reactos/dll/3rdparty/libpng/pngtrans.c

   1
   2 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
   3  *
   4  * Last changed in libpng 1.6.18 [July 23, 2015]
   5  * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
   6  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   7  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   8  *
   9  * This code is released under the libpng license.
  10  * For conditions of distribution and use, see the disclaimer
  11  * and license in png.h
  12  */
  13
  14 #include "pngpriv.h"
  15
  16 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
  17
  18 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
  19 /* Turn on BGR-to-RGB mapping */
  20 void PNGAPI
  21 png_set_bgr(png_structrp png_ptr)
  22 {
  23    png_debug(1, "in png_set_bgr");
  24
  25    if (png_ptr == NULL)
  26       return;
  27
  28    png_ptr->transformations |= PNG_BGR;
  29 }
  30 #endif
  31
  32 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
  33 /* Turn on 16-bit byte swapping */
  34 void PNGAPI
  35 png_set_swap(png_structrp png_ptr)
  36 {
  37    png_debug(1, "in png_set_swap");
  38
  39    if (png_ptr == NULL)
  40       return;
  41
  42    if (png_ptr->bit_depth == 16)
  43       png_ptr->transformations |= PNG_SWAP_BYTES;
  44 }
  45 #endif
  46
  47 #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
  48 /* Turn on pixel packing */
  49 void PNGAPI
  50 png_set_packing(png_structrp png_ptr)
  51 {
  52    png_debug(1, "in png_set_packing");
  53
  54    if (png_ptr == NULL)
  55       return;
  56
  57    if (png_ptr->bit_depth < 8)
  58    {
  59       png_ptr->transformations |= PNG_PACK;
  60 #     ifdef PNG_WRITE_SUPPORTED
  61          png_ptr->usr_bit_depth = 8;
  62 #     endif
  63    }
  64 }
  65 #endif
  66
  67 #if defined(PNG_READ_PACKSWAP_SUPPORTED)||defined(PNG_WRITE_PACKSWAP_SUPPORTED)
  68 /* Turn on packed pixel swapping */
  69 void PNGAPI
  70 png_set_packswap(png_structrp png_ptr)
  71 {
  72    png_debug(1, "in png_set_packswap");
  73
  74    if (png_ptr == NULL)
  75       return;
  76
  77    if (png_ptr->bit_depth < 8)
  78       png_ptr->transformations |= PNG_PACKSWAP;
  79 }
  80 #endif
  81
  82 #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
  83 void PNGAPI
  84 png_set_shift(png_structrp png_ptr, png_const_color_8p true_bits)
  85 {
  86    png_debug(1, "in png_set_shift");
  87
  88    if (png_ptr == NULL)
  89       return;
  90
  91    png_ptr->transformations |= PNG_SHIFT;
  92    png_ptr->shift = *true_bits;
  93 }
  94 #endif
  95
  96 #if defined(PNG_READ_INTERLACING_SUPPORTED) || \
  97     defined(PNG_WRITE_INTERLACING_SUPPORTED)
  98 int PNGAPI
  99 png_set_interlace_handling(png_structrp png_ptr)
 100 {
 101    png_debug(1, "in png_set_interlace handling");
 102
 103    if (png_ptr != 0 && png_ptr->interlaced != 0)
 104    {
 105       png_ptr->transformations |= PNG_INTERLACE;
 106       return (7);
 107    }
 108
 109    return (1);
 110 }
 111 #endif
 112
 113 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
 114 /* Add a filler byte on read, or remove a filler or alpha byte on write.
 115  * The filler type has changed in v0.95 to allow future 2-byte fillers
 116  * for 48-bit input data, as well as to avoid problems with some compilers
 117  * that don't like bytes as parameters.
 118  */
 119 void PNGAPI
 120 png_set_filler(png_structrp png_ptr, png_uint_32 filler, int filler_loc)
 121 {
 122    png_debug(1, "in png_set_filler");
 123
 124    if (png_ptr == NULL)
 125       return;
 126
 127    /* In libpng 1.6 it is possible to determine whether this is a read or write
 128     * operation and therefore to do more checking here for a valid call.
 129     */
 130    if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
 131    {
 132 #     ifdef PNG_READ_FILLER_SUPPORTED
 133          /* On read png_set_filler is always valid, regardless of the base PNG
 134           * format, because other transformations can give a format where the
 135           * filler code can execute (basically an 8 or 16-bit component RGB or G
 136           * format.)
 137           *
 138           * NOTE: usr_channels is not used by the read code!  (This has led to
 139           * confusion in the past.)  The filler is only used in the read code.
 140           */
 141          png_ptr->filler = (png_uint_16)filler;
 142 #     else
 143          png_app_error(png_ptr, "png_set_filler not supported on read");
 144          PNG_UNUSED(filler) /* not used in the write case */
 145          return;
 146 #     endif
 147    }
 148
 149    else /* write */
 150    {
 151 #     ifdef PNG_WRITE_FILLER_SUPPORTED
 152          /* On write the usr_channels parameter must be set correctly at the
 153           * start to record the number of channels in the app-supplied data.
 154           */
 155          switch (png_ptr->color_type)
 156          {
 157             case PNG_COLOR_TYPE_RGB:
 158                png_ptr->usr_channels = 4;
 159                break;
 160
 161             case PNG_COLOR_TYPE_GRAY:
 162                if (png_ptr->bit_depth >= 8)
 163                {
 164                   png_ptr->usr_channels = 2;
 165                   break;
 166                }
 167
 168                else
 169                {
 170                   /* There simply isn't any code in libpng to strip out bits
 171                    * from bytes when the components are less than a byte in
 172                    * size!
 173                    */
 174                   png_app_error(png_ptr,
 175                      "png_set_filler is invalid for low bit depth gray output");
 176                   return;
 177                }
 178
 179             default:
 180                png_app_error(png_ptr,
 181                   "png_set_filler: inappropriate color type");
 182                return;
 183          }
 184 #     else
 185          png_app_error(png_ptr, "png_set_filler not supported on write");
 186          return;
 187 #     endif
 188    }
 189
 190    /* Here on success - libpng supports the operation, set the transformation
 191     * and the flag to say where the filler channel is.
 192     */
 193    png_ptr->transformations |= PNG_FILLER;
 194
 195    if (filler_loc == PNG_FILLER_AFTER)
 196       png_ptr->flags |= PNG_FLAG_FILLER_AFTER;
 197
 198    else
 199       png_ptr->flags &= ~PNG_FLAG_FILLER_AFTER;
 200 }
 201
 202 /* Added to libpng-1.2.7 */
 203 void PNGAPI
 204 png_set_add_alpha(png_structrp png_ptr, png_uint_32 filler, int filler_loc)
 205 {
 206    png_debug(1, "in png_set_add_alpha");
 207
 208    if (png_ptr == NULL)
 209       return;
 210
 211    png_set_filler(png_ptr, filler, filler_loc);
 212    /* The above may fail to do anything. */
 213    if ((png_ptr->transformations & PNG_FILLER) != 0)
 214       png_ptr->transformations |= PNG_ADD_ALPHA;
 215 }
 216
 217 #endif
 218
 219 #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
 220     defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
 221 void PNGAPI
 222 png_set_swap_alpha(png_structrp png_ptr)
 223 {
 224    png_debug(1, "in png_set_swap_alpha");
 225
 226    if (png_ptr == NULL)
 227       return;
 228
 229    png_ptr->transformations |= PNG_SWAP_ALPHA;
 230 }
 231 #endif
 232
 233 #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
 234     defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
 235 void PNGAPI
 236 png_set_invert_alpha(png_structrp png_ptr)
 237 {
 238    png_debug(1, "in png_set_invert_alpha");
 239
 240    if (png_ptr == NULL)
 241       return;
 242
 243    png_ptr->transformations |= PNG_INVERT_ALPHA;
 244 }
 245 #endif
 246
 247 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
 248 void PNGAPI
 249 png_set_invert_mono(png_structrp png_ptr)
 250 {
 251    png_debug(1, "in png_set_invert_mono");
 252
 253    if (png_ptr == NULL)
 254       return;
 255
 256    png_ptr->transformations |= PNG_INVERT_MONO;
 257 }
 258
 259 /* Invert monochrome grayscale data */
 260 void /* PRIVATE */
 261 png_do_invert(png_row_infop row_info, png_bytep row)
 262 {
 263    png_debug(1, "in png_do_invert");
 264
 265   /* This test removed from libpng version 1.0.13 and 1.2.0:
 266    *   if (row_info->bit_depth == 1 &&
 267    */
 268    if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
 269    {
 270       png_bytep rp = row;
 271       png_size_t i;
 272       png_size_t istop = row_info->rowbytes;
 273
 274       for (i = 0; i < istop; i++)
 275       {
 276          *rp = (png_byte)(~(*rp));
 277          rp++;
 278       }
 279    }
 280
 281    else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
 282       row_info->bit_depth == 8)
 283    {
 284       png_bytep rp = row;
 285       png_size_t i;
 286       png_size_t istop = row_info->rowbytes;
 287
 288       for (i = 0; i < istop; i += 2)
 289       {
 290          *rp = (png_byte)(~(*rp));
 291          rp += 2;
 292       }
 293    }
 294
 295 #ifdef PNG_16BIT_SUPPORTED
 296    else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
 297       row_info->bit_depth == 16)
 298    {
 299       png_bytep rp = row;
 300       png_size_t i;
 301       png_size_t istop = row_info->rowbytes;
 302
 303       for (i = 0; i < istop; i += 4)
 304       {
 305          *rp = (png_byte)(~(*rp));
 306          *(rp + 1) = (png_byte)(~(*(rp + 1)));
 307          rp += 4;
 308       }
 309    }
 310 #endif
 311 }
 312 #endif
 313
 314 #ifdef PNG_16BIT_SUPPORTED
 315 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
 316 /* Swaps byte order on 16-bit depth images */
 317 void /* PRIVATE */
 318 png_do_swap(png_row_infop row_info, png_bytep row)
 319 {
 320    png_debug(1, "in png_do_swap");
 321
 322    if (row_info->bit_depth == 16)
 323    {
 324       png_bytep rp = row;
 325       png_uint_32 i;
 326       png_uint_32 istop= row_info->width * row_info->channels;
 327
 328       for (i = 0; i < istop; i++, rp += 2)
 329       {
 330 #ifdef PNG_BUILTIN_BSWAP16_SUPPORTED
 331          /* Feature added to libpng-1.6.11 for testing purposes, not
 332           * enabled by default.
 333           */
 334          *(png_uint_16*)rp = __builtin_bswap16(*(png_uint_16*)rp);
 335 #else
 336          png_byte t = *rp;
 337          *rp = *(rp + 1);
 338          *(rp + 1) = t;
 339 #endif
 340       }
 341    }
 342 }
 343 #endif
 344 #endif
 345
 346 #if defined(PNG_READ_PACKSWAP_SUPPORTED)||defined(PNG_WRITE_PACKSWAP_SUPPORTED)
 347 static PNG_CONST png_byte onebppswaptable[256] = {
 348    0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0,
 349    0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0,
 350    0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8,
 351    0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8,
 352    0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4,
 353    0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4,
 354    0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC,
 355    0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC,
 356    0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2,
 357    0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2,
 358    0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA,
 359    0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,
 360    0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6,
 361    0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6,
 362    0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE,
 363    0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE,
 364    0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1,
 365    0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,
 366    0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9,
 367    0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9,
 368    0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5,
 369    0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5,
 370    0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED,
 371    0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,
 372    0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3,
 373    0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3,
 374    0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB,
 375    0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB,
 376    0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7,
 377    0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7,
 378    0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF,
 379    0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF
 380 };
 381
 382 static PNG_CONST png_byte twobppswaptable[256] = {
 383    0x00, 0x40, 0x80, 0xC0, 0x10, 0x50, 0x90, 0xD0,
 384    0x20, 0x60, 0xA0, 0xE0, 0x30, 0x70, 0xB0, 0xF0,
 385    0x04, 0x44, 0x84, 0xC4, 0x14, 0x54, 0x94, 0xD4,
 386    0x24, 0x64, 0xA4, 0xE4, 0x34, 0x74, 0xB4, 0xF4,
 387    0x08, 0x48, 0x88, 0xC8, 0x18, 0x58, 0x98, 0xD8,
 388    0x28, 0x68, 0xA8, 0xE8, 0x38, 0x78, 0xB8, 0xF8,
 389    0x0C, 0x4C, 0x8C, 0xCC, 0x1C, 0x5C, 0x9C, 0xDC,
 390    0x2C, 0x6C, 0xAC, 0xEC, 0x3C, 0x7C, 0xBC, 0xFC,
 391    0x01, 0x41, 0x81, 0xC1, 0x11, 0x51, 0x91, 0xD1,
 392    0x21, 0x61, 0xA1, 0xE1, 0x31, 0x71, 0xB1, 0xF1,
 393    0x05, 0x45, 0x85, 0xC5, 0x15, 0x55, 0x95, 0xD5,
 394    0x25, 0x65, 0xA5, 0xE5, 0x35, 0x75, 0xB5, 0xF5,
 395    0x09, 0x49, 0x89, 0xC9, 0x19, 0x59, 0x99, 0xD9,
 396    0x29, 0x69, 0xA9, 0xE9, 0x39, 0x79, 0xB9, 0xF9,
 397    0x0D, 0x4D, 0x8D, 0xCD, 0x1D, 0x5D, 0x9D, 0xDD,
 398    0x2D, 0x6D, 0xAD, 0xED, 0x3D, 0x7D, 0xBD, 0xFD,
 399    0x02, 0x42, 0x82, 0xC2, 0x12, 0x52, 0x92, 0xD2,
 400    0x22, 0x62, 0xA2, 0xE2, 0x32, 0x72, 0xB2, 0xF2,
 401    0x06, 0x46, 0x86, 0xC6, 0x16, 0x56, 0x96, 0xD6,
 402    0x26, 0x66, 0xA6, 0xE6, 0x36, 0x76, 0xB6, 0xF6,
 403    0x0A, 0x4A, 0x8A, 0xCA, 0x1A, 0x5A, 0x9A, 0xDA,
 404    0x2A, 0x6A, 0xAA, 0xEA, 0x3A, 0x7A, 0xBA, 0xFA,
 405    0x0E, 0x4E, 0x8E, 0xCE, 0x1E, 0x5E, 0x9E, 0xDE,
 406    0x2E, 0x6E, 0xAE, 0xEE, 0x3E, 0x7E, 0xBE, 0xFE,
 407    0x03, 0x43, 0x83, 0xC3, 0x13, 0x53, 0x93, 0xD3,
 408    0x23, 0x63, 0xA3, 0xE3, 0x33, 0x73, 0xB3, 0xF3,
 409    0x07, 0x47, 0x87, 0xC7, 0x17, 0x57, 0x97, 0xD7,
 410    0x27, 0x67, 0xA7, 0xE7, 0x37, 0x77, 0xB7, 0xF7,
 411    0x0B, 0x4B, 0x8B, 0xCB, 0x1B, 0x5B, 0x9B, 0xDB,
 412    0x2B, 0x6B, 0xAB, 0xEB, 0x3B, 0x7B, 0xBB, 0xFB,
 413    0x0F, 0x4F, 0x8F, 0xCF, 0x1F, 0x5F, 0x9F, 0xDF,
 414    0x2F, 0x6F, 0xAF, 0xEF, 0x3F, 0x7F, 0xBF, 0xFF
 415 };
 416
 417 static PNG_CONST png_byte fourbppswaptable[256] = {
 418    0x00, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70,
 419    0x80, 0x90, 0xA0, 0xB0, 0xC0, 0xD0, 0xE0, 0xF0,
 420    0x01, 0x11, 0x21, 0x31, 0x41, 0x51, 0x61, 0x71,
 421    0x81, 0x91, 0xA1, 0xB1, 0xC1, 0xD1, 0xE1, 0xF1,
 422    0x02, 0x12, 0x22, 0x32, 0x42, 0x52, 0x62, 0x72,
 423    0x82, 0x92, 0xA2, 0xB2, 0xC2, 0xD2, 0xE2, 0xF2,
 424    0x03, 0x13, 0x23, 0x33, 0x43, 0x53, 0x63, 0x73,
 425    0x83, 0x93, 0xA3, 0xB3, 0xC3, 0xD3, 0xE3, 0xF3,
 426    0x04, 0x14, 0x24, 0x34, 0x44, 0x54, 0x64, 0x74,
 427    0x84, 0x94, 0xA4, 0xB4, 0xC4, 0xD4, 0xE4, 0xF4,
 428    0x05, 0x15, 0x25, 0x35, 0x45, 0x55, 0x65, 0x75,
 429    0x85, 0x95, 0xA5, 0xB5, 0xC5, 0xD5, 0xE5, 0xF5,
 430    0x06, 0x16, 0x26, 0x36, 0x46, 0x56, 0x66, 0x76,
 431    0x86, 0x96, 0xA6, 0xB6, 0xC6, 0xD6, 0xE6, 0xF6,
 432    0x07, 0x17, 0x27, 0x37, 0x47, 0x57, 0x67, 0x77,
 433    0x87, 0x97, 0xA7, 0xB7, 0xC7, 0xD7, 0xE7, 0xF7,
 434    0x08, 0x18, 0x28, 0x38, 0x48, 0x58, 0x68, 0x78,
 435    0x88, 0x98, 0xA8, 0xB8, 0xC8, 0xD8, 0xE8, 0xF8,
 436    0x09, 0x19, 0x29, 0x39, 0x49, 0x59, 0x69, 0x79,
 437    0x89, 0x99, 0xA9, 0xB9, 0xC9, 0xD9, 0xE9, 0xF9,
 438    0x0A, 0x1A, 0x2A, 0x3A, 0x4A, 0x5A, 0x6A, 0x7A,
 439    0x8A, 0x9A, 0xAA, 0xBA, 0xCA, 0xDA, 0xEA, 0xFA,
 440    0x0B, 0x1B, 0x2B, 0x3B, 0x4B, 0x5B, 0x6B, 0x7B,
 441    0x8B, 0x9B, 0xAB, 0xBB, 0xCB, 0xDB, 0xEB, 0xFB,
 442    0x0C, 0x1C, 0x2C, 0x3C, 0x4C, 0x5C, 0x6C, 0x7C,
 443    0x8C, 0x9C, 0xAC, 0xBC, 0xCC, 0xDC, 0xEC, 0xFC,
 444    0x0D, 0x1D, 0x2D, 0x3D, 0x4D, 0x5D, 0x6D, 0x7D,
 445    0x8D, 0x9D, 0xAD, 0xBD, 0xCD, 0xDD, 0xED, 0xFD,
 446    0x0E, 0x1E, 0x2E, 0x3E, 0x4E, 0x5E, 0x6E, 0x7E,
 447    0x8E, 0x9E, 0xAE, 0xBE, 0xCE, 0xDE, 0xEE, 0xFE,
 448    0x0F, 0x1F, 0x2F, 0x3F, 0x4F, 0x5F, 0x6F, 0x7F,
 449    0x8F, 0x9F, 0xAF, 0xBF, 0xCF, 0xDF, 0xEF, 0xFF
 450 };
 451
 452 /* Swaps pixel packing order within bytes */
 453 void /* PRIVATE */
 454 png_do_packswap(png_row_infop row_info, png_bytep row)
 455 {
 456    png_debug(1, "in png_do_packswap");
 457
 458    if (row_info->bit_depth < 8)
 459    {
 460       png_bytep rp;
 461       png_const_bytep end, table;
 462
 463       end = row + row_info->rowbytes;
 464
 465       if (row_info->bit_depth == 1)
 466          table = onebppswaptable;
 467
 468       else if (row_info->bit_depth == 2)
 469          table = twobppswaptable;
 470
 471       else if (row_info->bit_depth == 4)
 472          table = fourbppswaptable;
 473
 474       else
 475          return;
 476
 477       for (rp = row; rp < end; rp++)
 478          *rp = table[*rp];
 479    }
 480 }
 481 #endif /* PACKSWAP || WRITE_PACKSWAP */
 482
 483 #if defined(PNG_WRITE_FILLER_SUPPORTED) || \
 484     defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
 485 /* Remove a channel - this used to be 'png_do_strip_filler' but it used a
 486  * somewhat weird combination of flags to determine what to do.  All the calls
 487  * to png_do_strip_filler are changed in 1.5.2 to call this instead with the
 488  * correct arguments.
 489  *
 490  * The routine isn't general - the channel must be the channel at the start or
 491  * end (not in the middle) of each pixel.
 492  */
 493 void /* PRIVATE */
 494 png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
 495 {
 496    png_bytep sp = row; /* source pointer */
 497    png_bytep dp = row; /* destination pointer */
 498    png_bytep ep = row + row_info->rowbytes; /* One beyond end of row */
 499
 500    /* At the start sp will point to the first byte to copy and dp to where
 501     * it is copied to.  ep always points just beyond the end of the row, so
 502     * the loop simply copies (channels-1) channels until sp reaches ep.
 503     *
 504     * at_start:        0 -- convert AG, XG, ARGB, XRGB, AAGG, XXGG, etc.
 505     *            nonzero -- convert GA, GX, RGBA, RGBX, GGAA, RRGGBBXX, etc.
 506     */
 507
 508    /* GA, GX, XG cases */
 509    if (row_info->channels == 2)
 510    {
 511       if (row_info->bit_depth == 8)
 512       {
 513          if (at_start != 0) /* Skip initial filler */
 514             ++sp;
 515          else          /* Skip initial channel and, for sp, the filler */
 516             sp += 2, ++dp;
 517
 518          /* For a 1 pixel wide image there is nothing to do */
 519          while (sp < ep)
 520             *dp++ = *sp, sp += 2;
 521
 522          row_info->pixel_depth = 8;
 523       }
 524
 525       else if (row_info->bit_depth == 16)
 526       {
 527          if (at_start != 0) /* Skip initial filler */
 528             sp += 2;
 529          else          /* Skip initial channel and, for sp, the filler */
 530             sp += 4, dp += 2;
 531
 532          while (sp < ep)
 533             *dp++ = *sp++, *dp++ = *sp, sp += 3;
 534
 535          row_info->pixel_depth = 16;
 536       }
 537
 538       else
 539          return; /* bad bit depth */
 540
 541       row_info->channels = 1;
 542
 543       /* Finally fix the color type if it records an alpha channel */
 544       if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
 545          row_info->color_type = PNG_COLOR_TYPE_GRAY;
 546    }
 547
 548    /* RGBA, RGBX, XRGB cases */
 549    else if (row_info->channels == 4)
 550    {
 551       if (row_info->bit_depth == 8)
 552       {
 553          if (at_start != 0) /* Skip initial filler */
 554             ++sp;
 555          else          /* Skip initial channels and, for sp, the filler */
 556             sp += 4, dp += 3;
 557
 558          /* Note that the loop adds 3 to dp and 4 to sp each time. */
 559          while (sp < ep)
 560             *dp++ = *sp++, *dp++ = *sp++, *dp++ = *sp, sp += 2;
 561
 562          row_info->pixel_depth = 24;
 563       }
 564
 565       else if (row_info->bit_depth == 16)
 566       {
 567          if (at_start != 0) /* Skip initial filler */
 568             sp += 2;
 569          else          /* Skip initial channels and, for sp, the filler */
 570             sp += 8, dp += 6;
 571
 572          while (sp < ep)
 573          {
 574             /* Copy 6 bytes, skip 2 */
 575             *dp++ = *sp++, *dp++ = *sp++;
 576             *dp++ = *sp++, *dp++ = *sp++;
 577             *dp++ = *sp++, *dp++ = *sp, sp += 3;
 578          }
 579
 580          row_info->pixel_depth = 48;
 581       }
 582
 583       else
 584          return; /* bad bit depth */
 585
 586       row_info->channels = 3;
 587
 588       /* Finally fix the color type if it records an alpha channel */
 589       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 590          row_info->color_type = PNG_COLOR_TYPE_RGB;
 591    }
 592
 593    else
 594       return; /* The filler channel has gone already */
 595
 596    /* Fix the rowbytes value. */
 597    row_info->rowbytes = dp-row;
 598 }
 599 #endif
 600
 601 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
 602 /* Swaps red and blue bytes within a pixel */
 603 void /* PRIVATE */
 604 png_do_bgr(png_row_infop row_info, png_bytep row)
 605 {
 606    png_debug(1, "in png_do_bgr");
 607
 608    if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
 609    {
 610       png_uint_32 row_width = row_info->width;
 611       if (row_info->bit_depth == 8)
 612       {
 613          if (row_info->color_type == PNG_COLOR_TYPE_RGB)
 614          {
 615             png_bytep rp;
 616             png_uint_32 i;
 617
 618             for (i = 0, rp = row; i < row_width; i++, rp += 3)
 619             {
 620                png_byte save = *rp;
 621                *rp = *(rp + 2);
 622                *(rp + 2) = save;
 623             }
 624          }
 625
 626          else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 627          {
 628             png_bytep rp;
 629             png_uint_32 i;
 630
 631             for (i = 0, rp = row; i < row_width; i++, rp += 4)
 632             {
 633                png_byte save = *rp;
 634                *rp = *(rp + 2);
 635                *(rp + 2) = save;
 636             }
 637          }
 638       }
 639
 640 #ifdef PNG_16BIT_SUPPORTED
 641       else if (row_info->bit_depth == 16)
 642       {
 643          if (row_info->color_type == PNG_COLOR_TYPE_RGB)
 644          {
 645             png_bytep rp;
 646             png_uint_32 i;
 647
 648             for (i = 0, rp = row; i < row_width; i++, rp += 6)
 649             {
 650                png_byte save = *rp;
 651                *rp = *(rp + 4);
 652                *(rp + 4) = save;
 653                save = *(rp + 1);
 654                *(rp + 1) = *(rp + 5);
 655                *(rp + 5) = save;
 656             }
 657          }
 658
 659          else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 660          {
 661             png_bytep rp;
 662             png_uint_32 i;
 663
 664             for (i = 0, rp = row; i < row_width; i++, rp += 8)
 665             {
 666                png_byte save = *rp;
 667                *rp = *(rp + 4);
 668                *(rp + 4) = save;
 669                save = *(rp + 1);
 670                *(rp + 1) = *(rp + 5);
 671                *(rp + 5) = save;
 672             }
 673          }
 674       }
 675 #endif
 676    }
 677 }
 678 #endif /* READ_BGR || WRITE_BGR */
 679
 680 #if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) || \
 681     defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED)
 682 /* Added at libpng-1.5.10 */
 683 void /* PRIVATE */
 684 png_do_check_palette_indexes(png_structrp png_ptr, png_row_infop row_info)
 685 {
 686    if (png_ptr->num_palette < (1 << row_info->bit_depth) &&
 687       png_ptr->num_palette > 0) /* num_palette can be 0 in MNG files */
 688    {
 689       /* Calculations moved outside switch in an attempt to stop different
 690        * compiler warnings.  'padding' is in *bits* within the last byte, it is
 691        * an 'int' because pixel_depth becomes an 'int' in the expression below,
 692        * and this calculation is used because it avoids warnings that other
 693        * forms produced on either GCC or MSVC.
 694        */
 695       int padding = (-row_info->pixel_depth * row_info->width) & 7;
 696       png_bytep rp = png_ptr->row_buf + row_info->rowbytes;
 697
 698       switch (row_info->bit_depth)
 699       {
 700          case 1:
 701          {
 702             /* in this case, all bytes must be 0 so we don't need
 703              * to unpack the pixels except for the rightmost one.
 704              */
 705             for (; rp > png_ptr->row_buf; rp--)
 706             {
 707               if ((*rp >> padding) != 0)
 708                  png_ptr->num_palette_max = 1;
 709               padding = 0;
 710             }
 711
 712             break;
 713          }
 714
 715          case 2:
 716          {
 717             for (; rp > png_ptr->row_buf; rp--)
 718             {
 719               int i = ((*rp >> padding) & 0x03);
 720
 721               if (i > png_ptr->num_palette_max)
 722                  png_ptr->num_palette_max = i;
 723
 724               i = (((*rp >> padding) >> 2) & 0x03);
 725
 726               if (i > png_ptr->num_palette_max)
 727                  png_ptr->num_palette_max = i;
 728
 729               i = (((*rp >> padding) >> 4) & 0x03);
 730
 731               if (i > png_ptr->num_palette_max)
 732                  png_ptr->num_palette_max = i;
 733
 734               i = (((*rp >> padding) >> 6) & 0x03);
 735
 736               if (i > png_ptr->num_palette_max)
 737                  png_ptr->num_palette_max = i;
 738
 739               padding = 0;
 740             }
 741
 742             break;
 743          }
 744
 745          case 4:
 746          {
 747             for (; rp > png_ptr->row_buf; rp--)
 748             {
 749               int i = ((*rp >> padding) & 0x0f);
 750
 751               if (i > png_ptr->num_palette_max)
 752                  png_ptr->num_palette_max = i;
 753
 754               i = (((*rp >> padding) >> 4) & 0x0f);
 755
 756               if (i > png_ptr->num_palette_max)
 757                  png_ptr->num_palette_max = i;
 758
 759               padding = 0;
 760             }
 761
 762             break;
 763          }
 764
 765          case 8:
 766          {
 767             for (; rp > png_ptr->row_buf; rp--)
 768             {
 769                if (*rp > png_ptr->num_palette_max)
 770                   png_ptr->num_palette_max = (int) *rp;
 771             }
 772
 773             break;
 774          }
 775
 776          default:
 777             break;
 778       }
 779    }
 780 }
 781 #endif /* CHECK_FOR_INVALID_INDEX */
 782
 783 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
 784     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
 785 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
 786 void PNGAPI
 787 png_set_user_transform_info(png_structrp png_ptr, png_voidp
 788    user_transform_ptr, int user_transform_depth, int user_transform_channels)
 789 {
 790    png_debug(1, "in png_set_user_transform_info");
 791
 792    if (png_ptr == NULL)
 793       return;
 794
 795 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
 796    if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
 797       (png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
 798    {
 799       png_app_error(png_ptr,
 800             "info change after png_start_read_image or png_read_update_info");
 801       return;
 802    }
 803 #endif
 804
 805    png_ptr->user_transform_ptr = user_transform_ptr;
 806    png_ptr->user_transform_depth = (png_byte)user_transform_depth;
 807    png_ptr->user_transform_channels = (png_byte)user_transform_channels;
 808 }
 809 #endif
 810
 811 /* This function returns a pointer to the user_transform_ptr associated with
 812  * the user transform functions.  The application should free any memory
 813  * associated with this pointer before png_write_destroy and png_read_destroy
 814  * are called.
 815  */
 816 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
 817 png_voidp PNGAPI
 818 png_get_user_transform_ptr(png_const_structrp png_ptr)
 819 {
 820    if (png_ptr == NULL)
 821       return (NULL);
 822
 823    return png_ptr->user_transform_ptr;
 824 }
 825 #endif
 826
 827 #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
 828 png_uint_32 PNGAPI
 829 png_get_current_row_number(png_const_structrp png_ptr)
 830 {
 831    /* See the comments in png.h - this is the sub-image row when reading an
 832     * interlaced image.
 833     */
 834    if (png_ptr != NULL)
 835       return png_ptr->row_number;
 836
 837    return PNG_UINT_32_MAX; /* help the app not to fail silently */
 838 }
 839
 840 png_byte PNGAPI
 841 png_get_current_pass_number(png_const_structrp png_ptr)
 842 {
 843    if (png_ptr != NULL)
 844       return png_ptr->pass;
 845    return 8; /* invalid */
 846 }
 847 #endif /* USER_TRANSFORM_INFO */
 848 #endif /* READ_USER_TRANSFORM || WRITE_USER_TRANSFORM */
 849 #endif /* READ || WRITE */