third_party/libpng/pngwtran.c

   1
   2 /* pngwtran.c - transforms the data in a row for PNG writers
   3  *
   4  * Last changed in libpng 1.2.43 [February 25, 2010]
   5  * Copyright (c) 1998-2010 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 #define PNG_INTERNAL
  15 #define PNG_NO_PEDANTIC_WARNINGS
  16 #include "png.h"
  17 #ifdef PNG_WRITE_SUPPORTED
  18
  19 /* Transform the data according to the user's wishes.  The order of
  20  * transformations is significant.
  21  */
  22 void /* PRIVATE */
  23 png_do_write_transformations(png_structp png_ptr)
  24 {
  25    png_debug(1, "in png_do_write_transformations");
  26
  27    if (png_ptr == NULL)
  28       return;
  29
  30 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
  31    if (png_ptr->transformations & PNG_USER_TRANSFORM)
  32       if (png_ptr->write_user_transform_fn != NULL)
  33         (*(png_ptr->write_user_transform_fn)) /* User write transform
  34                                                  function */
  35           (png_ptr,                    /* png_ptr */
  36            &(png_ptr->row_info),       /* row_info:     */
  37              /*  png_uint_32 width;          width of row */
  38              /*  png_uint_32 rowbytes;       number of bytes in row */
  39              /*  png_byte color_type;        color type of pixels */
  40              /*  png_byte bit_depth;         bit depth of samples */
  41              /*  png_byte channels;          number of channels (1-4) */
  42              /*  png_byte pixel_depth;       bits per pixel (depth*channels) */
  43            png_ptr->row_buf + 1);      /* start of pixel data for row */
  44 #endif
  45 #ifdef PNG_WRITE_FILLER_SUPPORTED
  46    if (png_ptr->transformations & PNG_FILLER)
  47       png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
  48          png_ptr->flags);
  49 #endif
  50 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
  51    if (png_ptr->transformations & PNG_PACKSWAP)
  52       png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
  53 #endif
  54 #ifdef PNG_WRITE_PACK_SUPPORTED
  55    if (png_ptr->transformations & PNG_PACK)
  56       png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
  57          (png_uint_32)png_ptr->bit_depth);
  58 #endif
  59 #ifdef PNG_WRITE_SWAP_SUPPORTED
  60    if (png_ptr->transformations & PNG_SWAP_BYTES)
  61       png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
  62 #endif
  63 #ifdef PNG_WRITE_SHIFT_SUPPORTED
  64    if (png_ptr->transformations & PNG_SHIFT)
  65       png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
  66          &(png_ptr->shift));
  67 #endif
  68 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
  69    if (png_ptr->transformations & PNG_SWAP_ALPHA)
  70       png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
  71 #endif
  72 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
  73    if (png_ptr->transformations & PNG_INVERT_ALPHA)
  74       png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
  75 #endif
  76 #ifdef PNG_WRITE_BGR_SUPPORTED
  77    if (png_ptr->transformations & PNG_BGR)
  78       png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
  79 #endif
  80 #ifdef PNG_WRITE_INVERT_SUPPORTED
  81    if (png_ptr->transformations & PNG_INVERT_MONO)
  82       png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
  83 #endif
  84 }
  85
  86 #ifdef PNG_WRITE_PACK_SUPPORTED
  87 /* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The
  88  * row_info bit depth should be 8 (one pixel per byte).  The channels
  89  * should be 1 (this only happens on grayscale and paletted images).
  90  */
  91 void /* PRIVATE */
  92 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
  93 {
  94    png_debug(1, "in png_do_pack");
  95
  96    if (row_info->bit_depth == 8 &&
  97 #ifdef PNG_USELESS_TESTS_SUPPORTED
  98        row != NULL && row_info != NULL &&
  99 #endif
 100       row_info->channels == 1)
 101    {
 102       switch ((int)bit_depth)
 103       {
 104          case 1:
 105          {
 106             png_bytep sp, dp;
 107             int mask, v;
 108             png_uint_32 i;
 109             png_uint_32 row_width = row_info->width;
 110
 111             sp = row;
 112             dp = row;
 113             mask = 0x80;
 114             v = 0;
 115
 116             for (i = 0; i < row_width; i++)
 117             {
 118                if (*sp != 0)
 119                   v |= mask;
 120                sp++;
 121                if (mask > 1)
 122                   mask >>= 1;
 123                else
 124                {
 125                   mask = 0x80;
 126                   *dp = (png_byte)v;
 127                   dp++;
 128                   v = 0;
 129                }
 130             }
 131             if (mask != 0x80)
 132                *dp = (png_byte)v;
 133             break;
 134          }
 135          case 2:
 136          {
 137             png_bytep sp, dp;
 138             int shift, v;
 139             png_uint_32 i;
 140             png_uint_32 row_width = row_info->width;
 141
 142             sp = row;
 143             dp = row;
 144             shift = 6;
 145             v = 0;
 146             for (i = 0; i < row_width; i++)
 147             {
 148                png_byte value;
 149
 150                value = (png_byte)(*sp & 0x03);
 151                v |= (value << shift);
 152                if (shift == 0)
 153                {
 154                   shift = 6;
 155                   *dp = (png_byte)v;
 156                   dp++;
 157                   v = 0;
 158                }
 159                else
 160                   shift -= 2;
 161                sp++;
 162             }
 163             if (shift != 6)
 164                *dp = (png_byte)v;
 165             break;
 166          }
 167          case 4:
 168          {
 169             png_bytep sp, dp;
 170             int shift, v;
 171             png_uint_32 i;
 172             png_uint_32 row_width = row_info->width;
 173
 174             sp = row;
 175             dp = row;
 176             shift = 4;
 177             v = 0;
 178             for (i = 0; i < row_width; i++)
 179             {
 180                png_byte value;
 181
 182                value = (png_byte)(*sp & 0x0f);
 183                v |= (value << shift);
 184
 185                if (shift == 0)
 186                {
 187                   shift = 4;
 188                   *dp = (png_byte)v;
 189                   dp++;
 190                   v = 0;
 191                }
 192                else
 193                   shift -= 4;
 194
 195                sp++;
 196             }
 197             if (shift != 4)
 198                *dp = (png_byte)v;
 199             break;
 200          }
 201       }
 202       row_info->bit_depth = (png_byte)bit_depth;
 203       row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
 204       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
 205          row_info->width);
 206    }
 207 }
 208 #endif
 209
 210 #ifdef PNG_WRITE_SHIFT_SUPPORTED
 211 /* Shift pixel values to take advantage of whole range.  Pass the
 212  * true number of bits in bit_depth.  The row should be packed
 213  * according to row_info->bit_depth.  Thus, if you had a row of
 214  * bit depth 4, but the pixels only had values from 0 to 7, you
 215  * would pass 3 as bit_depth, and this routine would translate the
 216  * data to 0 to 15.
 217  */
 218 void /* PRIVATE */
 219 png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
 220 {
 221    png_debug(1, "in png_do_shift");
 222
 223 #ifdef PNG_USELESS_TESTS_SUPPORTED
 224    if (row != NULL && row_info != NULL &&
 225 #else
 226    if (
 227 #endif
 228       row_info->color_type != PNG_COLOR_TYPE_PALETTE)
 229    {
 230       int shift_start[4], shift_dec[4];
 231       int channels = 0;
 232
 233       if (row_info->color_type & PNG_COLOR_MASK_COLOR)
 234       {
 235          shift_start[channels] = row_info->bit_depth - bit_depth->red;
 236          shift_dec[channels] = bit_depth->red;
 237          channels++;
 238          shift_start[channels] = row_info->bit_depth - bit_depth->green;
 239          shift_dec[channels] = bit_depth->green;
 240          channels++;
 241          shift_start[channels] = row_info->bit_depth - bit_depth->blue;
 242          shift_dec[channels] = bit_depth->blue;
 243          channels++;
 244       }
 245       else
 246       {
 247          shift_start[channels] = row_info->bit_depth - bit_depth->gray;
 248          shift_dec[channels] = bit_depth->gray;
 249          channels++;
 250       }
 251       if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
 252       {
 253          shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
 254          shift_dec[channels] = bit_depth->alpha;
 255          channels++;
 256       }
 257
 258       /* With low row depths, could only be grayscale, so one channel */
 259       if (row_info->bit_depth < 8)
 260       {
 261          png_bytep bp = row;
 262          png_uint_32 i;
 263          png_byte mask;
 264          png_uint_32 row_bytes = row_info->rowbytes;
 265
 266          if (bit_depth->gray == 1 && row_info->bit_depth == 2)
 267             mask = 0x55;
 268          else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
 269             mask = 0x11;
 270          else
 271             mask = 0xff;
 272
 273          for (i = 0; i < row_bytes; i++, bp++)
 274          {
 275             png_uint_16 v;
 276             int j;
 277
 278             v = *bp;
 279             *bp = 0;
 280             for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
 281             {
 282                if (j > 0)
 283                   *bp |= (png_byte)((v << j) & 0xff);
 284                else
 285                   *bp |= (png_byte)((v >> (-j)) & mask);
 286             }
 287          }
 288       }
 289       else if (row_info->bit_depth == 8)
 290       {
 291          png_bytep bp = row;
 292          png_uint_32 i;
 293          png_uint_32 istop = channels * row_info->width;
 294
 295          for (i = 0; i < istop; i++, bp++)
 296          {
 297
 298             png_uint_16 v;
 299             int j;
 300             int c = (int)(i%channels);
 301
 302             v = *bp;
 303             *bp = 0;
 304             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
 305             {
 306                if (j > 0)
 307                   *bp |= (png_byte)((v << j) & 0xff);
 308                else
 309                   *bp |= (png_byte)((v >> (-j)) & 0xff);
 310             }
 311          }
 312       }
 313       else
 314       {
 315          png_bytep bp;
 316          png_uint_32 i;
 317          png_uint_32 istop = channels * row_info->width;
 318
 319          for (bp = row, i = 0; i < istop; i++)
 320          {
 321             int c = (int)(i%channels);
 322             png_uint_16 value, v;
 323             int j;
 324
 325             v = (png_uint_16)(((png_uint_16)(*bp) << 8) + *(bp + 1));
 326             value = 0;
 327             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
 328             {
 329                if (j > 0)
 330                   value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
 331                else
 332                   value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
 333             }
 334             *bp++ = (png_byte)(value >> 8);
 335             *bp++ = (png_byte)(value & 0xff);
 336          }
 337       }
 338    }
 339 }
 340 #endif
 341
 342 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
 343 void /* PRIVATE */
 344 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
 345 {
 346    png_debug(1, "in png_do_write_swap_alpha");
 347
 348 #ifdef PNG_USELESS_TESTS_SUPPORTED
 349    if (row != NULL && row_info != NULL)
 350 #endif
 351    {
 352       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 353       {
 354          /* This converts from ARGB to RGBA */
 355          if (row_info->bit_depth == 8)
 356          {
 357             png_bytep sp, dp;
 358             png_uint_32 i;
 359             png_uint_32 row_width = row_info->width;
 360             for (i = 0, sp = dp = row; i < row_width; i++)
 361             {
 362                png_byte save = *(sp++);
 363                *(dp++) = *(sp++);
 364                *(dp++) = *(sp++);
 365                *(dp++) = *(sp++);
 366                *(dp++) = save;
 367             }
 368          }
 369          /* This converts from AARRGGBB to RRGGBBAA */
 370          else
 371          {
 372             png_bytep sp, dp;
 373             png_uint_32 i;
 374             png_uint_32 row_width = row_info->width;
 375
 376             for (i = 0, sp = dp = row; i < row_width; i++)
 377             {
 378                png_byte save[2];
 379                save[0] = *(sp++);
 380                save[1] = *(sp++);
 381                *(dp++) = *(sp++);
 382                *(dp++) = *(sp++);
 383                *(dp++) = *(sp++);
 384                *(dp++) = *(sp++);
 385                *(dp++) = *(sp++);
 386                *(dp++) = *(sp++);
 387                *(dp++) = save[0];
 388                *(dp++) = save[1];
 389             }
 390          }
 391       }
 392       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
 393       {
 394          /* This converts from AG to GA */
 395          if (row_info->bit_depth == 8)
 396          {
 397             png_bytep sp, dp;
 398             png_uint_32 i;
 399             png_uint_32 row_width = row_info->width;
 400
 401             for (i = 0, sp = dp = row; i < row_width; i++)
 402             {
 403                png_byte save = *(sp++);
 404                *(dp++) = *(sp++);
 405                *(dp++) = save;
 406             }
 407          }
 408          /* This converts from AAGG to GGAA */
 409          else
 410          {
 411             png_bytep sp, dp;
 412             png_uint_32 i;
 413             png_uint_32 row_width = row_info->width;
 414
 415             for (i = 0, sp = dp = row; i < row_width; i++)
 416             {
 417                png_byte save[2];
 418                save[0] = *(sp++);
 419                save[1] = *(sp++);
 420                *(dp++) = *(sp++);
 421                *(dp++) = *(sp++);
 422                *(dp++) = save[0];
 423                *(dp++) = save[1];
 424             }
 425          }
 426       }
 427    }
 428 }
 429 #endif
 430
 431 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
 432 void /* PRIVATE */
 433 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
 434 {
 435    png_debug(1, "in png_do_write_invert_alpha");
 436
 437 #ifdef PNG_USELESS_TESTS_SUPPORTED
 438    if (row != NULL && row_info != NULL)
 439 #endif
 440    {
 441       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 442       {
 443          /* This inverts the alpha channel in RGBA */
 444          if (row_info->bit_depth == 8)
 445          {
 446             png_bytep sp, dp;
 447             png_uint_32 i;
 448             png_uint_32 row_width = row_info->width;
 449             for (i = 0, sp = dp = row; i < row_width; i++)
 450             {
 451                /* Does nothing
 452                *(dp++) = *(sp++);
 453                *(dp++) = *(sp++);
 454                *(dp++) = *(sp++);
 455                */
 456                sp+=3; dp = sp;
 457                *(dp++) = (png_byte)(255 - *(sp++));
 458             }
 459          }
 460          /* This inverts the alpha channel in RRGGBBAA */
 461          else
 462          {
 463             png_bytep sp, dp;
 464             png_uint_32 i;
 465             png_uint_32 row_width = row_info->width;
 466
 467             for (i = 0, sp = dp = row; i < row_width; i++)
 468             {
 469                /* Does nothing
 470                *(dp++) = *(sp++);
 471                *(dp++) = *(sp++);
 472                *(dp++) = *(sp++);
 473                *(dp++) = *(sp++);
 474                *(dp++) = *(sp++);
 475                *(dp++) = *(sp++);
 476                */
 477                sp+=6; dp = sp;
 478                *(dp++) = (png_byte)(255 - *(sp++));
 479                *(dp++) = (png_byte)(255 - *(sp++));
 480             }
 481          }
 482       }
 483       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
 484       {
 485          /* This inverts the alpha channel in GA */
 486          if (row_info->bit_depth == 8)
 487          {
 488             png_bytep sp, dp;
 489             png_uint_32 i;
 490             png_uint_32 row_width = row_info->width;
 491
 492             for (i = 0, sp = dp = row; i < row_width; i++)
 493             {
 494                *(dp++) = *(sp++);
 495                *(dp++) = (png_byte)(255 - *(sp++));
 496             }
 497          }
 498          /* This inverts the alpha channel in GGAA */
 499          else
 500          {
 501             png_bytep sp, dp;
 502             png_uint_32 i;
 503             png_uint_32 row_width = row_info->width;
 504
 505             for (i = 0, sp = dp = row; i < row_width; i++)
 506             {
 507                /* Does nothing
 508                *(dp++) = *(sp++);
 509                *(dp++) = *(sp++);
 510                */
 511                sp+=2; dp = sp;
 512                *(dp++) = (png_byte)(255 - *(sp++));
 513                *(dp++) = (png_byte)(255 - *(sp++));
 514             }
 515          }
 516       }
 517    }
 518 }
 519 #endif
 520
 521 #ifdef PNG_MNG_FEATURES_SUPPORTED
 522 /* Undoes intrapixel differencing  */
 523 void /* PRIVATE */
 524 png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
 525 {
 526    png_debug(1, "in png_do_write_intrapixel");
 527
 528    if (
 529 #ifdef PNG_USELESS_TESTS_SUPPORTED
 530        row != NULL && row_info != NULL &&
 531 #endif
 532        (row_info->color_type & PNG_COLOR_MASK_COLOR))
 533    {
 534       int bytes_per_pixel;
 535       png_uint_32 row_width = row_info->width;
 536       if (row_info->bit_depth == 8)
 537       {
 538          png_bytep rp;
 539          png_uint_32 i;
 540
 541          if (row_info->color_type == PNG_COLOR_TYPE_RGB)
 542             bytes_per_pixel = 3;
 543          else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 544             bytes_per_pixel = 4;
 545          else
 546             return;
 547
 548          for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
 549          {
 550             *(rp)   = (png_byte)((*rp     - *(rp+1))&0xff);
 551             *(rp+2) = (png_byte)((*(rp+2) - *(rp+1))&0xff);
 552          }
 553       }
 554       else if (row_info->bit_depth == 16)
 555       {
 556          png_bytep rp;
 557          png_uint_32 i;
 558
 559          if (row_info->color_type == PNG_COLOR_TYPE_RGB)
 560             bytes_per_pixel = 6;
 561          else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 562             bytes_per_pixel = 8;
 563          else
 564             return;
 565
 566          for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
 567          {
 568             png_uint_32 s0   = (*(rp  ) << 8) | *(rp+1);
 569             png_uint_32 s1   = (*(rp+2) << 8) | *(rp+3);
 570             png_uint_32 s2   = (*(rp+4) << 8) | *(rp+5);
 571             png_uint_32 red  = (png_uint_32)((s0 - s1) & 0xffffL);
 572             png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
 573             *(rp  ) = (png_byte)((red >> 8) & 0xff);
 574             *(rp+1) = (png_byte)(red & 0xff);
 575             *(rp+4) = (png_byte)((blue >> 8) & 0xff);
 576             *(rp+5) = (png_byte)(blue & 0xff);
 577          }
 578       }
 579    }
 580 }
 581 #endif /* PNG_MNG_FEATURES_SUPPORTED */
 582 #endif /* PNG_WRITE_SUPPORTED */