As a graphical means for explaining the Android coordinate drawing system, I will use a cute spaceship graphic. We will not suddenly be adding spaceships to Sub' Hunter but we will use the graphics that follow in the fifth project starting in Chapter 18, Introduction to Design Patterns and much more!.
As we will see, drawing a Bitmap is trivial. But the coordinate system that we use to draw our graphics onto needs a brief explanation.
When we draw a Bitmap object to the screen we pass in the coordinates we want to draw the object at. The available coordinates of a given Android device depend upon the resolution of its screen.
For example, the Google Pixel phone has a screen resolution of 1920 pixels (across) by 1080 pixels (down) when held in landscape view.
The numbering system of these coordinates starts in the top left-hand corner at 0,0 and proceeds down and to the right until the bottom right corner is pixel 1919, 1079. The apparent 1-pixel...