Fabric.js Clip Canvas (or object group) To Polygon

Question

I have a canvas drawn in Fabric.js that i am adding a group of rectangles to, i want to limit the edges of those rectangles as a group to not go outside a certain area.

Answer 1

You can just render a shape inside canvas.clipTo :)

I just loaded a random SVG shape in kitchensink and did this:

var shape = canvas.item(0);
canvas.remove(shape);
canvas.clipTo = function(ctx) {
  shape.render(ctx);
};

As you can see, entire canvas is now clipped by that SVG shape.

Answer 2

You may also try this one: http://jsfiddle.net/ZxYCP/198/

var clipPoly = new fabric.Polygon([
    { x: 180, y: 10 },
    { x: 300, y: 50 },
    { x: 300, y: 180 },
    { x: 180, y: 220 }
], {
    originX: 'left',
    originY: 'top',
    left: 180,
    top: 10,
    width: 200,
    height: 200,
    fill: '#DDD', /* use transparent for no fill */
    strokeWidth: 0,
    selectable: false
});

You can simply use Polygon to clip. Answer is based on @natchiketa idea in this question Multiple clipping areas on Fabric.js canvas