src/png/pngwtran.c


/* pngwtran.c - transforms the data in a row for PNG writers
 *
 * Last changed in libpng 1.4.1 [February 25, 2010]
 * Copyright (c) 1998-2010 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_NO_PEDANTIC_WARNINGS
#include "png.h"
#ifdef PNG_WRITE_SUPPORTED
#include "pngpriv.h"

/* 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 &&
      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");

   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_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");

   {
      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");

   {
      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 (
       (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 */
Commit	Line	Data
	1
	2	/* pngwtran.c - transforms the data in a row for PNG writers
	3	*
	4	* Last changed in libpng 1.4.1 [February 25, 2010]
	5	* Copyright (c) 1998-2010 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	#define PNG_NO_PEDANTIC_WARNINGS
	15	#include "png.h"
	16	#ifdef PNG_WRITE_SUPPORTED
	17	#include "pngpriv.h"
	18
	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)
	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	&(png_ptr->row_info), /* row_info: */
	37	/* png_uint_32 width; width of row */
	38	/* png_uint_32 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	#ifdef PNG_WRITE_FILLER_SUPPORTED
	46	if (png_ptr->transformations & PNG_FILLER)
	47	png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
	48	png_ptr->flags);
	49	#endif
	50	#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
	51	if (png_ptr->transformations & PNG_PACKSWAP)
	52	png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
	53	#endif
	54	#ifdef PNG_WRITE_PACK_SUPPORTED
	55	if (png_ptr->transformations & PNG_PACK)
	56	png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
	57	(png_uint_32)png_ptr->bit_depth);
	58	#endif
	59	#ifdef PNG_WRITE_SWAP_SUPPORTED
	60	if (png_ptr->transformations & PNG_SWAP_BYTES)
	61	png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
	62	#endif
	63	#ifdef PNG_WRITE_SHIFT_SUPPORTED
	64	if (png_ptr->transformations & PNG_SHIFT)
	65	png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
	66	&(png_ptr->shift));
	67	#endif
	68	#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
	69	if (png_ptr->transformations & PNG_SWAP_ALPHA)
	70	png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
	71	#endif
	72	#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
	73	if (png_ptr->transformations & PNG_INVERT_ALPHA)
	74	png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
	75	#endif
	76	#ifdef PNG_WRITE_BGR_SUPPORTED
	77	if (png_ptr->transformations & PNG_BGR)
	78	png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
	79	#endif
	80	#ifdef PNG_WRITE_INVERT_SUPPORTED
	81	if (png_ptr->transformations & PNG_INVERT_MONO)
	82	png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
	83	#endif
	84	}
	85
	86	#ifdef PNG_WRITE_PACK_SUPPORTED
	87	/* Pack pixels into bytes. Pass the true bit depth in bit_depth. The
	88	* row_info bit depth should be 8 (one pixel per byte). The channels
	89	* should be 1 (this only happens on grayscale and paletted images).
	90	*/
	91	void /* PRIVATE */
	92	png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
	93	{
	94	png_debug(1, "in png_do_pack");
	95
	96	if (row_info->bit_depth == 8 &&
	97	row_info->channels == 1)
	98	{
	99	switch ((int)bit_depth)
	100	{
	101	case 1:
	102	{
	103	png_bytep sp, dp;
	104	int mask, v;
	105	png_uint_32 i;
	106	png_uint_32 row_width = row_info->width;
	107
	108	sp = row;
	109	dp = row;
	110	mask = 0x80;
	111	v = 0;
	112
	113	for (i = 0; i < row_width; i++)
	114	{
	115	if (*sp != 0)
	116	v \|= mask;
	117	sp++;
	118	if (mask > 1)
	119	mask >>= 1;
	120	else
	121	{
	122	mask = 0x80;
	123	*dp = (png_byte)v;
	124	dp++;
	125	v = 0;
	126	}
	127	}
	128	if (mask != 0x80)
	129	*dp = (png_byte)v;
	130	break;
	131	}
	132	case 2:
	133	{
	134	png_bytep sp, dp;
	135	int shift, v;
	136	png_uint_32 i;
	137	png_uint_32 row_width = row_info->width;
	138
	139	sp = row;
	140	dp = row;
	141	shift = 6;
	142	v = 0;
	143	for (i = 0; i < row_width; i++)
	144	{
	145	png_byte value;
	146
	147	value = (png_byte)(*sp & 0x03);
	148	v \|= (value << shift);
	149	if (shift == 0)
	150	{
	151	shift = 6;
	152	*dp = (png_byte)v;
	153	dp++;
	154	v = 0;
	155	}
	156	else
	157	shift -= 2;
	158	sp++;
	159	}
	160	if (shift != 6)
	161	*dp = (png_byte)v;
	162	break;
	163	}
	164	case 4:
	165	{
	166	png_bytep sp, dp;
	167	int shift, v;
	168	png_uint_32 i;
	169	png_uint_32 row_width = row_info->width;
	170
	171	sp = row;
	172	dp = row;
	173	shift = 4;
	174	v = 0;
	175	for (i = 0; i < row_width; i++)
	176	{
	177	png_byte value;
	178
	179	value = (png_byte)(*sp & 0x0f);
	180	v \|= (value << shift);
	181
	182	if (shift == 0)
	183	{
	184	shift = 4;
	185	*dp = (png_byte)v;
	186	dp++;
	187	v = 0;
	188	}
	189	else
	190	shift -= 4;
	191
	192	sp++;
	193	}
	194	if (shift != 4)
	195	*dp = (png_byte)v;
	196	break;
	197	}
	198	}
	199	row_info->bit_depth = (png_byte)bit_depth;
	200	row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
	201	row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
	202	row_info->width);
	203	}
	204	}
	205	#endif
	206
	207	#ifdef PNG_WRITE_SHIFT_SUPPORTED
	208	/* Shift pixel values to take advantage of whole range. Pass the
	209	* true number of bits in bit_depth. The row should be packed
	210	* according to row_info->bit_depth. Thus, if you had a row of
	211	* bit depth 4, but the pixels only had values from 0 to 7, you
	212	* would pass 3 as bit_depth, and this routine would translate the
	213	* data to 0 to 15.
	214	*/
	215	void /* PRIVATE */
	216	png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
	217	{
	218	png_debug(1, "in png_do_shift");
	219
	220	if (
	221	row_info->color_type != PNG_COLOR_TYPE_PALETTE)
	222	{
	223	int shift_start[4], shift_dec[4];
	224	int channels = 0;
	225
	226	if (row_info->color_type & PNG_COLOR_MASK_COLOR)
	227	{
	228	shift_start[channels] = row_info->bit_depth - bit_depth->red;
	229	shift_dec[channels] = bit_depth->red;
	230	channels++;
	231	shift_start[channels] = row_info->bit_depth - bit_depth->green;
	232	shift_dec[channels] = bit_depth->green;
	233	channels++;
	234	shift_start[channels] = row_info->bit_depth - bit_depth->blue;
	235	shift_dec[channels] = bit_depth->blue;
	236	channels++;
	237	}
	238	else
	239	{
	240	shift_start[channels] = row_info->bit_depth - bit_depth->gray;
	241	shift_dec[channels] = bit_depth->gray;
	242	channels++;
	243	}
	244	if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
	245	{
	246	shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
	247	shift_dec[channels] = bit_depth->alpha;
	248	channels++;
	249	}
	250
	251	/* With low row depths, could only be grayscale, so one channel */
	252	if (row_info->bit_depth < 8)
	253	{
	254	png_bytep bp = row;
	255	png_uint_32 i;
	256	png_byte mask;
	257	png_uint_32 row_bytes = row_info->rowbytes;
	258
	259	if (bit_depth->gray == 1 && row_info->bit_depth == 2)
	260	mask = 0x55;
	261	else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
	262	mask = 0x11;
	263	else
	264	mask = 0xff;
	265
	266	for (i = 0; i < row_bytes; i++, bp++)
	267	{
	268	png_uint_16 v;
	269	int j;
	270
	271	v = *bp;
	272	*bp = 0;
	273	for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
	274	{
	275	if (j > 0)
	276	*bp \|= (png_byte)((v << j) & 0xff);
	277	else
	278	*bp \|= (png_byte)((v >> (-j)) & mask);
	279	}
	280	}
	281	}
	282	else if (row_info->bit_depth == 8)
	283	{
	284	png_bytep bp = row;
	285	png_uint_32 i;
	286	png_uint_32 istop = channels * row_info->width;
	287
	288	for (i = 0; i < istop; i++, bp++)
	289	{
	290
	291	png_uint_16 v;
	292	int j;
	293	int c = (int)(i%channels);
	294
	295	v = *bp;
	296	*bp = 0;
	297	for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
	298	{
	299	if (j > 0)
	300	*bp \|= (png_byte)((v << j) & 0xff);
	301	else
	302	*bp \|= (png_byte)((v >> (-j)) & 0xff);
	303	}
	304	}
	305	}
	306	else
	307	{
	308	png_bytep bp;
	309	png_uint_32 i;
	310	png_uint_32 istop = channels * row_info->width;
	311
	312	for (bp = row, i = 0; i < istop; i++)
	313	{
	314	int c = (int)(i%channels);
	315	png_uint_16 value, v;
	316	int j;
	317
	318	v = (png_uint_16)(((png_uint_16)(bp) << 8) + (bp + 1));
	319	value = 0;
	320	for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
	321	{
	322	if (j > 0)
	323	value \|= (png_uint_16)((v << j) & (png_uint_16)0xffff);
	324	else
	325	value \|= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
	326	}
	327	*bp++ = (png_byte)(value >> 8);
	328	*bp++ = (png_byte)(value & 0xff);
	329	}
	330	}
	331	}
	332	}
	333	#endif
	334
	335	#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
	336	void /* PRIVATE */
	337	png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
	338	{
	339	png_debug(1, "in png_do_write_swap_alpha");
	340
	341	{
	342	if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	343	{
	344	/* This converts from ARGB to RGBA */
	345	if (row_info->bit_depth == 8)
	346	{
	347	png_bytep sp, dp;
	348	png_uint_32 i;
	349	png_uint_32 row_width = row_info->width;
	350	for (i = 0, sp = dp = row; i < row_width; i++)
	351	{
	352	png_byte save = *(sp++);
	353	(dp++) = (sp++);
	354	(dp++) = (sp++);
	355	(dp++) = (sp++);
	356	*(dp++) = save;
	357	}
	358	}
	359	/* This converts from AARRGGBB to RRGGBBAA */
	360	else
	361	{
	362	png_bytep sp, dp;
	363	png_uint_32 i;
	364	png_uint_32 row_width = row_info->width;
	365
	366	for (i = 0, sp = dp = row; i < row_width; i++)
	367	{
	368	png_byte save[2];
	369	save[0] = *(sp++);
	370	save[1] = *(sp++);
	371	(dp++) = (sp++);
	372	(dp++) = (sp++);
	373	(dp++) = (sp++);
	374	(dp++) = (sp++);
	375	(dp++) = (sp++);
	376	(dp++) = (sp++);
	377	*(dp++) = save[0];
	378	*(dp++) = save[1];
	379	}
	380	}
	381	}
	382	else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
	383	{
	384	/* This converts from AG to GA */
	385	if (row_info->bit_depth == 8)
	386	{
	387	png_bytep sp, dp;
	388	png_uint_32 i;
	389	png_uint_32 row_width = row_info->width;
	390
	391	for (i = 0, sp = dp = row; i < row_width; i++)
	392	{
	393	png_byte save = *(sp++);
	394	(dp++) = (sp++);
	395	*(dp++) = save;
	396	}
	397	}
	398	/* This converts from AAGG to GGAA */
	399	else
	400	{
	401	png_bytep sp, dp;
	402	png_uint_32 i;
	403	png_uint_32 row_width = row_info->width;
	404
	405	for (i = 0, sp = dp = row; i < row_width; i++)
	406	{
	407	png_byte save[2];
	408	save[0] = *(sp++);
	409	save[1] = *(sp++);
	410	(dp++) = (sp++);
	411	(dp++) = (sp++);
	412	*(dp++) = save[0];
	413	*(dp++) = save[1];
	414	}
	415	}
	416	}
	417	}
	418	}
	419	#endif
	420
	421	#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
	422	void /* PRIVATE */
	423	png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
	424	{
	425	png_debug(1, "in png_do_write_invert_alpha");
	426
	427	{
	428	if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	429	{
	430	/* This inverts the alpha channel in RGBA */
	431	if (row_info->bit_depth == 8)
	432	{
	433	png_bytep sp, dp;
	434	png_uint_32 i;
	435	png_uint_32 row_width = row_info->width;
	436	for (i = 0, sp = dp = row; i < row_width; i++)
	437	{
	438	/* Does nothing
	439	(dp++) = (sp++);
	440	(dp++) = (sp++);
	441	(dp++) = (sp++);
	442	*/
	443	sp+=3; dp = sp;
	444	(dp++) = (png_byte)(255 - (sp++));
	445	}
	446	}
	447	/* This inverts the alpha channel in RRGGBBAA */
	448	else
	449	{
	450	png_bytep sp, dp;
	451	png_uint_32 i;
	452	png_uint_32 row_width = row_info->width;
	453
	454	for (i = 0, sp = dp = row; i < row_width; i++)
	455	{
	456	/* Does nothing
	457	(dp++) = (sp++);
	458	(dp++) = (sp++);
	459	(dp++) = (sp++);
	460	(dp++) = (sp++);
	461	(dp++) = (sp++);
	462	(dp++) = (sp++);
	463	*/
	464	sp+=6; dp = sp;
	465	(dp++) = (png_byte)(255 - (sp++));
	466	(dp++) = (png_byte)(255 - (sp++));
	467	}
	468	}
	469	}
	470	else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
	471	{
	472	/* This inverts the alpha channel in GA */
	473	if (row_info->bit_depth == 8)
	474	{
	475	png_bytep sp, dp;
	476	png_uint_32 i;
	477	png_uint_32 row_width = row_info->width;
	478
	479	for (i = 0, sp = dp = row; i < row_width; i++)
	480	{
	481	(dp++) = (sp++);
	482	(dp++) = (png_byte)(255 - (sp++));
	483	}
	484	}
	485	/* This inverts the alpha channel in GGAA */
	486	else
	487	{
	488	png_bytep sp, dp;
	489	png_uint_32 i;
	490	png_uint_32 row_width = row_info->width;
	491
	492	for (i = 0, sp = dp = row; i < row_width; i++)
	493	{
	494	/* Does nothing
	495	(dp++) = (sp++);
	496	(dp++) = (sp++);
	497	*/
	498	sp+=2; dp = sp;
	499	(dp++) = (png_byte)(255 - (sp++));
	500	(dp++) = (png_byte)(255 - (sp++));
	501	}
	502	}
	503	}
	504	}
	505	}
	506	#endif
	507
	508	#ifdef PNG_MNG_FEATURES_SUPPORTED
	509	/* Undoes intrapixel differencing */
	510	void /* PRIVATE */
	511	png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
	512	{
	513	png_debug(1, "in png_do_write_intrapixel");
	514
	515	if (
	516	(row_info->color_type & PNG_COLOR_MASK_COLOR))
	517	{
	518	int bytes_per_pixel;
	519	png_uint_32 row_width = row_info->width;
	520	if (row_info->bit_depth == 8)
	521	{
	522	png_bytep rp;
	523	png_uint_32 i;
	524
	525	if (row_info->color_type == PNG_COLOR_TYPE_RGB)
	526	bytes_per_pixel = 3;
	527	else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	528	bytes_per_pixel = 4;
	529	else
	530	return;
	531
	532	for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
	533	{
	534	(rp) = (png_byte)((rp - *(rp+1))&0xff);
	535	(rp+2) = (png_byte)(((rp+2) - *(rp+1))&0xff);
	536	}
	537	}
	538	else if (row_info->bit_depth == 16)
	539	{
	540	png_bytep rp;
	541	png_uint_32 i;
	542
	543	if (row_info->color_type == PNG_COLOR_TYPE_RGB)
	544	bytes_per_pixel = 6;
	545	else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	546	bytes_per_pixel = 8;
	547	else
	548	return;
	549
	550	for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
	551	{
	552	png_uint_32 s0 = ((rp ) << 8) \| (rp+1);
	553	png_uint_32 s1 = ((rp+2) << 8) \| (rp+3);
	554	png_uint_32 s2 = ((rp+4) << 8) \| (rp+5);
	555	png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
	556	png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
	557	*(rp ) = (png_byte)((red >> 8) & 0xff);
	558	*(rp+1) = (png_byte)(red & 0xff);
	559	*(rp+4) = (png_byte)((blue >> 8) & 0xff);
	560	*(rp+5) = (png_byte)(blue & 0xff);
	561	}
	562	}
	563	}
	564	}
	565	#endif /* PNG_MNG_FEATURES_SUPPORTED */
	566	#endif /* PNG_WRITE_SUPPORTED */