public static FastBitmap Encode(FastBitmap input, FilterType[] filters)
{
FastBitmap ret = new FastBitmap(input.Width, input.Height);
ret.Lock();
// .NET's Bitmap.Width/Height isn't thread-safe
int width = input.Width;
int height = input.Height;
// encode the first line with zero subtype
for (int x = 0; x < width; x++)
{
ret.SetPixel(x, 0, input.GetPixel(x, 0));
}
Parallel.For(1, input.Height, y =>
{
FilterType type = filters[y];
switch (type)
{
case FilterType.None:
for (int x = 0; x < width; x++)
{
ret.SetPixel(x, y, input.GetPixel(x, y));
}
break;
case FilterType.Sub:
ret.SetPixel(0, y, input.GetPixel(0, y));
for (int x = 1; x < width; x++)
{
Color original = input.GetPixel(x, y);
Color left = input.GetPixel(x - 1, y);
Color delta = ColorHelpers.Delta(original, left);
ret.SetPixel(x, y, delta);
}
break;
case FilterType.Up:
for (int x = 0; x < width; x++)
{
Color original = input.GetPixel(x, y);
Color up = input.GetPixel(x, y - 1);
Color delta = ColorHelpers.Delta(original, up);
ret.SetPixel(x, y, delta);
}
break;
case FilterType.Average:
ret.SetPixel(0, y, input.GetPixel(0, y));
for (int x = 1; x < width; x++)
{
Color original = input.GetPixel(x, y);
Color left = input.GetPixel(x - 1, y);
Color up = input.GetPixel(x, y - 1);
Color avg = ColorHelpers.Average(left, up);
Color delta = ColorHelpers.Delta(original, avg);
ret.SetPixel(x, y, delta);
}
break;
case FilterType.Paeth:
ret.SetPixel(0, y, input.GetPixel(0, y));
for (int x = 1; x < width; x++)
{
Color original = input.GetPixel(x, y);
Color left = input.GetPixel(x - 1, y);
Color up = input.GetPixel(x, y - 1);
Color diagonal = input.GetPixel(x - 1, y - 1);
Color paeth = ColorHelpers.PickPaeth(left, up, diagonal);
Color delta = ColorHelpers.Delta(original, paeth);
ret.SetPixel(x, y, delta);
}
break;
default:
throw new Exception("This should never ever happen");
}
});
return(ret);
}
public static FastBitmap Decode(FastBitmap input, FilterType[] filters, FastBitmap output = null)
{
if (output == null)
{
output = new FastBitmap(input.Width, input.Height);
output.Lock();
}
// .NET's Bitmap.Width/Height isn't thread-safe
int width = input.Width;
int height = input.Height;
// decode the first line with zero subtype
for (int x = 0; x < width; x++)
{
output.SetPixel(x, 0, input.GetPixel(x, 0));
}
for (int y = 1; y < height; y++)
{
FilterType type = filters[y];
switch (type)
{
case FilterType.None:
for (int x = 0; x < width; x++)
{
output.SetPixel(x, y, input.GetPixel(x, y));
}
break;
case FilterType.Sub:
output.SetPixel(0, y, input.GetPixel(0, y));
for (int x = 1; x < width; x++)
{
Color original = input.GetPixel(x, y);
Color left = output.GetPixel(x - 1, y);
Color delta = ColorHelpers.OverflowingAdd(original, left);
output.SetPixel(x, y, delta);
}
break;
case FilterType.Up:
for (int x = 0; x < width; x++)
{
Color original = input.GetPixel(x, y);
Color up = output.GetPixel(x, y - 1);
Color delta = ColorHelpers.OverflowingAdd(up, original);
output.SetPixel(x, y, delta);
}
break;
case FilterType.Average:
output.SetPixel(0, y, input.GetPixel(0, y));
for (int x = 1; x < width; x++)
{
Color original = input.GetPixel(x, y);
Color left = output.GetPixel(x - 1, y);
Color up = output.GetPixel(x, y - 1);
Color avg = ColorHelpers.Average(left, up);
Color delta = ColorHelpers.OverflowingAdd(avg, original);
output.SetPixel(x, y, delta);
}
break;
case FilterType.Paeth:
output.SetPixel(0, y, input.GetPixel(0, y));
for (int x = 1; x < width; x++)
{
Color original = input.GetPixel(x, y);
Color left = output.GetPixel(x - 1, y);
Color up = output.GetPixel(x, y - 1);
Color diagonal = output.GetPixel(x - 1, y - 1);
Color paeth = ColorHelpers.PickPaeth(left, up, diagonal);
Color delta = ColorHelpers.OverflowingAdd(paeth, original);
output.SetPixel(x, y, delta);
}
break;
default:
throw new Exception("This should never ever happen");
}
}
return(output);
}
public static void TestColor(FastBitmap bmp, int x, int y)
{
Color clr = bmp.GetPixel(x, y);
Console.WriteLine("({0},{1}) is {2}, {3}, {4}", x, y, clr.R, clr.G, clr.B);
}