Color control on the canvas – coloring figures

The previous section focused on the selection of colors from a canvas but this selection didn't really have an effect yet. In this section, we will actually use the selected color. Assigning a color can be tricky if we are not careful. If you recall, in Chapter 3, Widget Events – Binding Actions, Color is a context instruction that we must add to the canvas. Moreover, we have to be sure that we add the instruction before we draw the actual figure. Basically, selecting a color is similar to picking a crayon color to draw on a piece of paper. Until you change the crayon, you will continue drawing with its color.

Note

When the color of the context changes, it stays in that state until some other instruction modifies it explicitly. In Chapter 2, Graphics – the Canvas, we use PushMatrix and PopMatrix for a similar problem but they only apply to transformation instructions (Translate, Rotate, and Scale) because they relate to the coordinate space (that...