src/png/pngwtran.c


/* pngwtran.c - transforms the data in a row for PNG writers
 *
 * Last changed in libpng 1.5.6 [November 3, 2011]
 * Copyright (c) 1998-2011 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
 */

#include "pngpriv.h"

#ifdef PNG_WRITE_SUPPORTED

#ifdef PNG_WRITE_TRANSFORMS_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_row_infop row_info)
{
   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 */
             row_info,  /* row_info: */
                /*  png_uint_32 width;       width of row */
                /*  png_size_t 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_channel(row_info, png_ptr->row_buf + 1,
         !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
#endif

#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
   if (png_ptr->transformations & PNG_PACKSWAP)
      png_do_packswap(row_info, png_ptr->row_buf + 1);
#endif

#ifdef PNG_WRITE_PACK_SUPPORTED
   if (png_ptr->transformations & PNG_PACK)
      png_do_pack(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(row_info, png_ptr->row_buf + 1);
#endif

#ifdef PNG_WRITE_SHIFT_SUPPORTED
   if (png_ptr->transformations & PNG_SHIFT)
      png_do_shift(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(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(row_info, png_ptr->row_buf + 1);
#endif

#ifdef PNG_WRITE_BGR_SUPPORTED
   if (png_ptr->transformations & PNG_BGR)
      png_do_bgr(row_info, png_ptr->row_buf + 1);
#endif

#ifdef PNG_WRITE_INVERT_SUPPORTED
   if (png_ptr->transformations & PNG_INVERT_MONO)
      png_do_invert(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 &&
      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;
         }

         default:
            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_const_color_8p bit_depth)
{
   png_debug(1, "in png_do_shift");

   if (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_size_t i;
         png_byte mask;
         png_size_t 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");

   {
      if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
      {
         if (row_info->bit_depth == 8)
         {
            /* This converts from ARGB to RGBA */
            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;
            }
         }

#ifdef PNG_WRITE_16BIT_SUPPORTED
         else
         {
            /* This converts from AARRGGBB to RRGGBBAA */
            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];
            }
         }
#endif /* PNG_WRITE_16BIT_SUPPORTED */
      }

      else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
      {
         if (row_info->bit_depth == 8)
         {
            /* This converts from AG to GA */
            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;
            }
         }

#ifdef PNG_WRITE_16BIT_SUPPORTED
         else
         {
            /* This converts from AAGG to GGAA */
            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 /* PNG_WRITE_16BIT_SUPPORTED */
      }
   }
}
#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");

   {
      if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
      {
         if (row_info->bit_depth == 8)
         {
            /* This inverts the alpha channel in RGBA */
            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++));
            }
         }

#ifdef PNG_WRITE_16BIT_SUPPORTED
         else
         {
            /* This inverts the alpha channel in RRGGBBAA */
            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++));
            }
         }
#endif /* PNG_WRITE_16BIT_SUPPORTED */
      }

      else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
      {
         if (row_info->bit_depth == 8)
         {
            /* This inverts the alpha channel in GA */
            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++));
            }
         }

#ifdef PNG_WRITE_16BIT_SUPPORTED
         else
         {
            /* This inverts the alpha channel in GGAA */
            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 /* PNG_WRITE_16BIT_SUPPORTED */
      }
   }
}
#endif
#endif /* PNG_WRITE_TRANSFORMS_SUPPORTED */

#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 ((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);
         }
      }

#ifdef PNG_WRITE_16BIT_SUPPORTED
      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_WRITE_16BIT_SUPPORTED */
   }
}
#endif /* PNG_MNG_FEATURES_SUPPORTED */
#endif /* PNG_WRITE_SUPPORTED */
Commit	Line	Data
	1
	2	/* pngwtran.c - transforms the data in a row for PNG writers
	3	*
	4	* Last changed in libpng 1.5.6 [November 3, 2011]
	5	* Copyright (c) 1998-2011 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
	18	#ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
	19	/* Transform the data according to the user's wishes. The order of
	20	* transformations is significant.
	21	*/
	22	void /* PRIVATE */
	23	png_do_write_transformations(png_structp png_ptr, png_row_infop row_info)
	24	{
	25	png_debug(1, "in png_do_write_transformations");
	26
	27	if (png_ptr == NULL)
	28	return;
	29
	30	#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
	31	if (png_ptr->transformations & PNG_USER_TRANSFORM)
	32	if (png_ptr->write_user_transform_fn != NULL)
	33	((png_ptr->write_user_transform_fn)) / User write transform
	34	function */
	35	(png_ptr, /* png_ptr */
	36	row_info, /* row_info: */
	37	/* png_uint_32 width; width of row */
	38	/* png_size_t rowbytes; number of bytes in row */
	39	/* png_byte color_type; color type of pixels */
	40	/* png_byte bit_depth; bit depth of samples */
	41	/* png_byte channels; number of channels (1-4) */
	42	/* png_byte pixel_depth; bits per pixel (depthchannels) /
	43	png_ptr->row_buf + 1); /* start of pixel data for row */
	44	#endif
	45
	46	#ifdef PNG_WRITE_FILLER_SUPPORTED
	47	if (png_ptr->transformations & PNG_FILLER)
	48	png_do_strip_channel(row_info, png_ptr->row_buf + 1,
	49	!(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
	50	#endif
	51
	52	#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
	53	if (png_ptr->transformations & PNG_PACKSWAP)
	54	png_do_packswap(row_info, png_ptr->row_buf + 1);
	55	#endif
	56
	57	#ifdef PNG_WRITE_PACK_SUPPORTED
	58	if (png_ptr->transformations & PNG_PACK)
	59	png_do_pack(row_info, png_ptr->row_buf + 1,
	60	(png_uint_32)png_ptr->bit_depth);
	61	#endif
	62
	63	#ifdef PNG_WRITE_SWAP_SUPPORTED
	64	if (png_ptr->transformations & PNG_SWAP_BYTES)
	65	png_do_swap(row_info, png_ptr->row_buf + 1);
	66	#endif
	67
	68	#ifdef PNG_WRITE_SHIFT_SUPPORTED
	69	if (png_ptr->transformations & PNG_SHIFT)
	70	png_do_shift(row_info, png_ptr->row_buf + 1,
	71	&(png_ptr->shift));
	72	#endif
	73
	74	#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
	75	if (png_ptr->transformations & PNG_SWAP_ALPHA)
	76	png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
	77	#endif
	78
	79	#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
	80	if (png_ptr->transformations & PNG_INVERT_ALPHA)
	81	png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
	82	#endif
	83
	84	#ifdef PNG_WRITE_BGR_SUPPORTED
	85	if (png_ptr->transformations & PNG_BGR)
	86	png_do_bgr(row_info, png_ptr->row_buf + 1);
	87	#endif
	88
	89	#ifdef PNG_WRITE_INVERT_SUPPORTED
	90	if (png_ptr->transformations & PNG_INVERT_MONO)
	91	png_do_invert(row_info, png_ptr->row_buf + 1);
	92	#endif
	93	}
	94
	95	#ifdef PNG_WRITE_PACK_SUPPORTED
	96	/* Pack pixels into bytes. Pass the true bit depth in bit_depth. The
	97	* row_info bit depth should be 8 (one pixel per byte). The channels
	98	* should be 1 (this only happens on grayscale and paletted images).
	99	*/
	100	void /* PRIVATE */
	101	png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
	102	{
	103	png_debug(1, "in png_do_pack");
	104
	105	if (row_info->bit_depth == 8 &&
	106	row_info->channels == 1)
	107	{
	108	switch ((int)bit_depth)
	109	{
	110	case 1:
	111	{
	112	png_bytep sp, dp;
	113	int mask, v;
	114	png_uint_32 i;
	115	png_uint_32 row_width = row_info->width;
	116
	117	sp = row;
	118	dp = row;
	119	mask = 0x80;
	120	v = 0;
	121
	122	for (i = 0; i < row_width; i++)
	123	{
	124	if (*sp != 0)
	125	v \|= mask;
	126
	127	sp++;
	128
	129	if (mask > 1)
	130	mask >>= 1;
	131
	132	else
	133	{
	134	mask = 0x80;
	135	*dp = (png_byte)v;
	136	dp++;
	137	v = 0;
	138	}
	139	}
	140
	141	if (mask != 0x80)
	142	*dp = (png_byte)v;
	143
	144	break;
	145	}
	146
	147	case 2:
	148	{
	149	png_bytep sp, dp;
	150	int shift, v;
	151	png_uint_32 i;
	152	png_uint_32 row_width = row_info->width;
	153
	154	sp = row;
	155	dp = row;
	156	shift = 6;
	157	v = 0;
	158
	159	for (i = 0; i < row_width; i++)
	160	{
	161	png_byte value;
	162
	163	value = (png_byte)(*sp & 0x03);
	164	v \|= (value << shift);
	165
	166	if (shift == 0)
	167	{
	168	shift = 6;
	169	*dp = (png_byte)v;
	170	dp++;
	171	v = 0;
	172	}
	173
	174	else
	175	shift -= 2;
	176
	177	sp++;
	178	}
	179
	180	if (shift != 6)
	181	*dp = (png_byte)v;
	182
	183	break;
	184	}
	185
	186	case 4:
	187	{
	188	png_bytep sp, dp;
	189	int shift, v;
	190	png_uint_32 i;
	191	png_uint_32 row_width = row_info->width;
	192
	193	sp = row;
	194	dp = row;
	195	shift = 4;
	196	v = 0;
	197
	198	for (i = 0; i < row_width; i++)
	199	{
	200	png_byte value;
	201
	202	value = (png_byte)(*sp & 0x0f);
	203	v \|= (value << shift);
	204
	205	if (shift == 0)
	206	{
	207	shift = 4;
	208	*dp = (png_byte)v;
	209	dp++;
	210	v = 0;
	211	}
	212
	213	else
	214	shift -= 4;
	215
	216	sp++;
	217	}
	218
	219	if (shift != 4)
	220	*dp = (png_byte)v;
	221
	222	break;
	223	}
	224
	225	default:
	226	break;
	227	}
	228
	229	row_info->bit_depth = (png_byte)bit_depth;
	230	row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
	231	row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
	232	row_info->width);
	233	}
	234	}
	235	#endif
	236
	237	#ifdef PNG_WRITE_SHIFT_SUPPORTED
	238	/* Shift pixel values to take advantage of whole range. Pass the
	239	* true number of bits in bit_depth. The row should be packed
	240	* according to row_info->bit_depth. Thus, if you had a row of
	241	* bit depth 4, but the pixels only had values from 0 to 7, you
	242	* would pass 3 as bit_depth, and this routine would translate the
	243	* data to 0 to 15.
	244	*/
	245	void /* PRIVATE */
	246	png_do_shift(png_row_infop row_info, png_bytep row,
	247	png_const_color_8p bit_depth)
	248	{
	249	png_debug(1, "in png_do_shift");
	250
	251	if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
	252	{
	253	int shift_start[4], shift_dec[4];
	254	int channels = 0;
	255
	256	if (row_info->color_type & PNG_COLOR_MASK_COLOR)
	257	{
	258	shift_start[channels] = row_info->bit_depth - bit_depth->red;
	259	shift_dec[channels] = bit_depth->red;
	260	channels++;
	261
	262	shift_start[channels] = row_info->bit_depth - bit_depth->green;
	263	shift_dec[channels] = bit_depth->green;
	264	channels++;
	265
	266	shift_start[channels] = row_info->bit_depth - bit_depth->blue;
	267	shift_dec[channels] = bit_depth->blue;
	268	channels++;
	269	}
	270
	271	else
	272	{
	273	shift_start[channels] = row_info->bit_depth - bit_depth->gray;
	274	shift_dec[channels] = bit_depth->gray;
	275	channels++;
	276	}
	277
	278	if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
	279	{
	280	shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
	281	shift_dec[channels] = bit_depth->alpha;
	282	channels++;
	283	}
	284
	285	/* With low row depths, could only be grayscale, so one channel */
	286	if (row_info->bit_depth < 8)
	287	{
	288	png_bytep bp = row;
	289	png_size_t i;
	290	png_byte mask;
	291	png_size_t row_bytes = row_info->rowbytes;
	292
	293	if (bit_depth->gray == 1 && row_info->bit_depth == 2)
	294	mask = 0x55;
	295
	296	else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
	297	mask = 0x11;
	298
	299	else
	300	mask = 0xff;
	301
	302	for (i = 0; i < row_bytes; i++, bp++)
	303	{
	304	png_uint_16 v;
	305	int j;
	306
	307	v = *bp;
	308	*bp = 0;
	309
	310	for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
	311	{
	312	if (j > 0)
	313	*bp \|= (png_byte)((v << j) & 0xff);
	314
	315	else
	316	*bp \|= (png_byte)((v >> (-j)) & mask);
	317	}
	318	}
	319	}
	320
	321	else if (row_info->bit_depth == 8)
	322	{
	323	png_bytep bp = row;
	324	png_uint_32 i;
	325	png_uint_32 istop = channels * row_info->width;
	326
	327	for (i = 0; i < istop; i++, bp++)
	328	{
	329
	330	png_uint_16 v;
	331	int j;
	332	int c = (int)(i%channels);
	333
	334	v = *bp;
	335	*bp = 0;
	336
	337	for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
	338	{
	339	if (j > 0)
	340	*bp \|= (png_byte)((v << j) & 0xff);
	341
	342	else
	343	*bp \|= (png_byte)((v >> (-j)) & 0xff);
	344	}
	345	}
	346	}
	347
	348	else
	349	{
	350	png_bytep bp;
	351	png_uint_32 i;
	352	png_uint_32 istop = channels * row_info->width;
	353
	354	for (bp = row, i = 0; i < istop; i++)
	355	{
	356	int c = (int)(i%channels);
	357	png_uint_16 value, v;
	358	int j;
	359
	360	v = (png_uint_16)(((png_uint_16)(bp) << 8) + (bp + 1));
	361	value = 0;
	362
	363	for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
	364	{
	365	if (j > 0)
	366	value \|= (png_uint_16)((v << j) & (png_uint_16)0xffff);
	367
	368	else
	369	value \|= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
	370	}
	371	*bp++ = (png_byte)(value >> 8);
	372	*bp++ = (png_byte)(value & 0xff);
	373	}
	374	}
	375	}
	376	}
	377	#endif
	378
	379	#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
	380	void /* PRIVATE */
	381	png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
	382	{
	383	png_debug(1, "in png_do_write_swap_alpha");
	384
	385	{
	386	if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	387	{
	388	if (row_info->bit_depth == 8)
	389	{
	390	/* This converts from ARGB to RGBA */
	391	png_bytep sp, dp;
	392	png_uint_32 i;
	393	png_uint_32 row_width = row_info->width;
	394
	395	for (i = 0, sp = dp = row; i < row_width; i++)
	396	{
	397	png_byte save = *(sp++);
	398	(dp++) = (sp++);
	399	(dp++) = (sp++);
	400	(dp++) = (sp++);
	401	*(dp++) = save;
	402	}
	403	}
	404
	405	#ifdef PNG_WRITE_16BIT_SUPPORTED
	406	else
	407	{
	408	/* This converts from AARRGGBB to RRGGBBAA */
	409	png_bytep sp, dp;
	410	png_uint_32 i;
	411	png_uint_32 row_width = row_info->width;
	412
	413	for (i = 0, sp = dp = row; i < row_width; i++)
	414	{
	415	png_byte save[2];
	416	save[0] = *(sp++);
	417	save[1] = *(sp++);
	418	(dp++) = (sp++);
	419	(dp++) = (sp++);
	420	(dp++) = (sp++);
	421	(dp++) = (sp++);
	422	(dp++) = (sp++);
	423	(dp++) = (sp++);
	424	*(dp++) = save[0];
	425	*(dp++) = save[1];
	426	}
	427	}
	428	#endif /* PNG_WRITE_16BIT_SUPPORTED */
	429	}
	430
	431	else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
	432	{
	433	if (row_info->bit_depth == 8)
	434	{
	435	/* This converts from AG to GA */
	436	png_bytep sp, dp;
	437	png_uint_32 i;
	438	png_uint_32 row_width = row_info->width;
	439
	440	for (i = 0, sp = dp = row; i < row_width; i++)
	441	{
	442	png_byte save = *(sp++);
	443	(dp++) = (sp++);
	444	*(dp++) = save;
	445	}
	446	}
	447
	448	#ifdef PNG_WRITE_16BIT_SUPPORTED
	449	else
	450	{
	451	/* This converts from AAGG to GGAA */
	452	png_bytep sp, dp;
	453	png_uint_32 i;
	454	png_uint_32 row_width = row_info->width;
	455
	456	for (i = 0, sp = dp = row; i < row_width; i++)
	457	{
	458	png_byte save[2];
	459	save[0] = *(sp++);
	460	save[1] = *(sp++);
	461	(dp++) = (sp++);
	462	(dp++) = (sp++);
	463	*(dp++) = save[0];
	464	*(dp++) = save[1];
	465	}
	466	}
	467	#endif /* PNG_WRITE_16BIT_SUPPORTED */
	468	}
	469	}
	470	}
	471	#endif
	472
	473	#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
	474	void /* PRIVATE */
	475	png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
	476	{
	477	png_debug(1, "in png_do_write_invert_alpha");
	478
	479	{
	480	if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	481	{
	482	if (row_info->bit_depth == 8)
	483	{
	484	/* This inverts the alpha channel in RGBA */
	485	png_bytep sp, dp;
	486	png_uint_32 i;
	487	png_uint_32 row_width = row_info->width;
	488
	489	for (i = 0, sp = dp = row; i < row_width; i++)
	490	{
	491	/* Does nothing
	492	(dp++) = (sp++);
	493	(dp++) = (sp++);
	494	(dp++) = (sp++);
	495	*/
	496	sp+=3; dp = sp;
	497	(dp++) = (png_byte)(255 - (sp++));
	498	}
	499	}
	500
	501	#ifdef PNG_WRITE_16BIT_SUPPORTED
	502	else
	503	{
	504	/* This inverts the alpha channel in RRGGBBAA */
	505	png_bytep sp, dp;
	506	png_uint_32 i;
	507	png_uint_32 row_width = row_info->width;
	508
	509	for (i = 0, sp = dp = row; i < row_width; i++)
	510	{
	511	/* Does nothing
	512	(dp++) = (sp++);
	513	(dp++) = (sp++);
	514	(dp++) = (sp++);
	515	(dp++) = (sp++);
	516	(dp++) = (sp++);
	517	(dp++) = (sp++);
	518	*/
	519	sp+=6; dp = sp;
	520	(dp++) = (png_byte)(255 - (sp++));
	521	(dp++) = (png_byte)(255 - (sp++));
	522	}
	523	}
	524	#endif /* PNG_WRITE_16BIT_SUPPORTED */
	525	}
	526
	527	else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
	528	{
	529	if (row_info->bit_depth == 8)
	530	{
	531	/* This inverts the alpha channel in GA */
	532	png_bytep sp, dp;
	533	png_uint_32 i;
	534	png_uint_32 row_width = row_info->width;
	535
	536	for (i = 0, sp = dp = row; i < row_width; i++)
	537	{
	538	(dp++) = (sp++);
	539	(dp++) = (png_byte)(255 - (sp++));
	540	}
	541	}
	542
	543	#ifdef PNG_WRITE_16BIT_SUPPORTED
	544	else
	545	{
	546	/* This inverts the alpha channel in GGAA */
	547	png_bytep sp, dp;
	548	png_uint_32 i;
	549	png_uint_32 row_width = row_info->width;
	550
	551	for (i = 0, sp = dp = row; i < row_width; i++)
	552	{
	553	/* Does nothing
	554	(dp++) = (sp++);
	555	(dp++) = (sp++);
	556	*/
	557	sp+=2; dp = sp;
	558	(dp++) = (png_byte)(255 - (sp++));
	559	(dp++) = (png_byte)(255 - (sp++));
	560	}
	561	}
	562	#endif /* PNG_WRITE_16BIT_SUPPORTED */
	563	}
	564	}
	565	}
	566	#endif
	567	#endif /* PNG_WRITE_TRANSFORMS_SUPPORTED */
	568
	569	#ifdef PNG_MNG_FEATURES_SUPPORTED
	570	/* Undoes intrapixel differencing */
	571	void /* PRIVATE */
	572	png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
	573	{
	574	png_debug(1, "in png_do_write_intrapixel");
	575
	576	if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
	577	{
	578	int bytes_per_pixel;
	579	png_uint_32 row_width = row_info->width;
	580	if (row_info->bit_depth == 8)
	581	{
	582	png_bytep rp;
	583	png_uint_32 i;
	584
	585	if (row_info->color_type == PNG_COLOR_TYPE_RGB)
	586	bytes_per_pixel = 3;
	587
	588	else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	589	bytes_per_pixel = 4;
	590
	591	else
	592	return;
	593
	594	for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
	595	{
	596	(rp) = (png_byte)((rp - *(rp + 1)) & 0xff);
	597	(rp + 2) = (png_byte)(((rp + 2) - *(rp + 1)) & 0xff);
	598	}
	599	}
	600
	601	#ifdef PNG_WRITE_16BIT_SUPPORTED
	602	else if (row_info->bit_depth == 16)
	603	{
	604	png_bytep rp;
	605	png_uint_32 i;
	606
	607	if (row_info->color_type == PNG_COLOR_TYPE_RGB)
	608	bytes_per_pixel = 6;
	609
	610	else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	611	bytes_per_pixel = 8;
	612
	613	else
	614	return;
	615
	616	for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
	617	{
	618	png_uint_32 s0 = ((rp ) << 8) \| (rp + 1);
	619	png_uint_32 s1 = ((rp + 2) << 8) \| (rp + 3);
	620	png_uint_32 s2 = ((rp + 4) << 8) \| (rp + 5);
	621	png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
	622	png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
	623	*(rp ) = (png_byte)((red >> 8) & 0xff);
	624	*(rp + 1) = (png_byte)(red & 0xff);
	625	*(rp + 4) = (png_byte)((blue >> 8) & 0xff);
	626	*(rp + 5) = (png_byte)(blue & 0xff);
	627	}
	628	}
	629	#endif /* PNG_WRITE_16BIT_SUPPORTED */
	630	}
	631	}
	632	#endif /* PNG_MNG_FEATURES_SUPPORTED */
	633	#endif /* PNG_WRITE_SUPPORTED */