nuclear@2: 
nuclear@2: /* pngwtran.c - transforms the data in a row for PNG writers
nuclear@2:  *
nuclear@2:  * Last changed in libpng 1.2.9 April 14, 2006
nuclear@2:  * For conditions of distribution and use, see copyright notice in png.h
nuclear@2:  * Copyright (c) 1998-2006 Glenn Randers-Pehrson
nuclear@2:  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
nuclear@2:  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
nuclear@2:  */
nuclear@2: 
nuclear@2: #define PNG_INTERNAL
nuclear@2: #include "png.h"
nuclear@2: #ifdef PNG_WRITE_SUPPORTED
nuclear@2: 
nuclear@2: /* Transform the data according to the user's wishes.  The order of
nuclear@2:  * transformations is significant.
nuclear@2:  */
nuclear@2: void /* PRIVATE */
nuclear@2: png_do_write_transformations(png_structp png_ptr)
nuclear@2: {
nuclear@2:    png_debug(1, "in png_do_write_transformations\n");
nuclear@2: 
nuclear@2:    if (png_ptr == NULL)
nuclear@2:       return;
nuclear@2: 
nuclear@2: #if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
nuclear@2:    if (png_ptr->transformations & PNG_USER_TRANSFORM)
nuclear@2:       if (png_ptr->write_user_transform_fn != NULL)
nuclear@2:         (*(png_ptr->write_user_transform_fn)) /* user write transform function */
nuclear@2:           (png_ptr,                    /* png_ptr */
nuclear@2:            &(png_ptr->row_info),       /* row_info:     */
nuclear@2:              /*  png_uint_32 width;          width of row */
nuclear@2:              /*  png_uint_32 rowbytes;       number of bytes in row */
nuclear@2:              /*  png_byte color_type;        color type of pixels */
nuclear@2:              /*  png_byte bit_depth;         bit depth of samples */
nuclear@2:              /*  png_byte channels;          number of channels (1-4) */
nuclear@2:              /*  png_byte pixel_depth;       bits per pixel (depth*channels) */
nuclear@2:            png_ptr->row_buf + 1);      /* start of pixel data for row */
nuclear@2: #endif
nuclear@2: #if defined(PNG_WRITE_FILLER_SUPPORTED)
nuclear@2:    if (png_ptr->transformations & PNG_FILLER)
nuclear@2:       png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
nuclear@2:          png_ptr->flags);
nuclear@2: #endif
nuclear@2: #if defined(PNG_WRITE_PACKSWAP_SUPPORTED)
nuclear@2:    if (png_ptr->transformations & PNG_PACKSWAP)
nuclear@2:       png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
nuclear@2: #endif
nuclear@2: #if defined(PNG_WRITE_PACK_SUPPORTED)
nuclear@2:    if (png_ptr->transformations & PNG_PACK)
nuclear@2:       png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
nuclear@2:          (png_uint_32)png_ptr->bit_depth);
nuclear@2: #endif
nuclear@2: #if defined(PNG_WRITE_SWAP_SUPPORTED)
nuclear@2:    if (png_ptr->transformations & PNG_SWAP_BYTES)
nuclear@2:       png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
nuclear@2: #endif
nuclear@2: #if defined(PNG_WRITE_SHIFT_SUPPORTED)
nuclear@2:    if (png_ptr->transformations & PNG_SHIFT)
nuclear@2:       png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
nuclear@2:          &(png_ptr->shift));
nuclear@2: #endif
nuclear@2: #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
nuclear@2:    if (png_ptr->transformations & PNG_SWAP_ALPHA)
nuclear@2:       png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
nuclear@2: #endif
nuclear@2: #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
nuclear@2:    if (png_ptr->transformations & PNG_INVERT_ALPHA)
nuclear@2:       png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
nuclear@2: #endif
nuclear@2: #if defined(PNG_WRITE_BGR_SUPPORTED)
nuclear@2:    if (png_ptr->transformations & PNG_BGR)
nuclear@2:       png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
nuclear@2: #endif
nuclear@2: #if defined(PNG_WRITE_INVERT_SUPPORTED)
nuclear@2:    if (png_ptr->transformations & PNG_INVERT_MONO)
nuclear@2:       png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
nuclear@2: #endif
nuclear@2: }
nuclear@2: 
nuclear@2: #if defined(PNG_WRITE_PACK_SUPPORTED)
nuclear@2: /* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The
nuclear@2:  * row_info bit depth should be 8 (one pixel per byte).  The channels
nuclear@2:  * should be 1 (this only happens on grayscale and paletted images).
nuclear@2:  */
nuclear@2: void /* PRIVATE */
nuclear@2: png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
nuclear@2: {
nuclear@2:    png_debug(1, "in png_do_pack\n");
nuclear@2:    if (row_info->bit_depth == 8 &&
nuclear@2: #if defined(PNG_USELESS_TESTS_SUPPORTED)
nuclear@2:        row != NULL && row_info != NULL &&
nuclear@2: #endif
nuclear@2:       row_info->channels == 1)
nuclear@2:    {
nuclear@2:       switch ((int)bit_depth)
nuclear@2:       {
nuclear@2:          case 1:
nuclear@2:          {
nuclear@2:             png_bytep sp, dp;
nuclear@2:             int mask, v;
nuclear@2:             png_uint_32 i;
nuclear@2:             png_uint_32 row_width = row_info->width;
nuclear@2: 
nuclear@2:             sp = row;
nuclear@2:             dp = row;
nuclear@2:             mask = 0x80;
nuclear@2:             v = 0;
nuclear@2: 
nuclear@2:             for (i = 0; i < row_width; i++)
nuclear@2:             {
nuclear@2:                if (*sp != 0)
nuclear@2:                   v |= mask;
nuclear@2:                sp++;
nuclear@2:                if (mask > 1)
nuclear@2:                   mask >>= 1;
nuclear@2:                else
nuclear@2:                {
nuclear@2:                   mask = 0x80;
nuclear@2:                   *dp = (png_byte)v;
nuclear@2:                   dp++;
nuclear@2:                   v = 0;
nuclear@2:                }
nuclear@2:             }
nuclear@2:             if (mask != 0x80)
nuclear@2:                *dp = (png_byte)v;
nuclear@2:             break;
nuclear@2:          }
nuclear@2:          case 2:
nuclear@2:          {
nuclear@2:             png_bytep sp, dp;
nuclear@2:             int shift, v;
nuclear@2:             png_uint_32 i;
nuclear@2:             png_uint_32 row_width = row_info->width;
nuclear@2: 
nuclear@2:             sp = row;
nuclear@2:             dp = row;
nuclear@2:             shift = 6;
nuclear@2:             v = 0;
nuclear@2:             for (i = 0; i < row_width; i++)
nuclear@2:             {
nuclear@2:                png_byte value;
nuclear@2: 
nuclear@2:                value = (png_byte)(*sp & 0x03);
nuclear@2:                v |= (value << shift);
nuclear@2:                if (shift == 0)
nuclear@2:                {
nuclear@2:                   shift = 6;
nuclear@2:                   *dp = (png_byte)v;
nuclear@2:                   dp++;
nuclear@2:                   v = 0;
nuclear@2:                }
nuclear@2:                else
nuclear@2:                   shift -= 2;
nuclear@2:                sp++;
nuclear@2:             }
nuclear@2:             if (shift != 6)
nuclear@2:                *dp = (png_byte)v;
nuclear@2:             break;
nuclear@2:          }
nuclear@2:          case 4:
nuclear@2:          {
nuclear@2:             png_bytep sp, dp;
nuclear@2:             int shift, v;
nuclear@2:             png_uint_32 i;
nuclear@2:             png_uint_32 row_width = row_info->width;
nuclear@2: 
nuclear@2:             sp = row;
nuclear@2:             dp = row;
nuclear@2:             shift = 4;
nuclear@2:             v = 0;
nuclear@2:             for (i = 0; i < row_width; i++)
nuclear@2:             {
nuclear@2:                png_byte value;
nuclear@2: 
nuclear@2:                value = (png_byte)(*sp & 0x0f);
nuclear@2:                v |= (value << shift);
nuclear@2: 
nuclear@2:                if (shift == 0)
nuclear@2:                {
nuclear@2:                   shift = 4;
nuclear@2:                   *dp = (png_byte)v;
nuclear@2:                   dp++;
nuclear@2:                   v = 0;
nuclear@2:                }
nuclear@2:                else
nuclear@2:                   shift -= 4;
nuclear@2: 
nuclear@2:                sp++;
nuclear@2:             }
nuclear@2:             if (shift != 4)
nuclear@2:                *dp = (png_byte)v;
nuclear@2:             break;
nuclear@2:          }
nuclear@2:       }
nuclear@2:       row_info->bit_depth = (png_byte)bit_depth;
nuclear@2:       row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
nuclear@2:       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
nuclear@2:          row_info->width);
nuclear@2:    }
nuclear@2: }
nuclear@2: #endif
nuclear@2: 
nuclear@2: #if defined(PNG_WRITE_SHIFT_SUPPORTED)
nuclear@2: /* Shift pixel values to take advantage of whole range.  Pass the
nuclear@2:  * true number of bits in bit_depth.  The row should be packed
nuclear@2:  * according to row_info->bit_depth.  Thus, if you had a row of
nuclear@2:  * bit depth 4, but the pixels only had values from 0 to 7, you
nuclear@2:  * would pass 3 as bit_depth, and this routine would translate the
nuclear@2:  * data to 0 to 15.
nuclear@2:  */
nuclear@2: void /* PRIVATE */
nuclear@2: png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
nuclear@2: {
nuclear@2:    png_debug(1, "in png_do_shift\n");
nuclear@2: #if defined(PNG_USELESS_TESTS_SUPPORTED)
nuclear@2:    if (row != NULL && row_info != NULL &&
nuclear@2: #else
nuclear@2:    if (
nuclear@2: #endif
nuclear@2:       row_info->color_type != PNG_COLOR_TYPE_PALETTE)
nuclear@2:    {
nuclear@2:       int shift_start[4], shift_dec[4];
nuclear@2:       int channels = 0;
nuclear@2: 
nuclear@2:       if (row_info->color_type & PNG_COLOR_MASK_COLOR)
nuclear@2:       {
nuclear@2:          shift_start[channels] = row_info->bit_depth - bit_depth->red;
nuclear@2:          shift_dec[channels] = bit_depth->red;
nuclear@2:          channels++;
nuclear@2:          shift_start[channels] = row_info->bit_depth - bit_depth->green;
nuclear@2:          shift_dec[channels] = bit_depth->green;
nuclear@2:          channels++;
nuclear@2:          shift_start[channels] = row_info->bit_depth - bit_depth->blue;
nuclear@2:          shift_dec[channels] = bit_depth->blue;
nuclear@2:          channels++;
nuclear@2:       }
nuclear@2:       else
nuclear@2:       {
nuclear@2:          shift_start[channels] = row_info->bit_depth - bit_depth->gray;
nuclear@2:          shift_dec[channels] = bit_depth->gray;
nuclear@2:          channels++;
nuclear@2:       }
nuclear@2:       if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
nuclear@2:       {
nuclear@2:          shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
nuclear@2:          shift_dec[channels] = bit_depth->alpha;
nuclear@2:          channels++;
nuclear@2:       }
nuclear@2: 
nuclear@2:       /* with low row depths, could only be grayscale, so one channel */
nuclear@2:       if (row_info->bit_depth < 8)
nuclear@2:       {
nuclear@2:          png_bytep bp = row;
nuclear@2:          png_uint_32 i;
nuclear@2:          png_byte mask;
nuclear@2:          png_uint_32 row_bytes = row_info->rowbytes;
nuclear@2: 
nuclear@2:          if (bit_depth->gray == 1 && row_info->bit_depth == 2)
nuclear@2:             mask = 0x55;
nuclear@2:          else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
nuclear@2:             mask = 0x11;
nuclear@2:          else
nuclear@2:             mask = 0xff;
nuclear@2: 
nuclear@2:          for (i = 0; i < row_bytes; i++, bp++)
nuclear@2:          {
nuclear@2:             png_uint_16 v;
nuclear@2:             int j;
nuclear@2: 
nuclear@2:             v = *bp;
nuclear@2:             *bp = 0;
nuclear@2:             for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
nuclear@2:             {
nuclear@2:                if (j > 0)
nuclear@2:                   *bp |= (png_byte)((v << j) & 0xff);
nuclear@2:                else
nuclear@2:                   *bp |= (png_byte)((v >> (-j)) & mask);
nuclear@2:             }
nuclear@2:          }
nuclear@2:       }
nuclear@2:       else if (row_info->bit_depth == 8)
nuclear@2:       {
nuclear@2:          png_bytep bp = row;
nuclear@2:          png_uint_32 i;
nuclear@2:          png_uint_32 istop = channels * row_info->width;
nuclear@2: 
nuclear@2:          for (i = 0; i < istop; i++, bp++)
nuclear@2:          {
nuclear@2: 
nuclear@2:             png_uint_16 v;
nuclear@2:             int j;
nuclear@2:             int c = (int)(i%channels);
nuclear@2: 
nuclear@2:             v = *bp;
nuclear@2:             *bp = 0;
nuclear@2:             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
nuclear@2:             {
nuclear@2:                if (j > 0)
nuclear@2:                   *bp |= (png_byte)((v << j) & 0xff);
nuclear@2:                else
nuclear@2:                   *bp |= (png_byte)((v >> (-j)) & 0xff);
nuclear@2:             }
nuclear@2:          }
nuclear@2:       }
nuclear@2:       else
nuclear@2:       {
nuclear@2:          png_bytep bp;
nuclear@2:          png_uint_32 i;
nuclear@2:          png_uint_32 istop = channels * row_info->width;
nuclear@2: 
nuclear@2:          for (bp = row, i = 0; i < istop; i++)
nuclear@2:          {
nuclear@2:             int c = (int)(i%channels);
nuclear@2:             png_uint_16 value, v;
nuclear@2:             int j;
nuclear@2: 
nuclear@2:             v = (png_uint_16)(((png_uint_16)(*bp) << 8) + *(bp + 1));
nuclear@2:             value = 0;
nuclear@2:             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
nuclear@2:             {
nuclear@2:                if (j > 0)
nuclear@2:                   value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
nuclear@2:                else
nuclear@2:                   value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
nuclear@2:             }
nuclear@2:             *bp++ = (png_byte)(value >> 8);
nuclear@2:             *bp++ = (png_byte)(value & 0xff);
nuclear@2:          }
nuclear@2:       }
nuclear@2:    }
nuclear@2: }
nuclear@2: #endif
nuclear@2: 
nuclear@2: #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
nuclear@2: void /* PRIVATE */
nuclear@2: png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
nuclear@2: {
nuclear@2:    png_debug(1, "in png_do_write_swap_alpha\n");
nuclear@2: #if defined(PNG_USELESS_TESTS_SUPPORTED)
nuclear@2:    if (row != NULL && row_info != NULL)
nuclear@2: #endif
nuclear@2:    {
nuclear@2:       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
nuclear@2:       {
nuclear@2:          /* This converts from ARGB to RGBA */
nuclear@2:          if (row_info->bit_depth == 8)
nuclear@2:          {
nuclear@2:             png_bytep sp, dp;
nuclear@2:             png_uint_32 i;
nuclear@2:             png_uint_32 row_width = row_info->width;
nuclear@2:             for (i = 0, sp = dp = row; i < row_width; i++)
nuclear@2:             {
nuclear@2:                png_byte save = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = save;
nuclear@2:             }
nuclear@2:          }
nuclear@2:          /* This converts from AARRGGBB to RRGGBBAA */
nuclear@2:          else
nuclear@2:          {
nuclear@2:             png_bytep sp, dp;
nuclear@2:             png_uint_32 i;
nuclear@2:             png_uint_32 row_width = row_info->width;
nuclear@2: 
nuclear@2:             for (i = 0, sp = dp = row; i < row_width; i++)
nuclear@2:             {
nuclear@2:                png_byte save[2];
nuclear@2:                save[0] = *(sp++);
nuclear@2:                save[1] = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = save[0];
nuclear@2:                *(dp++) = save[1];
nuclear@2:             }
nuclear@2:          }
nuclear@2:       }
nuclear@2:       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
nuclear@2:       {
nuclear@2:          /* This converts from AG to GA */
nuclear@2:          if (row_info->bit_depth == 8)
nuclear@2:          {
nuclear@2:             png_bytep sp, dp;
nuclear@2:             png_uint_32 i;
nuclear@2:             png_uint_32 row_width = row_info->width;
nuclear@2: 
nuclear@2:             for (i = 0, sp = dp = row; i < row_width; i++)
nuclear@2:             {
nuclear@2:                png_byte save = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = save;
nuclear@2:             }
nuclear@2:          }
nuclear@2:          /* This converts from AAGG to GGAA */
nuclear@2:          else
nuclear@2:          {
nuclear@2:             png_bytep sp, dp;
nuclear@2:             png_uint_32 i;
nuclear@2:             png_uint_32 row_width = row_info->width;
nuclear@2: 
nuclear@2:             for (i = 0, sp = dp = row; i < row_width; i++)
nuclear@2:             {
nuclear@2:                png_byte save[2];
nuclear@2:                save[0] = *(sp++);
nuclear@2:                save[1] = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = save[0];
nuclear@2:                *(dp++) = save[1];
nuclear@2:             }
nuclear@2:          }
nuclear@2:       }
nuclear@2:    }
nuclear@2: }
nuclear@2: #endif
nuclear@2: 
nuclear@2: #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
nuclear@2: void /* PRIVATE */
nuclear@2: png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
nuclear@2: {
nuclear@2:    png_debug(1, "in png_do_write_invert_alpha\n");
nuclear@2: #if defined(PNG_USELESS_TESTS_SUPPORTED)
nuclear@2:    if (row != NULL && row_info != NULL)
nuclear@2: #endif
nuclear@2:    {
nuclear@2:       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
nuclear@2:       {
nuclear@2:          /* This inverts the alpha channel in RGBA */
nuclear@2:          if (row_info->bit_depth == 8)
nuclear@2:          {
nuclear@2:             png_bytep sp, dp;
nuclear@2:             png_uint_32 i;
nuclear@2:             png_uint_32 row_width = row_info->width;
nuclear@2:             for (i = 0, sp = dp = row; i < row_width; i++)
nuclear@2:             {
nuclear@2:                /* does nothing
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                */
nuclear@2:                sp+=3; dp = sp;
nuclear@2:                *(dp++) = (png_byte)(255 - *(sp++));
nuclear@2:             }
nuclear@2:          }
nuclear@2:          /* This inverts the alpha channel in RRGGBBAA */
nuclear@2:          else
nuclear@2:          {
nuclear@2:             png_bytep sp, dp;
nuclear@2:             png_uint_32 i;
nuclear@2:             png_uint_32 row_width = row_info->width;
nuclear@2: 
nuclear@2:             for (i = 0, sp = dp = row; i < row_width; i++)
nuclear@2:             {
nuclear@2:                /* does nothing
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                */
nuclear@2:                sp+=6; dp = sp;
nuclear@2:                *(dp++) = (png_byte)(255 - *(sp++));
nuclear@2:                *(dp++) = (png_byte)(255 - *(sp++));
nuclear@2:             }
nuclear@2:          }
nuclear@2:       }
nuclear@2:       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
nuclear@2:       {
nuclear@2:          /* This inverts the alpha channel in GA */
nuclear@2:          if (row_info->bit_depth == 8)
nuclear@2:          {
nuclear@2:             png_bytep sp, dp;
nuclear@2:             png_uint_32 i;
nuclear@2:             png_uint_32 row_width = row_info->width;
nuclear@2: 
nuclear@2:             for (i = 0, sp = dp = row; i < row_width; i++)
nuclear@2:             {
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = (png_byte)(255 - *(sp++));
nuclear@2:             }
nuclear@2:          }
nuclear@2:          /* This inverts the alpha channel in GGAA */
nuclear@2:          else
nuclear@2:          {
nuclear@2:             png_bytep sp, dp;
nuclear@2:             png_uint_32 i;
nuclear@2:             png_uint_32 row_width = row_info->width;
nuclear@2: 
nuclear@2:             for (i = 0, sp = dp = row; i < row_width; i++)
nuclear@2:             {
nuclear@2:                /* does nothing
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                *(dp++) = *(sp++);
nuclear@2:                */
nuclear@2:                sp+=2; dp = sp;
nuclear@2:                *(dp++) = (png_byte)(255 - *(sp++));
nuclear@2:                *(dp++) = (png_byte)(255 - *(sp++));
nuclear@2:             }
nuclear@2:          }
nuclear@2:       }
nuclear@2:    }
nuclear@2: }
nuclear@2: #endif
nuclear@2: 
nuclear@2: #if defined(PNG_MNG_FEATURES_SUPPORTED)
nuclear@2: /* undoes intrapixel differencing  */
nuclear@2: void /* PRIVATE */
nuclear@2: png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
nuclear@2: {
nuclear@2:    png_debug(1, "in png_do_write_intrapixel\n");
nuclear@2:    if (
nuclear@2: #if defined(PNG_USELESS_TESTS_SUPPORTED)
nuclear@2:        row != NULL && row_info != NULL &&
nuclear@2: #endif
nuclear@2:        (row_info->color_type & PNG_COLOR_MASK_COLOR))
nuclear@2:    {
nuclear@2:       int bytes_per_pixel;
nuclear@2:       png_uint_32 row_width = row_info->width;
nuclear@2:       if (row_info->bit_depth == 8)
nuclear@2:       {
nuclear@2:          png_bytep rp;
nuclear@2:          png_uint_32 i;
nuclear@2: 
nuclear@2:          if (row_info->color_type == PNG_COLOR_TYPE_RGB)
nuclear@2:             bytes_per_pixel = 3;
nuclear@2:          else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
nuclear@2:             bytes_per_pixel = 4;
nuclear@2:          else
nuclear@2:             return;
nuclear@2: 
nuclear@2:          for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
nuclear@2:          {
nuclear@2:             *(rp)   = (png_byte)((*rp     - *(rp+1))&0xff);
nuclear@2:             *(rp+2) = (png_byte)((*(rp+2) - *(rp+1))&0xff);
nuclear@2:          }
nuclear@2:       }
nuclear@2:       else if (row_info->bit_depth == 16)
nuclear@2:       {
nuclear@2:          png_bytep rp;
nuclear@2:          png_uint_32 i;
nuclear@2: 
nuclear@2:          if (row_info->color_type == PNG_COLOR_TYPE_RGB)
nuclear@2:             bytes_per_pixel = 6;
nuclear@2:          else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
nuclear@2:             bytes_per_pixel = 8;
nuclear@2:          else
nuclear@2:             return;
nuclear@2: 
nuclear@2:          for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
nuclear@2:          {
nuclear@2:             png_uint_32 s0   = (*(rp  ) << 8) | *(rp+1);
nuclear@2:             png_uint_32 s1   = (*(rp+2) << 8) | *(rp+3);
nuclear@2:             png_uint_32 s2   = (*(rp+4) << 8) | *(rp+5);
nuclear@2:             png_uint_32 red  = (png_uint_32)((s0 - s1) & 0xffffL);
nuclear@2:             png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
nuclear@2:             *(rp  ) = (png_byte)((red >> 8) & 0xff);
nuclear@2:             *(rp+1) = (png_byte)(red & 0xff);
nuclear@2:             *(rp+4) = (png_byte)((blue >> 8) & 0xff);
nuclear@2:             *(rp+5) = (png_byte)(blue & 0xff);
nuclear@2:          }
nuclear@2:       }
nuclear@2:    }
nuclear@2: }
nuclear@2: #endif /* PNG_MNG_FEATURES_SUPPORTED */
nuclear@2: #endif /* PNG_WRITE_SUPPORTED */