BitBltStretchBlt

BitBlt and StretchBlt are Windows GDI functions used for copying blocks of pixel data. BitBlt stands for "Bit Block Transfer" and is the more fundamental of the two. It copies a rectangular area from a source device context to a destination device context. The copying process can be modified by a raster operation (ROP) code, which specifies how the source, destination, and pattern (if any) are combined. Common ROP codes include SRCCOPY (simple copy), SRCAND (bitwise AND), and SRCPAINT (bitwise OR).

StretchBlt extends BitBlt by allowing the copied block to be stretched or compressed during the transfer. This means the source rectangle does not have to be the same size as the destination rectangle. StretchBlt uses specified width and height values for both the source and destination rectangles to determine the scaling factor. Additionally, StretchBlt offers raster operation codes similar to BitBlt and can also perform dithering to improve the appearance of stretched images, especially when reducing color depth. The choice between BitBlt and StretchBlt depends on whether scaling is required. BitBlt is generally faster when no scaling is needed.