@Jason - I appreciate the testing and review.
Currently assigning the bitmap to a Sprite class is commented out as default. I figured this wasted RAM (/ program memory?) if the user chooses another blitting method or if the sprite is never used...?
Is that a fair assumption?
Might the API be extended in the future, with other blitting classes? (e.g. simple non-masked bitmap, or a screen pattern fill, etc.)