ResolveBitmapOperation is called when a bitmap should be rendered by an operation that is not supported in WPF (defined in second parameter). The Func can be used to convert the bitmap so it will support the oparation - for example for alpha blending we can convert black to transparent. The second parameter defines the dwRop or blendoperation function defined by metadata - see GDI+ documentation for more info.

public Func<Bitmap, uint, Bitmap> ResolveBitmapOperation