32(br); /* file size */ |
| 174 |
(void)rdint32(br); /* reserved word */ |
| 175 |
bmPos = rdint32(br); /* offset to bitmap */ |
| 176 |
hdrSiz = 2 + 3*4 + rdint32(br); /* header size */ |
| 177 |
if (hdrSiz < 2 + 6*4 + 2*2 + 6*4) |
| 178 |
goto err; |
| 179 |
br->hdr->width = rdint32(br); /* bitmap width */ |
| 180 |
br->hdr->height = rdint32(br); /* bitmap height */ |
| 181 |
if (((br->hdr->width <= 0) | (br->hdr->height == 0))) |
| 182 |
goto err; |
| 183 |
if ((br->hdr->yIsDown = br->hdr->height < 0)) |
| 184 |
br->hdr->height = -br->hdr->height; |
| 185 |
if (rduint16(br) != 1) /* number of planes */ |
| 186 |
goto err; |
| 187 |
br->hdr->bpp = rduint16(br); /* bits per pixel */ |
| 188 |
br->hdr->compr = rdint32(br); /* compression mode */ |
| 189 |
(void)rdint32(br); /* bitmap size */ |
| 190 |
br->hdr->hRes = rdint32(br); /* horizontal resolution */ |
| 191 |
br->hdr->vRes = rdint32(br); /* vertical resolution */ |
| 192 |
br->hdr->nColors = rdint32(br); /* # colors used */ |
| 193 |
if (!br->hdr->nColors && br->hdr->bpp <= 8) |
| 194 |
br->hdr->nColors = 1<<br->hdr->bpp; |
| 195 |
br->hdr->impColors = rdint32(br); /* # important colors */ |
| 196 |
if (br->hdr->impColors < 0) |
| 197 |
goto err; /* catch premature EOF */ |
| 198 |
if (!BMPheaderOK(br->hdr)) |
| 199 |
goto err; |
| 200 |
palSiz = sizeof(RGBquad)*br->hdr->nColors; |
| 201 |
if (br->hdr->impColors <= 0) |
| 202 |
br->hdr->impColors = br->hdr->nColors; |
| 203 |
/* extend header */ |
| 204 |
if (bmPos < hdrSiz + palSiz) |
| 205 |
goto err; |
| 206 |
br->hdr->infoSiz = bmPos - (hdrSiz + palSiz); |
| 207 |
if (br->hdr->nColors > 0 || br->hdr->infoSiz > 0) { |
| 208 |
br->hdr = (BMPHeader *)realloc(br->hdr, |
| 209 |
sizeof(BMPHeader) + |
| 210 |
palSiz + br->hdr->infoSiz); |
| 211 |
if (br->hdr == NULL) |
| 212 |
goto err; |
| 213 |
} |
| 214 |
/* read colors or fields */ |
| 215 |
if (br->hdr->compr == BI_BITFIELDS) { |
| 216 |
BMPbitField(br->hdr)[0] = (uint32)rdint32(br); |
| 217 |
BMPbitField(br->hdr)[1] = (uint32)rdint32(br); |
| 218 |
BMPbitField(br->hdr)[2] = (uint32)rdint32(br); |
| 219 |
} else if (rdbytes((char *)br->hdr->palette, palSiz, br) != BIR_OK) |
| 220 |
goto err; |
| 221 |
/* read add'l information */ |
| 222 |
if (rdbytes(BMPinfo(br->hdr), br->hdr->infoSiz, br) != BIR_OK) |
| 223 |
goto err; |
| 224 |
/* read first scanline */ |
| 225 |
br->scanline = (uint8 *)calloc(getScanSiz(br->hdr), sizeof(uint8)); |
| 226 |
if (br->scanline == NULL) |
| 227 |
goto err; |
| 228 |
br->yscan = -1; |
| 229 |
if (seek != NULL && ((br->hdr->compr == BI_RLE8) | |
| 230 |
(br->hdr->compr == BI_RLE4))) { |
| 231 |
BMPReader *newbr = (BMPReader *)realloc(br, |
| 232 |
sizeof(BMPReader) + |
| 233 |
sizeof(br->scanpos[0]) * |
| 234 |
br->hdr->height); |
| 235 |
if (newbr == NULL) |
| 236 |
goto err; |
| 237 |
br = newbr; |
| 238 |
memset(br->scanpos+1, 0, |
| 239 |
sizeof(br->scanpos[0])*br->hdr->height); |
| 240 |
} |
| 241 |
br->scanpos[0] = br->fpos; |
| 242 |
if (BMPreadScanline(br) == BIR_OK) |
| 243 |
return br; |
| 244 |
err: |
| 245 |
if (br->hdr != NULL) |
| 246 |
free(br->hdr); |
| 247 |
if (br->scanline != NULL) |
| 248 |
free(br->scanline); |
| 249 |
free(br); |
| 250 |
return NULL; |
| 251 |
} |
| 252 |
|
| 253 |
/* Determine if image is grayscale */ |
| 254 |
int |
| 255 |
BMPisGrayscale(const BMPHeader *hdr) |
| 256 |
{ |
| 257 |
const RGBquad *rgbp; |
| 258 |
int n; |
| 259 |
|
| 260 |
if (hdr == NULL) |
| 261 |
return -1; |
| 262 |
if (hdr->bpp > 8) /* assume they had a reason for it */ |
| 263 |
return 0; |
| 264 |
for (rgbp = hdr->palette, n = hdr->impColors; n-- > 0; rgbp++) |
| 265 |
if ((rgbp->r != rgbp->g) | (rgbp->g != rgbp->b)) |
| 266 |
return 0; |
| 267 |
return 1; /* all colors neutral in map */ |
| 268 |
} |
| 269 |
|
| 270 |
/* Read and decode next BMP scanline */ |
| 271 |
int |
| 272 |
BMPreadScanline(BMPReader *br) |
| 273 |
{ |
| 274 |
int n; |
| 275 |
int8 *sp; |
| 276 |
|
| 277 |
if (br->yscan + 1 >= br->hdr->height) |
| 278 |
return BIR_EOF; |
| 279 |
br->yscan++; /* prepare to read */ |
| 280 |
n = getScanSiz(br->hdr); /* reading uncompressed data? */ |
| 281 |
if (br->hdr->compr == BI_UNCOMPR || br->hdr->compr == BI_BITFIELDS) |
| 282 |
return rdbytes((char *)br->scanline, n, br); |
| 283 |
/* |
| 284 |
* RLE4/RLE8 Decoding |
| 285 |
* |
| 286 |
* Certain aspects of this scheme are completely insane, so |
| 287 |
* we don't support them. Fortunately, they rarely appear. |
| 288 |
* One is the mid-file EOD (0x0001) and another is the ill-conceived |
| 289 |
* "delta" (0x0002), which is like a "goto" statement for bitmaps. |
| 290 |
* Whoever thought this up should be wrestled to the ground and told |
| 291 |
* why it's impossible to support such a scheme in any reasonable way. |
| 292 |
* Also, RLE4 mode allows runs to stop halfway through a byte, |
| 293 |
* which is likewise uncodeable, so we don't even try. |
| 294 |
* Finally, the scanline break is ambiguous -- we assume here that |
| 295 |
* it is required at the end of each scanline, though I haven't |
| 296 |
* found anywhere this is written. Otherwise, we would read to |
| 297 |
* the end of the scanline, assuming the next bit of data belongs |
| 298 |
* the following scan. If a break follows the last pixel, as it |
| 299 |
* seems to in the files I've tested out of Photoshop, you end up |
| 300 |
* painting every other line black. Also, I assume any skipped |
| 301 |
* pixels are painted with color 0, which is often black. Nowhere |
| 302 |
* is it specified what we should assume for missing pixels. This |
| 303 |
* is undoubtedly the most brain-dead format I've ever encountered. |
| 304 |
*/ |
| 305 |
sp = (int8 *)br->scanline; |
| 306 |
n = br->hdr->width; |
| 307 |
if (br->hdr->compr == BI_RLE4) |
| 308 |
n = (n + 1) >> 1; |
| 309 |
while (n > 0) { |
| 310 |
int skipOdd, len, val; |
| 311 |
|
| 312 |
if (rdbyte(len, br) == EOF) |
| 313 |
return BIR_TRUNCATED; |
| 314 |
if (len > 0) { /* got a run */ |
| 315 |
if (br->hdr->compr == BI_RLE4) { |
| 316 |
if (len & 1) |
| 317 |
return BIR_UNSUPPORTED; |
| 318 |
len >>= 1; |
| 319 |
} |
| 320 |
if (len > n) |
| 321 |
return BIR_RLERROR; |
| 322 |
if (rdbyte(val, br) == EOF) |
| 323 |
return BIR_TRUNCATED; |
| 324 |
n -= len; |
| 325 |
while (len--) |
| 326 |
*sp++ = val; |
| 327 |
continue; |
| 328 |
} |
| 329 |
/* check for escape */ |
| 330 |
switch (rdbyte(len, br)) { |
| 331 |
case EOF: |
| 332 |
return BIR_TRUNCATED; |
| 333 |
case 0: /* end of line */ |
| 334 |
while (n--) |
| 335 |
*sp++ = 0; |
| 336 |
/* leaves n == -1 as flag for test after loop */ |
| 337 |
continue; |
| 338 |
case 1: /* end of bitmap */ |
| 339 |
case 2: /* delta */ |
| 340 |
return BIR_UNSUPPORTED; |
| 341 |
} |
| 342 |
/* absolute mode */ |
| 343 |
if (br->hdr->compr == BI_RLE4) { |
| 344 |
if (len & 1) |
| 345 |
return BIR_UNSUPPORTED; |
| 346 |
len >>= 1; |
| 347 |
} |
| 348 |
skipOdd = len & 1; |
| 349 |
if (len > n) |
| 350 |
return BIR_RLERROR; |
| 351 |
n -= len; |
| 352 |
while (len--) { |
| 353 |
if (rdbyte(val, br) == EOF) |
| 354 |
return BIR_TRUNCATED; |
| 355 |
*sp++ = val; |
| 356 |
} |
| 357 |
if (skipOdd && rdbyte(val, br) == EOF) |
| 358 |
return BIR_TRUNCATED; |
| 359 |
} |
| 360 |
/* verify break at end of line */ |
| 361 |
if (!n && (rdbyte(n, br) != 0 || (rdbyte(n, br) != 0 && |
| 362 |
(n != 1 || br->yscan != br->hdr->height-1)))) |
| 363 |
return BIR_RLERROR; |
| 364 |
if (br->seek != NULL) /* record next scanline position */ |
| 365 |
br->scanpos[br->yscan + 1] = br->fpos; |
| 366 |
return BIR_OK; |
| 367 |
} |
| 368 |
|
| 369 |
/* Read a specific scanline */ |
| 370 |
int |
| 371 |
BMPseekScanline(int y, BMPReader *br) |
| 372 |
{ |
| 373 |
int rv; |
| 374 |
/* check arguments */ |
| 375 |
if (br == NULL) |
| 376 |
return BIR_EOF; |
| 377 |
if (y < 0) |
| 378 |
return BIR_SEEKERR; |
| 379 |
if (y >= br->hdr->height) |
| 380 |
return BIR_EOF; |
| 381 |
/* already read? */ |
| 382 |
if (y == br->yscan) |
| 383 |
return BIR_OK; |
| 384 |
/* shall we seek? */ |
| 385 |
if (y != br->yscan + 1 && br->seek != NULL) { |
| 386 |
int yseek; |
| 387 |
uint32 seekp; |
| 388 |
if (br->hdr->compr == BI_UNCOMPR || |
| 389 |
br->hdr->compr == BI_BITFIELDS) { |
| 390 |
yseek = y; |
| 391 |
seekp = br->scanpos[0] + y*getScanSiz(br->hdr); |
| 392 |
} else { |
| 393 |
yseek = br->yscan + 1; |
| 394 |
while (yseek < y && br->scanpos[yseek+1] != 0) |
| 395 |
++yseek; |
| 396 |
if (y < yseek && br->scanpos[yseek=y] == 0) |
| 397 |
return BIR_SEEKERR; |
| 398 |
seekp = br->scanpos[yseek]; |
| 399 |
} |
| 400 |
if ((rv = rdseek(seekp, br)) != BIR_OK) |
| 401 |
return rv; |
| 402 |
br->yscan = yseek - 1; |
| 403 |
} else if (y < br->yscan) /* else we can't back up */ |
| 404 |
return BIR_SEEKERR; |
| 405 |
/* read until we get there */ |
| 406 |
while (br->yscan < y) |
| 407 |
if ((rv = BMPreadScanline(br)) != BIR_OK) |
| 408 |
return rv; |
| 409 |
return BIR_OK; |
| 410 |
} |
| 411 |
|
| 412 |
/* Get ith pixel from last scanline */ |
| 413 |
RGBquad |
| 414 |
BMPdecodePixel(int i, const BMPReader *br) |
| 415 |
{ |
| 416 |
static const uint32 std16mask[3] = {0x7c00, 0x3e0, 0x1f}; |
| 417 |
static const RGBquad black = {0, 0, 0, 0}; |
| 418 |
const uint32 *mask; |
| 419 |
const uint8 *pp; |
| 420 |
uint32 pval, v; |
| 421 |
RGBquad cval; |
| 422 |
|
| 423 |
if (((br == NULL) | (i < 0)) || i >= br->hdr->width) |
| 424 |
return black; |
| 425 |
|
| 426 |
cval.padding = 0; |
| 427 |
|
| 428 |
switch (br->hdr->bpp) { |
| 429 |
case 24: |
| 430 |
pp = br->scanline + 3*i; |
| 431 |
cval.b = *pp++; |
| 432 |
cval.g = *pp++; |
| 433 |
cval.r = *pp; |
| 434 |
return cval; |
| 435 |
case 32: |
| 436 |
if (br->hdr->compr == BI_UNCOMPR) |
| 437 |
return ((RGBquad *)br->scanline)[i]; |
| 438 |
/* convert bit fields */ |
| 439 |
pp = br->scanline + 4*i; |
| 440 |
pval = *pp++; |
| 441 |
pval |= *pp++ << 8; |
| 442 |
pval |= *pp++ << 16; |
| 443 |
pval |= *pp << 24; |
| 444 |
mask = BMPbitField(br->hdr); |
| 445 |
v = pval & mask[0]; |
| 446 |
while (v & ~0xff) v >>= 8; |
| 447 |
cval.r = v; |
| 448 |
v = pval & mask[1]; |
| 449 |
while (v & ~0xff) v >>= 8; |
| 450 |
cval.g = v; |
| 451 |
v = pval & mask[2]; |
| 452 |
while (v & ~0xff) v >>= 8; |
| 453 |
cval.b = v; |
| 454 |
return cval; |
| 455 |
case 8: |
| 456 |
return br->hdr->palette[br->scanline[i]]; |
| 457 |
case 1: |
| 458 |
return br->hdr->palette[br->scanline[i>>3]>>(7-(i&7)) & 1]; |
| 459 |
case 4: |
| 460 |
return br->hdr->palette[br->scanline[i>>1]>>(i&1?4:0) & 0xf]; |
| 461 |
case 16: |
| 462 |
pp = br->scanline + 2*i; |
| 463 |
pval = *pp++; |
| 464 |
pval |= *pp++ << 8; |
| 465 |
mask = std16mask; |
| 466 |
if (br->hdr->compr == BI_BITFIELDS) |
| 467 |
mask = BMPbitField(br->hdr); |
| 468 |
cval.r = ((pval & mask[0]) << 8) / (mask[0] + 1); |
| 469 |
cval.g = ((pval & mask[1]) << 8) / (mask[1] + 1); |
| 470 |
cval.b = ((pval & mask[2]) << 8) / (mask[2] + 1); |
| 471 |
return cval; |
| 472 |
} |
| 473 |
return black; /* should never happen */ |
| 474 |
} |
| 475 |
|
| 476 |
/* Free BMP reader resources */ |
| 477 |
void |
| 478 |
BMPfreeReader(BMPReader *br) |
| 479 |
{ |
| 480 |
if (br == NULL) |
| 481 |
return; |
| 482 |
free(br->hdr); |
| 483 |
free(br->scanline); |
| 484 |
free(br); |
| 485 |
} |
| 486 |
|
| 487 |
/* stdio getc() callback */ |
| 488 |
int |
| 489 |
stdio_getc(void *p) |
| 490 |
{ |
| 491 |
if (!p) |
| 492 |
return EOF; |
| 493 |
return getc((FILE *)p); |
| 494 |
} |
| 495 |
|
| 496 |
/* stdio putc() callback */ |
| 497 |
void |
| 498 |
stdio_putc(int c, void *p) |
| 499 |
{ |
| 500 |
if (p) |
| 501 |
putc(c, (FILE *)p); |
| 502 |
} |
| 503 |
|
| 504 |
/* stdio fseek() callback */ |
| 505 |
int |
| 506 |
stdio_fseek(uint32 pos, void *p) |
| 507 |
{ |
| 508 |
if (!p) |
| 509 |
return -1; |
| 510 |
return fseek((FILE *)p, (long)pos, 0); |
| 511 |
} |
| 512 |
|
| 513 |
/* Allocate uncompressed (24-bit) RGB header */ |
| 514 |
BMPHeader * |
| 515 |
BMPtruecolorHeader(int xr, int yr, int infolen) |
| 516 |
{ |
| 517 |
BMPHeader *hdr; |
| 518 |
|
| 519 |
if (xr <= 0 || yr <= 0 || infolen < 0) |
| 520 |
return NULL; |
| 521 |
hdr = (BMPHeader *)malloc(sizeof(BMPHeader) - sizeof(hdr->palette) + |
| 522 |
infolen); |
| 523 |
if (hdr == NULL) |
| 524 |
return NULL; |
| 525 |
hdr->width = xr; |
| 526 |
hdr->height = yr; |
| 527 |
hdr->yIsDown = 0; /* default to upwards order */ |
| 528 |
hdr->bpp = 24; |
| 529 |
hdr->compr = BI_UNCOMPR; |
| 530 |
hdr->hRes = hdr->vRes = 2835; /* default to 72 ppi */ |
| 531 |
hdr->nColors = hdr->impColors = 0; |
| 532 |
if ((hdr->infoSiz = infolen) > 0) |
| 533 |
memset(BMPinfo(hdr), 0, hdr->infoSiz); |
| 534 |
return hdr; |
| 535 |
} |
| 536 |
|
| 537 |
/* Allocate color-mapped header (defaults to minimal grayscale) */ |
| 538 |
BMPHeader * |
| 539 |
BMPmappedHeader(int xr, int yr, int infolen, int ncolors) |
| 540 |
{ |
| 541 |
int n; |
| 542 |
BMPHeader *hdr; |
| 543 |
|
| 544 |
if (xr <= 0 || yr <= 0 || infolen < 0 || ncolors < 2) |
| 545 |
return NULL; |
| 546 |
if (ncolors <= 2) |
| 547 |
n = 1; |
| 548 |
else if (ncolors <= 16) |
| 549 |
n = 4; |
| 550 |
else if (ncolors <= 256) |
| 551 |
n = 8; |
| 552 |
else |
| 553 |
return NULL; |
| 554 |
hdr = (BMPHeader *)malloc(sizeof(BMPHeader) + |
| 555 |
sizeof(RGBquad)*((size_t)1<<n) - |
| 556 |
sizeof(hdr->palette) + |
| 557 |
infolen); |
| 558 |
if (hdr == NULL) |
| 559 |
return NULL; |
| 560 |
hdr->width = xr; |
| 561 |
hdr->height = yr; |
| 562 |
hdr->yIsDown = 0; /* default to upwards order */ |
| 563 |
hdr->bpp = n; |
| 564 |
hdr->compr = BI_UNCOMPR; /* compression needs seek */ |
| 565 |
hdr->hRes = hdr->vRes = 2835; /* default to 72 ppi */ |
| 566 |
hdr->nColors = ncolors; |
| 567 |
hdr->impColors = 0; /* says all colors important */ |
| 568 |
hdr->infoSiz = infolen; |
| 569 |
memset(hdr->palette, 0, sizeof(RGBquad)*((size_t)1<<n) + infolen); |
| 570 |
for (n = ncolors; n--; ) |
| 571 |
hdr->palette[n].r = hdr->palette[n].g = |
| 572 |
hdr->palette[n].b = n*255/(ncolors-1); |
| 573 |
return hdr; |
| 574 |
} |
| 575 |
|
| 576 |
/* put byte to writer */ |
| 577 |
#define wrbyte(c,bw) ( (*(bw)->cput)(c,(bw)->c_data), \ |
| 578 |
++(bw)->fpos > (bw)->flen ? \ |
| 579 |
((bw)->flen = (bw)->fpos) : \ |
| 580 |
(bw)->fpos ) |
| 581 |
|
| 582 |
/* Write out a string of bytes */ |
| 583 |
static void |
| 584 |
wrbytes(char *bp, uint32 n, BMPWriter *bw) |
| 585 |
{ |
| 586 |
while (n--) |
| 587 |
wrbyte(*bp++, bw); |
| 588 |
} |
| 589 |
|
| 590 |
/* Write 32-bit integer in littlendian order */ |
| 591 |
static void |
| 592 |
wrint32(int32 i, BMPWriter *bw) |
| 593 |
{ |
| 594 |
wrbyte(i& 0xff, bw); |
| 595 |
wrbyte(i>>8 & 0xff, bw); |
| 596 |
wrbyte(i>>16 & 0xff, bw); |
| 597 |
wrbyte(i>>24 & 0xff, bw); |
| 598 |
} |
| 599 |
|
| 600 |
/* Write 16-bit unsigned integer in littlendian order */ |
| 601 |
static void |
| 602 |
wruint16(uint16 ui, BMPWriter *bw) |
| 603 |
{ |
| 604 |
wrbyte(ui & 0xff, bw); |
| 605 |
wrbyte(ui>>8 & 0xff, bw); |
| 606 |
} |
| 607 |
|
| 608 |
/* Seek to the specified file position, returning 0 (BIR_OK) on success */ |
| 609 |
static int |
| 610 |
wrseek(uint32 pos, BMPWriter *bw) |
| 611 |
{ |
| 612 |
if (pos == bw->fpos) |
| 613 |
return BIR_OK; |
| 614 |
if (bw->seek == NULL) |
| 615 |
return BIR_SEEKERR; |
| 616 |
if ((*bw->seek)(pos, bw->c_data) != 0) |
| 617 |
return BIR_SEEKERR; |
| 618 |
bw->fpos = pos; |
| 619 |
if (pos > bw->flen) |
| 620 |
bw->flen = pos; |
| 621 |
return BIR_OK; |
| 622 |
} |
| 623 |
|
| 624 |
/* Open BMP stream for writing */ |
| 625 |
BMPWriter * |
| 626 |
BMPopenWriter(void (*cput)(int, void *), int (*seek)(uint32, void *), |
| 627 |
void *c_data, BMPHeader *hdr) |
| 628 |
{ |
| 629 |
BMPWriter *bw; |
| 630 |
uint32 hdrSiz, palSiz, scanSiz, bmSiz; |
| 631 |
/* check arguments */ |
| 632 |
if (cput == NULL) |
| 633 |
return NULL; |
| 634 |
if (cput == &stdio_putc && c_data == NULL) |
| 635 |
return NULL; /* stdio error condition */ |
| 636 |
if (!BMPheaderOK(hdr)) |
| 637 |
return NULL; |
| 638 |
if ((hdr->bpp == 16) | (hdr->compr == BI_RLE4)) |
| 639 |
return NULL; /* unsupported */ |
| 640 |
/* no seek means we may have the wrong file length, but most app's don't care |
| 641 |
if (seek == NULL && ((hdr->compr == BI_RLE8) | (hdr->compr == BI_RLE4))) |
| 642 |
return NULL; |
| 643 |
*/ |
| 644 |
/* compute sizes */ |
| 645 |
hdrSiz = 2 + 6*4 + 2*2 + 6*4; |
| 646 |
if (hdr->compr == BI_BITFIELDS) |
| 647 |
hdrSiz += sizeof(uint32)*3; |
| 648 |
palSiz = sizeof(RGBquad)*hdr->nColors; |
| 649 |
scanSiz = getScanSiz(hdr); |
| 650 |
bmSiz = hdr->height*scanSiz; /* wrong if compressed */ |
| 651 |
/* initialize writer */ |
| 652 |
bw = (BMPWriter *)malloc(sizeof(BMPWriter)); |
| 653 |
if (bw == NULL) |
| 654 |
return NULL; |
| 655 |
bw->hdr = hdr; |
| 656 |
bw->yscan = 0; |
| 657 |
bw->scanline = (uint8 *)calloc(scanSiz, sizeof(uint8)); |
| 658 |
if (bw->scanline == NULL) { |
| 659 |
free(bw); |
| 660 |
return NULL; |
| 661 |
} |
| 662 |
bw->fbmp = hdrSiz + palSiz + hdr->infoSiz; |
| 663 |
bw->fpos = bw->flen = 0; |
| 664 |
bw->cput = cput; |
| 665 |
bw->seek = seek; |
| 666 |
bw->c_data = c_data; |
| 667 |
/* write out header */ |
| 668 |
wrbyte('B', bw); wrbyte('M', bw); /* magic number */ |
| 669 |
wrint32(bw->fbmp + bmSiz, bw); /* file size */ |
| 670 |
wrint32(0, bw); /* reserved word */ |
| 671 |
wrint32(bw->fbmp, bw); /* offset to bitmap */ |
| 672 |
wrint32(hdrSiz - bw->fpos, bw); /* info header size */ |
| 673 |
wrint32(hdr->width, bw); /* bitmap width */ |
| 674 |
if (hdr->yIsDown) /* bitmap height */ |
| 675 |
wrint32(-hdr->height, bw); |
| 676 |
else |
| 677 |
wrint32(hdr->height, bw); |
| 678 |
wruint16(1, bw); /* number of planes */ |
| 679 |
wruint16(hdr->bpp, bw); /* bits per pixel */ |
| 680 |
wrint32(hdr->compr, bw); /* compression mode */ |
| 681 |
wrint32(bmSiz, bw); /* bitmap size */ |
| 682 |
wrint32(hdr->hRes, bw); /* horizontal resolution */ |
| 683 |
wrint32(hdr->vRes, bw); /* vertical resolution */ |
| 684 |
wrint32(hdr->nColors, bw); /* # colors used */ |
| 685 |
wrint32(hdr->impColors, bw); /* # important colors */ |
| 686 |
/* write out color palette */ |
| 687 |
wrbytes((char *)hdr->palette, palSiz, bw); |
| 688 |
/* write add'l information */ |
| 689 |
wrbytes(BMPinfo(hdr), hdr->infoSiz, bw); |
| 690 |
#ifndef NDEBUG |
| 691 |
if (bw->fpos != bw->fbmp) { |
| 692 |
fputs("Coding error 1 in BMPopenWriter\n", stderr); |
| 693 |
exit(1); |
| 694 |
} |
| 695 |
#endif |
| 696 |
return bw; |
| 697 |
} |
| 698 |
|
| 699 |
/* Find position of next run of 5 or more identical bytes, or 255 if none */ |
| 700 |
static int |
| 701 |
findNextRun(const int8 *bp, int len) |
| 702 |
{ |
| 703 |
int pos, cnt; |
| 704 |
/* look for run */ |
| 705 |
for (pos = 0; (len > 0) & (pos < 255); pos++, bp++, len--) { |
| 706 |
if (len < 5) /* no hope left? */ |
| 707 |
continue; |
| 708 |
cnt = 1; /* else let's try it */ |
| 709 |
while (bp[cnt] == bp[0]) |
| 710 |
if (++cnt >= 5) |
| 711 |
return pos; /* long enough */ |
| 712 |
} |
| 713 |
return pos; /* didn't find any */ |
| 714 |
} |
| 715 |
|
| 716 |
/* Write the current scanline */ |
| 717 |
int |
| 718 |
BMPwriteScanline(BMPWriter *bw) |
| 719 |
{ |
| 720 |
const int8 *sp; |
| 721 |
int n; |
| 722 |
|
| 723 |
if (bw->yscan >= bw->hdr->height) |
| 724 |
return BIR_EOF; |
| 725 |
/* writing uncompressed? */ |
| 726 |
if (bw->hdr->compr == BI_UNCOMPR || bw->hdr->compr == BI_BITFIELDS) { |
| 727 |
uint32 scanSiz = getScanSiz(bw->hdr); |
| 728 |
uint32 slpos = bw->fbmp + bw->yscan*scanSiz; |
| 729 |
if (wrseek(slpos, bw) != BIR_OK) |
| 730 |
return BIR_SEEKERR; |
| 731 |
wrbytes((char *)bw->scanline, scanSiz, bw); |
| 732 |
bw->yscan++; |
| 733 |
return BIR_OK; |
| 734 |
} |
| 735 |
/* |
| 736 |
* RLE8 Encoding |
| 737 |
* |
| 738 |
* See the notes in BMPreadScanline() on this encoding. Needless |
| 739 |
* to say, we avoid the nuttier aspects of this specification. |
| 740 |
* We also assume that every scanline ends in a line break |
| 741 |
* (0x0000) except for the last, which ends in a bitmap break |
| 742 |
* (0x0001). We don't support RLE4 at all; it's too awkward. |
| 743 |
*/ |
| 744 |
sp = (const int8 *)bw->scanline; |
| 745 |
n = bw->hdr->width; |
| 746 |
while (n > 0) { |
| 747 |
int cnt, val; |
| 748 |
cnt = findNextRun(sp, n); /* 0-255 < n */ |
| 749 |
if (cnt >= 3) { /* output absolute */ |
| 750 |
int skipOdd = cnt & 1; |
| 751 |
wrbyte(0, bw); |
| 752 |
wrbyte(cnt, bw); |
| 753 |
n -= cnt; |
| 754 |
while (cnt--) |
| 755 |
wrbyte(*sp++, bw); |
| 756 |
if (skipOdd) |
| 757 |
wrbyte(0, bw); |
| 758 |
} |
| 759 |
if (n <= 0) /* was that it? */ |
| 760 |
break; |
| 761 |
val = *sp++; /* output run */ |
| 762 |
for (cnt = 1; --n && cnt < 255; cnt++, sp++) |
| 763 |
if (*sp != val) |
| 764 |
break; |
| 765 |
wrbyte(cnt, bw); |
| 766 |
wrbyte(val, bw); |
| 767 |
} |
| 768 |
bw->yscan++; /* write line break or EOD */ |
| 769 |
if (bw->yscan == bw->hdr->height) { |
| 770 |
wrbyte(0, bw); wrbyte(1, bw); /* end of bitmap marker */ |
| 771 |
if (wrseek(2, bw) != BIR_OK) |
| 772 |
return BIR_OK; /* no one may care */ |
| 773 |
wrint32(bw->flen, bw); /* correct file length */ |
| 774 |
if (wrseek(34, bw) != BIR_OK) |
| 775 |
return BIR_OK; |
| 776 |
wrint32(bw->flen-bw->fbmp, bw); /* correct bitmap length */ |
| 777 |
} else { |
| 778 |
wrbyte(0, bw); wrbyte(0, bw); /* end of line marker */ |
| 779 |
} |
| 780 |
return BIR_OK; |
| 781 |
} |
| 782 |
|
| 783 |
/* Free BMP writer resources */ |
| 784 |
void |
| 785 |
BMPfreeWriter(BMPWriter *bw) |
| 786 |
{ |
| 787 |
if (bw == NULL) |
| 788 |
return; |
| 789 |
free(bw->hdr); |
| 790 |
free(bw->scanline); |
| 791 |
free(bw); |
| 792 |
} |
