src/png/pngwtran.c


/* pngwtran.c - transforms the data in a row for PNG writers
 *
 * Last changed in libpng 1.6.0 [February 14, 2013]
 * Copyright (c) 1998-2013 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_structrp 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;
         unsigned int 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++)
         {
            int j;
            unsigned int v, out;

            v = *bp;
            out = 0;

            for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
            {
               if (j > 0)
                  out |= v << j;

               else
                  out |= (v >> (-j)) & mask;
            }

            *bp = (png_byte)(out & 0xff);
         }
      }

      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++)
         {

            const unsigned int c = i%channels;
            int j;
            unsigned int v, out;

            v = *bp;
            out = 0;

            for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
            {
               if (j > 0)
                  out |= v << j;

               else
                  out |= v >> (-j);
            }

            *bp = (png_byte)(out & 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++)
         {
            const unsigned int c = i%channels;
            int j;
            unsigned int value, v;

            v = png_get_uint_16(bp);
            value = 0;

            for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
            {
               if (j > 0)
                  value |= v << j;

               else
                  value |= v >> (-j);
            }
            *bp++ = (png_byte)((value >> 8) & 0xff);
            *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 1.6.0 [February 14, 2013]
	5	* Copyright (c) 1998-2013 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_structrp 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	unsigned int 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	int j;
	305	unsigned int v, out;
	306
	307	v = *bp;
	308	out = 0;
	309
	310	for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
	311	{
	312	if (j > 0)
	313	out \|= v << j;
	314
	315	else
	316	out \|= (v >> (-j)) & mask;
	317	}
	318
	319	*bp = (png_byte)(out & 0xff);
	320	}
	321	}
	322
	323	else if (row_info->bit_depth == 8)
	324	{
	325	png_bytep bp = row;
	326	png_uint_32 i;
	327	png_uint_32 istop = channels * row_info->width;
	328
	329	for (i = 0; i < istop; i++, bp++)
	330	{
	331
	332	const unsigned int c = i%channels;
	333	int j;
	334	unsigned int v, out;
	335
	336	v = *bp;
	337	out = 0;
	338
	339	for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
	340	{
	341	if (j > 0)
	342	out \|= v << j;
	343
	344	else
	345	out \|= v >> (-j);
	346	}
	347
	348	*bp = (png_byte)(out & 0xff);
	349	}
	350	}
	351
	352	else
	353	{
	354	png_bytep bp;
	355	png_uint_32 i;
	356	png_uint_32 istop = channels * row_info->width;
	357
	358	for (bp = row, i = 0; i < istop; i++)
	359	{
	360	const unsigned int c = i%channels;
	361	int j;
	362	unsigned int value, v;
	363
	364	v = png_get_uint_16(bp);
	365	value = 0;
	366
	367	for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
	368	{
	369	if (j > 0)
	370	value \|= v << j;
	371
	372	else
	373	value \|= v >> (-j);
	374	}
	375	*bp++ = (png_byte)((value >> 8) & 0xff);
	376	*bp++ = (png_byte)(value & 0xff);
	377	}
	378	}
	379	}
	380	}
	381	#endif
	382
	383	#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
	384	void /* PRIVATE */
	385	png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
	386	{
	387	png_debug(1, "in png_do_write_swap_alpha");
	388
	389	{
	390	if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	391	{
	392	if (row_info->bit_depth == 8)
	393	{
	394	/* This converts from ARGB to RGBA */
	395	png_bytep sp, dp;
	396	png_uint_32 i;
	397	png_uint_32 row_width = row_info->width;
	398
	399	for (i = 0, sp = dp = row; i < row_width; i++)
	400	{
	401	png_byte save = *(sp++);
	402	(dp++) = (sp++);
	403	(dp++) = (sp++);
	404	(dp++) = (sp++);
	405	*(dp++) = save;
	406	}
	407	}
	408
	409	#ifdef PNG_WRITE_16BIT_SUPPORTED
	410	else
	411	{
	412	/* This converts from AARRGGBB to RRGGBBAA */
	413	png_bytep sp, dp;
	414	png_uint_32 i;
	415	png_uint_32 row_width = row_info->width;
	416
	417	for (i = 0, sp = dp = row; i < row_width; i++)
	418	{
	419	png_byte save[2];
	420	save[0] = *(sp++);
	421	save[1] = *(sp++);
	422	(dp++) = (sp++);
	423	(dp++) = (sp++);
	424	(dp++) = (sp++);
	425	(dp++) = (sp++);
	426	(dp++) = (sp++);
	427	(dp++) = (sp++);
	428	*(dp++) = save[0];
	429	*(dp++) = save[1];
	430	}
	431	}
	432	#endif /* PNG_WRITE_16BIT_SUPPORTED */
	433	}
	434
	435	else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
	436	{
	437	if (row_info->bit_depth == 8)
	438	{
	439	/* This converts from AG to GA */
	440	png_bytep sp, dp;
	441	png_uint_32 i;
	442	png_uint_32 row_width = row_info->width;
	443
	444	for (i = 0, sp = dp = row; i < row_width; i++)
	445	{
	446	png_byte save = *(sp++);
	447	(dp++) = (sp++);
	448	*(dp++) = save;
	449	}
	450	}
	451
	452	#ifdef PNG_WRITE_16BIT_SUPPORTED
	453	else
	454	{
	455	/* This converts from AAGG to GGAA */
	456	png_bytep sp, dp;
	457	png_uint_32 i;
	458	png_uint_32 row_width = row_info->width;
	459
	460	for (i = 0, sp = dp = row; i < row_width; i++)
	461	{
	462	png_byte save[2];
	463	save[0] = *(sp++);
	464	save[1] = *(sp++);
	465	(dp++) = (sp++);
	466	(dp++) = (sp++);
	467	*(dp++) = save[0];
	468	*(dp++) = save[1];
	469	}
	470	}
	471	#endif /* PNG_WRITE_16BIT_SUPPORTED */
	472	}
	473	}
	474	}
	475	#endif
	476
	477	#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
	478	void /* PRIVATE */
	479	png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
	480	{
	481	png_debug(1, "in png_do_write_invert_alpha");
	482
	483	{
	484	if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	485	{
	486	if (row_info->bit_depth == 8)
	487	{
	488	/* This inverts the alpha channel in RGBA */
	489	png_bytep sp, dp;
	490	png_uint_32 i;
	491	png_uint_32 row_width = row_info->width;
	492
	493	for (i = 0, sp = dp = row; i < row_width; i++)
	494	{
	495	/* Does nothing
	496	(dp++) = (sp++);
	497	(dp++) = (sp++);
	498	(dp++) = (sp++);
	499	*/
	500	sp+=3; dp = sp;
	501	(dp++) = (png_byte)(255 - (sp++));
	502	}
	503	}
	504
	505	#ifdef PNG_WRITE_16BIT_SUPPORTED
	506	else
	507	{
	508	/* This inverts the alpha channel in RRGGBBAA */
	509	png_bytep sp, dp;
	510	png_uint_32 i;
	511	png_uint_32 row_width = row_info->width;
	512
	513	for (i = 0, sp = dp = row; i < row_width; i++)
	514	{
	515	/* Does nothing
	516	(dp++) = (sp++);
	517	(dp++) = (sp++);
	518	(dp++) = (sp++);
	519	(dp++) = (sp++);
	520	(dp++) = (sp++);
	521	(dp++) = (sp++);
	522	*/
	523	sp+=6; dp = sp;
	524	(dp++) = (png_byte)(255 - (sp++));
	525	(dp++) = (png_byte)(255 - (sp++));
	526	}
	527	}
	528	#endif /* PNG_WRITE_16BIT_SUPPORTED */
	529	}
	530
	531	else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
	532	{
	533	if (row_info->bit_depth == 8)
	534	{
	535	/* This inverts the alpha channel in GA */
	536	png_bytep sp, dp;
	537	png_uint_32 i;
	538	png_uint_32 row_width = row_info->width;
	539
	540	for (i = 0, sp = dp = row; i < row_width; i++)
	541	{
	542	(dp++) = (sp++);
	543	(dp++) = (png_byte)(255 - (sp++));
	544	}
	545	}
	546
	547	#ifdef PNG_WRITE_16BIT_SUPPORTED
	548	else
	549	{
	550	/* This inverts the alpha channel in GGAA */
	551	png_bytep sp, dp;
	552	png_uint_32 i;
	553	png_uint_32 row_width = row_info->width;
	554
	555	for (i = 0, sp = dp = row; i < row_width; i++)
	556	{
	557	/* Does nothing
	558	(dp++) = (sp++);
	559	(dp++) = (sp++);
	560	*/
	561	sp+=2; dp = sp;
	562	(dp++) = (png_byte)(255 - (sp++));
	563	(dp++) = (png_byte)(255 - (sp++));
	564	}
	565	}
	566	#endif /* PNG_WRITE_16BIT_SUPPORTED */
	567	}
	568	}
	569	}
	570	#endif
	571	#endif /* PNG_WRITE_TRANSFORMS_SUPPORTED */
	572
	573	#ifdef PNG_MNG_FEATURES_SUPPORTED
	574	/* Undoes intrapixel differencing */
	575	void /* PRIVATE */
	576	png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
	577	{
	578	png_debug(1, "in png_do_write_intrapixel");
	579
	580	if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
	581	{
	582	int bytes_per_pixel;
	583	png_uint_32 row_width = row_info->width;
	584	if (row_info->bit_depth == 8)
	585	{
	586	png_bytep rp;
	587	png_uint_32 i;
	588
	589	if (row_info->color_type == PNG_COLOR_TYPE_RGB)
	590	bytes_per_pixel = 3;
	591
	592	else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	593	bytes_per_pixel = 4;
	594
	595	else
	596	return;
	597
	598	for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
	599	{
	600	(rp) = (png_byte)((rp - *(rp + 1)) & 0xff);
	601	(rp + 2) = (png_byte)(((rp + 2) - *(rp + 1)) & 0xff);
	602	}
	603	}
	604
	605	#ifdef PNG_WRITE_16BIT_SUPPORTED
	606	else if (row_info->bit_depth == 16)
	607	{
	608	png_bytep rp;
	609	png_uint_32 i;
	610
	611	if (row_info->color_type == PNG_COLOR_TYPE_RGB)
	612	bytes_per_pixel = 6;
	613
	614	else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	615	bytes_per_pixel = 8;
	616
	617	else
	618	return;
	619
	620	for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
	621	{
	622	png_uint_32 s0 = ((rp ) << 8) \| (rp + 1);
	623	png_uint_32 s1 = ((rp + 2) << 8) \| (rp + 3);
	624	png_uint_32 s2 = ((rp + 4) << 8) \| (rp + 5);
	625	png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
	626	png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
	627	*(rp ) = (png_byte)((red >> 8) & 0xff);
	628	*(rp + 1) = (png_byte)(red & 0xff);
	629	*(rp + 4) = (png_byte)((blue >> 8) & 0xff);
	630	*(rp + 5) = (png_byte)(blue & 0xff);
	631	}
	632	}
	633	#endif /* PNG_WRITE_16BIT_SUPPORTED */
	634	}
	635	}
	636	#endif /* PNG_MNG_FEATURES_SUPPORTED */
	637	#endif /* PNG_WRITE_SUPPORTED */