How can I add pan and zoom controls to a Processing.js canvas?

I can draw sh开发者_StackOverflowapes on a canvas. Now I'd like to let users pan and zoom in and out using keyboard controls.

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You could use variable to keep track of user feedback for zoom and pan, which you use as arguments to the translate()(pan) and scale()(zoom) functions.

It might help to have a look how Proessing.js fits with js/html/css.

HTH