// Palette indices point to a current palette row (containing 16 indices) and are 4 bits
// 2 bits: run length
// 2 bits: mode:
// 0: color index = 4 bits
// run length = run length + 2
// 1: read new color index (4 bits) each iteration
// run length = run length + 1
// 2: change paletteRow = 4 bits
//
// Vertical pixel order
private static void DecodeRLEPaletteRowsV(byte[] buffer, int width, int height, int stripX, byte[] source, int sourcePos, bool transparent)
{
int x = stripX;
int y = 0;
int code = -1;
byte color = 0;
int paletteRow = 0;
int runlength = 0;
LEBitStream sourceStream = new LEBitStream(source, sourcePos);
while (x < stripX + 8)
{
while (y < height)
{
if (runlength > 0)
{
if (code >> 2 == 1)
{
color = (byte)sourceStream.GetBits(4);
}
runlength--;
buffer[y * width + x] = (byte)(paletteRow * 16 + color);
y++;
continue;
}
code = sourceStream.GetBits(4);
switch (code >> 2)
{
case 0:
color = (byte)sourceStream.GetBits(4);
runlength = ((code & 3) + 2);
break;
case 1:
runlength = ((code & 3) + 1);
break;
case 2:
paletteRow = sourceStream.GetBits(4);
break;
}
}
y = 0;
x++;
}
}
private static void DecodeMajMinH(byte[] buffer, int width, int height, int stripX, byte[] source, int sourcePos, int indexSize, bool transparent)
{
int runlength = 0;
LEBitStream sourceStream = new LEBitStream(source, sourcePos);
byte color = sourceStream.GetByte();
int x = stripX;
int y = 0;
while (y < height)
{
while (x < stripX + 8)
{
buffer[y * width + x] = color;
x++;
if (runlength > 0)
{
runlength--;
continue;
}
if (sourceStream.GetBit() == 0) // 0
{
}
else if (sourceStream.GetBit() == 0) // 10
{
color = (byte)(sourceStream.GetBits(indexSize));
}
else // 11
{
int code = sourceStream.GetBits(3) - 4;
if (code != 0)
{
color = (byte)(color + code);
}
else
{
runlength = sourceStream.GetBits(8) - 1;
}
}
}
x = stripX;
y++;
}
}
// Predecessor of ZigZag codec
// Vertical pixel order
private static void DecodeOldZigZagV(byte[] buffer, int width, int height, int stripX, byte[] source, int sourcePos, bool transparent)
{
int x = stripX;
int y = 0;
int sub = 1;
byte color = source[sourcePos++];
LEBitStream sourceStream = new LEBitStream(source, sourcePos);
while (x < stripX + 8)
{
while (y < height)
{
buffer[y * width + x] = color;
y++;
if (sourceStream.GetBit() == 0) // 0
{
// do nothing (draw pixel, same color)
}
else if (sourceStream.GetBit() == 0) // 10
{
sub = -sub;
color = (byte)(color - sub);
}
else if (sourceStream.GetBit() == 0) // 110
{
color = (byte)(color - sub);
}
else // 111
{
sub = 1;
color = (byte)sourceStream.GetBits(8);
}
}
y = 0;
x++;
}
}
private static void DecodeZigzagH(byte[] buffer, int width, int height, int stripX, byte[] source, int sourcePos, int indexSize, bool transparent)
{
int sub = 1;
LEBitStream sourceStream = new LEBitStream(source, sourcePos);
byte color = sourceStream.GetByte();
int x = stripX;
int y = 0;
while (y < height)
{
while (x < stripX + 8)
{
buffer[y * width + x] = color;
if (sourceStream.GetBit() == 0) // 0
{
// Do nothing (draw pixel, same color)
}
else if (sourceStream.GetBit() == 0) // 10
{
color = (byte)(sourceStream.GetBits(indexSize));
sub = 1;
}
else if (sourceStream.GetBit() == 0) // 110
{
color = (byte)(color - sub);
}
else // 111
{
sub = -sub;
color = (byte)(color - sub);
}
x++;
}
x = stripX;
y++;
}
}
