Skip to content
This repository

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

file 1997 lines (1680 sloc) 52.624 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
#include "imgif.h"
#include <gif_lib.h>
#ifdef _MSC_VER
#include <io.h>
#else
#include <unistd.h>
#endif
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>

/*
=head1 NAME

imgif.c - read and write gif files for Imager

=head1 SYNOPSIS

i_img *img;
i_img *imgs[count];
int fd;
int *colour_table,
int colours;
int max_colours; // number of bits per colour
int pixdev; // how much noise to add
i_color fixed[N]; // fixed palette entries
int fixedlen; // number of fixed colours
int success; // non-zero on success
char *data; // a GIF file in memory
int length; // how big data is
int reader(char *, char *, int, int);
int writer(char *, char *, int);
char *userdata; // user's data, whatever it is
i_quantize quant;
i_gif_opts opts;

img = i_readgif(fd, &colour_table, &colours);
success = i_writegif(img, fd, max_colours, pixdev, fixedlen, fixed);
success = i_writegifmc(img, fd, max_colours);
img = i_readgif_scalar(data, length, &colour_table, &colours);
img = i_readgif_callback(cb, userdata, &colour_table, &colours);
success = i_writegif_gen(&quant, fd, imgs, count, &opts);
success = i_writegif_callback(&quant, writer, userdata, maxlength,
imgs, count, &opts);

=head1 DESCRIPTION

This source file provides the C level interface to reading and writing
GIF files for Imager.

This has been tested with giflib 3 and 4, though you lose the callback
functionality with giflib3.

=head1 REFERENCE

=over

=cut
*/

#if defined(GIFLIB_MAJOR) && GIFLIB_MAJOR >= 5
#define myDGifOpen(userPtr, readFunc, Error) DGifOpen((userPtr), (readFunc), (Error))
#define myEGifOpen(userPtr, readFunc, Error) EGifOpen((userPtr), (readFunc), (Error))
#define myGifError(gif) ((gif)->Error)
#define MakeMapObject GifMakeMapObject
#define FreeMapObject GifFreeMapObject

#else
static GifFileType *
myDGifOpen(void *userPtr, InputFunc readFunc, int *error) {
  GifFileType *result = DGifOpen(userPtr, readFunc);
  if (!result)
    *error = GifLastError();

  return result;
}
static GifFileType *
myEGifOpen(void *userPtr, OutputFunc outputFunc, int *error) {
  GifFileType *result = EGifOpen(userPtr, outputFunc);
  if (!result)
    *error = GifLastError();

  return result;
}
#define myGifError(gif) GifLastError()

#endif

static char const *gif_error_msg(int code);
static void gif_push_error(int code);

/* Make some variables global, so we could access them faster: */

static const int
  InterlacedOffset[] = { 0, 4, 2, 1 }, /* The way Interlaced image should. */
  InterlacedJumps[] = { 8, 8, 4, 2 }; /* be read - offsets and jumps... */

static
void
i_colortable_copy(int **colour_table, int *colours, ColorMapObject *colourmap) {
  GifColorType *mapentry;
  int q;
  int colourmapsize = colourmap->ColorCount;

  if(colours) *colours = colourmapsize;
  if(!colour_table) return;
  
  *colour_table = mymalloc(sizeof(int) * colourmapsize * 3);
  memset(*colour_table, 0, sizeof(int) * colourmapsize * 3);

  for(q=0; q<colourmapsize; q++) {
    mapentry = &colourmap->Colors[q];
    (*colour_table)[q*3 + 0] = mapentry->Red;
    (*colour_table)[q*3 + 1] = mapentry->Green;
    (*colour_table)[q*3 + 2] = mapentry->Blue;
  }
}

#ifdef GIF_LIB_VERSION

static const
char gif_version_str[] = GIF_LIB_VERSION;

double
i_giflib_version(void) {
  const char *p = gif_version_str;

  while (*p && (*p < '0' || *p > '9'))
    ++p;

  if (!*p)
    return 0;

  return strtod(p, NULL);
}

#else

double
i_giflib_version(void) {
  return GIFLIB_MAJOR + GIFLIB_MINOR * 0.1;
}

#endif

/*
=item i_readgif_low(GifFileType *GifFile, int **colour_table, int *colours)

Internal. Low-level function for reading a GIF file. The caller must
create the appropriate GifFileType object and pass it in.

=cut
*/

i_img *
i_readgif_low(GifFileType *GifFile, int **colour_table, int *colours) {
  i_img *im;
  int i, j, Size, Row, Col, Width, Height, ExtCode, Count, x;
  int cmapcnt = 0, ImageNum = 0, BackGround = 0, ColorMapSize = 0;
  ColorMapObject *ColorMap;
 
  GifRecordType RecordType;
  GifByteType *Extension;
  
  GifRowType GifRow;
  GifColorType *ColorMapEntry;
  i_color col;

  mm_log((1,"i_readgif_low(GifFile %p, colour_table %p, colours %p)\n", GifFile, colour_table, colours));

  /* it's possible that the caller has called us with *colour_table being
non-NULL, but we check that to see if we need to free an allocated
colour table on error.
*/
  if (colour_table) *colour_table = NULL;

  BackGround = GifFile->SBackGroundColor;
  ColorMap = (GifFile->Image.ColorMap ? GifFile->Image.ColorMap : GifFile->SColorMap);

  if (ColorMap) {
    ColorMapSize = ColorMap->ColorCount;
    i_colortable_copy(colour_table, colours, ColorMap);
    cmapcnt++;
  }
  
  if (!i_int_check_image_file_limits(GifFile->SWidth, GifFile->SHeight, 3, sizeof(i_sample_t))) {
    if (colour_table && *colour_table) {
      myfree(*colour_table);
      *colour_table = NULL;
    }
    DGifCloseFile(GifFile);
    mm_log((1, "i_readgif: image size exceeds limits\n"));
    return NULL;
  }

  im = i_img_8_new(GifFile->SWidth, GifFile->SHeight, 3);
  if (!im) {
    if (colour_table && *colour_table) {
      myfree(*colour_table);
      *colour_table = NULL;
    }
    DGifCloseFile(GifFile);
    return NULL;
  }

  Size = GifFile->SWidth * sizeof(GifPixelType);
  
  GifRow = mymalloc(Size);

  for (i = 0; i < GifFile->SWidth; i++) GifRow[i] = GifFile->SBackGroundColor;
  
  /* Scan the content of the GIF file and load the image(s) in: */
  do {
    if (DGifGetRecordType(GifFile, &RecordType) == GIF_ERROR) {
      gif_push_error(myGifError(GifFile));
      i_push_error(0, "Unable to get record type");
      if (colour_table && *colour_table) {
myfree(*colour_table);
*colour_table = NULL;
      }
      myfree(GifRow);
      i_img_destroy(im);
      DGifCloseFile(GifFile);
      return NULL;
    }
    
    switch (RecordType) {
    case IMAGE_DESC_RECORD_TYPE:
      if (DGifGetImageDesc(GifFile) == GIF_ERROR) {
gif_push_error(myGifError(GifFile));
i_push_error(0, "Unable to get image descriptor");
if (colour_table && *colour_table) {
myfree(*colour_table);
*colour_table = NULL;
}
myfree(GifRow);
i_img_destroy(im);
DGifCloseFile(GifFile);
return NULL;
      }

      if (( ColorMap = (GifFile->Image.ColorMap ? GifFile->Image.ColorMap : GifFile->SColorMap) )) {
mm_log((1, "Adding local colormap\n"));
ColorMapSize = ColorMap->ColorCount;
if ( cmapcnt == 0) {
i_colortable_copy(colour_table, colours, ColorMap);
cmapcnt++;
}
      } else {
/* No colormap and we are about to read in the image - abandon for now */
mm_log((1, "Going in with no colormap\n"));
i_push_error(0, "Image does not have a local or a global color map");
/* we can't have allocated a colour table here */
myfree(GifRow);
i_img_destroy(im);
DGifCloseFile(GifFile);
return NULL;
      }
      
      Row = GifFile->Image.Top; /* Image Position relative to Screen. */
      Col = GifFile->Image.Left;
      Width = GifFile->Image.Width;
      Height = GifFile->Image.Height;
      ImageNum++;
      mm_log((1,"i_readgif_low: Image %d at (%d, %d) [%dx%d]: \n",ImageNum, Col, Row, Width, Height));

      if (GifFile->Image.Left + GifFile->Image.Width > GifFile->SWidth ||
GifFile->Image.Top + GifFile->Image.Height > GifFile->SHeight) {
i_push_errorf(0, "Image %d is not confined to screen dimension, aborted.\n",ImageNum);
if (colour_table && *colour_table) {
myfree(*colour_table);
*colour_table = NULL;
}
myfree(GifRow);
i_img_destroy(im);
DGifCloseFile(GifFile);
return NULL;
      }
      if (GifFile->Image.Interlace) {

for (Count = i = 0; i < 4; i++) for (j = Row + InterlacedOffset[i]; j < Row + Height; j += InterlacedJumps[i]) {
Count++;
if (DGifGetLine(GifFile, GifRow, Width) == GIF_ERROR) {
gif_push_error(myGifError(GifFile));
i_push_error(0, "Reading GIF line");
if (colour_table && *colour_table) {
myfree(*colour_table);
*colour_table = NULL;
}
myfree(GifRow);
i_img_destroy(im);
DGifCloseFile(GifFile);
return NULL;
}

for (x = 0; x < Width; x++) {
ColorMapEntry = &ColorMap->Colors[GifRow[x]];
col.rgb.r = ColorMapEntry->Red;
col.rgb.g = ColorMapEntry->Green;
col.rgb.b = ColorMapEntry->Blue;
i_ppix(im,Col+x,j,&col);
}

}
      }
      else {
for (i = 0; i < Height; i++) {
if (DGifGetLine(GifFile, GifRow, Width) == GIF_ERROR) {
gif_push_error(myGifError(GifFile));
i_push_error(0, "Reading GIF line");
if (colour_table && *colour_table) {
myfree(*colour_table);
*colour_table = NULL;
}
myfree(GifRow);
i_img_destroy(im);
DGifCloseFile(GifFile);
return NULL;
}

for (x = 0; x < Width; x++) {
ColorMapEntry = &ColorMap->Colors[GifRow[x]];
col.rgb.r = ColorMapEntry->Red;
col.rgb.g = ColorMapEntry->Green;
col.rgb.b = ColorMapEntry->Blue;
i_ppix(im, Col+x, Row, &col);
}
Row++;
}
      }
      break;
    case EXTENSION_RECORD_TYPE:
      /* Skip any extension blocks in file: */
      if (DGifGetExtension(GifFile, &ExtCode, &Extension) == GIF_ERROR) {
gif_push_error(myGifError(GifFile));
i_push_error(0, "Reading extension record");
if (colour_table && *colour_table) {
myfree(*colour_table);
*colour_table = NULL;
}
myfree(GifRow);
i_img_destroy(im);
DGifCloseFile(GifFile);
return NULL;
      }
      while (Extension != NULL) {
if (DGifGetExtensionNext(GifFile, &Extension) == GIF_ERROR) {
gif_push_error(myGifError(GifFile));
i_push_error(0, "reading next block of extension");
if (colour_table && *colour_table) {
myfree(*colour_table);
*colour_table = NULL;
}
myfree(GifRow);
i_img_destroy(im);
DGifCloseFile(GifFile);
return NULL;
}
      }
      break;
    case TERMINATE_RECORD_TYPE:
      break;
    default: /* Should be traps by DGifGetRecordType. */
      break;
    }
  } while (RecordType != TERMINATE_RECORD_TYPE);
  
  myfree(GifRow);
  
  if (DGifCloseFile(GifFile) == GIF_ERROR) {
    gif_push_error(myGifError(GifFile));
    i_push_error(0, "Closing GIF file object");
    if (colour_table && *colour_table) {
      myfree(*colour_table);
      *colour_table = NULL;
    }
    i_img_destroy(im);
    return NULL;
  }

  i_tags_set(&im->tags, "i_format", "gif", -1);

  return im;
}

/*

Internal function called by i_readgif_multi_low() in error handling

*/
static void
free_images(i_img **imgs, int count) {
  int i;
  
  if (count) {
    for (i = 0; i < count; ++i)
      i_img_destroy(imgs[i]);
    myfree(imgs);
  }
}

/*
=item i_readgif_multi_low(GifFileType *gf, int *count, int page)

Reads one of more gif images from the given GIF file.

Returns a pointer to an array of i_img *, and puts the count into
*count.

If page is not -1 then the given image _only_ is returned from the
file, where the first image is 0, the second 1 and so on.

Unlike the normal i_readgif*() functions the images are paletted
images rather than a combined RGB image.

This functions sets tags on the images returned:

=over

=item gif_left

the offset of the image from the left of the "screen" ("Image Left
Position")

=item gif_top

the offset of the image from the top of the "screen" ("Image Top Position")

=item gif_interlace

non-zero if the image was interlaced ("Interlace Flag")

=item gif_screen_width

=item gif_screen_height

the size of the logical screen ("Logical Screen Width",
"Logical Screen Height")

=item gif_local_map

Non-zero if this image had a local color map.

=item gif_background

The index in the global colormap of the logical screen's background
color. This is only set if the current image uses the global
colormap.

=item gif_trans_index

The index of the color in the colormap used for transparency. If the
image has a transparency then it is returned as a 4 channel image with
the alpha set to zero in this palette entry. ("Transparent Color Index")

=item gif_delay

The delay until the next frame is displayed, in 1/100 of a second.
("Delay Time").

=item gif_user_input

whether or not a user input is expected before continuing (view dependent)
("User Input Flag").

=item gif_disposal

how the next frame is displayed ("Disposal Method")

=item gif_loop

the number of loops from the Netscape Loop extension. This may be zero.

=item gif_comment

the first block of the first gif comment before each image.

=back

Where applicable, the ("name") is the name of that field from the GIF89
standard.

=cut
*/

i_img **
i_readgif_multi_low(GifFileType *GifFile, int *count, int page) {
  i_img *img;
  int i, j, Size, Width, Height, ExtCode, Count;
  int ImageNum = 0, BackGround = 0, ColorMapSize = 0;
  ColorMapObject *ColorMap;
 
  GifRecordType RecordType;
  GifByteType *Extension;
  
  GifRowType GifRow;
  int got_gce = 0;
  int trans_index = 0; /* transparent index if we see a GCE */
  int gif_delay = 0; /* delay from a GCE */
  int user_input = 0; /* user input flag from a GCE */
  int disposal = 0; /* disposal method from a GCE */
  int got_ns_loop = 0;
  int ns_loop = 0;
  char *comment = NULL; /* a comment */
  i_img **results = NULL;
  int result_alloc = 0;
  int channels;
  int image_colors = 0;
  i_color black; /* used to expand the palette if needed */

  for (i = 0; i < MAXCHANNELS; ++i)
    black.channel[i] = 0;
  
  *count = 0;

  mm_log((1,"i_readgif_multi_low(GifFile %p, , count %p)\n", GifFile, count));

  BackGround = GifFile->SBackGroundColor;

  Size = GifFile->SWidth * sizeof(GifPixelType);
  
  GifRow = (GifRowType) mymalloc(Size);

  /* Scan the content of the GIF file and load the image(s) in: */
  do {
    if (DGifGetRecordType(GifFile, &RecordType) == GIF_ERROR) {
      gif_push_error(myGifError(GifFile));
      i_push_error(0, "Unable to get record type");
      free_images(results, *count);
      DGifCloseFile(GifFile);
      myfree(GifRow);
      if (comment)
myfree(comment);
      return NULL;
    }
    
    switch (RecordType) {
    case IMAGE_DESC_RECORD_TYPE:
      if (DGifGetImageDesc(GifFile) == GIF_ERROR) {
gif_push_error(myGifError(GifFile));
i_push_error(0, "Unable to get image descriptor");
        free_images(results, *count);
DGifCloseFile(GifFile);
myfree(GifRow);
if (comment)
myfree(comment);
return NULL;
      }

      Width = GifFile->Image.Width;
      Height = GifFile->Image.Height;
      if (page == -1 || page == ImageNum) {
if (( ColorMap = (GifFile->Image.ColorMap ? GifFile->Image.ColorMap : GifFile->SColorMap) )) {
mm_log((1, "Adding local colormap\n"));
ColorMapSize = ColorMap->ColorCount;
} else {
/* No colormap and we are about to read in the image -
abandon for now */
mm_log((1, "Going in with no colormap\n"));
i_push_error(0, "Image does not have a local or a global color map");
free_images(results, *count);
DGifCloseFile(GifFile);
myfree(GifRow);
if (comment)
myfree(comment);
return NULL;
}

channels = 3;
if (got_gce && trans_index >= 0)
channels = 4;
if (!i_int_check_image_file_limits(Width, Height, channels, sizeof(i_sample_t))) {
free_images(results, *count);
mm_log((1, "i_readgif: image size exceeds limits\n"));
DGifCloseFile(GifFile);
myfree(GifRow);
if (comment)
myfree(comment);
return NULL;
}
img = i_img_pal_new(Width, Height, channels, 256);
if (!img) {
free_images(results, *count);
DGifCloseFile(GifFile);
if (comment)
myfree(comment);
myfree(GifRow);
return NULL;
}
/* populate the palette of the new image */
mm_log((1, "ColorMapSize %d\n", ColorMapSize));
for (i = 0; i < ColorMapSize; ++i) {
i_color col;
col.rgba.r = ColorMap->Colors[i].Red;
col.rgba.g = ColorMap->Colors[i].Green;
col.rgba.b = ColorMap->Colors[i].Blue;
if (channels == 4 && trans_index == i)
col.rgba.a = 0;
else
col.rgba.a = 255;

i_addcolors(img, &col, 1);
}
image_colors = ColorMapSize;
++*count;
if (*count > result_alloc) {
if (result_alloc == 0) {
result_alloc = 5;
results = mymalloc(result_alloc * sizeof(i_img *));
}
else {
/* myrealloc never fails (it just dies if it can't allocate) */
result_alloc *= 2;
results = myrealloc(results, result_alloc * sizeof(i_img *));
}
}
results[*count-1] = img;
i_tags_set(&img->tags, "i_format", "gif", -1);
i_tags_setn(&img->tags, "gif_left", GifFile->Image.Left);
/**(char *)0 = 1;*/
i_tags_setn(&img->tags, "gif_top", GifFile->Image.Top);
i_tags_setn(&img->tags, "gif_interlace", GifFile->Image.Interlace);
i_tags_setn(&img->tags, "gif_screen_width", GifFile->SWidth);
i_tags_setn(&img->tags, "gif_screen_height", GifFile->SHeight);
i_tags_setn(&img->tags, "gif_colormap_size", ColorMapSize);
if (GifFile->SColorMap && !GifFile->Image.ColorMap) {
i_tags_setn(&img->tags, "gif_background",
GifFile->SBackGroundColor);
}
if (GifFile->Image.ColorMap) {
i_tags_setn(&img->tags, "gif_localmap", 1);
}
if (got_gce) {
if (trans_index >= 0) {
i_color trans;
i_tags_setn(&img->tags, "gif_trans_index", trans_index);
i_getcolors(img, trans_index, &trans, 1);
i_tags_set_color(&img->tags, "gif_trans_color", 0, &trans);
}
i_tags_setn(&img->tags, "gif_delay", gif_delay);
i_tags_setn(&img->tags, "gif_user_input", user_input);
i_tags_setn(&img->tags, "gif_disposal", disposal);
}
got_gce = 0;
if (got_ns_loop)
i_tags_setn(&img->tags, "gif_loop", ns_loop);
if (comment) {
i_tags_set(&img->tags, "gif_comment", comment, strlen(comment));
myfree(comment);
comment = NULL;
}

mm_log((1,"i_readgif_multi_low: Image %d at (%d, %d) [%dx%d]: \n",
ImageNum, GifFile->Image.Left, GifFile->Image.Top, Width, Height));

if (GifFile->Image.Left + GifFile->Image.Width > GifFile->SWidth ||
GifFile->Image.Top + GifFile->Image.Height > GifFile->SHeight) {
i_push_errorf(0, "Image %d is not confined to screen dimension, aborted.\n",ImageNum);
free_images(results, *count);
DGifCloseFile(GifFile);
myfree(GifRow);
if (comment)
myfree(comment);
return(0);
}

if (GifFile->Image.Interlace) {
for (Count = i = 0; i < 4; i++) {
for (j = InterlacedOffset[i]; j < Height;
j += InterlacedJumps[i]) {
Count++;
if (DGifGetLine(GifFile, GifRow, Width) == GIF_ERROR) {
gif_push_error(myGifError(GifFile));
i_push_error(0, "Reading GIF line");
free_images(results, *count);
DGifCloseFile(GifFile);
myfree(GifRow);
if (comment)
myfree(comment);
return NULL;
}

/* range check the scanline if needed */
if (image_colors != 256) {
int x;
for (x = 0; x < Width; ++x) {
while (GifRow[x] >= image_colors) {
/* expand the palette since a palette index is too big */
i_addcolors(img, &black, 1);
++image_colors;
}
}
}

i_ppal(img, 0, Width, j, GifRow);
}
}
}
else {
for (i = 0; i < Height; i++) {
if (DGifGetLine(GifFile, GifRow, Width) == GIF_ERROR) {
gif_push_error(myGifError(GifFile));
i_push_error(0, "Reading GIF line");
free_images(results, *count);
DGifCloseFile(GifFile);
myfree(GifRow);
if (comment)
myfree(comment);
return NULL;
}

/* range check the scanline if needed */
if (image_colors != 256) {
int x;
for (x = 0; x < Width; ++x) {
while (GifRow[x] >= image_colors) {
/* expand the palette since a palette index is too big */
i_addcolors(img, &black, 1);
++image_colors;
}
}
}

i_ppal(img, 0, Width, i, GifRow);
}
}

/* must be only one image wanted and that was it */
if (page != -1) {
myfree(GifRow);
DGifCloseFile(GifFile);
if (comment)
myfree(comment);
return results;
}
      }
      else {
/* skip the image */
/* whether interlaced or not, it has the same number of lines */
/* giflib does't have an interface to skip the image data */
for (i = 0; i < Height; i++) {
if (DGifGetLine(GifFile, GifRow, Width) == GIF_ERROR) {
gif_push_error(myGifError(GifFile));
i_push_error(0, "Reading GIF line");
free_images(results, *count);
myfree(GifRow);
DGifCloseFile(GifFile);
if (comment)
myfree(comment);
return NULL;
}
}

/* kill the comment so we get the right comment for the page */
if (comment) {
myfree(comment);
comment = NULL;
}
      }
      ImageNum++;
      break;
    case EXTENSION_RECORD_TYPE:
      /* Skip any extension blocks in file: */
      if (DGifGetExtension(GifFile, &ExtCode, &Extension) == GIF_ERROR) {
gif_push_error(myGifError(GifFile));
i_push_error(0, "Reading extension record");
        free_images(results, *count);
myfree(GifRow);
DGifCloseFile(GifFile);
if (comment)
myfree(comment);
return NULL;
      }
      /* possibly this should be an error, but "be liberal in what you accept" */
      if (!Extension)
break;
      if (ExtCode == 0xF9) {
        got_gce = 1;
        if (Extension[1] & 1)
          trans_index = Extension[4];
        else
          trans_index = -1;
        gif_delay = Extension[2] + 256 * Extension[3];
        user_input = (Extension[1] & 2) != 0;
        disposal = (Extension[1] >> 2) & 7;
      }
      if (ExtCode == 0xFF && *Extension == 11) {
        if (memcmp(Extension+1, "NETSCAPE2.0", 11) == 0) {
          if (DGifGetExtensionNext(GifFile, &Extension) == GIF_ERROR) {
            gif_push_error(myGifError(GifFile));
            i_push_error(0, "reading loop extension");
            free_images(results, *count);
myfree(GifRow);
DGifCloseFile(GifFile);
if (comment)
myfree(comment);
            return NULL;
          }
          if (Extension && *Extension == 3) {
            got_ns_loop = 1;
            ns_loop = Extension[2] + 256 * Extension[3];
          }
        }
      }
      else if (ExtCode == 0xFE) {
        /* while it's possible for a GIF file to contain more than one
comment, I'm only implementing a single comment per image,
with the comment saved into the following image.
If someone wants more than that they can implement it.
I also don't handle comments that take more than one block.
*/
        if (!comment) {
          comment = mymalloc(*Extension+1);
          memcpy(comment, Extension+1, *Extension);
          comment[*Extension] = '\0';
        }
      }
      while (Extension != NULL) {
if (DGifGetExtensionNext(GifFile, &Extension) == GIF_ERROR) {
gif_push_error(myGifError(GifFile));
i_push_error(0, "reading next block of extension");
          free_images(results, *count);
myfree(GifRow);
DGifCloseFile(GifFile);
if (comment)
myfree(comment);
return NULL;
}
      }
      break;
    case TERMINATE_RECORD_TYPE:
      break;
    default: /* Should be trapped by DGifGetRecordType. */
      break;
    }
  } while (RecordType != TERMINATE_RECORD_TYPE);

  if (comment) {
    if (*count) {
      i_tags_set(&(results[*count-1]->tags), "gif_comment", comment,
                 strlen(comment));
    }
    myfree(comment);
  }
  
  myfree(GifRow);
  
  if (DGifCloseFile(GifFile) == GIF_ERROR) {
    gif_push_error(myGifError(GifFile));
    i_push_error(0, "Closing GIF file object");
    free_images(results, *count);
    return NULL;
  }

  if (ImageNum && page != -1) {
    /* there were images, but the page selected wasn't found */
    i_push_errorf(0, "page %d not found (%d total)", page, ImageNum);
    free_images(results, *count);
    return NULL;
  }

  return results;
}

static int io_glue_read_cb(GifFileType *gft, GifByteType *buf, int length);

/*
=item i_readgif_multi_wiol(ig, int *count)

=cut
*/

i_img **
i_readgif_multi_wiol(io_glue *ig, int *count) {
  GifFileType *GifFile;
  int gif_error;

  i_clear_error();
  
  if ((GifFile = myDGifOpen((void *)ig, io_glue_read_cb, &gif_error )) == NULL) {
    gif_push_error(gif_error);
    i_push_error(0, "Cannot create giflib callback object");
    mm_log((1,"i_readgif_multi_wiol: Unable to open callback datasource.\n"));
    return NULL;
  }
    
  return i_readgif_multi_low(GifFile, count, -1);
}

static int
io_glue_read_cb(GifFileType *gft, GifByteType *buf, int length) {
  io_glue *ig = (io_glue *)gft->UserData;

  return i_io_read(ig, buf, length);
}

i_img *
i_readgif_wiol(io_glue *ig, int **color_table, int *colors) {
  GifFileType *GifFile;
  int gif_error;

  i_clear_error();

  if ((GifFile = myDGifOpen((void *)ig, io_glue_read_cb, &gif_error )) == NULL) {
    gif_push_error(gif_error);
    i_push_error(0, "Cannot create giflib callback object");
    mm_log((1,"i_readgif_wiol: Unable to open callback datasource.\n"));
    return NULL;
  }
    
  return i_readgif_low(GifFile, color_table, colors);
}

/*
=item i_readgif_single_low(GifFile, page)

Lower level function to read a single image from a GIF.

page must be non-negative.

=cut
*/
static i_img *
i_readgif_single_low(GifFileType *GifFile, int page) {
  int count = 0;
  i_img **imgs;

  imgs = i_readgif_multi_low(GifFile, &count, page);

  if (imgs && count) {
    i_img *result = imgs[0];

    myfree(imgs);
    return result;
  }
  else {
    /* i_readgif_multi_low() handles the errors appropriately */
    return NULL;
  }
}

/*
=item i_readgif_single_wiol(ig, page)

Read a single page from a GIF image file, where the page is indexed
from 0.

Returns NULL if the page isn't found.

=cut
*/

i_img *
i_readgif_single_wiol(io_glue *ig, int page) {
  GifFileType *GifFile;
  int gif_error;

  i_clear_error();
  if (page < 0) {
    i_push_error(0, "page must be non-negative");
    return NULL;
  }


  if ((GifFile = myDGifOpen((void *)ig, io_glue_read_cb, &gif_error )) == NULL) {
    gif_push_error(gif_error);
    i_push_error(0, "Cannot create giflib callback object");
    mm_log((1,"i_readgif_wiol: Unable to open callback datasource.\n"));
    return NULL;
  }
    
  return i_readgif_single_low(GifFile, page);
}

/*
=item do_write(GifFileType *gf, i_gif_opts *opts, i_img *img, i_palidx *data)

Internal. Low level image write function. Writes in interlace if
that was requested in the GIF options.

Returns non-zero on success.

=cut
*/
static undef_int
do_write(GifFileType *gf, int interlace, i_img *img, i_palidx *data) {
  if (interlace) {
    int i, j;
    for (i = 0; i < 4; ++i) {
      for (j = InterlacedOffset[i]; j < img->ysize; j += InterlacedJumps[i]) {
if (EGifPutLine(gf, data+j*img->xsize, img->xsize) == GIF_ERROR) {
gif_push_error(myGifError(gf));
i_push_error(0, "Could not save image data:");
mm_log((1, "Error in EGifPutLine\n"));
EGifCloseFile(gf);
return 0;
}
      }
    }
  }
  else {
    int y;
    for (y = 0; y < img->ysize; ++y) {
      if (EGifPutLine(gf, data, img->xsize) == GIF_ERROR) {
gif_push_error(myGifError(gf));
i_push_error(0, "Could not save image data:");
mm_log((1, "Error in EGifPutLine\n"));
EGifCloseFile(gf);
return 0;
      }
      data += img->xsize;
    }
  }

  return 1;
}

/*
=item do_gce(GifFileType *gf, int index, i_gif_opts *opts, int want_trans, int trans_index)

Internal. Writes the GIF graphics control extension, if necessary.

Returns non-zero on success.

=cut
*/

static int
do_gce(GifFileType *gf, i_img *img, int want_trans, int trans_index)
{
  unsigned char gce[4] = {0};
  int want_gce = 0;
  int delay;
  int user_input;
  int disposal_method;

  if (want_trans) {
    gce[0] |= 1;
    gce[3] = trans_index;
    ++want_gce;
  }
  if (i_tags_get_int(&img->tags, "gif_delay", 0, &delay)) {
    gce[1] = delay % 256;
    gce[2] = delay / 256;
    ++want_gce;
  }
  if (i_tags_get_int(&img->tags, "gif_user_input", 0, &user_input)
      && user_input) {
    gce[0] |= 2;
    ++want_gce;
  }
  if (i_tags_get_int(&img->tags, "gif_disposal", 0, &disposal_method)) {
    gce[0] |= (disposal_method & 3) << 2;
    ++want_gce;
  }
  if (want_gce) {
    if (EGifPutExtension(gf, 0xF9, sizeof(gce), gce) == GIF_ERROR) {
      gif_push_error(myGifError(gf));
      i_push_error(0, "Could not save GCE");
    }
  }
  return 1;
}

/*
=item do_comments(gf, img)

Write any comments in the image.

=cut
*/

static int
do_comments(GifFileType *gf, i_img *img) {
  int pos = -1;

  while (i_tags_find(&img->tags, "gif_comment", pos+1, &pos)) {
    if (img->tags.tags[pos].data) {
      if (EGifPutComment(gf, img->tags.tags[pos].data) == GIF_ERROR) {
        return 0;
      }
    }
    else {
      char buf[50];
#ifdef IMAGER_SNPRINTF
      snprintf(buf, sizeof(buf), "%d", img->tags.tags[pos].idata);
#else
      sprintf(buf, "%d", img->tags.tags[pos].idata);
#endif
      if (EGifPutComment(gf, buf) == GIF_ERROR) {
        return 0;
      }
    }
  }

  return 1;
}

/*
=item do_ns_loop(GifFileType *gf, i_gif_opts *opts)

Internal. Add the Netscape2.0 loop extension block, if requested.

Giflib/libungif prior to 4.1.1 didn't support writing application
extension blocks, so we don't attempt to write them for older versions.

Giflib/libungif prior to 4.1.3 used the wrong write mechanism when
writing extension blocks so that they could only be written to files.

=cut
*/

static int
do_ns_loop(GifFileType *gf, i_img *img)
{
  /* EGifPutExtension() doesn't appear to handle application
extension blocks in any way
Since giflib wraps the fd with a FILE * (and puts that in its
private data), we can't do an end-run and write the data
directly to the fd.
There's no open interface that takes a FILE * either, so we
can't workaround it that way either.
If giflib's callback interface wasn't broken by default, I'd
force file writes to use callbacks, but it is broken by default.
*/
  /* yes this was another attempt at supporting the loop extension */
  int loop_count;
  if (i_tags_get_int(&img->tags, "gif_loop", 0, &loop_count)) {
    unsigned char nsle[12] = "NETSCAPE2.0";
    unsigned char subblock[3];

    subblock[0] = 1;
    subblock[1] = loop_count % 256;
    subblock[2] = loop_count / 256;

#if defined(GIFLIB_MAJOR) && GIFLIB_MAJOR >= 5
    if (EGifPutExtensionLeader(gf, APPLICATION_EXT_FUNC_CODE) == GIF_ERROR
|| EGifPutExtensionBlock(gf, 11, nsle) == GIF_ERROR
|| EGifPutExtensionBlock(gf, 3, subblock) == GIF_ERROR
|| EGifPutExtensionTrailer(gf) == GIF_ERROR) {
      gif_push_error(myGifError(gf));
      i_push_error(0, "writing loop extension");
      return 0;
    }
#else
    if (EGifPutExtensionFirst(gf, APPLICATION_EXT_FUNC_CODE, 11, nsle) == GIF_ERROR) {
      gif_push_error(myGifError(gf));
      i_push_error(0, "writing loop extension");
      return 0;
    }
    if (EGifPutExtensionLast(gf, APPLICATION_EXT_FUNC_CODE, 3, subblock) == GIF_ERROR) {
      gif_push_error(myGifError(gf));
      i_push_error(0, "writing loop extension sub-block");
      return 0;
    }
#endif
  }

  return 1;
}

/*
=item make_gif_map(i_quantize *quant, int want_trans)

Create a giflib color map object from an Imager color map.

=cut
*/

static ColorMapObject *
make_gif_map(i_quantize *quant, i_img *img, int want_trans) {
  GifColorType colors[256];
  int i;
  int size = quant->mc_count;
  int map_size;
  ColorMapObject *map;
  i_color trans;

  for (i = 0; i < quant->mc_count; ++i) {
    colors[i].Red = quant->mc_colors[i].rgb.r;
    colors[i].Green = quant->mc_colors[i].rgb.g;
    colors[i].Blue = quant->mc_colors[i].rgb.b;
  }
  if (want_trans) {
    if (!i_tags_get_color(&img->tags, "gif_trans_color", 0, &trans))
      trans.rgb.r = trans.rgb.g = trans.rgb.b = 0;
    colors[size].Red = trans.rgb.r;
    colors[size].Green = trans.rgb.g;
    colors[size].Blue = trans.rgb.b;
    ++size;
  }
  map_size = 1;
  while (map_size < size)
    map_size <<= 1;
  /* giflib spews for 1 colour maps, reasonable, I suppose */
  if (map_size == 1)
    map_size = 2;
  while (i < map_size) {
    colors[i].Red = colors[i].Green = colors[i].Blue = 0;
    ++i;
  }
  
  map = MakeMapObject(map_size, colors);
  mm_log((1, "XXX map is at %p and colors at %p\n", map, map->Colors));
  if (!map) {
    i_push_error(0, "Could not create color map object");
    return NULL;
  }
  return map;
}

/*
=item gif_set_version(i_quantize *quant, i_img *imgs, int count)

We need to call EGifSetGifVersion() before opening the file - put that
common code here.

Unfortunately giflib 4.1.0 crashes when we use this. Internally
giflib 4.1.0 has code:

static char *GifVersionPrefix = GIF87_STAMP;

and the code that sets the version internally does:

strncpy(&GifVersionPrefix[3], Version, 3);

which is very broken.

Failing to set the correct GIF version doesn't seem to cause a problem
with readers.

Modern versions (4.1.4 anyway) of giflib/libungif handle
EGifSetGifVersion correctly.

If t/t105gif.t crashes here then run Makefile.PL with
--nogifsetversion, eg.:

perl Makefile.PL --nogifsetversion

or install a less buggy giflib.

This code is completely unnecessary in giflib 5

=cut
*/

static void
gif_set_version(i_quantize *quant, i_img **imgs, int count) {
#if !defined(GIFLIB_MAJOR) || GIFLIB_MAJOR < 5
  int need_89a = 0;
  int temp;
  int i;

  if (quant->transp != tr_none)
    need_89a = 1;
  else {
    for (i = 0; i < count; ++i) {
      if (i_tags_get_int(&imgs[i]->tags, "gif_delay", 0, &temp)) {
        need_89a = 1;
        break;
      }
      if (i_tags_get_int(&imgs[i]->tags, "gif_user_input", 0, &temp) && temp) {
        need_89a = 1;
        break;
      }
      if (i_tags_get_int(&imgs[i]->tags, "gif_disposal", 0, &temp)) {
        need_89a = 1;
        break;
      }
      if (i_tags_get_int(&imgs[i]->tags, "gif_loop", 0, &temp)) {
        need_89a = 1;
        break;
      }
    }
  }
  if (need_89a)
     EGifSetGifVersion("89a");
  else
     EGifSetGifVersion("87a");
#endif
}

static int
in_palette(i_color *c, i_quantize *quant, int size) {
  int i;

  for (i = 0; i < size; ++i) {
    if (c->channel[0] == quant->mc_colors[i].channel[0]
        && c->channel[1] == quant->mc_colors[i].channel[1]
        && c->channel[2] == quant->mc_colors[i].channel[2]) {
      return i;
    }
  }

  return -1;
}

/*
=item has_common_palette(imgs, count, quant)

Tests if all the given images are paletted and their colors are in the
palette produced.

Previously this would build a consolidated palette from the source,
but that meant that if the caller supplied a static palette (or
specified a fixed palette like "webmap") then we wouldn't be
quantizing to the caller specified palette.

=cut
*/

static int
has_common_palette(i_img **imgs, int count, i_quantize *quant) {
  int i;
  int imgn;
  char used[256];
  int col_count;

  /* we try to build a common palette here, if we can manage that, then
that's the palette we use */
  for (imgn = 0; imgn < count; ++imgn) {
    int eliminate_unused;
    if (imgs[imgn]->type != i_palette_type)
      return 0;

    if (!i_tags_get_int(&imgs[imgn]->tags, "gif_eliminate_unused", 0,
                        &eliminate_unused)) {
      eliminate_unused = 1;
    }

    if (eliminate_unused) {
      i_palidx *line = mymalloc(sizeof(i_palidx) * imgs[imgn]->xsize);
      int x, y;
      memset(used, 0, sizeof(used));

      for (y = 0; y < imgs[imgn]->ysize; ++y) {
        i_gpal(imgs[imgn], 0, imgs[imgn]->xsize, y, line);
        for (x = 0; x < imgs[imgn]->xsize; ++x)
          used[line[x]] = 1;
      }

      myfree(line);
    }
    else {
      /* assume all are in use */
      memset(used, 1, sizeof(used));
    }

    col_count = i_colorcount(imgs[imgn]);
    for (i = 0; i < col_count; ++i) {
      i_color c;
      
      i_getcolors(imgs[imgn], i, &c, 1);
      if (used[i]) {
        if (in_palette(&c, quant, quant->mc_count) < 0) {
mm_log((1, " color not found in palette, no palette shortcut\n"));
  
return 0;
        }
      }
    }
  }

  mm_log((1, " all colors found in palette, palette shortcut\n"));

  return 1;
}

static i_palidx *
quant_paletted(i_quantize *quant, i_img *img) {
  i_palidx *data = mymalloc(sizeof(i_palidx) * img->xsize * img->ysize);
  i_palidx *p = data;
  i_palidx trans[256];
  int i;
  i_img_dim x, y;

  /* build a translation table */
  for (i = 0; i < i_colorcount(img); ++i) {
    i_color c;
    i_getcolors(img, i, &c, 1);
    trans[i] = in_palette(&c, quant, quant->mc_count);
  }

  for (y = 0; y < img->ysize; ++y) {
    i_gpal(img, 0, img->xsize, y, data+img->xsize * y);
    for (x = 0; x < img->xsize; ++x) {
      *p = trans[*p];
      ++p;
    }
  }

  return data;
}

/*
=item i_writegif_low(i_quantize *quant, GifFileType *gf, i_img **imgs, int count, i_gif_opts *opts)

Internal. Low-level function that does the high-level GIF processing
:)

Returns non-zero on success.

=cut
*/

static undef_int
i_writegif_low(i_quantize *quant, GifFileType *gf, i_img **imgs, int count) {
  unsigned char *result = NULL;
  int color_bits;
  ColorMapObject *map;
  int scrw = 0, scrh = 0;
  int imgn, orig_count, orig_size;
  int posx, posy;
  int trans_index = -1;
  int *localmaps;
  int anylocal;
  i_img **glob_imgs; /* images that will use the global color map */
  int glob_img_count;
  i_color *orig_colors = quant->mc_colors;
  i_color *glob_colors = NULL;
  int glob_color_count = 0;
  int glob_want_trans;
  int glob_paletted = 0; /* the global map was made from the image palettes */
  int colors_paletted = 0;
  int want_trans = 0;
  int interlace;
  int gif_background;

  mm_log((1, "i_writegif_low(quant %p, gf %p, imgs %p, count %d)\n",
quant, gf, imgs, count));
  
  /* *((char *)0) = 1; */ /* used to break into the debugger */
  
  if (count <= 0) {
    i_push_error(0, "No images provided to write");
    return 0; /* what are you smoking? */
  }

  /* sanity is nice */
  if (quant->mc_size > 256)
    quant->mc_size = 256;
  if (quant->mc_count > quant->mc_size)
    quant->mc_count = quant->mc_size;

  if (!i_tags_get_int(&imgs[0]->tags, "gif_screen_width", 0, &scrw))
    scrw = 0;
  if (!i_tags_get_int(&imgs[0]->tags, "gif_screen_height", 0, &scrh))
    scrh = 0;

  anylocal = 0;
  localmaps = mymalloc(sizeof(int) * count);
  glob_imgs = mymalloc(sizeof(i_img *) * count);
  glob_img_count = 0;
  glob_want_trans = 0;
  for (imgn = 0; imgn < count; ++imgn) {
    i_img *im = imgs[imgn];
    if (im->xsize > 0xFFFF || im->ysize > 0xFFFF) {
      i_push_error(0, "image too large for GIF");
      return 0;
    }
    
    posx = posy = 0;
    i_tags_get_int(&im->tags, "gif_left", 0, &posx);
    if (posx < 0) posx = 0;
    i_tags_get_int(&im->tags, "gif_top", 0, &posy);
    if (posy < 0) posy = 0;
    if (im->xsize + posx > scrw)
      scrw = im->xsize + posx;
    if (im->ysize + posy > scrh)
      scrh = im->ysize + posy;
    if (!i_tags_get_int(&im->tags, "gif_local_map", 0, localmaps+imgn))
      localmaps[imgn] = 0;
    if (localmaps[imgn])
      anylocal = 1;
    else {
      if (im->channels == 4) {
        glob_want_trans = 1;
      }
      glob_imgs[glob_img_count++] = im;
    }
  }
  glob_want_trans = glob_want_trans && quant->transp != tr_none ;

  if (scrw > 0xFFFF || scrh > 0xFFFF) {
    i_push_error(0, "screen size too large for GIF");
    return 0;
  }

  orig_count = quant->mc_count;
  orig_size = quant->mc_size;

  if (glob_img_count) {
    /* this is ugly */
    glob_colors = mymalloc(sizeof(i_color) * quant->mc_size);
    quant->mc_colors = glob_colors;
    memcpy(glob_colors, orig_colors, sizeof(i_color) * quant->mc_count);
    /* we have some images that want to use the global map */
    if (glob_want_trans && quant->mc_count == 256) {
      mm_log((2, " disabling transparency for global map - no space\n"));
      glob_want_trans = 0;
    }
    if (glob_want_trans && quant->mc_size == 256) {
      mm_log((2, " reserving color for transparency\n"));
      --quant->mc_size;
    }

    i_quant_makemap(quant, glob_imgs, glob_img_count);
    glob_paletted = has_common_palette(glob_imgs, glob_img_count, quant);
    glob_color_count = quant->mc_count;
    quant->mc_colors = orig_colors;
  }

  /* use the global map if we have one, otherwise use the local map */
  gif_background = 0;
  if (glob_colors) {
    quant->mc_colors = glob_colors;
    quant->mc_count = glob_color_count;
    want_trans = glob_want_trans && imgs[0]->channels == 4;

    if (!i_tags_get_int(&imgs[0]->tags, "gif_background", 0, &gif_background))
      gif_background = 0;
    if (gif_background < 0)
      gif_background = 0;
    if (gif_background >= glob_color_count)
      gif_background = 0;
  }
  else {
    want_trans = quant->transp != tr_none && imgs[0]->channels == 4;
    i_quant_makemap(quant, imgs, 1);
    colors_paletted = has_common_palette(imgs, 1, quant);
  }

  if ((map = make_gif_map(quant, imgs[0], want_trans)) == NULL) {
    myfree(glob_colors);
    myfree(localmaps);
    myfree(glob_imgs);
    quant->mc_colors = orig_colors;
    EGifCloseFile(gf);
    mm_log((1, "Error in MakeMapObject"));
    return 0;
  }
  color_bits = 1;
  if (anylocal) {
    /* since we don't know how big some the local palettes could be
we need to base the bits on the maximum number of colors */
    while (orig_size > (1 << color_bits))
      ++color_bits;
  }
  else {
    int count = quant->mc_count;
    if (want_trans)
      ++count;
    while (count > (1 << color_bits))
      ++color_bits;
  }
  
  if (EGifPutScreenDesc(gf, scrw, scrh, color_bits,
                        gif_background, map) == GIF_ERROR) {
    myfree(glob_colors);
    myfree(localmaps);
    myfree(glob_imgs);
    quant->mc_colors = orig_colors;
    gif_push_error(myGifError(gf));
    i_push_error(0, "Could not save screen descriptor");
    FreeMapObject(map);
    myfree(result);
    EGifCloseFile(gf);
    mm_log((1, "Error in EGifPutScreenDesc."));
    return 0;
  }
  FreeMapObject(map);

  if (!i_tags_get_int(&imgs[0]->tags, "gif_left", 0, &posx))
    posx = 0;
  if (!i_tags_get_int(&imgs[0]->tags, "gif_top", 0, &posy))
    posy = 0;

  if (!localmaps[0]) {
    map = NULL;
    colors_paletted = glob_paletted;
  }
  else {
    /* if this image has a global map the colors in quant don't
belong to this image, so build a palette */
    if (glob_colors) {
      /* generate the local map for this image */
      quant->mc_colors = orig_colors;
      quant->mc_size = orig_size;
      quant->mc_count = orig_count;
      want_trans = quant->transp != tr_none && imgs[0]->channels == 4;

      /* if the caller gives us too many colours we can't do transparency */
      if (want_trans && quant->mc_count == 256)
        want_trans = 0;
      /* if they want transparency but give us a big size, make it smaller
to give room for a transparency colour */
      if (want_trans && quant->mc_size == 256)
        --quant->mc_size;
      i_quant_makemap(quant, imgs, 1);
      colors_paletted = has_common_palette(imgs, 1, quant);
      if ((map = make_gif_map(quant, imgs[0], want_trans)) == NULL) {
myfree(glob_colors);
myfree(localmaps);
myfree(glob_imgs);
        EGifCloseFile(gf);
        quant->mc_colors = orig_colors;
        mm_log((1, "Error in MakeMapObject"));
        return 0;
      }
    }
    else {
      /* the map we wrote was the map for this image - don't set the local
map */
      map = NULL;
    }
  }

  if (colors_paletted)
    result = quant_paletted(quant, imgs[0]);
  else
    result = i_quant_translate(quant, imgs[0]);
  if (!result) {
    myfree(glob_colors);
    myfree(localmaps);
    myfree(glob_imgs);
    quant->mc_colors = orig_colors;
    EGifCloseFile(gf);
    return 0;
  }
  if (want_trans) {
    i_quant_transparent(quant, result, imgs[0], quant->mc_count);
    trans_index = quant->mc_count;
  }

  if (!do_ns_loop(gf, imgs[0])) {
    myfree(glob_colors);
    myfree(localmaps);
    myfree(glob_imgs);
    quant->mc_colors = orig_colors;
    return 0;
  }

  if (!do_gce(gf, imgs[0], want_trans, trans_index)) {
    myfree(glob_colors);
    myfree(localmaps);
    myfree(glob_imgs);
    quant->mc_colors = orig_colors;
    myfree(result);
    EGifCloseFile(gf);
    return 0;
  }

  if (!do_comments(gf, imgs[0])) {
    myfree(glob_colors);
    myfree(localmaps);
    myfree(glob_imgs);
    quant->mc_colors = orig_colors;
    myfree(result);
    EGifCloseFile(gf);
    return 0;
  }

  if (!i_tags_get_int(&imgs[0]->tags, "gif_interlace", 0, &interlace))
    interlace = 0;
  if (EGifPutImageDesc(gf, posx, posy, imgs[0]->xsize, imgs[0]->ysize,
                       interlace, map) == GIF_ERROR) {
    myfree(glob_colors);
    myfree(localmaps);
    myfree(glob_imgs);
    quant->mc_colors = orig_colors;
    gif_push_error(myGifError(gf));
    i_push_error(0, "Could not save image descriptor");
    EGifCloseFile(gf);
    mm_log((1, "Error in EGifPutImageDesc."));
    return 0;
  }
  if (map)
    FreeMapObject(map);

  if (!do_write(gf, interlace, imgs[0], result)) {
    myfree(glob_colors);
    myfree(localmaps);
    myfree(glob_imgs);
    quant->mc_colors = orig_colors;
    EGifCloseFile(gf);
    myfree(result);
    return 0;
  }
  myfree(result);

  /* that first awful image is out of the way, do the rest */
  for (imgn = 1; imgn < count; ++imgn) {
    if (localmaps[imgn]) {
      quant->mc_colors = orig_colors;
      quant->mc_count = orig_count;
      quant->mc_size = orig_size;

      want_trans = quant->transp != tr_none
&& imgs[imgn]->channels == 4;
      /* if the caller gives us too many colours we can't do transparency */
      if (want_trans && quant->mc_count == 256)
want_trans = 0;
      /* if they want transparency but give us a big size, make it smaller
to give room for a transparency colour */
      if (want_trans && quant->mc_size == 256)
--quant->mc_size;

      if (has_common_palette(imgs+imgn, 1, quant)) {
        result = quant_paletted(quant, imgs[imgn]);
      }
      else {
        i_quant_makemap(quant, imgs+imgn, 1);
        result = i_quant_translate(quant, imgs[imgn]);
      }
      if (!result) {
myfree(glob_colors);
myfree(localmaps);
myfree(glob_imgs);
        quant->mc_colors = orig_colors;
        EGifCloseFile(gf);
        mm_log((1, "error in i_quant_translate()"));
        return 0;
      }
      if (want_trans) {
        i_quant_transparent(quant, result, imgs[imgn], quant->mc_count);
        trans_index = quant->mc_count;
      }

      if ((map = make_gif_map(quant, imgs[imgn], want_trans)) == NULL) {
myfree(glob_colors);
myfree(localmaps);
myfree(glob_imgs);
        quant->mc_colors = orig_colors;
        myfree(result);
        EGifCloseFile(gf);
        mm_log((1, "Error in MakeMapObject."));
        return 0;
      }
    }
    else {
      quant->mc_colors = glob_colors;
      quant->mc_count = glob_color_count;
      if (glob_paletted)
        result = quant_paletted(quant, imgs[imgn]);
      else
        result = i_quant_translate(quant, imgs[imgn]);
      want_trans = glob_want_trans && imgs[imgn]->channels == 4;
      if (want_trans) {
        i_quant_transparent(quant, result, imgs[imgn], quant->mc_count);
        trans_index = quant->mc_count;
      }
      map = NULL;
    }

    if (!do_gce(gf, imgs[imgn], want_trans, trans_index)) {
      myfree(glob_colors);
      myfree(localmaps);
      myfree(glob_imgs);
      quant->mc_colors = orig_colors;
      myfree(result);
      EGifCloseFile(gf);
      return 0;
    }

    if (!do_comments(gf, imgs[imgn])) {
      myfree(glob_colors);
      myfree(localmaps);
      myfree(glob_imgs);
      quant->mc_colors = orig_colors;
      myfree(result);
      EGifCloseFile(gf);
      return 0;
    }

    if (!i_tags_get_int(&imgs[imgn]->tags, "gif_left", 0, &posx))
      posx = 0;
    if (!i_tags_get_int(&imgs[imgn]->tags, "gif_top", 0, &posy))
      posy = 0;

    if (!i_tags_get_int(&imgs[imgn]->tags, "gif_interlace", 0, &interlace))
      interlace = 0;
    if (EGifPutImageDesc(gf, posx, posy, imgs[imgn]->xsize,
                         imgs[imgn]->ysize, interlace, map) == GIF_ERROR) {
      myfree(glob_colors);
      myfree(localmaps);
      myfree(glob_imgs);
      quant->mc_colors = orig_colors;
      gif_push_error(myGifError(gf));
      i_push_error(0, "Could not save image descriptor");
      myfree(result);
      if (map)
        FreeMapObject(map);
      EGifCloseFile(gf);
      mm_log((1, "Error in EGifPutImageDesc."));
      return 0;
    }
    if (map)
      FreeMapObject(map);
    
    if (!do_write(gf, interlace, imgs[imgn], result)) {
      myfree(glob_colors);
      myfree(localmaps);
      myfree(glob_imgs);
      quant->mc_colors = orig_colors;
      EGifCloseFile(gf);
      myfree(result);
      return 0;
    }
    myfree(result);
  }

  if (EGifCloseFile(gf) == GIF_ERROR) {
    myfree(glob_colors);
    myfree(localmaps);
    myfree(glob_imgs);
    gif_push_error(myGifError(gf));
    i_push_error(0, "Could not close GIF file");
    mm_log((1, "Error in EGifCloseFile\n"));
    return 0;
  }
  if (glob_colors) {
    int i;
    for (i = 0; i < glob_color_count; ++i)
      orig_colors[i] = glob_colors[i];
  }

  myfree(glob_colors);
  myfree(localmaps);
  myfree(glob_imgs);
  quant->mc_colors = orig_colors;

  return 1;
}

static int
io_glue_write_cb(GifFileType *gft, const GifByteType *data, int length) {
  io_glue *ig = (io_glue *)gft->UserData;

  return i_io_write(ig, data, length);
}


/*
=item i_writegif_wiol(ig, quant, opts, imgs, count)

=cut
*/
undef_int
i_writegif_wiol(io_glue *ig, i_quantize *quant, i_img **imgs,
                int count) {
  GifFileType *GifFile;
  int gif_error;
  int result;

  i_clear_error();

  gif_set_version(quant, imgs, count);
  
  if ((GifFile = myEGifOpen((void *)ig, io_glue_write_cb, &gif_error )) == NULL) {
    gif_push_error(gif_error);
    i_push_error(0, "Cannot create giflib callback object");
    mm_log((1,"i_writegif_wiol: Unable to open callback datasource.\n"));
    return 0;
  }
  
  result = i_writegif_low(quant, GifFile, imgs, count);
  
  if (i_io_close(ig))
    return 0;
  
  return result;
}

/*
=item gif_error_msg(int code)

Grabs the most recent giflib error code from GifLastError() and
returns a string that describes that error.

Returns NULL for unknown error codes.

=cut
*/

static char const *
gif_error_msg(int code) {
#if defined(GIFLIB_MAJOR) && GIFLIB_MAJOR >= 5
  return GifErrorString(code);
#else
  switch (code) {
  case E_GIF_ERR_OPEN_FAILED: /* should not see this */
    return "Failed to open given file";
    
  case E_GIF_ERR_WRITE_FAILED:
    return "Write failed";

  case E_GIF_ERR_HAS_SCRN_DSCR: /* should not see this */
    return "Screen descriptor already passed to giflib";

  case E_GIF_ERR_HAS_IMAG_DSCR: /* should not see this */
    return "Image descriptor already passed to giflib";
    
  case E_GIF_ERR_NO_COLOR_MAP: /* should not see this */
    return "Neither global nor local color map set";

  case E_GIF_ERR_DATA_TOO_BIG: /* should not see this */
    return "Too much pixel data passed to giflib";

  case E_GIF_ERR_NOT_ENOUGH_MEM:
    return "Out of memory";
    
  case E_GIF_ERR_DISK_IS_FULL:
    return "Disk is full";
    
  case E_GIF_ERR_CLOSE_FAILED: /* should not see this */
    return "File close failed";
 
  case E_GIF_ERR_NOT_WRITEABLE: /* should not see this */
    return "File not writable";

  case D_GIF_ERR_OPEN_FAILED:
    return "Failed to open file";
    
  case D_GIF_ERR_READ_FAILED:
    return "Failed to read from file";

  case D_GIF_ERR_NOT_GIF_FILE:
    return "File is not a GIF file";

  case D_GIF_ERR_NO_SCRN_DSCR:
    return "No screen descriptor detected - invalid file";

  case D_GIF_ERR_NO_IMAG_DSCR:
    return "No image descriptor detected - invalid file";

  case D_GIF_ERR_NO_COLOR_MAP:
    return "No global or local color map found";

  case D_GIF_ERR_WRONG_RECORD:
    return "Wrong record type detected - invalid file?";

  case D_GIF_ERR_DATA_TOO_BIG:
    return "Data in file too big for image";

  case D_GIF_ERR_NOT_ENOUGH_MEM:
    return "Out of memory";

  case D_GIF_ERR_CLOSE_FAILED:
    return "Close failed";

  case D_GIF_ERR_NOT_READABLE:
    return "File not opened for read";

  case D_GIF_ERR_IMAGE_DEFECT:
    return "Defective image";

  case D_GIF_ERR_EOF_TOO_SOON:
    return "Unexpected EOF - invalid file";

  default:
    return NULL;
  }
#endif
}

/*
=item gif_push_error(code)

Utility function that takes the current GIF error code, converts it to
an error message and pushes it on the error stack.

=cut
*/

static void
gif_push_error(int code) {
  const char *msg = gif_error_msg(code);
  if (msg)
    i_push_error(code, msg);
  else
    i_push_errorf(code, "Unknown GIF error %d", code);
}

/*
=head1 AUTHOR

Arnar M. Hrafnkelsson, addi@umich.edu

=head1 SEE ALSO

perl(1), Imager(3)

=cut

*/
Something went wrong with that request. Please try again.