/* pngwtran.c - transforms the data in a row for PNG writers

 *

 * Last changed in libpng 1.2.43 [February 25, 2010]

 * Copyright (c) 1998-2002,2004,2006-2010 Glenn Randers-Pehrson

 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)

 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

 *

 * This code is released under the libpng license.

 * For conditions of distribution and use, see the disclaimer

 * and license in png.h

 */

#define PNG_INTERNAL

#define PNG_NO_PEDANTIC_WARNINGS

#include "png.h"

#ifdef PNG_WRITE_SUPPORTED

/* Transform the data according to the user's wishes.  The order of

 * transformations is significant.

 */

void /* PRIVATE */

png_do_write_transformations(png_structp png_ptr)

{

   png_debug(1, "in png_do_write_transformations");

   if (png_ptr == NULL)

      return;

#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED

   if (png_ptr->transformations & PNG_USER_TRANSFORM)

      if (png_ptr->write_user_transform_fn != NULL)

        (*(png_ptr->write_user_transform_fn)) /* User write transform

                                                 function */

          (png_ptr,                    /* png_ptr */

           &(png_ptr->row_info),       /* row_info:     */

             /*  png_uint_32 width;          width of row */

             /*  png_uint_32 rowbytes;       number of bytes in row */

             /*  png_byte color_type;        color type of pixels */

             /*  png_byte bit_depth;         bit depth of samples */

             /*  png_byte channels;          number of channels (1-4) */

             /*  png_byte pixel_depth;       bits per pixel (depth*channels) */

           png_ptr->row_buf + 1);      /* start of pixel data for row */

#endif

#ifdef PNG_WRITE_FILLER_SUPPORTED

   if (png_ptr->transformations & PNG_FILLER)

      png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,

         png_ptr->flags);

#endif

#ifdef PNG_WRITE_PACKSWAP_SUPPORTED

   if (png_ptr->transformations & PNG_PACKSWAP)

      png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);

#endif

#ifdef PNG_WRITE_PACK_SUPPORTED

   if (png_ptr->transformations & PNG_PACK)

      png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,

         (png_uint_32)png_ptr->bit_depth);

#endif

#ifdef PNG_WRITE_SWAP_SUPPORTED

   if (png_ptr->transformations & PNG_SWAP_BYTES)

      png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);

#endif

#ifdef PNG_WRITE_SHIFT_SUPPORTED

   if (png_ptr->transformations & PNG_SHIFT)

      png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,

         &(png_ptr->shift));

#endif

#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED

   if (png_ptr->transformations & PNG_SWAP_ALPHA)

      png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);

#endif

#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED

   if (png_ptr->transformations & PNG_INVERT_ALPHA)

      png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);

#endif

#ifdef PNG_WRITE_BGR_SUPPORTED

   if (png_ptr->transformations & PNG_BGR)

      png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);

#endif

#ifdef PNG_WRITE_INVERT_SUPPORTED

   if (png_ptr->transformations & PNG_INVERT_MONO)

      png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);

#endif

}

#ifdef PNG_WRITE_PACK_SUPPORTED

/* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The

 * row_info bit depth should be 8 (one pixel per byte).  The channels

 * should be 1 (this only happens on grayscale and paletted images).

 */

void /* PRIVATE */

png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)

{

   png_debug(1, "in png_do_pack");

   if (row_info->bit_depth == 8 &&

#ifdef PNG_USELESS_TESTS_SUPPORTED

       row != NULL && row_info != NULL &&

#endif

      row_info->channels == 1)

   {

      switch ((int)bit_depth)

      {

         case 1:

         {

            png_bytep sp, dp;

            int mask, v;

            png_uint_32 i;

            png_uint_32 row_width = row_info->width;

            sp = row;

            dp = row;

            mask = 0x80;

            v = 0;

            for (i = 0; i < row_width; i++)

            {

               if (*sp != 0)

                  v |= mask;

               sp++;

               if (mask > 1)

                  mask >>= 1;

               else

               {

                  mask = 0x80;

                  *dp = (png_byte)v;

                  dp++;

                  v = 0;

               }

            }

            if (mask != 0x80)

               *dp = (png_byte)v;

            break;

         }

         case 2:

         {

            png_bytep sp, dp;

            int shift, v;

            png_uint_32 i;

            png_uint_32 row_width = row_info->width;

            sp = row;

            dp = row;

            shift = 6;

            v = 0;

            for (i = 0; i < row_width; i++)

            {

               png_byte value;

               value = (png_byte)(*sp & 0x03);

               v |= (value << shift);

               if (shift == 0)

               {

                  shift = 6;

                  *dp = (png_byte)v;

                  dp++;

                  v = 0;

               }

               else

                  shift -= 2;

               sp++;

            }

            if (shift != 6)

               *dp = (png_byte)v;

            break;

         }

         case 4:

         {

            png_bytep sp, dp;

            int shift, v;

            png_uint_32 i;

            png_uint_32 row_width = row_info->width;

            sp = row;

            dp = row;

            shift = 4;

            v = 0;

            for (i = 0; i < row_width; i++)

            {

               png_byte value;

               value = (png_byte)(*sp & 0x0f);

               v |= (value << shift);

               if (shift == 0)

               {

                  shift = 4;

                  *dp = (png_byte)v;

                  dp++;

                  v = 0;

               }

               else

                  shift -= 4;

               sp++;

            }

            if (shift != 4)

               *dp = (png_byte)v;

            break;

         }

      }

      row_info->bit_depth = (png_byte)bit_depth;

      row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);

      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,

         row_info->width);

   }

}

#endif

#ifdef PNG_WRITE_SHIFT_SUPPORTED

/* Shift pixel values to take advantage of whole range.  Pass the

 * true number of bits in bit_depth.  The row should be packed

 * according to row_info->bit_depth.  Thus, if you had a row of

 * bit depth 4, but the pixels only had values from 0 to 7, you

 * would pass 3 as bit_depth, and this routine would translate the

 * data to 0 to 15.

 */

void /* PRIVATE */

png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)

{

   png_debug(1, "in png_do_shift");

#ifdef PNG_USELESS_TESTS_SUPPORTED

   if (row != NULL && row_info != NULL &&

#else

   if (

#endif

      row_info->color_type != PNG_COLOR_TYPE_PALETTE)

   {

      int shift_start[4], shift_dec[4];

      int channels = 0;

      if (row_info->color_type & PNG_COLOR_MASK_COLOR)

      {

         shift_start[channels] = row_info->bit_depth - bit_depth->red;

         shift_dec[channels] = bit_depth->red;

         channels++;

         shift_start[channels] = row_info->bit_depth - bit_depth->green;

         shift_dec[channels] = bit_depth->green;

         channels++;

         shift_start[channels] = row_info->bit_depth - bit_depth->blue;

         shift_dec[channels] = bit_depth->blue;

         channels++;

      }

      else

      {

         shift_start[channels] = row_info->bit_depth - bit_depth->gray;

         shift_dec[channels] = bit_depth->gray;

         channels++;

      }

      if (row_info->color_type & PNG_COLOR_MASK_ALPHA)

      {

         shift_start[channels] = row_info->bit_depth - bit_depth->alpha;

         shift_dec[channels] = bit_depth->alpha;

         channels++;

      }

      /* With low row depths, could only be grayscale, so one channel */

      if (row_info->bit_depth < 8)

      {

         png_bytep bp = row;

         png_uint_32 i;

         png_byte mask;

         png_uint_32 row_bytes = row_info->rowbytes;

         if (bit_depth->gray == 1 && row_info->bit_depth == 2)

            mask = 0x55;

         else if (row_info->bit_depth == 4 && bit_depth->gray == 3)

            mask = 0x11;

         else

            mask = 0xff;

         for (i = 0; i < row_bytes; i++, bp++)

         {

            png_uint_16 v;

            int j;

            v = *bp;

            *bp = 0;

            for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])

            {

               if (j > 0)

                  *bp |= (png_byte)((v << j) & 0xff);

               else

                  *bp |= (png_byte)((v >> (-j)) & mask);

            }

         }

      }

      else if (row_info->bit_depth == 8)

      {

         png_bytep bp = row;

         png_uint_32 i;

         png_uint_32 istop = channels * row_info->width;

         for (i = 0; i < istop; i++, bp++)

         {

            png_uint_16 v;

            int j;

            int c = (int)(i%channels);

            v = *bp;

            *bp = 0;

            for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])

            {

               if (j > 0)

                  *bp |= (png_byte)((v << j) & 0xff);

               else

                  *bp |= (png_byte)((v >> (-j)) & 0xff);

            }

         }

      }

      else

      {

         png_bytep bp;

         png_uint_32 i;

         png_uint_32 istop = channels * row_info->width;

         for (bp = row, i = 0; i < istop; i++)

         {

            int c = (int)(i%channels);

            png_uint_16 value, v;

            int j;

            v = (png_uint_16)(((png_uint_16)(*bp) << 8) + *(bp + 1));

            value = 0;

            for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])

            {

               if (j > 0)

                  value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);

               else

                  value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);

            }

            *bp++ = (png_byte)(value >> 8);

            *bp++ = (png_byte)(value & 0xff);

         }

      }

   }

}

#endif

#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED

void /* PRIVATE */

png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)

{

   png_debug(1, "in png_do_write_swap_alpha");

#ifdef PNG_USELESS_TESTS_SUPPORTED

   if (row != NULL && row_info != NULL)

#endif

   {

      if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)

      {

         /* This converts from ARGB to RGBA */

         if (row_info->bit_depth == 8)

         {

            png_bytep sp, dp;

            png_uint_32 i;

            png_uint_32 row_width = row_info->width;

            for (i = 0, sp = dp = row; i < row_width; i++)

            {

               png_byte save = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = save;

            }

         }

         /* This converts from AARRGGBB to RRGGBBAA */

         else

         {

            png_bytep sp, dp;

            png_uint_32 i;

            png_uint_32 row_width = row_info->width;

            for (i = 0, sp = dp = row; i < row_width; i++)

            {

               png_byte save[2];

               save[0] = *(sp++);

               save[1] = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = save[0];

               *(dp++) = save[1];

            }

         }

      }

      else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)

      {

         /* This converts from AG to GA */

         if (row_info->bit_depth == 8)

         {

            png_bytep sp, dp;

            png_uint_32 i;

            png_uint_32 row_width = row_info->width;

            for (i = 0, sp = dp = row; i < row_width; i++)

            {

               png_byte save = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = save;

            }

         }

         /* This converts from AAGG to GGAA */

         else

         {

            png_bytep sp, dp;

            png_uint_32 i;

            png_uint_32 row_width = row_info->width;

            for (i = 0, sp = dp = row; i < row_width; i++)

            {

               png_byte save[2];

               save[0] = *(sp++);

               save[1] = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = save[0];

               *(dp++) = save[1];

            }

         }

      }

   }

}

#endif

#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED

void /* PRIVATE */

png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)

{

   png_debug(1, "in png_do_write_invert_alpha");

#ifdef PNG_USELESS_TESTS_SUPPORTED

   if (row != NULL && row_info != NULL)

#endif

   {

      if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)

      {

         /* This inverts the alpha channel in RGBA */

         if (row_info->bit_depth == 8)

         {

            png_bytep sp, dp;

            png_uint_32 i;

            png_uint_32 row_width = row_info->width;

            for (i = 0, sp = dp = row; i < row_width; i++)

            {

               /* Does nothing

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               */

               sp+=3; dp = sp;

               *(dp++) = (png_byte)(255 - *(sp++));

            }

         }

         /* This inverts the alpha channel in RRGGBBAA */

         else

         {

            png_bytep sp, dp;

            png_uint_32 i;

            png_uint_32 row_width = row_info->width;

            for (i = 0, sp = dp = row; i < row_width; i++)

            {

               /* Does nothing

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               */

               sp+=6; dp = sp;

               *(dp++) = (png_byte)(255 - *(sp++));

               *(dp++) = (png_byte)(255 - *(sp++));

            }

         }

      }

      else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)

      {

         /* This inverts the alpha channel in GA */

         if (row_info->bit_depth == 8)

         {

            png_bytep sp, dp;

            png_uint_32 i;

            png_uint_32 row_width = row_info->width;

            for (i = 0, sp = dp = row; i < row_width; i++)

            {

               *(dp++) = *(sp++);

               *(dp++) = (png_byte)(255 - *(sp++));

            }

         }

         /* This inverts the alpha channel in GGAA */

         else

         {

            png_bytep sp, dp;

            png_uint_32 i;

            png_uint_32 row_width = row_info->width;

            for (i = 0, sp = dp = row; i < row_width; i++)

            {

               /* Does nothing

               *(dp++) = *(sp++);

               *(dp++) = *(sp++);

               */

               sp+=2; dp = sp;

               *(dp++) = (png_byte)(255 - *(sp++));

               *(dp++) = (png_byte)(255 - *(sp++));

            }

         }

      }

   }

}

#endif

#ifdef PNG_MNG_FEATURES_SUPPORTED

/* Undoes intrapixel differencing  */

void /* PRIVATE */

png_do_write_intrapixel(png_row_infop row_info, png_bytep row)

{

   png_debug(1, "in png_do_write_intrapixel");

   if (

#ifdef PNG_USELESS_TESTS_SUPPORTED

       row != NULL && row_info != NULL &&

#endif

       (row_info->color_type & PNG_COLOR_MASK_COLOR))

   {

      int bytes_per_pixel;

      png_uint_32 row_width = row_info->width;

      if (row_info->bit_depth == 8)

      {

         png_bytep rp;

         png_uint_32 i;

         if (row_info->color_type == PNG_COLOR_TYPE_RGB)

            bytes_per_pixel = 3;

         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)

            bytes_per_pixel = 4;

         else

            return;

         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)

         {

            *(rp)   = (png_byte)((*rp     - *(rp+1))&0xff);

            *(rp+2) = (png_byte)((*(rp+2) - *(rp+1))&0xff);

         }

      }

      else if (row_info->bit_depth == 16)

      {

         png_bytep rp;

         png_uint_32 i;

         if (row_info->color_type == PNG_COLOR_TYPE_RGB)

            bytes_per_pixel = 6;

         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)

            bytes_per_pixel = 8;

         else

            return;

         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)

         {

            png_uint_32 s0   = (*(rp  ) << 8) | *(rp+1);

            png_uint_32 s1   = (*(rp+2) << 8) | *(rp+3);

            png_uint_32 s2   = (*(rp+4) << 8) | *(rp+5);

            png_uint_32 red  = (png_uint_32)((s0 - s1) & 0xffffL);

            png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);

            *(rp  ) = (png_byte)((red >> 8) & 0xff);

            *(rp+1) = (png_byte)(red & 0xff);

            *(rp+4) = (png_byte)((blue >> 8) & 0xff);

            *(rp+5) = (png_byte)(blue & 0xff);

         }

      }

   }

}

#endif /* PNG_MNG_FEATURES_SUPPORTED */

#endif /* PNG_WRITE_SUPPORTED */