Using an interesting tool, you can explode out views into layers to see how they all composite together to achieve the final image. I think it looks cool:
Drawing individual images is expensive, so you can see what we’ve done here is load three bitmap pictures once and we rotate (animate) the outer pointer to change the track.
Below is the vertical toolbar that slides out. The little fuel ones are hidden underneath and animated out. You can see the transparency of the toolbar is set to about 95% so you can see just a tiny amount of map underneath (to look natural). The GPU must go and calculate all of the blending required for doing this as you pan the map (at 60 fps) leaving less than 16 milliseconds to do all the calculations in order to maintain smooth scrolling.
Here’s the whole main map screen minus the backing map. You can see the GPU has to composite, crop and blend many layers of images with a different z (vertical) order to achieve the final image. You can override the z order of an object in code to force it to appear at the top of the screen.
Here is the final image with all cropping and blending done. Cool !