The Android coordinate system
As we can see, drawing a bitmap is trivial. But the coordinate system that we use to draw our graphics onto needs a brief explanation.
Plotting and drawing
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 1,920 pixels (across) by 1,080 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, which is pixel 1919, 1079. The apparent 1-pixel disparity between 1920 and 1919 and 1080 and 1079 is because the numbering starts at 0.
So, when we draw a bitmap or anything else to the screen (such as Canvas circles and rectangles), we must specify an x, y coordinate.
Furthermore, a bitmap (or Canvas shape...