canvas.clearRect

    cavas.clearRect(x1, y1, x2, y2)

Make transparent a rectangle defined by the bounding area of x1,y2 to x2,y2.

Parameters

Parameter	Type	Description
x1	number	The x position of the first corner.
y1	number	The y position of the first corner.
x2	number	The x position of the second corner.
y2	number	The y position of the second corner.

Example

    // Fill a canvas with red and poke a transparent hole in the middle of it
    function makeTransparentHole(name) {
        var canvas = sb.getCanvas(name);
        var holeWidth = canvas.width / 3;
        var holeHeight = canvas.height / 3;
        canvas.fill(0xff0000);
        canvas.clearRect(holeWidth, holeHeight, 2*holeWidth, 2*holeHeight);
    }