Question

Trying to double the size of a circle onclick(). Doesn’t seem to be working?

HTML

<canvas id="drawing" width="600px" height="600px" onclick="resize()"></canvas>

Javascript

        window.onload = function() {
            canvas=document.getElementById("drawing");
            context=canvas.getContext("2d");
            var centerX = canvas.width / 2;
            var centerY = canvas.height / 2;
            var radius = 70;

            context.beginPath();
            context.arc(centerX, centerY, radius, 0, 2 * Math.PI, false);
            context.fillStyle = 'green';
            context.fill();
        }

        function resize () {
            context.fillStyle= "#701be0"; // This changes the rectangle to blue
            context.fill();
            context.scale(10.5, 2.5); 
        }

Answer 1

You need to redraw your circle again and also keep in mind that context.scale() will also scale its position so i wouldn’t recommend to do it this way. You can just draw a new circle over with bigger radius.

jsFiddle – http://jsfiddle.net/DSFMq/