Is it easy to overhaul the Mario Zechner game engine?

Question

Android

In the book Mario Zechner - Beginning Android Games - to work with Canvas, he created a small framework, with which he continued to work, making a simple game.
Unfortunately, for drawing, image stretching is used. If at the time of the release of the first edition this could be understood due to the small number of Android devices, now when there are hundreds and thousands of them, this does not look like a good idea, although this approach continues to be used in new editions.
Is it possible somehow without a particularly large loss of nerve cells to remake this framework under letterbox? Perhaps there is already a ready-made version, I could not find it. Or a game engine as close as possible in simplicity, which would not stretch, but use letterbox.