Animation, sprite sheets, and the Snake home screen

In the previous chapter, we used a bitmap to draw text, a circle, a line, and a single pixel on the blank bitmap we created in Java code. We then displayed the bitmap with all of its doodling using the Canvas class. Now we will look at a technique to draw two dimensional images, sometimes referred to as sprites. These are made from predrawn images. The images can be as simple as a plain pong ball or as complex as a glorious two-dimensional character with muscle definition, elaborate clothing, weapons, and hair.

So far, we have animated with unchanging objects, that is, we have moved a static unchanging image around the screen. In this section, we will see how to not only display a predrawn bitmap image on the screen but also continually alter it to create the illusion of on-the-spot animation.

Of course, the ultimate combination would be to animate the bitmap both by changing its image and moving it around at the same time. We will see that...