Understanding canvases

This is an introduction to CANVAS drawing.

A canvas element defines a drawing area in a form, to show basic colored shapes.


This feature is deprecated, its use is discouraged although not prohibited.

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.


Consider using Web Components for specific drawing needs (charts, graphics). For example, Genero BDL provides the build-in Web Component fglsvgcanvas.