private unsafe void RenderOneToOne(Cairo.ImageSurface src, Cairo.ImageSurface dst, Gdk.Point offset, bool checker)
{
Gdk.Rectangle srcRect = new Gdk.Rectangle(offset, dst.GetBounds().Size);
srcRect.Intersect(src.GetBounds());
ColorBgra *src_ptr = (ColorBgra *)src.DataPtr;
ColorBgra *dst_ptr = (ColorBgra *)dst.DataPtr;
int src_width = src.Width;
int dst_width = dst.Width;
int dst_height = dst.Height;
for (int dstRow = 0; dstRow < srcRect.Height; ++dstRow)
{
ColorBgra *dstRowPtr = dst.GetRowAddressUnchecked(dst_ptr, dst_width, dstRow);
ColorBgra *srcRowPtr = src.GetPointAddressUnchecked(src_ptr, src_width, offset.X, dstRow + offset.Y);
int dstCol = offset.X;
int dstColEnd = offset.X + srcRect.Width;
int checkerY = dstRow + offset.Y;
while (dstCol < dstColEnd)
{
// Blend it over the checkerboard background
if (checker)
{
int b = srcRowPtr->B;
int g = srcRowPtr->G;
int r = srcRowPtr->R;
int a = srcRowPtr->A;
int v = (((dstCol ^ checkerY) & 8) << 3) + 191;
a = a + (a >> 7);
int vmia = v * (256 - a);
r = ((r * a) + vmia) >> 8;
g = ((g * a) + vmia) >> 8;
b = ((b * a) + vmia) >> 8;
dstRowPtr->Bgra = (uint)b + ((uint)g << 8) + ((uint)r << 16) + ((uint)255 << 24);
}
else
{
*dstRowPtr = *srcRowPtr;
}
++dstRowPtr;
++srcRowPtr;
++dstCol;
}
}
}
