// Add filler channel if we have RGB color
static unsafe void png_do_read_filler(ref png_row_info row_info, byte[] row, uint filler, PNG_FLAG flags)
{
uint i;
uint row_width=row_info.width;
byte hi_filler=(byte)((filler>>8)&0xff);
byte lo_filler=(byte)(filler&0xff);
fixed(byte* row_=row)
{
byte* sp=row_+1; // skip filter value
if(row_info.color_type==PNG_COLOR_TYPE.GRAY)
{
if(row_info.bit_depth==8)
{
// This changes the data from G to GX
if((flags&PNG_FLAG.FILLER_AFTER)==PNG_FLAG.FILLER_AFTER)
{
sp+=row_width;
byte* dp=sp+row_width;
for(i=1; i<row_width; i++)
{
*(--dp)=lo_filler;
*(--dp)=*(--sp);
}
*(--dp)=lo_filler;
row_info.channels=2;
row_info.pixel_depth=16;
row_info.rowbytes=row_width*2;
}
else // This changes the data from G to XG
{
sp+=row_width;
byte* dp=sp+row_width;
for(i=0; i<row_width; i++)
{
*(--dp)=*(--sp);
*(--dp)=lo_filler;
}
row_info.channels=2;
row_info.pixel_depth=16;
row_info.rowbytes=row_width*2;
}
}
else if(row_info.bit_depth==16)
{
// This changes the data from GG to GGXX
if((flags&PNG_FLAG.FILLER_AFTER)==PNG_FLAG.FILLER_AFTER)
{
sp+=row_width*2;
byte* dp=sp+row_width*2;
for(i=1; i<row_width; i++)
{
*(--dp)=hi_filler;
*(--dp)=lo_filler;
*(--dp)=*(--sp);
*(--dp)=*(--sp);
}
*(--dp)=hi_filler;
*(--dp)=lo_filler;
row_info.channels=2;
row_info.pixel_depth=32;
row_info.rowbytes=row_width*4;
}
else // This changes the data from GG to XXGG
{
sp+=row_width*2;
byte* dp=sp+row_width*2;
for(i=0; i<row_width; i++)
{
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=hi_filler;
*(--dp)=lo_filler;
}
row_info.channels=2;
row_info.pixel_depth=32;
row_info.rowbytes=row_width*4;
}
}
} // COLOR_TYPE==GRAY
else if(row_info.color_type==PNG_COLOR_TYPE.RGB)
{
if(row_info.bit_depth==8)
{
// This changes the data from RGB to RGBX
if((flags&PNG_FLAG.FILLER_AFTER)==PNG_FLAG.FILLER_AFTER)
{
sp+=row_width*3;
byte* dp=sp+row_width;
for(i=1; i<row_width; i++)
{
*(--dp)=lo_filler;
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=*(--sp);
}
*(--dp)=lo_filler;
row_info.channels=4;
row_info.pixel_depth=32;
row_info.rowbytes=row_width*4;
}
else // This changes the data from RGB to XRGB
{
sp+=row_width*3;
byte* dp=sp+row_width;
for(i=0; i<row_width; i++)
{
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=lo_filler;
}
row_info.channels=4;
row_info.pixel_depth=32;
row_info.rowbytes=row_width*4;
}
}
else if(row_info.bit_depth==16)
{
// This changes the data from RRGGBB to RRGGBBXX
if((flags&PNG_FLAG.FILLER_AFTER)==PNG_FLAG.FILLER_AFTER)
{
sp+=row_width*6;
byte* dp=sp+row_width*2;
for(i=1; i<row_width; i++)
{
*(--dp)=hi_filler;
*(--dp)=lo_filler;
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=*(--sp);
}
*(--dp)=hi_filler;
*(--dp)=lo_filler;
row_info.channels=4;
row_info.pixel_depth=64;
row_info.rowbytes=row_width*8;
}
else // This changes the data from RRGGBB to XXRRGGBB
{
sp+=row_width*6;
byte* dp=sp+row_width*2;
for(i=0; i<row_width; i++)
{
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=*(--sp);
*(--dp)=hi_filler;
*(--dp)=lo_filler;
}
row_info.channels=4;
row_info.pixel_depth=64;
row_info.rowbytes=row_width*8;
}
}
} // COLOR_TYPE==RGB
}
}
// remove filler or alpha byte(s)
static unsafe void png_do_strip_filler(ref png_row_info row_info, byte[] row, PNG_FLAG flags)
{
fixed(byte *row_ = row)
{
byte *sp = row_ + 1; // skip filter value
byte *dp = row_ + 1; // skip filter value
uint row_width = row_info.width;
uint i;
if (row_info.channels == 4 && (row_info.color_type == PNG_COLOR_TYPE.RGB ||
(row_info.color_type == PNG_COLOR_TYPE.RGB_ALPHA && (flags & PNG_FLAG.STRIP_ALPHA) == PNG_FLAG.STRIP_ALPHA)))
{
if (row_info.bit_depth == 8)
{
// This converts from RGBX or RGBA to RGB
if ((flags & PNG_FLAG.FILLER_AFTER) == PNG_FLAG.FILLER_AFTER)
{
dp += 3; sp += 4;
for (i = 1; i < row_width; i++)
{
*dp++ = *sp++;
*dp++ = *sp++;
*dp++ = *sp++;
sp++;
}
}
// This converts from XRGB or ARGB to RGB
else
{
for (i = 0; i < row_width; i++)
{
sp++;
*dp++ = *sp++;
*dp++ = *sp++;
*dp++ = *sp++;
}
}
row_info.pixel_depth = 24;
row_info.rowbytes = row_width * 3;
}
else // if(row_info->bit_depth==16)
{
if ((flags & PNG_FLAG.FILLER_AFTER) == PNG_FLAG.FILLER_AFTER)
{
// This converts from RRGGBBXX or RRGGBBAA to RRGGBB
sp += 8; dp += 6;
for (i = 1; i < row_width; i++)
{
*dp++ = *sp++;
*dp++ = *sp++;
*dp++ = *sp++;
*dp++ = *sp++;
*dp++ = *sp++;
*dp++ = *sp++;
sp += 2;
}
}
else
{
// This converts from XXRRGGBB or AARRGGBB to RRGGBB
for (i = 0; i < row_width; i++)
{
sp += 2;
*dp++ = *sp++;
*dp++ = *sp++;
*dp++ = *sp++;
*dp++ = *sp++;
*dp++ = *sp++;
*dp++ = *sp++;
}
}
row_info.pixel_depth = 48;
row_info.rowbytes = row_width * 6;
}
row_info.channels = 3;
}
else if (row_info.channels == 2 && (row_info.color_type == PNG_COLOR_TYPE.GRAY ||
(row_info.color_type == PNG_COLOR_TYPE.GRAY_ALPHA && (flags & PNG_FLAG.STRIP_ALPHA) == PNG_FLAG.STRIP_ALPHA)))
{
if (row_info.bit_depth == 8)
{
// This converts from GX or GA to G
if ((flags & PNG_FLAG.FILLER_AFTER) == PNG_FLAG.FILLER_AFTER)
{
for (i = 0; i < row_width; i++)
{
*dp++ = *sp++;
sp++;
}
}
// This converts from XG or AG to G
else
{
for (i = 0; i < row_width; i++)
{
sp++;
*dp++ = *sp++;
}
}
row_info.pixel_depth = 8;
row_info.rowbytes = row_width;
}
else // if(row_info->bit_depth==16)
{
if ((flags & PNG_FLAG.FILLER_AFTER) == PNG_FLAG.FILLER_AFTER)
{
// This converts from GGXX or GGAA to GG
sp += 4; dp += 2;
for (i = 1; i < row_width; i++)
{
*dp++ = *sp++;
*dp++ = *sp++;
sp += 2;
}
}
else
{
// This converts from XXGG or AAGG to GG
for (i = 0; i < row_width; i++)
{
sp += 2;
*dp++ = *sp++;
*dp++ = *sp++;
}
}
row_info.pixel_depth = 16;
row_info.rowbytes = row_width * 2;
}
row_info.channels = 1;
}
}
if ((flags & PNG_FLAG.STRIP_ALPHA) == PNG_FLAG.STRIP_ALPHA)
{
row_info.color_type &= ~PNG_COLOR_TYPE.ALPHA_MASK;
}
}
// remove filler or alpha byte(s)
static unsafe void png_do_strip_filler(ref png_row_info row_info, byte[] row, PNG_FLAG flags)
{
fixed(byte* row_=row)
{
byte* sp=row_+1;// skip filter value
byte* dp=row_+1;// skip filter value
uint row_width=row_info.width;
uint i;
if(row_info.channels==4&&(row_info.color_type==PNG_COLOR_TYPE.RGB||
(row_info.color_type==PNG_COLOR_TYPE.RGB_ALPHA&&(flags&PNG_FLAG.STRIP_ALPHA)==PNG_FLAG.STRIP_ALPHA)))
{
if(row_info.bit_depth==8)
{
// This converts from RGBX or RGBA to RGB
if((flags&PNG_FLAG.FILLER_AFTER)==PNG_FLAG.FILLER_AFTER)
{
dp+=3; sp+=4;
for(i=1; i<row_width; i++)
{
*dp++=*sp++;
*dp++=*sp++;
*dp++=*sp++;
sp++;
}
}
// This converts from XRGB or ARGB to RGB
else
{
for(i=0; i<row_width; i++)
{
sp++;
*dp++=*sp++;
*dp++=*sp++;
*dp++=*sp++;
}
}
row_info.pixel_depth=24;
row_info.rowbytes=row_width*3;
}
else // if(row_info->bit_depth==16)
{
if((flags&PNG_FLAG.FILLER_AFTER)==PNG_FLAG.FILLER_AFTER)
{
// This converts from RRGGBBXX or RRGGBBAA to RRGGBB
sp+=8; dp+=6;
for(i=1; i<row_width; i++)
{
*dp++=*sp++;
*dp++=*sp++;
*dp++=*sp++;
*dp++=*sp++;
*dp++=*sp++;
*dp++=*sp++;
sp+=2;
}
}
else
{
// This converts from XXRRGGBB or AARRGGBB to RRGGBB
for(i=0; i<row_width; i++)
{
sp+=2;
*dp++=*sp++;
*dp++=*sp++;
*dp++=*sp++;
*dp++=*sp++;
*dp++=*sp++;
*dp++=*sp++;
}
}
row_info.pixel_depth=48;
row_info.rowbytes=row_width*6;
}
row_info.channels=3;
}
else if(row_info.channels==2&&(row_info.color_type==PNG_COLOR_TYPE.GRAY||
(row_info.color_type==PNG_COLOR_TYPE.GRAY_ALPHA&&(flags&PNG_FLAG.STRIP_ALPHA)==PNG_FLAG.STRIP_ALPHA)))
{
if(row_info.bit_depth==8)
{
// This converts from GX or GA to G
if((flags&PNG_FLAG.FILLER_AFTER)==PNG_FLAG.FILLER_AFTER)
{
for(i=0; i<row_width; i++)
{
*dp++=*sp++;
sp++;
}
}
// This converts from XG or AG to G
else
{
for(i=0; i<row_width; i++)
{
sp++;
*dp++=*sp++;
}
}
row_info.pixel_depth=8;
row_info.rowbytes=row_width;
}
else // if(row_info->bit_depth==16)
{
if((flags&PNG_FLAG.FILLER_AFTER)==PNG_FLAG.FILLER_AFTER)
{
// This converts from GGXX or GGAA to GG
sp+=4; dp+=2;
for(i=1; i<row_width; i++)
{
*dp++=*sp++;
*dp++=*sp++;
sp+=2;
}
}
else
{
// This converts from XXGG or AAGG to GG
for(i=0; i<row_width; i++)
{
sp+=2;
*dp++=*sp++;
*dp++=*sp++;
}
}
row_info.pixel_depth=16;
row_info.rowbytes=row_width*2;
}
row_info.channels=1;
}
}
if((flags&PNG_FLAG.STRIP_ALPHA)==PNG_FLAG.STRIP_ALPHA) row_info.color_type&=~PNG_COLOR_TYPE.ALPHA_MASK;
}
