A Context for the Shapes

In this tutorial, we will make an Object called drawing that will contain the shapes. The context for drawing the shapes is a HTML DOM element called a canvas so that has to form part of the drawing class along with a list of the objects that are being contained.

The object drawing is a good example of the concept of composition since it is entirely made up of other objects.

Implementation

Below, you can see the class drawing that is used to create the "world" for the shape objects to reside in.

Make note of the following:

• the constructor defines two attributes canvas and objects where canvas is a HTML DOM element and objects is a list
• and that is all that the drawing is composed of