Copies rectangular part of SrcImage to DstImage.
public procedure CopyTo(SrcX: LongInt; SrcY: LongInt; Width: LongInt; Height: LongInt; DstImage: TBaseImage; DstX: LongInt; DstY: LongInt);
No blending is performed - alpha is simply copied to destination image. Operates also with negative X and Y coordinates. Note that copying is fastest for images in the same data format (and slowest for images in special formats).