src/png/pngwtran.c

   1
   2 /* pngwtran.c - transforms the data in a row for PNG writers
   3  *
   4  * libpng 1.0.1
   5  * For conditions of distribution and use, see copyright notice in png.h
   6  * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
   7  * Copyright (c) 1996, 1997 Andreas Dilger
   8  * Copyright (c) 1998, Glenn Randers-Pehrson
   9  * March 15, 1998
  10  */
  11
  12 #define PNG_INTERNAL
  13 #include "png.h"
  14
  15 /* Transform the data according to the users wishes.  The order of
  16  * transformations is significant.
  17  */
  18 void
  19 png_do_write_transformations(png_structp png_ptr)
  20 {
  21    png_debug(1, "in png_do_write_transformations\n");
  22
  23 #if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
  24    if (png_ptr->transformations & PNG_USER_TRANSFORM)
  25       if(png_ptr->write_user_transform_fn != NULL)
  26         (*(png_ptr->write_user_transform_fn)) /* user write transform function */
  27           (png_ptr,                    /* png_ptr */
  28            &(png_ptr->row_info),       /* row_info:     */
  29              /*  png_uint_32 width;          width of row */
  30              /*  png_uint_32 rowbytes;       number of bytes in row */
  31              /*  png_byte color_type;        color type of pixels */
  32              /*  png_byte bit_depth;         bit depth of samples */
  33              /*  png_byte channels;          number of channels (1-4) */
  34              /*  png_byte pixel_depth;       bits per pixel (depth*channels) */
  35            png_ptr->row_buf + 1);      /* start of pixel data for row */
  36 #endif
  37 #if defined(PNG_WRITE_FILLER_SUPPORTED)
  38    if (png_ptr->transformations & PNG_FILLER)
  39       png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
  40          png_ptr->flags);
  41 #endif
  42 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED)
  43    if (png_ptr->transformations & PNG_PACKSWAP)
  44       png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
  45 #endif
  46 #if defined(PNG_WRITE_PACK_SUPPORTED)
  47    if (png_ptr->transformations & PNG_PACK)
  48       png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
  49          (png_uint_32)png_ptr->bit_depth);
  50 #endif
  51 #if defined(PNG_WRITE_SHIFT_SUPPORTED)
  52    if (png_ptr->transformations & PNG_SHIFT)
  53       png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
  54          &(png_ptr->shift));
  55 #endif
  56 #if defined(PNG_WRITE_SWAP_SUPPORTED)
  57    if (png_ptr->transformations & PNG_SWAP_BYTES)
  58       png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
  59 #endif
  60 #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
  61    if (png_ptr->transformations & PNG_INVERT_ALPHA)
  62       png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
  63 #endif
  64 #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
  65    if (png_ptr->transformations & PNG_SWAP_ALPHA)
  66       png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
  67 #endif
  68 #if defined(PNG_WRITE_BGR_SUPPORTED)
  69    if (png_ptr->transformations & PNG_BGR)
  70       png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
  71 #endif
  72 #if defined(PNG_WRITE_INVERT_SUPPORTED)
  73    if (png_ptr->transformations & PNG_INVERT_MONO)
  74       png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
  75 #endif
  76 }
  77
  78 #if defined(PNG_WRITE_PACK_SUPPORTED)
  79 /* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The
  80  * row_info bit depth should be 8 (one pixel per byte).  The channels
  81  * should be 1 (this only happens on grayscale and paletted images).
  82  */
  83 void
  84 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
  85 {
  86    png_debug(1, "in png_do_pack\n");
  87    if (row_info->bit_depth == 8 &&
  88 #if defined(PNG_USELESS_TESTS_SUPPORTED)
  89        row != NULL && row_info != NULL &&
  90 #endif
  91       row_info->channels == 1)
  92    {
  93       switch ((int)bit_depth)
  94       {
  95          case 1:
  96          {
  97             png_bytep sp, dp;
  98             int mask, v;
  99             png_uint_32 i;
 100
 101             sp = row;
 102             dp = row;
 103             mask = 0x80;
 104             v = 0;
 105             for (i = 0; i < row_info->width; i++)
 106             {
 107                if (*sp != 0)
 108                   v |= mask;
 109                sp++;
 110                if (mask > 1)
 111                   mask >>= 1;
 112                else
 113                {
 114                   mask = 0x80;
 115                   *dp = (png_byte)v;
 116                   dp++;
 117                   v = 0;
 118                }
 119             }
 120             if (mask != 0x80)
 121                *dp = (png_byte)v;
 122             break;
 123          }
 124          case 2:
 125          {
 126             png_bytep sp, dp;
 127             int shift, v;
 128             png_uint_32 i;
 129
 130             sp = row;
 131             dp = row;
 132             shift = 6;
 133             v = 0;
 134             for (i = 0; i < row_info->width; i++)
 135             {
 136                png_byte value;
 137
 138                value = (png_byte)(*sp & 0x3);
 139                v |= (value << shift);
 140                if (shift == 0)
 141                {
 142                   shift = 6;
 143                   *dp = (png_byte)v;
 144                   dp++;
 145                   v = 0;
 146                }
 147                else
 148                   shift -= 2;
 149                sp++;
 150             }
 151             if (shift != 6)
 152                *dp = (png_byte)v;
 153             break;
 154          }
 155          case 4:
 156          {
 157             png_bytep sp, dp;
 158             int shift, v;
 159             png_uint_32 i;
 160
 161             sp = row;
 162             dp = row;
 163             shift = 4;
 164             v = 0;
 165             for (i = 0; i < row_info->width; i++)
 166             {
 167                png_byte value;
 168
 169                value = (png_byte)(*sp & 0xf);
 170                v |= (value << shift);
 171
 172                if (shift == 0)
 173                {
 174                   shift = 4;
 175                   *dp = (png_byte)v;
 176                   dp++;
 177                   v = 0;
 178                }
 179                else
 180                   shift -= 4;
 181
 182                sp++;
 183             }
 184             if (shift != 4)
 185                *dp = (png_byte)v;
 186             break;
 187          }
 188       }
 189       row_info->bit_depth = (png_byte)bit_depth;
 190       row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
 191       row_info->rowbytes =
 192          ((row_info->width * row_info->pixel_depth + 7) >> 3);
 193    }
 194 }
 195 #endif
 196
 197 #if defined(PNG_WRITE_SHIFT_SUPPORTED)
 198 /* Shift pixel values to take advantage of whole range.  Pass the
 199  * true number of bits in bit_depth.  The row should be packed
 200  * according to row_info->bit_depth.  Thus, if you had a row of
 201  * bit depth 4, but the pixels only had values from 0 to 7, you
 202  * would pass 3 as bit_depth, and this routine would translate the
 203  * data to 0 to 15.
 204  */
 205 void
 206 png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
 207 {
 208    png_debug(1, "in png_do_shift\n");
 209 #if defined(PNG_USELESS_TESTS_SUPPORTED)
 210    if (row != NULL && row_info != NULL &&
 211 #else
 212    if (
 213 #endif
 214       row_info->color_type != PNG_COLOR_TYPE_PALETTE)
 215    {
 216       int shift_start[4], shift_dec[4];
 217       png_uint_32 channels;
 218
 219       channels = 0;
 220       if (row_info->color_type & PNG_COLOR_MASK_COLOR)
 221       {
 222          shift_start[channels] = row_info->bit_depth - bit_depth->red;
 223          shift_dec[channels] = bit_depth->red;
 224          channels++;
 225          shift_start[channels] = row_info->bit_depth - bit_depth->green;
 226          shift_dec[channels] = bit_depth->green;
 227          channels++;
 228          shift_start[channels] = row_info->bit_depth - bit_depth->blue;
 229          shift_dec[channels] = bit_depth->blue;
 230          channels++;
 231       }
 232       else
 233       {
 234          shift_start[channels] = row_info->bit_depth - bit_depth->gray;
 235          shift_dec[channels] = bit_depth->gray;
 236          channels++;
 237       }
 238       if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
 239       {
 240          shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
 241          shift_dec[channels] = bit_depth->alpha;
 242          channels++;
 243       }
 244
 245       /* with low row depths, could only be grayscale, so one channel */
 246       if (row_info->bit_depth < 8)
 247       {
 248          png_bytep bp;
 249          png_uint_32 i;
 250          png_byte mask;
 251
 252          if (bit_depth->gray == 1 && row_info->bit_depth == 2)
 253             mask = 0x55;
 254          else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
 255             mask = 0x11;
 256          else
 257             mask = 0xff;
 258
 259          for (bp = row, i = 0; i < row_info->rowbytes; i++, bp++)
 260          {
 261             png_uint_16 v;
 262             int j;
 263
 264             v = *bp;
 265             *bp = 0;
 266             for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
 267             {
 268                if (j > 0)
 269                   *bp |= (png_byte)((v << j) & 0xff);
 270                else
 271                   *bp |= (png_byte)((v >> (-j)) & mask);
 272             }
 273          }
 274       }
 275       else if (row_info->bit_depth == 8)
 276       {
 277          png_bytep bp;
 278          png_uint_32 i;
 279
 280          for (bp = row, i = 0; i < row_info->width; i++)
 281          {
 282             png_uint_32 c;
 283
 284             for (c = 0; c < channels; c++, bp++)
 285             {
 286                png_uint_16 v;
 287                int j;
 288
 289                v = *bp;
 290                *bp = 0;
 291                for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
 292                {
 293                   if (j > 0)
 294                      *bp |= (png_byte)((v << j) & 0xff);
 295                   else
 296                      *bp |= (png_byte)((v >> (-j)) & 0xff);
 297                }
 298             }
 299          }
 300       }
 301       else
 302       {
 303          png_bytep bp;
 304          png_uint_32 i;
 305
 306          for (bp = row, i = 0; i < row_info->width * row_info->channels; i++)
 307          {
 308             png_uint_32 c;
 309
 310             for (c = 0; c < channels; c++, bp += 2)
 311             {
 312                png_uint_16 value, v;
 313                int j;
 314
 315                v = ((png_uint_16)(*bp) << 8) + *(bp + 1);
 316                value = 0;
 317                for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
 318                {
 319                   if (j > 0)
 320                      value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
 321                   else
 322                      value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
 323                }
 324                *bp = (png_byte)(value >> 8);
 325                *(bp + 1) = (png_byte)(value & 0xff);
 326             }
 327          }
 328       }
 329    }
 330 }
 331 #endif
 332
 333 #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
 334 void
 335 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
 336 {
 337    png_debug(1, "in png_do_write_swap_alpha\n");
 338 #if defined(PNG_USELESS_TESTS_SUPPORTED)
 339    if (row != NULL && row_info != NULL)
 340 #endif
 341    {
 342       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 343       {
 344          /* This converts from ARGB to RGBA */
 345          if (row_info->bit_depth == 8)
 346          {
 347             png_bytep sp, dp;
 348             png_byte save;
 349             png_uint_32 i;
 350
 351             for (i = 0, sp = dp = row; i < row_info->width; i++)
 352             {
 353                save = *(sp++);
 354                *(dp++) = *(sp++);
 355                *(dp++) = *(sp++);
 356                *(dp++) = *(sp++);
 357                *(dp++) = save;
 358             }
 359          }
 360          /* This converts from AARRGGBB to RRGGBBAA */
 361          else
 362          {
 363             png_bytep sp, dp;
 364             png_byte save[2];
 365             png_uint_32 i;
 366
 367             for (i = 0, sp = dp = row; i < row_info->width; i++)
 368             {
 369                save[0] = *(sp++);
 370                save[1] = *(sp++);
 371                *(dp++) = *(sp++);
 372                *(dp++) = *(sp++);
 373                *(dp++) = *(sp++);
 374                *(dp++) = *(sp++);
 375                *(dp++) = *(sp++);
 376                *(dp++) = *(sp++);
 377                *(dp++) = save[0];
 378                *(dp++) = save[1];
 379             }
 380          }
 381       }
 382       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
 383       {
 384          /* This converts from AG to GA */
 385          if (row_info->bit_depth == 8)
 386          {
 387             png_bytep sp, dp;
 388             png_byte save;
 389             png_uint_32 i;
 390
 391             for (i = 0, sp = dp = row; i < row_info->width; i++)
 392             {
 393                save = *(sp++);
 394                *(dp++) = *(sp++);
 395                *(dp++) = save;
 396             }
 397          }
 398          /* This converts from AAGG to GGAA */
 399          else
 400          {
 401             png_bytep sp, dp;
 402             png_byte save[2];
 403             png_uint_32 i;
 404
 405             for (i = 0, sp = dp = row; i < row_info->width; i++)
 406             {
 407                save[0] = *(sp++);
 408                save[1] = *(sp++);
 409                *(dp++) = *(sp++);
 410                *(dp++) = *(sp++);
 411                *(dp++) = save[0];
 412                *(dp++) = save[1];
 413             }
 414          }
 415       }
 416    }
 417 }
 418 #endif
 419
 420 #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
 421 void
 422 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
 423 {
 424    png_debug(1, "in png_do_write_invert_alpha\n");
 425 #if defined(PNG_USELESS_TESTS_SUPPORTED)
 426    if (row != NULL && row_info != NULL)
 427 #endif
 428    {
 429       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 430       {
 431          /* This inverts the alpha channel in RGBA */
 432          if (row_info->bit_depth == 8)
 433          {
 434             png_bytep sp, dp;
 435             png_uint_32 i;
 436
 437             for (i = 0, sp = dp = row; i < row_info->width; i++)
 438             {
 439                *(dp++) = *(sp++);
 440                *(dp++) = *(sp++);
 441                *(dp++) = *(sp++);
 442                *(dp++) = 255 - *(sp++);
 443             }
 444          }
 445          /* This inverts the alpha channel in RRGGBBAA */
 446          else
 447          {
 448             png_bytep sp, dp;
 449             png_uint_32 i;
 450
 451             for (i = 0, sp = dp = row; i < row_info->width; i++)
 452             {
 453                *(dp++) = *(sp++);
 454                *(dp++) = *(sp++);
 455                *(dp++) = *(sp++);
 456                *(dp++) = *(sp++);
 457                *(dp++) = *(sp++);
 458                *(dp++) = *(sp++);
 459                *(dp++) = 255 - *(sp++);
 460                *(dp++) = 255 - *(sp++);
 461             }
 462          }
 463       }
 464       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
 465       {
 466          /* This inverts the alpha channel in GA */
 467          if (row_info->bit_depth == 8)
 468          {
 469             png_bytep sp, dp;
 470             png_uint_32 i;
 471
 472             for (i = 0, sp = dp = row; i < row_info->width; i++)
 473             {
 474                *(dp++) = *(sp++);
 475                *(dp++) = 255 - *(sp++);
 476             }
 477          }
 478          /* This inverts the alpha channel in GGAA */
 479          else
 480          {
 481             png_bytep sp, dp;
 482             png_uint_32 i;
 483
 484             for (i = 0, sp = dp = row; i < row_info->width; i++)
 485             {
 486                *(dp++) = *(sp++);
 487                *(dp++) = *(sp++);
 488                *(dp++) = 255 - *(sp++);
 489                *(dp++) = 255 - *(sp++);
 490             }
 491          }
 492       }
 493    }
 494 }
 495 #endif