public PNG_INFO png_get_bKGD(ref png_color_16 background)
{
if ((info_ptr_valid & PNG_INFO.bKGD) != PNG_INFO.bKGD)
{
return(PNG_INFO.None);
}
background = info_ptr_background;
return(PNG_INFO.bKGD);
}
public PNG_INFO png_get_tRNS(ref byte[] trans_alpha, ref ushort num_trans, ref png_color_16 trans_color)
{
if ((info_ptr_valid & PNG_INFO.tRNS) != PNG_INFO.tRNS)
{
return(PNG_INFO.None);
}
trans_color = info_ptr_trans_color;
trans_alpha = (info_ptr_color_type == PNG_COLOR_TYPE.PALETTE)?info_ptr_trans_alpha:null;
num_trans = info_ptr_num_trans;
return(PNG_INFO.tRNS);
}
public void png_set_tRNS(png_color_16 trans_color)
{
int sample_max = (1 << info_ptr_bit_depth);
if ((info_ptr_color_type == PNG_COLOR_TYPE.GRAY &&
(int)trans_color.gray > sample_max) ||
(info_ptr_color_type == PNG_COLOR_TYPE.RGB &&
((int)trans_color.red > sample_max ||
(int)trans_color.green > sample_max ||
(int)trans_color.blue > sample_max)))
{
Debug.WriteLine("tRNS chunk has out-of-range samples for bit_depth");
}
this.trans_color = info_ptr_trans_color = trans_color;
num_trans = info_ptr_num_trans = 1;
info_ptr_valid |= PNG_INFO.tRNS;
}
public PNG_INFO png_get_tRNS(ref byte[] trans_alpha, ref ushort num_trans, ref png_color_16 trans_color)
{
if((info_ptr_valid&PNG_INFO.tRNS)!=PNG_INFO.tRNS) return PNG_INFO.None;
trans_color=info_ptr_trans_color;
trans_alpha=(info_ptr_color_type==PNG_COLOR_TYPE.PALETTE)?info_ptr_trans_alpha:null;
num_trans=info_ptr_num_trans;
return PNG_INFO.tRNS;
}
public PNG_INFO png_get_bKGD(ref png_color_16 background)
{
if((info_ptr_valid&PNG_INFO.bKGD)!=PNG_INFO.bKGD) return PNG_INFO.None;
background=info_ptr_background;
return PNG_INFO.bKGD;
}
void png_handle_bKGD(uint length)
{
if((mode&PNG_MODE.HAVE_IHDR)!=PNG_MODE.HAVE_IHDR) throw new PNG_Exception("Missing IHDR before bKGD");
else if((mode&PNG_MODE.HAVE_IDAT)==PNG_MODE.HAVE_IDAT)
{
Debug.WriteLine("Invalid bKGD after IDAT");
png_crc_finish(length);
return;
}
else if(color_type==PNG_COLOR_TYPE.PALETTE&&!((mode&PNG_MODE.HAVE_PLTE)==PNG_MODE.HAVE_PLTE))
{
Debug.WriteLine("Missing PLTE before bKGD");
png_crc_finish(length);
return;
}
else if((info_ptr_valid&PNG_INFO.bKGD)==PNG_INFO.bKGD)
{
Debug.WriteLine("Duplicate bKGD chunk");
png_crc_finish(length);
return;
}
uint truelen=2;
if(color_type==PNG_COLOR_TYPE.PALETTE) truelen=1;
else if((color_type&PNG_COLOR_TYPE.COLOR_MASK)==PNG_COLOR_TYPE.COLOR_MASK) truelen=6;
if(length!=truelen)
{
Debug.WriteLine("Incorrect bKGD chunk length");
png_crc_finish(length);
return;
}
byte[] buf=new byte[truelen];
png_crc_read(buf, truelen);
if(png_crc_finish(0)) return;
png_color_16 background=new png_color_16();
// We convert the index value into RGB components so that we can allow
// arbitrary RGB values for background when we have transparency, and
// so it is easy to determine the RGB values of the background color
// from the info_ptr struct.
if(color_type==PNG_COLOR_TYPE.PALETTE)
{
background.index=buf[0];
if(info_ptr_palette.Length!=0)
{
if(buf[0]>info_ptr_palette.Length)
{
Debug.WriteLine("Incorrect bKGD chunk index value");
return;
}
background.red=(ushort)palette[buf[0]].red;
background.green=(ushort)palette[buf[0]].green;
background.blue=(ushort)palette[buf[0]].blue;
}
}
else if((color_type&PNG_COLOR_TYPE.COLOR_MASK)!=PNG_COLOR_TYPE.COLOR_MASK)
{
background.red=background.green=background.blue=background.gray=png_get_uint_16(buf);
}
else
{
background.red=png_get_uint_16(buf);
background.green=png_get_uint_16(buf, 2);
background.blue=png_get_uint_16(buf, 4);
}
png_set_bKGD(background);
}
void png_handle_tRNS(uint length)
{
if((mode&PNG_MODE.HAVE_IHDR)!=PNG_MODE.HAVE_IHDR) throw new PNG_Exception("Missing IHDR before tRNS");
else if((mode&PNG_MODE.HAVE_IDAT)==PNG_MODE.HAVE_IDAT)
{
Debug.WriteLine("Invalid tRNS after IDAT");
png_crc_finish(length);
return;
}
else if((info_ptr_valid&PNG_INFO.tRNS)==PNG_INFO.tRNS)
{
Debug.WriteLine("Duplicate tRNS chunk");
png_crc_finish(length);
return;
}
trans_color=new png_color_16();
if(color_type==PNG_COLOR_TYPE.GRAY)
{
if(length!=2)
{
Debug.WriteLine("Incorrect tRNS chunk length");
png_crc_finish(length);
return;
}
png_crc_read(buf4, 2);
if(png_crc_finish(0)) return;
num_trans=1;
trans_color.gray=png_get_uint_16(buf4);
png_set_tRNS(trans_color);
}
else if(color_type==PNG_COLOR_TYPE.RGB)
{
if(length!=6)
{
Debug.WriteLine("Incorrect tRNS chunk length");
png_crc_finish(length);
return;
}
byte[] buf=new byte[6];
png_crc_read(buf, 6);
if(png_crc_finish(0)) return;
num_trans=1;
trans_color.red=png_get_uint_16(buf);
trans_color.green=png_get_uint_16(buf, 2);
trans_color.blue=png_get_uint_16(buf, 4);
png_set_tRNS(trans_color);
}
else if(color_type==PNG_COLOR_TYPE.PALETTE)
{
if(!((mode&PNG_MODE.HAVE_PLTE)==PNG_MODE.HAVE_PLTE)) Debug.WriteLine("Missing PLTE before tRNS"); // Should be an error, but we can cope with it.
if(length>palette.Length||length>PNG.MAX_PALETTE_LENGTH)
{
Debug.WriteLine("Incorrect tRNS chunk length");
png_crc_finish(length);
return;
}
if(length==0)
{
Debug.WriteLine("Zero length tRNS chunk");
png_crc_finish(length);
return;
}
byte[] readbuf=new byte[length];
png_crc_read(readbuf, length);
if(png_crc_finish(0)) return;
num_trans=(ushort)length;
png_set_tRNS(readbuf);
}
else
{
Debug.WriteLine("tRNS chunk not allowed with alpha channel");
png_crc_finish(length);
num_trans=0;
}
}
public void png_set_bKGD(png_color_16 background)
{
info_ptr_background = background;
info_ptr_valid |= PNG_INFO.bKGD;
}
public void png_set_tRNS(png_color_16 trans_color)
{
int sample_max=(1<<info_ptr_bit_depth);
if((info_ptr_color_type==PNG_COLOR_TYPE.GRAY&&
(int)trans_color.gray>sample_max)||
(info_ptr_color_type==PNG_COLOR_TYPE.RGB&&
((int)trans_color.red>sample_max||
(int)trans_color.green>sample_max||
(int)trans_color.blue>sample_max)))
Debug.WriteLine("tRNS chunk has out-of-range samples for bit_depth");
this.trans_color=info_ptr_trans_color=trans_color;
num_trans=info_ptr_num_trans=1;
info_ptr_valid|=PNG_INFO.tRNS;
}
public void png_set_bKGD(png_color_16 background)
{
info_ptr_background=background;
info_ptr_valid|=PNG_INFO.bKGD;
}
// write the background chunk
void png_write_bKGD(png_color_16 back, PNG_COLOR_TYPE color_type)
{
byte[] buf=new byte[6];
if(color_type==PNG_COLOR_TYPE.PALETTE)
{
uint num_palette=0;
if(palette!=null) num_palette=(uint)palette.Length;
if((num_palette!=0||(mng_features_permitted&PNG_FLAG_MNG.EMPTY_PLTE)!=PNG_FLAG_MNG.EMPTY_PLTE)&&back.index>=num_palette)
{
Debug.WriteLine("Invalid background palette index");
return;
}
buf[0]=back.index;
png_write_chunk(PNG.bKGD, buf, 1);
}
else if((color_type&PNG_COLOR_TYPE.COLOR_MASK)==PNG_COLOR_TYPE.COLOR_MASK)
{
png_save_uint_16(buf, back.red);
png_save_uint_16(buf, 2, back.green);
png_save_uint_16(buf, 4, back.blue);
if(bit_depth==8&&(buf[0]|buf[2]|buf[4])!=0)
{
Debug.WriteLine("Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
return;
}
png_write_chunk(PNG.bKGD, buf, 6);
}
else
{
if(back.gray>=(1<<bit_depth))
{
Debug.WriteLine("Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
return;
}
png_save_uint_16(buf, back.gray);
png_write_chunk(PNG.bKGD, buf, 2);
}
}
// write the tRNS chunk
void png_write_tRNS(byte[] trans_alpha, png_color_16 tran, int num_trans, PNG_COLOR_TYPE color_type)
{
byte[] buf=new byte[6];
if(color_type==PNG_COLOR_TYPE.PALETTE)
{
if(num_trans<=0||num_trans>palette.Length)
{
Debug.WriteLine("Invalid number of transparent colors specified");
return;
}
// write the chunk out as it is
png_write_chunk(PNG.tRNS, trans_alpha, (uint)num_trans);
}
else if(color_type==PNG_COLOR_TYPE.GRAY)
{
// one 16 bit value
if(tran.gray>=(1<<bit_depth))
{
Debug.WriteLine("Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
return;
}
png_save_uint_16(buf, tran.gray);
png_write_chunk(PNG.tRNS, buf, 2);
}
else if(color_type==PNG_COLOR_TYPE.RGB)
{
// three 16 bit values
png_save_uint_16(buf, tran.red);
png_save_uint_16(buf, 2, tran.green);
png_save_uint_16(buf, 4, tran.blue);
if(bit_depth==8&&(buf[0]|buf[2]|buf[4])!=0)
{
Debug.WriteLine("Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
return;
}
png_write_chunk(PNG.tRNS, buf, 6);
}
else Debug.WriteLine("Can't write tRNS with an alpha channel");
}
// If the bit depth < 8, it is expanded to 8. Also, if the already
// expanded transparency value is supplied, an alpha channel is built.
static unsafe void png_do_expand_with_trans_values(ref png_row_info row_info, byte[] row, ref png_color_16 trans_value)
{
int shift, value;
uint row_width=row_info.width;
fixed(byte* row_=row)
{
byte* sp=row_+1; // skip filter value
byte* dp=row_+1; // skip filter value
if(row_info.color_type==PNG_COLOR_TYPE.GRAY)
{
ushort gray=trans_value.gray;
if(row_info.bit_depth<8)
{
switch(row_info.bit_depth)
{
case 1:
{
gray=(ushort)((gray&0x01)*0xff);
sp+=(row_width-1)>>3;
dp+=row_width-1;
shift=7-(int)((row_width+7)&0x07);
for(uint i=0; i<row_width; i++)
{
if(((*sp>>shift)&0x01)==0x01) *dp=0xff;
else *dp=0;
if(shift==7)
{
shift=0;
sp--;
}
else shift++;
dp--;
}
}
break;
case 2:
{
gray=(ushort)((gray&0x03)*0x55);
sp+=(row_width-1)>>2;
dp+=row_width-1;
shift=(int)((3-((row_width+3)&0x03))<<1);
for(uint i=0; i<row_width; i++)
{
value=(*sp>>shift)&0x03;
*dp=(byte)(value|(value<<2)|(value<<4)|(value<<6));
if(shift==6)
{
shift=0;
sp--;
}
else shift+=2;
dp--;
}
}
break;
case 4:
{
gray=(ushort)((gray&0x0f)*0x11);
sp+=(row_width-1)>>1;
dp+=row_width-1;
shift=(int)((1-((row_width+1)&0x01))<<2);
for(uint i=0; i<row_width; i++)
{
value=(*sp>>shift)&0x0f;
*dp=(byte)(value|(value<<4));
if(shift==4)
{
shift=0;
sp--;
}
else shift=4;
dp--;
}
}
break;
}
row_info.bit_depth=8;
row_info.pixel_depth=8;
row_info.rowbytes=row_width;
// reset to start values
sp=row_+1; // skip filter value
dp=row_+1; // skip filter value
} // if(row_info.bit_depth<8)
if(row_info.bit_depth==8)
{
gray=(byte)(gray&0xff);
sp+=row_width-1;
dp+=(row_width<<1)-1;
for(uint i=0; i<row_width; i++)
{
if(*sp==gray) *dp--=0;
else *dp--=0xff;
*dp--=*sp--;
}
}
else if(row_info.bit_depth==16)
{
byte gray_high=(byte)((gray>>8)&0xff);
byte gray_low=(byte)(gray&0xff);
sp+=row_info.rowbytes-1;
dp+=(row_info.rowbytes<<1)-1;
for(uint i=0; i<row_width; i++)
{
if(*(sp-1)==gray_high&&*(sp)==gray_low)
{
*dp--=0;
*dp--=0;
}
else
{
*dp--=0xff;
*dp--=0xff;
}
*dp--=*sp--;
*dp--=*sp--;
}
}
row_info.color_type=PNG_COLOR_TYPE.GRAY_ALPHA;
row_info.channels=2;
row_info.pixel_depth=(byte)(row_info.bit_depth<<1);
row_info.rowbytes=PNG_ROWBYTES(row_info.pixel_depth, row_width);
}
else if(row_info.color_type==PNG_COLOR_TYPE.RGB)
{
if(row_info.bit_depth==8)
{
byte red=(byte)(trans_value.red&0xff);
byte green=(byte)(trans_value.green&0xff);
byte blue=(byte)(trans_value.blue&0xff);
sp+=row_info.rowbytes-1;
dp+=(row_width<<2)-1;
for(uint i=0; i<row_width; i++)
{
if(*(sp-2)==red&&*(sp-1)==green&&*(sp)==blue) *dp--=0;
else *dp--=0xff;
*dp--=*sp--;
*dp--=*sp--;
*dp--=*sp--;
}
}
else if(row_info.bit_depth==16)
{
byte red_high=(byte)((trans_value.red>>8)&0xff);
byte green_high=(byte)((trans_value.green>>8)&0xff);
byte blue_high=(byte)((trans_value.blue>>8)&0xff);
byte red_low=(byte)(trans_value.red&0xff);
byte green_low=(byte)(trans_value.green&0xff);
byte blue_low=(byte)(trans_value.blue&0xff);
sp+=row_info.rowbytes-1;
dp+=(row_width<<3)-1;
for(uint i=0; i<row_width; i++)
{
if(*(sp-5)==red_high&&*(sp-4)==red_low&&*(sp-3)==green_high&&*(sp-2)==green_low&&*(sp-1)==blue_high&&*(sp)==blue_low)
{
*dp--=0;
*dp--=0;
}
else
{
*dp--=0xff;
*dp--=0xff;
}
*dp--=*sp--;
*dp--=*sp--;
*dp--=*sp--;
*dp--=*sp--;
*dp--=*sp--;
*dp--=*sp--;
}
}
row_info.color_type=PNG_COLOR_TYPE.RGB_ALPHA;
row_info.channels=4;
row_info.pixel_depth=(byte)(row_info.bit_depth<<2);
row_info.rowbytes=PNG_ROWBYTES(row_info.pixel_depth, row_width);
}
}
}
// Replace any alpha or transparency with the supplied background color.
// "background" is already in the screen gamma, while "background_1" is
// at a gamma of 1.0. Paletted files have already been taken care of.
static unsafe void png_do_background(ref png_row_info row_info, byte[] row, ref png_color_16 trans_color, ref png_color_16 background,
ref png_color_16 background_1, byte[] gamma_table, byte[] gamma_from_1, byte[] gamma_to_1, ushort[][] gamma_16,
ushort[][] gamma_16_from_1, ushort[][] gamma_16_to_1, int gamma_shift)
{
uint i;
uint row_width=row_info.width;
int shift;
if(!((row_info.color_type&PNG_COLOR_TYPE.ALPHA_MASK)!=PNG_COLOR_TYPE.ALPHA_MASK||
row_info.color_type!=PNG_COLOR_TYPE.PALETTE)) return;
fixed(byte* row_=row)
{
byte* sp=row_+1; // skip filter value
byte* dp=row_+1; // skip filter value
switch(row_info.color_type)
{
case PNG_COLOR_TYPE.GRAY:
{
switch(row_info.bit_depth)
{
case 1:
{
shift=7;
for(i=0; i<row_width; i++)
{
if((ushort)((*sp>>shift)&0x01)==trans_color.gray)
{
*sp&=(byte)((0x7f7f>>(7-shift))&0xff);
*sp|=(byte)(background.gray<<shift);
}
if(shift==0)
{
shift=7;
sp++;
}
else shift--;
}
}
break;
case 2:
{
shift=6;
if(gamma_table!=null)
{
for(i=0; i<row_width; i++)
{
if((ushort)((*sp>>shift)&0x03)==trans_color.gray)
{
*sp&=(byte)((0x3f3f>>(6-shift))&0xff);
*sp|=(byte)(background.gray<<shift);
}
else
{
byte p=(byte)((*sp>>shift)&0x03);
byte g=(byte)((gamma_table[p|(p<<2)|(p<<4)|(p<<6)]>>6)&0x03);
*sp&=(byte)((0x3f3f>>(6-shift))&0xff);
*sp|=(byte)(g<<shift);
}
if(shift==0)
{
shift=6;
sp++;
}
else shift-=2;
}
}
else
{
for(i=0; i<row_width; i++)
{
if((ushort)((*sp>>shift)&0x03)==trans_color.gray)
{
*sp&=(byte)((0x3f3f>>(6-shift))&0xff);
*sp|=(byte)(background.gray<<shift);
}
if(shift==0)
{
shift=6;
sp++;
}
else shift-=2;
}
}
}
break;
case 4:
{
shift=4;
if(gamma_table!=null)
{
for(i=0; i<row_width; i++)
{
if((ushort)((*sp>>shift)&0x0f)==trans_color.gray)
{
*sp&=(byte)((0xf0f>>(4-shift))&0xff);
*sp|=(byte)(background.gray<<shift);
}
else
{
byte p=(byte)((*sp>>shift)&0x0f);
byte g=(byte)((gamma_table[p|(p<<4)]>>4)&0x0f);
*sp&=(byte)((0xf0f>>(4-shift))&0xff);
*sp|=(byte)(g<<shift);
}
if(shift==0)
{
shift=4;
sp++;
}
else shift-=4;
}
}
else
{
for(i=0; i<row_width; i++)
{
if((ushort)((*sp>>shift)&0x0f)==trans_color.gray)
{
*sp&=(byte)((0xf0f>>(4-shift))&0xff);
*sp|=(byte)(background.gray<<shift);
}
if(shift==0)
{
shift=4;
sp++;
}
else shift-=4;
}
}
}
break;
case 8:
{
if(gamma_table!=null)
{
for(i=0; i<row_width; i++, sp++)
{
if(*sp==trans_color.gray) *sp=(byte)background.gray;
else *sp=gamma_table[*sp];
}
}
else
{
for(i=0; i<row_width; i++, sp++)
{
if(*sp==trans_color.gray) *sp=(byte)background.gray;
}
}
break;
}
case 16:
{
if(gamma_16!=null)
{
for(i=0; i<row_width; i++, sp+=2)
{
ushort v=(ushort)(((*sp)<<8)+*(sp+1));
if(v==trans_color.gray)
{ // background is already in screen gamma
*sp=(byte)((background.gray>>8)&0xff);
*(sp+1)=(byte)(background.gray&0xff);
}
else
{
v=gamma_16[*(sp+1)>>gamma_shift][*sp];
*sp=(byte)((v>>8)&0xff);
*(sp+1)=(byte)(v&0xff);
}
}
}
else
{
for(i=0; i<row_width; i++, sp+=2)
{
ushort v=(ushort)(((*sp)<<8)+*(sp+1));
if(v==trans_color.gray)
{
*sp=(byte)((background.gray>>8)&0xff);
*(sp+1)=(byte)(background.gray&0xff);
}
}
}
}
break;
} // switch(row_info->bit_depth)
}
break;
case PNG_COLOR_TYPE.RGB:
{
if(row_info.bit_depth==8)
{
if(gamma_table!=null)
{
for(i=0; i<row_width; i++, sp+=3)
{
if(*sp==trans_color.red&&*(sp+1)==trans_color.green&&*(sp+2)==trans_color.blue)
{
*sp=(byte)background.red;
*(sp+1)=(byte)background.green;
*(sp+2)=(byte)background.blue;
}
else
{
*sp=gamma_table[*sp];
*(sp+1)=gamma_table[*(sp+1)];
*(sp+2)=gamma_table[*(sp+2)];
}
}
}
else
{
for(i=0; i<row_width; i++, sp+=3)
{
if(*sp==trans_color.red&&*(sp+1)==trans_color.green&&*(sp+2)==trans_color.blue)
{
*sp=(byte)background.red;
*(sp+1)=(byte)background.green;
*(sp+2)=(byte)background.blue;
}
}
}
}
else // if(row_info->bit_depth==16)
{
if(gamma_16!=null)
{
for(i=0; i<row_width; i++, sp+=6)
{
ushort r=(ushort)(((*sp)<<8)+*(sp+1));
ushort g=(ushort)(((*(sp+2))<<8)+*(sp+3));
ushort b=(ushort)(((*(sp+4))<<8)+*(sp+5));
if(r==trans_color.red&&g==trans_color.green&&b==trans_color.blue)
{ // background is already in screen gamma
*sp=(byte)((background.red>>8)&0xff);
*(sp+1)=(byte)(background.red&0xff);
*(sp+2)=(byte)((background.green>>8)&0xff);
*(sp+3)=(byte)(background.green&0xff);
*(sp+4)=(byte)((background.blue>>8)&0xff);
*(sp+5)=(byte)(background.blue&0xff);
}
else
{
ushort v=gamma_16[*(sp+1)>>gamma_shift][*sp];
*sp=(byte)((v>>8)&0xff);
*(sp+1)=(byte)(v&0xff);
v=gamma_16[*(sp+3)>>gamma_shift][*(sp+2)];
*(sp+2)=(byte)((v>>8)&0xff);
*(sp+3)=(byte)(v&0xff);
v=gamma_16[*(sp+5)>>gamma_shift][*(sp+4)];
*(sp+4)=(byte)((v>>8)&0xff);
*(sp+5)=(byte)(v&0xff);
}
}
}
else
{
for(i=0; i<row_width; i++, sp+=6)
{
ushort r=(ushort)(((*sp)<<8)+*(sp+1));
ushort g=(ushort)(((*(sp+2))<<8)+*(sp+3));
ushort b=(ushort)(((*(sp+4))<<8)+*(sp+5));
if(r==trans_color.red&&g==trans_color.green&&b==trans_color.blue)
{
*sp=(byte)((background.red>>8)&0xff);
*(sp+1)=(byte)(background.red&0xff);
*(sp+2)=(byte)((background.green>>8)&0xff);
*(sp+3)=(byte)(background.green&0xff);
*(sp+4)=(byte)((background.blue>>8)&0xff);
*(sp+5)=(byte)(background.blue&0xff);
}
}
}
}
}
break;
case PNG_COLOR_TYPE.GRAY_ALPHA:
{
if(row_info.bit_depth==8)
{
if(gamma_to_1!=null&&gamma_from_1!=null&&gamma_table!=null)
{
for(i=0; i<row_width; i++, sp+=2, dp++)
{
ushort a=*(sp+1);
if(a==0xff) *dp=gamma_table[*sp];
else if(a==0) *dp=(byte)background.gray; // background is already in screen gamma
else
{
byte w, v=gamma_to_1[*sp];
//png_composite(w, v, a, background_1->gray);
w=(byte)(((ushort)v*a+background_1.gray*(ushort)(255-a)+(ushort)127)/255);
*dp=gamma_from_1[w];
}
}
}
else
{
for(i=0; i<row_width; i++, sp+=2, dp++)
{
byte a=*(sp+1);
if(a==0xff) *dp=*sp;
else if(a==0) *dp=(byte)background.gray;
else //png_composite(*dp, *sp, a, background_1->gray);
*dp=(byte)(((ushort)(*sp)*a+background_1.gray*(ushort)(255-a)+(ushort)127)/255);
}
}
}
else // if(png_ptr->bit_depth==16)
{
if(gamma_16!=null&&gamma_16_from_1!=null&&gamma_16_to_1!=null)
{
for(i=0; i<row_width; i++, sp+=4, dp+=2)
{
ushort a=(ushort)(((*(sp+2))<<8)+*(sp+3));
if(a==(ushort)0xffff)
{
ushort v=gamma_16[*(sp+1)>>gamma_shift][*sp];
*dp=(byte)((v>>8)&0xff);
*(dp+1)=(byte)(v&0xff);
}
else if(a==0)
{ // background is already in screen gamma
*dp=(byte)((background.gray>>8)&0xff);
*(dp+1)=(byte)(background.gray&0xff);
}
else
{
ushort v, w, g=gamma_16_to_1[*(sp+1)>>gamma_shift][*sp];
//png_composite_16(v, g, a, background_1->gray);
v=(ushort)(((uint)g*(uint)a+(uint)background_1.gray*(uint)(65535-(uint)a)+(uint)32767)/(uint)65535);
w=gamma_16_from_1[(v&0xff)>>gamma_shift][v>>8];
*dp=(byte)((w>>8)&0xff);
*(dp+1)=(byte)(w&0xff);
}
}
}
else
{
for(i=0; i<row_width; i++, sp+=4, dp+=2)
{
ushort a=(ushort)(((*(sp+2))<<8)+*(sp+3));
if(a==(ushort)0xffff)
{
//memcpy(dp, sp, 2);
*dp=*sp;
*(dp+1)=*(sp+1);
}
else if(a==0)
{
*dp=(byte)((background.gray>>8)&0xff);
*(dp+1)=(byte)(background.gray&0xff);
}
else
{
ushort v, g=(ushort)(((*sp)<<8)+*(sp+1));
//png_composite_16(v, g, a, background_1->gray);
v=(ushort)(((uint)g*(uint)a+(uint)(background_1.gray)*(uint)(65535-(uint)a)+(uint)32767)/(uint)65535);
*dp=(byte)((v>>8)&0xff);
*(dp+1)=(byte)(v&0xff);
}
}
}
}
}
break;
case PNG_COLOR_TYPE.RGB_ALPHA:
{
if(row_info.bit_depth==8)
{
if(gamma_to_1!=null&&gamma_from_1!=null&&gamma_table!=null)
{
for(i=0; i<row_width; i++, sp+=4, dp+=3)
{
byte a=*(sp+3);
if(a==0xff)
{
*dp=gamma_table[*sp];
*(dp+1)=gamma_table[*(sp+1)];
*(dp+2)=gamma_table[*(sp+2)];
}
else if(a==0)
{ // background is already in screen gamma
*dp=(byte)background.red;
*(dp+1)=(byte)background.green;
*(dp+2)=(byte)background.blue;
}
else
{
byte w, v=gamma_to_1[*sp];
// png_composite(w, v, a, background_1->red);
w=(byte)(((ushort)v*(ushort)a+background_1.red*(ushort)(255-(ushort)a)+(ushort)127)/255);
*dp=gamma_from_1[w];
v=gamma_to_1[*(sp+1)];
//png_composite(w, v, a, background_1->green);
w=(byte)(((ushort)v*(ushort)a+background_1.green*(ushort)(255-(ushort)a)+(ushort)127)/255);
*(dp+1)=gamma_from_1[w];
v=gamma_to_1[*(sp+2)];
//png_composite(w, v, a, background_1->blue);
w=(byte)(((ushort)v*(ushort)a+background_1.blue*(ushort)(255-(ushort)a)+(ushort)127)/255);
*(dp+2)=gamma_from_1[w];
}
}
}
else
{
for(i=0; i<row_width; i++, sp+=4, dp+=3)
{
byte a=*(sp+3);
if(a==0xff)
{
*dp=*sp;
*(dp+1)=*(sp+1);
*(dp+2)=*(sp+2);
}
else if(a==0)
{
*dp=(byte)background.red;
*(dp+1)=(byte)background.green;
*(dp+2)=(byte)background.blue;
}
else
{
//png_composite(*dp, *sp, a, background->red);
//png_composite(*(dp+1), *(sp+1), a, background->green);
//png_composite(*(dp+2), *(sp+2), a, background->blue);
*dp=(byte)(((ushort)(*sp)*(ushort)a+background.red*(ushort)(255-(ushort)a)+(ushort)127)/255);
*(dp+1)=(byte)(((ushort)(*(sp+1))*(ushort)a+background.green*(ushort)(255-(ushort)a)+(ushort)127)/255);
*(dp+2)=(byte)(((ushort)(*(sp+2))*(ushort)a+background.blue*(ushort)(255-(ushort)a)+(ushort)127)/255);
}
}
}
}
else //if (row_info->bit_depth==16)
{
if(gamma_16!=null&&gamma_16_from_1!=null&&gamma_16_to_1!=null)
{
for(i=0; i<row_width; i++, sp+=8, dp+=6)
{
ushort a=(ushort)(((ushort)(*(sp+6))<<8)+(ushort)(*(sp+7)));
if(a==(ushort)0xffff)
{
ushort v=gamma_16[*(sp+1)>>gamma_shift][*sp];
*dp=(byte)((v>>8)&0xff);
*(dp+1)=(byte)(v&0xff);
v=gamma_16[*(sp+3)>>gamma_shift][*(sp+2)];
*(dp+2)=(byte)((v>>8)&0xff);
*(dp+3)=(byte)(v&0xff);
v=gamma_16[*(sp+5)>>gamma_shift][*(sp+4)];
*(dp+4)=(byte)((v>>8)&0xff);
*(dp+5)=(byte)(v&0xff);
}
else if(a==0)
{ // background is already in screen gamma
*dp=(byte)((background.red>>8)&0xff);
*(dp+1)=(byte)(background.red&0xff);
*(dp+2)=(byte)((background.green>>8)&0xff);
*(dp+3)=(byte)(background.green&0xff);
*(dp+4)=(byte)((background.blue>>8)&0xff);
*(dp+5)=(byte)(background.blue&0xff);
}
else
{
ushort w, x, v=gamma_16_to_1[*(sp+1)>>gamma_shift][*sp];
//png_composite_16(w, v, a, background_1->red);
w=(ushort)(((uint)v*(uint)a+(uint)background_1.red*(uint)(65535-(uint)a)+(uint)32767)/(uint)65535);
x=gamma_16_from_1[((w&0xff)>>gamma_shift)][w>>8];
*dp=(byte)((x>>8)&0xff);
*(dp+1)=(byte)(x&0xff);
v=gamma_16_to_1[*(sp+3)>>gamma_shift][*(sp+2)];
//png_composite_16(w, v, a, background_1->green);
w=(ushort)(((uint)v*(uint)a+(uint)background_1.green*(uint)(65535-(uint)a)+(uint)32767)/(uint)65535);
x=gamma_16_from_1[((w&0xff)>>gamma_shift)][w>>8];
*(dp+2)=(byte)((x>>8)&0xff);
*(dp+3)=(byte)(x&0xff);
v=gamma_16_to_1[*(sp+5)>>gamma_shift][*(sp+4)];
//png_composite_16(w, v, a, background_1->blue);
w=(ushort)(((uint)v*(uint)a+(uint)background_1.blue*(uint)(65535-(uint)a)+(uint)32767)/(uint)65535);
x=gamma_16_from_1[(w&0xff)>>gamma_shift][w>>8];
*(dp+4)=(byte)((x>>8)&0xff);
*(dp+5)=(byte)(x&0xff);
}
}
}
else
{
for(i=0; i<row_width; i++, sp+=8, dp+=6)
{
ushort a=(ushort)(((ushort)(*(sp+6))<<8)+(ushort)(*(sp+7)));
if(a==(ushort)0xffff)
{
//memcpy(dp, sp, 6);
*dp=*sp;
*(dp+1)=*(sp+1);
*(dp+2)=*(sp+2);
*(dp+3)=*(sp+3);
*(dp+4)=*(sp+4);
*(dp+5)=*(sp+5);
}
else if(a==0)
{
*dp=(byte)((background.red>>8)&0xff);
*(dp+1)=(byte)(background.red&0xff);
*(dp+2)=(byte)((background.green>>8)&0xff);
*(dp+3)=(byte)(background.green&0xff);
*(dp+4)=(byte)((background.blue>>8)&0xff);
*(dp+5)=(byte)(background.blue&0xff);
}
else
{
ushort v;
ushort r=(ushort)(((*sp)<<8)+*(sp+1));
ushort g=(ushort)(((*(sp+2))<<8)+*(sp+3));
ushort b=(ushort)(((*(sp+4))<<8)+*(sp+5));
//png_composite_16(v, r, a, background->red);
v=(ushort)(((uint)r*(uint)a+(uint)background.red*(uint)(65535-(uint)a)+(uint)32767)/(uint)65535);
*dp=(byte)((v>>8)&0xff);
*(dp+1)=(byte)(v&0xff);
//png_composite_16(v, g, a, background->green);
v=(ushort)(((uint)g*(uint)a+(uint)background.green*(uint)(65535-(uint)a)+(uint)32767)/(uint)65535);
*(dp+2)=(byte)((v>>8)&0xff);
*(dp+3)=(byte)(v&0xff);
//png_composite_16(v, b, a, background->blue);
v=(ushort)(((uint)b*(uint)a+(uint)background.blue*(uint)(65535-(uint)a)+(uint)32767)/(uint)65535);
*(dp+4)=(byte)((v>>8)&0xff);
*(dp+5)=(byte)(v&0xff);
}
}
}
}
}
break;
} // switch(row_info->color_type)
} // fixed
if((row_info.color_type&PNG_COLOR_TYPE.ALPHA_MASK)==PNG_COLOR_TYPE.ALPHA_MASK)
{
row_info.color_type&=~PNG_COLOR_TYPE.ALPHA_MASK;
row_info.channels--;
row_info.pixel_depth=(byte)(row_info.channels*row_info.bit_depth);
row_info.rowbytes=PNG_ROWBYTES(row_info.pixel_depth, row_width);
}
}
// handle alpha and tRNS via a background color
public void png_set_background(png_color_16 background_color, PNG_BACKGROUND_GAMMA background_gamma_code, bool need_expand, double background_gamma)
{
if(background_gamma_code==PNG_BACKGROUND_GAMMA.UNKNOWN)
{
Debug.WriteLine("Application must supply a known background gamma");
return;
}
transformations|=PNG_TRANSFORMATION.BACKGROUND;
background=background_color;
this.background_gamma=background_gamma;
background_gamma_type=background_gamma_code;
transformations|=(need_expand?PNG_TRANSFORMATION.BACKGROUND_EXPAND:PNG_TRANSFORMATION.None);
}
