src/png/pngwtran.c

   1
   2 /* pngwtran.c - transforms the data in a row for PNG writers
   3  *
   4  * libpng 1.0.3 - January 14, 1999
   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, 1999 Glenn Randers-Pehrson
   9  */
  10
  11 #define PNG_INTERNAL
  12 #include "png.h"
  13
  14 /* Transform the data according to the user's wishes.  The order of
  15  * transformations is significant.
  16  */
  17 void
  18 png_do_write_transformations(png_structp png_ptr)
  19 {
  20    png_debug(1, "in png_do_write_transformations\n");
  21
  22 #if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
  23    if (png_ptr->transformations & PNG_USER_TRANSFORM)
  24       if(png_ptr->write_user_transform_fn != NULL)
  25         (*(png_ptr->write_user_transform_fn)) /* user write transform function */
  26           (png_ptr,                    /* png_ptr */
  27            &(png_ptr->row_info),       /* row_info:     */
  28              /*  png_uint_32 width;          width of row */
  29              /*  png_uint_32 rowbytes;       number of bytes in row */
  30              /*  png_byte color_type;        color type of pixels */
  31              /*  png_byte bit_depth;         bit depth of samples */
  32              /*  png_byte channels;          number of channels (1-4) */
  33              /*  png_byte pixel_depth;       bits per pixel (depth*channels) */
  34            png_ptr->row_buf + 1);      /* start of pixel data for row */
  35 #endif
  36 #if defined(PNG_WRITE_FILLER_SUPPORTED)
  37    if (png_ptr->transformations & PNG_FILLER)
  38       png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
  39          png_ptr->flags);
  40 #endif
  41 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED)
  42    if (png_ptr->transformations & PNG_PACKSWAP)
  43       png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
  44 #endif
  45 #if defined(PNG_WRITE_PACK_SUPPORTED)
  46    if (png_ptr->transformations & PNG_PACK)
  47       png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
  48          (png_uint_32)png_ptr->bit_depth);
  49 #endif
  50 #if defined(PNG_WRITE_SWAP_SUPPORTED)
  51    if (png_ptr->transformations & PNG_SWAP_BYTES)
  52       png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
  53 #endif
  54 #if defined(PNG_WRITE_SHIFT_SUPPORTED)
  55    if (png_ptr->transformations & PNG_SHIFT)
  56       png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
  57          &(png_ptr->shift));
  58 #endif
  59 #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
  60    if (png_ptr->transformations & PNG_INVERT_ALPHA)
  61       png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
  62 #endif
  63 #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
  64    if (png_ptr->transformations & PNG_SWAP_ALPHA)
  65       png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
  66 #endif
  67 #if defined(PNG_WRITE_BGR_SUPPORTED)
  68    if (png_ptr->transformations & PNG_BGR)
  69       png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
  70 #endif
  71 #if defined(PNG_WRITE_INVERT_SUPPORTED)
  72    if (png_ptr->transformations & PNG_INVERT_MONO)
  73       png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
  74 #endif
  75 }
  76
  77 #if defined(PNG_WRITE_PACK_SUPPORTED)
  78 /* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The
  79  * row_info bit depth should be 8 (one pixel per byte).  The channels
  80  * should be 1 (this only happens on grayscale and paletted images).
  81  */
  82 void
  83 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
  84 {
  85    png_debug(1, "in png_do_pack\n");
  86    if (row_info->bit_depth == 8 &&
  87 #if defined(PNG_USELESS_TESTS_SUPPORTED)
  88        row != NULL && row_info != NULL &&
  89 #endif
  90       row_info->channels == 1)
  91    {
  92       switch ((int)bit_depth)
  93       {
  94          case 1:
  95          {
  96             png_bytep sp, dp;
  97             int mask, v;
  98             png_uint_32 i;
  99             png_uint_32 row_width = row_info->width;
 100
 101             sp = row;
 102             dp = row;
 103             mask = 0x80;
 104             v = 0;
 105
 106             for (i = 0; i < row_width; i++)
 107             {
 108                if (*sp != 0)
 109                   v |= mask;
 110                sp++;
 111                if (mask > 1)
 112                   mask >>= 1;
 113                else
 114                {
 115                   mask = 0x80;
 116                   *dp = (png_byte)v;
 117                   dp++;
 118                   v = 0;
 119                }
 120             }
 121             if (mask != 0x80)
 122                *dp = (png_byte)v;
 123             break;
 124          }
 125          case 2:
 126          {
 127             png_bytep sp, dp;
 128             int shift, v;
 129             png_uint_32 i;
 130             png_uint_32 row_width = row_info->width;
 131
 132             sp = row;
 133             dp = row;
 134             shift = 6;
 135             v = 0;
 136             for (i = 0; i < row_width; i++)
 137             {
 138                png_byte value;
 139
 140                value = (png_byte)(*sp & 0x3);
 141                v |= (value << shift);
 142                if (shift == 0)
 143                {
 144                   shift = 6;
 145                   *dp = (png_byte)v;
 146                   dp++;
 147                   v = 0;
 148                }
 149                else
 150                   shift -= 2;
 151                sp++;
 152             }
 153             if (shift != 6)
 154                *dp = (png_byte)v;
 155             break;
 156          }
 157          case 4:
 158          {
 159             png_bytep sp, dp;
 160             int shift, v;
 161             png_uint_32 i;
 162             png_uint_32 row_width = row_info->width;
 163
 164             sp = row;
 165             dp = row;
 166             shift = 4;
 167             v = 0;
 168             for (i = 0; i < row_width; i++)
 169             {
 170                png_byte value;
 171
 172                value = (png_byte)(*sp & 0xf);
 173                v |= (value << shift);
 174
 175                if (shift == 0)
 176                {
 177                   shift = 4;
 178                   *dp = (png_byte)v;
 179                   dp++;
 180                   v = 0;
 181                }
 182                else
 183                   shift -= 4;
 184
 185                sp++;
 186             }
 187             if (shift != 4)
 188                *dp = (png_byte)v;
 189             break;
 190          }
 191       }
 192       row_info->bit_depth = (png_byte)bit_depth;
 193       row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
 194       row_info->rowbytes =
 195          ((row_info->width * row_info->pixel_depth + 7) >> 3);
 196    }
 197 }
 198 #endif
 199
 200 #if defined(PNG_WRITE_SHIFT_SUPPORTED)
 201 /* Shift pixel values to take advantage of whole range.  Pass the
 202  * true number of bits in bit_depth.  The row should be packed
 203  * according to row_info->bit_depth.  Thus, if you had a row of
 204  * bit depth 4, but the pixels only had values from 0 to 7, you
 205  * would pass 3 as bit_depth, and this routine would translate the
 206  * data to 0 to 15.
 207  */
 208 void
 209 png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
 210 {
 211    png_debug(1, "in png_do_shift\n");
 212 #if defined(PNG_USELESS_TESTS_SUPPORTED)
 213    if (row != NULL && row_info != NULL &&
 214 #else
 215    if (
 216 #endif
 217       row_info->color_type != PNG_COLOR_TYPE_PALETTE)
 218    {
 219       int shift_start[4], shift_dec[4];
 220       int channels = 0;
 221
 222       if (row_info->color_type & PNG_COLOR_MASK_COLOR)
 223       {
 224          shift_start[channels] = row_info->bit_depth - bit_depth->red;
 225          shift_dec[channels] = bit_depth->red;
 226          channels++;
 227          shift_start[channels] = row_info->bit_depth - bit_depth->green;
 228          shift_dec[channels] = bit_depth->green;
 229          channels++;
 230          shift_start[channels] = row_info->bit_depth - bit_depth->blue;
 231          shift_dec[channels] = bit_depth->blue;
 232          channels++;
 233       }
 234       else
 235       {
 236          shift_start[channels] = row_info->bit_depth - bit_depth->gray;
 237          shift_dec[channels] = bit_depth->gray;
 238          channels++;
 239       }
 240       if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
 241       {
 242          shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
 243          shift_dec[channels] = bit_depth->alpha;
 244          channels++;
 245       }
 246
 247       /* with low row depths, could only be grayscale, so one channel */
 248       if (row_info->bit_depth < 8)
 249       {
 250          png_bytep bp = row;
 251          png_uint_32 i;
 252          png_byte mask;
 253          png_uint_32 row_bytes = row_info->rowbytes;
 254
 255          if (bit_depth->gray == 1 && row_info->bit_depth == 2)
 256             mask = 0x55;
 257          else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
 258             mask = 0x11;
 259          else
 260             mask = 0xff;
 261
 262          for (i = 0; i < row_bytes; i++, bp++)
 263          {
 264             png_uint_16 v;
 265             int j;
 266
 267             v = *bp;
 268             *bp = 0;
 269             for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
 270             {
 271                if (j > 0)
 272                   *bp |= (png_byte)((v << j) & 0xff);
 273                else
 274                   *bp |= (png_byte)((v >> (-j)) & mask);
 275             }
 276          }
 277       }
 278       else if (row_info->bit_depth == 8)
 279       {
 280          png_bytep bp = row;
 281          png_uint_32 i;
 282          png_uint_32 istop = channels * row_info->width;
 283
 284          for (i = 0; i < istop; i++, bp++)
 285          {
 286
 287             png_uint_16 v;
 288             int j;
 289             int c = (int)(i%channels);
 290
 291             v = *bp;
 292             *bp = 0;
 293             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
 294             {
 295                if (j > 0)
 296                   *bp |= (png_byte)((v << j) & 0xff);
 297                else
 298                   *bp |= (png_byte)((v >> (-j)) & 0xff);
 299             }
 300          }
 301       }
 302       else
 303       {
 304          png_bytep bp;
 305          png_uint_32 i;
 306          png_uint_32 istop = channels * row_info->width;
 307
 308          for (bp = row, i = 0; i < istop; i++)
 309          {
 310             int c = (int)(i%channels);
 311             png_uint_16 value, v;
 312             int j;
 313
 314             v = ((png_uint_16)(*bp) << 8) + *(bp + 1);
 315             value = 0;
 316             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
 317             {
 318                if (j > 0)
 319                   value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
 320                else
 321                   value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
 322             }
 323             *bp++ = (png_byte)(value >> 8);
 324             *bp++ = (png_byte)(value & 0xff);
 325          }
 326       }
 327    }
 328 }
 329 #endif
 330
 331 #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
 332 void
 333 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
 334 {
 335    png_debug(1, "in png_do_write_swap_alpha\n");
 336 #if defined(PNG_USELESS_TESTS_SUPPORTED)
 337    if (row != NULL && row_info != NULL)
 338 #endif
 339    {
 340       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 341       {
 342          /* This converts from ARGB to RGBA */
 343          if (row_info->bit_depth == 8)
 344          {
 345             png_bytep sp, dp;
 346             png_uint_32 i;
 347             png_uint_32 row_width = row_info->width;
 348             for (i = 0, sp = dp = row; i < row_width; i++)
 349             {
 350                png_byte save = *(sp++);
 351                *(dp++) = *(sp++);
 352                *(dp++) = *(sp++);
 353                *(dp++) = *(sp++);
 354                *(dp++) = save;
 355             }
 356          }
 357          /* This converts from AARRGGBB to RRGGBBAA */
 358          else
 359          {
 360             png_bytep sp, dp;
 361             png_uint_32 i;
 362             png_uint_32 row_width = row_info->width;
 363
 364             for (i = 0, sp = dp = row; i < row_width; i++)
 365             {
 366                png_byte save[2];
 367                save[0] = *(sp++);
 368                save[1] = *(sp++);
 369                *(dp++) = *(sp++);
 370                *(dp++) = *(sp++);
 371                *(dp++) = *(sp++);
 372                *(dp++) = *(sp++);
 373                *(dp++) = *(sp++);
 374                *(dp++) = *(sp++);
 375                *(dp++) = save[0];
 376                *(dp++) = save[1];
 377             }
 378          }
 379       }
 380       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
 381       {
 382          /* This converts from AG to GA */
 383          if (row_info->bit_depth == 8)
 384          {
 385             png_bytep sp, dp;
 386             png_uint_32 i;
 387             png_uint_32 row_width = row_info->width;
 388
 389             for (i = 0, sp = dp = row; i < row_width; i++)
 390             {
 391                png_byte save = *(sp++);
 392                *(dp++) = *(sp++);
 393                *(dp++) = save;
 394             }
 395          }
 396          /* This converts from AAGG to GGAA */
 397          else
 398          {
 399             png_bytep sp, dp;
 400             png_uint_32 i;
 401             png_uint_32 row_width = row_info->width;
 402
 403             for (i = 0, sp = dp = row; i < row_width; i++)
 404             {
 405                png_byte save[2];
 406                save[0] = *(sp++);
 407                save[1] = *(sp++);
 408                *(dp++) = *(sp++);
 409                *(dp++) = *(sp++);
 410                *(dp++) = save[0];
 411                *(dp++) = save[1];
 412             }
 413          }
 414       }
 415    }
 416 }
 417 #endif
 418
 419 #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
 420 void
 421 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
 422 {
 423    png_debug(1, "in png_do_write_invert_alpha\n");
 424 #if defined(PNG_USELESS_TESTS_SUPPORTED)
 425    if (row != NULL && row_info != NULL)
 426 #endif
 427    {
 428       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 429       {
 430          /* This inverts the alpha channel in RGBA */
 431          if (row_info->bit_depth == 8)
 432          {
 433             png_bytep sp, dp;
 434             png_uint_32 i;
 435             png_uint_32 row_width = row_info->width;
 436             for (i = 0, sp = dp = row; i < row_width; i++)
 437             {
 438                *(dp++) = *(sp++);
 439                *(dp++) = *(sp++);
 440                *(dp++) = *(sp++);
 441                *(dp++) = 255 - *(sp++);
 442             }
 443          }
 444          /* This inverts the alpha channel in RRGGBBAA */
 445          else
 446          {
 447             png_bytep sp, dp;
 448             png_uint_32 i;
 449             png_uint_32 row_width = row_info->width;
 450
 451             for (i = 0, sp = dp = row; i < row_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             png_uint_32 row_width = row_info->width;
 472
 473             for (i = 0, sp = dp = row; i < row_width; i++)
 474             {
 475                *(dp++) = *(sp++);
 476                *(dp++) = 255 - *(sp++);
 477             }
 478          }
 479          /* This inverts the alpha channel in GGAA */
 480          else
 481          {
 482             png_bytep sp, dp;
 483             png_uint_32 i;
 484             png_uint_32 row_width = row_info->width;
 485
 486             for (i = 0, sp = dp = row; i < row_width; i++)
 487             {
 488                *(dp++) = *(sp++);
 489                *(dp++) = *(sp++);
 490                *(dp++) = 255 - *(sp++);
 491                *(dp++) = 255 - *(sp++);
 492             }
 493          }
 494       }
 495    }
 496 }
 497 #endif