The basic operations produce the following results. The Copy operation replaces the pixels in the destination with the pixels in the source, painting over the destination. These operations differ in how they affect the pixels under the black part. Xor inverts the pixels under the black part. Figure 3-2 shows how each of the basic transfer modes affects the source and destination images resulting in what is displayed on the screen.
Copy replaces the destination with the colored source.
Or mode results in the source image, regardless of the destination depth. Bic mode causes the foreground color in the source image to erase, resulting in the background color in the destination image. The initial transfer mode for drawing text is srcOr . This text drawing mode is recommended for all applications because it uses the least memory and draws the entire glyph in all cases. The srcOr mode only affects other parts of existing glyphs if the glyphs overlap.