media/libpng/pngwtran.c

   1
   2 /* pngwtran.c - transforms the data in a row for PNG writers
   3  *
   4  * Last changed in libpng 1.6.15 [November 20, 2014]
   5  * Copyright (c) 1998-2014 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 #ifdef PNG_WRITE_SUPPORTED
  17 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
  18
  19 #ifdef PNG_WRITE_PACK_SUPPORTED
  20 /* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The
  21  * row_info bit depth should be 8 (one pixel per byte).  The channels
  22  * should be 1 (this only happens on grayscale and paletted images).
  23  */
  24 static void
  25 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
  26 {
  27    png_debug(1, "in png_do_pack");
  28
  29    if (row_info->bit_depth == 8 &&
  30       row_info->channels == 1)
  31    {
  32       switch ((int)bit_depth)
  33       {
  34          case 1:
  35          {
  36             png_bytep sp, dp;
  37             int mask, v;
  38             png_uint_32 i;
  39             png_uint_32 row_width = row_info->width;
  40
  41             sp = row;
  42             dp = row;
  43             mask = 0x80;
  44             v = 0;
  45
  46             for (i = 0; i < row_width; i++)
  47             {
  48                if (*sp != 0)
  49                   v |= mask;
  50
  51                sp++;
  52
  53                if (mask > 1)
  54                   mask >>= 1;
  55
  56                else
  57                {
  58                   mask = 0x80;
  59                   *dp = (png_byte)v;
  60                   dp++;
  61                   v = 0;
  62                }
  63             }
  64
  65             if (mask != 0x80)
  66                *dp = (png_byte)v;
  67
  68             break;
  69          }
  70
  71          case 2:
  72          {
  73             png_bytep sp, dp;
  74             int shift, v;
  75             png_uint_32 i;
  76             png_uint_32 row_width = row_info->width;
  77
  78             sp = row;
  79             dp = row;
  80             shift = 6;
  81             v = 0;
  82
  83             for (i = 0; i < row_width; i++)
  84             {
  85                png_byte value;
  86
  87                value = (png_byte)(*sp & 0x03);
  88                v |= (value << shift);
  89
  90                if (shift == 0)
  91                {
  92                   shift = 6;
  93                   *dp = (png_byte)v;
  94                   dp++;
  95                   v = 0;
  96                }
  97
  98                else
  99                   shift -= 2;
 100
 101                sp++;
 102             }
 103
 104             if (shift != 6)
 105                *dp = (png_byte)v;
 106
 107             break;
 108          }
 109
 110          case 4:
 111          {
 112             png_bytep sp, dp;
 113             int shift, v;
 114             png_uint_32 i;
 115             png_uint_32 row_width = row_info->width;
 116
 117             sp = row;
 118             dp = row;
 119             shift = 4;
 120             v = 0;
 121
 122             for (i = 0; i < row_width; i++)
 123             {
 124                png_byte value;
 125
 126                value = (png_byte)(*sp & 0x0f);
 127                v |= (value << shift);
 128
 129                if (shift == 0)
 130                {
 131                   shift = 4;
 132                   *dp = (png_byte)v;
 133                   dp++;
 134                   v = 0;
 135                }
 136
 137                else
 138                   shift -= 4;
 139
 140                sp++;
 141             }
 142
 143             if (shift != 4)
 144                *dp = (png_byte)v;
 145
 146             break;
 147          }
 148
 149          default:
 150             break;
 151       }
 152
 153       row_info->bit_depth = (png_byte)bit_depth;
 154       row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
 155       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
 156           row_info->width);
 157    }
 158 }
 159 #endif
 160
 161 #ifdef PNG_WRITE_SHIFT_SUPPORTED
 162 /* Shift pixel values to take advantage of whole range.  Pass the
 163  * true number of bits in bit_depth.  The row should be packed
 164  * according to row_info->bit_depth.  Thus, if you had a row of
 165  * bit depth 4, but the pixels only had values from 0 to 7, you
 166  * would pass 3 as bit_depth, and this routine would translate the
 167  * data to 0 to 15.
 168  */
 169 static void
 170 png_do_shift(png_row_infop row_info, png_bytep row,
 171     png_const_color_8p bit_depth)
 172 {
 173    png_debug(1, "in png_do_shift");
 174
 175    if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
 176    {
 177       int shift_start[4], shift_dec[4];
 178       int channels = 0;
 179
 180       if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
 181       {
 182          shift_start[channels] = row_info->bit_depth - bit_depth->red;
 183          shift_dec[channels] = bit_depth->red;
 184          channels++;
 185
 186          shift_start[channels] = row_info->bit_depth - bit_depth->green;
 187          shift_dec[channels] = bit_depth->green;
 188          channels++;
 189
 190          shift_start[channels] = row_info->bit_depth - bit_depth->blue;
 191          shift_dec[channels] = bit_depth->blue;
 192          channels++;
 193       }
 194
 195       else
 196       {
 197          shift_start[channels] = row_info->bit_depth - bit_depth->gray;
 198          shift_dec[channels] = bit_depth->gray;
 199          channels++;
 200       }
 201
 202       if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
 203       {
 204          shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
 205          shift_dec[channels] = bit_depth->alpha;
 206          channels++;
 207       }
 208
 209       /* With low row depths, could only be grayscale, so one channel */
 210       if (row_info->bit_depth < 8)
 211       {
 212          png_bytep bp = row;
 213          png_size_t i;
 214          unsigned int mask;
 215          png_size_t row_bytes = row_info->rowbytes;
 216
 217          if (bit_depth->gray == 1 && row_info->bit_depth == 2)
 218             mask = 0x55;
 219
 220          else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
 221             mask = 0x11;
 222
 223          else
 224             mask = 0xff;
 225
 226          for (i = 0; i < row_bytes; i++, bp++)
 227          {
 228             int j;
 229             unsigned int v, out;
 230
 231             v = *bp;
 232             out = 0;
 233
 234             for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
 235             {
 236                if (j > 0)
 237                   out |= v << j;
 238
 239                else
 240                   out |= (v >> (-j)) & mask;
 241             }
 242
 243             *bp = (png_byte)(out & 0xff);
 244          }
 245       }
 246
 247       else if (row_info->bit_depth == 8)
 248       {
 249          png_bytep bp = row;
 250          png_uint_32 i;
 251          png_uint_32 istop = channels * row_info->width;
 252
 253          for (i = 0; i < istop; i++, bp++)
 254          {
 255
 256             const unsigned int c = i%channels;
 257             int j;
 258             unsigned int v, out;
 259
 260             v = *bp;
 261             out = 0;
 262
 263             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
 264             {
 265                if (j > 0)
 266                   out |= v << j;
 267
 268                else
 269                   out |= v >> (-j);
 270             }
 271
 272             *bp = (png_byte)(out & 0xff);
 273          }
 274       }
 275
 276       else
 277       {
 278          png_bytep bp;
 279          png_uint_32 i;
 280          png_uint_32 istop = channels * row_info->width;
 281
 282          for (bp = row, i = 0; i < istop; i++)
 283          {
 284             const unsigned int c = i%channels;
 285             int j;
 286             unsigned int value, v;
 287
 288             v = png_get_uint_16(bp);
 289             value = 0;
 290
 291             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
 292             {
 293                if (j > 0)
 294                   value |= v << j;
 295
 296                else
 297                   value |= v >> (-j);
 298             }
 299             *bp++ = (png_byte)((value >> 8) & 0xff);
 300             *bp++ = (png_byte)(value & 0xff);
 301          }
 302       }
 303    }
 304 }
 305 #endif
 306
 307 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
 308 static void
 309 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
 310 {
 311    png_debug(1, "in png_do_write_swap_alpha");
 312
 313    {
 314       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 315       {
 316          if (row_info->bit_depth == 8)
 317          {
 318             /* This converts from ARGB to RGBA */
 319             png_bytep sp, dp;
 320             png_uint_32 i;
 321             png_uint_32 row_width = row_info->width;
 322
 323             for (i = 0, sp = dp = row; i < row_width; i++)
 324             {
 325                png_byte save = *(sp++);
 326                *(dp++) = *(sp++);
 327                *(dp++) = *(sp++);
 328                *(dp++) = *(sp++);
 329                *(dp++) = save;
 330             }
 331          }
 332
 333 #ifdef PNG_WRITE_16BIT_SUPPORTED
 334          else
 335          {
 336             /* This converts from AARRGGBB to RRGGBBAA */
 337             png_bytep sp, dp;
 338             png_uint_32 i;
 339             png_uint_32 row_width = row_info->width;
 340
 341             for (i = 0, sp = dp = row; i < row_width; i++)
 342             {
 343                png_byte save[2];
 344                save[0] = *(sp++);
 345                save[1] = *(sp++);
 346                *(dp++) = *(sp++);
 347                *(dp++) = *(sp++);
 348                *(dp++) = *(sp++);
 349                *(dp++) = *(sp++);
 350                *(dp++) = *(sp++);
 351                *(dp++) = *(sp++);
 352                *(dp++) = save[0];
 353                *(dp++) = save[1];
 354             }
 355          }
 356 #endif /* WRITE_16BIT */
 357       }
 358
 359       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
 360       {
 361          if (row_info->bit_depth == 8)
 362          {
 363             /* This converts from AG to GA */
 364             png_bytep sp, dp;
 365             png_uint_32 i;
 366             png_uint_32 row_width = row_info->width;
 367
 368             for (i = 0, sp = dp = row; i < row_width; i++)
 369             {
 370                png_byte save = *(sp++);
 371                *(dp++) = *(sp++);
 372                *(dp++) = save;
 373             }
 374          }
 375
 376 #ifdef PNG_WRITE_16BIT_SUPPORTED
 377          else
 378          {
 379             /* This converts from AAGG to GGAA */
 380             png_bytep sp, dp;
 381             png_uint_32 i;
 382             png_uint_32 row_width = row_info->width;
 383
 384             for (i = 0, sp = dp = row; i < row_width; i++)
 385             {
 386                png_byte save[2];
 387                save[0] = *(sp++);
 388                save[1] = *(sp++);
 389                *(dp++) = *(sp++);
 390                *(dp++) = *(sp++);
 391                *(dp++) = save[0];
 392                *(dp++) = save[1];
 393             }
 394          }
 395 #endif /* WRITE_16BIT */
 396       }
 397    }
 398 }
 399 #endif
 400
 401 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
 402 static void
 403 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
 404 {
 405    png_debug(1, "in png_do_write_invert_alpha");
 406
 407    {
 408       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 409       {
 410          if (row_info->bit_depth == 8)
 411          {
 412             /* This inverts the alpha channel in RGBA */
 413             png_bytep sp, dp;
 414             png_uint_32 i;
 415             png_uint_32 row_width = row_info->width;
 416
 417             for (i = 0, sp = dp = row; i < row_width; i++)
 418             {
 419                /* Does nothing
 420                *(dp++) = *(sp++);
 421                *(dp++) = *(sp++);
 422                *(dp++) = *(sp++);
 423                */
 424                sp+=3; dp = sp;
 425                *(dp++) = (png_byte)(255 - *(sp++));
 426             }
 427          }
 428
 429 #ifdef PNG_WRITE_16BIT_SUPPORTED
 430          else
 431          {
 432             /* This inverts the alpha channel in RRGGBBAA */
 433             png_bytep sp, dp;
 434             png_uint_32 i;
 435             png_uint_32 row_width = row_info->width;
 436
 437             for (i = 0, sp = dp = row; i < row_width; i++)
 438             {
 439                /* Does nothing
 440                *(dp++) = *(sp++);
 441                *(dp++) = *(sp++);
 442                *(dp++) = *(sp++);
 443                *(dp++) = *(sp++);
 444                *(dp++) = *(sp++);
 445                *(dp++) = *(sp++);
 446                */
 447                sp+=6; dp = sp;
 448                *(dp++) = (png_byte)(255 - *(sp++));
 449                *(dp++) = (png_byte)(255 - *(sp++));
 450             }
 451          }
 452 #endif /* WRITE_16BIT */
 453       }
 454
 455       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
 456       {
 457          if (row_info->bit_depth == 8)
 458          {
 459             /* This inverts the alpha channel in GA */
 460             png_bytep sp, dp;
 461             png_uint_32 i;
 462             png_uint_32 row_width = row_info->width;
 463
 464             for (i = 0, sp = dp = row; i < row_width; i++)
 465             {
 466                *(dp++) = *(sp++);
 467                *(dp++) = (png_byte)(255 - *(sp++));
 468             }
 469          }
 470
 471 #ifdef PNG_WRITE_16BIT_SUPPORTED
 472          else
 473          {
 474             /* This inverts the alpha channel in GGAA */
 475             png_bytep sp, dp;
 476             png_uint_32 i;
 477             png_uint_32 row_width = row_info->width;
 478
 479             for (i = 0, sp = dp = row; i < row_width; i++)
 480             {
 481                /* Does nothing
 482                *(dp++) = *(sp++);
 483                *(dp++) = *(sp++);
 484                */
 485                sp+=2; dp = sp;
 486                *(dp++) = (png_byte)(255 - *(sp++));
 487                *(dp++) = (png_byte)(255 - *(sp++));
 488             }
 489          }
 490 #endif /* WRITE_16BIT */
 491       }
 492    }
 493 }
 494 #endif
 495
 496 /* Transform the data according to the user's wishes.  The order of
 497  * transformations is significant.
 498  */
 499 void /* PRIVATE */
 500 png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
 501 {
 502    png_debug(1, "in png_do_write_transformations");
 503
 504    if (png_ptr == NULL)
 505       return;
 506
 507 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
 508    if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
 509       if (png_ptr->write_user_transform_fn != NULL)
 510          (*(png_ptr->write_user_transform_fn)) /* User write transform
 511                                                  function */
 512              (png_ptr,  /* png_ptr */
 513              row_info,  /* row_info: */
 514                 /*  png_uint_32 width;       width of row */
 515                 /*  png_size_t rowbytes;     number of bytes in row */
 516                 /*  png_byte color_type;     color type of pixels */
 517                 /*  png_byte bit_depth;      bit depth of samples */
 518                 /*  png_byte channels;       number of channels (1-4) */
 519                 /*  png_byte pixel_depth;    bits per pixel (depth*channels) */
 520              png_ptr->row_buf + 1);      /* start of pixel data for row */
 521 #endif
 522
 523 #ifdef PNG_WRITE_FILLER_SUPPORTED
 524    if ((png_ptr->transformations & PNG_FILLER) != 0)
 525       png_do_strip_channel(row_info, png_ptr->row_buf + 1,
 526          !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
 527 #endif
 528
 529 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
 530    if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
 531       png_do_packswap(row_info, png_ptr->row_buf + 1);
 532 #endif
 533
 534 #ifdef PNG_WRITE_PACK_SUPPORTED
 535    if ((png_ptr->transformations & PNG_PACK) != 0)
 536       png_do_pack(row_info, png_ptr->row_buf + 1,
 537           (png_uint_32)png_ptr->bit_depth);
 538 #endif
 539
 540 #ifdef PNG_WRITE_SWAP_SUPPORTED
 541 #  ifdef PNG_16BIT_SUPPORTED
 542    if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
 543       png_do_swap(row_info, png_ptr->row_buf + 1);
 544 #  endif
 545 #endif
 546
 547 #ifdef PNG_WRITE_SHIFT_SUPPORTED
 548    if ((png_ptr->transformations & PNG_SHIFT) != 0)
 549       png_do_shift(row_info, png_ptr->row_buf + 1,
 550           &(png_ptr->shift));
 551 #endif
 552
 553 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
 554    if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
 555       png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
 556 #endif
 557
 558 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
 559    if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
 560       png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
 561 #endif
 562
 563 #ifdef PNG_WRITE_BGR_SUPPORTED
 564    if ((png_ptr->transformations & PNG_BGR) != 0)
 565       png_do_bgr(row_info, png_ptr->row_buf + 1);
 566 #endif
 567
 568 #ifdef PNG_WRITE_INVERT_SUPPORTED
 569    if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
 570       png_do_invert(row_info, png_ptr->row_buf + 1);
 571 #endif
 572 }
 573 #endif /* WRITE_TRANSFORMS */
 574 #endif /* WRITE */