Any Kivy Widget contains a Canvas object. Be careful with the name because it might be confusing:

The coordinate space refers to the place where we draw, what you might have thought to be the canvas is in the first place. In this chapter, you are going to learn how to draw and manipulate the representation of the widgets through the instructions that we add to the Canvas instances:

Any Widget contains its own Canvas but all of them share the same coordinate space. This has consequences; for example, if we add a Rotate instruction to a specific Canvas (let's say the Canvas of a Button); it will also affect all the subsequent graphic instructions that are going to be displayed in the coordinate space. It doesn't matter if the graphics belong to canvases of different widgets. A context instruction changes the context of the coordinate space and we are going to learn strategies to control this.

Another important concept related to this is the Widget. A Widget is pretty much a place marker (with its position and size), but not necessarily a placeholder because the instructions of the Canvas of a Widget are not restricted to the specific area of the Widget, but to the whole coordinate space. At the same time, the coordinate space is not even restricted to the visual space of the Kivy window and this might also create some difficulties.

In this chapter, you will learn the available statements to draw and change the context of the coordinate space. More importantly, you will understand the canvas as a set of instructions, the implications of sharing a coordinate space, and the concept of widgets as place markers. In the last section of the chapter, we will illustrate the acquired knowledge within the comic creator. Here, you will also learn the most common technique to deal with the problem of sharing the same coordinate space. By the end, we will be on complete control of the graphics that are displayed on the screen.