Understanding canvases

By using a canvas, you can draw simple shapes in a specific area of a form. Canvas can draw lines, rectangles, ovals, circles, texts, arcs, and polygons. Keys can be bound to graphical elements for selection with a right or left mouse click.

In programs, you select a given canvas area by name and you create the shapes in the abstract user interface tree by using the built-in DOM API, or helper functions.

The painted canvas is automatically displayed on the front end when an interactive instruction is executed, such as MENU or INPUT.

Each canvas element is identified by a unique number (id). You can use this identifier to bind mouse clicks to canvas elements.