Paint Game — Demonstrate the Painter class.
A Painter is an abstraction of the Canvas' Drawing API.
The goal is to produce shapes faster and with an streamlined API.
The Painter API is used to creates the shape primitives but it can also be used to draw directly on the canvas.
1) Line: first click sets start, second click sets end.
2) Pencil: hold mouse/touch and drag to draw.
3) Eraser: hold mouse/touch and drag to erase pixels.