Canvas reference: The clip() function

The clip() function allows you to restrict the drawing on the canvas to a particular area

The clip() function can be used when you want to restrict any drawing to a particular area of the canvas. You draw a path without stroking or filling it, call the clip() function and then any further drawing will be restricted to that area. There is (currently) no reset() function so you need to save the state of the canvas before you clip it and then restore it when you're finished - as the example shows.

You can also give a Path2D object to clip to which specifies the clipping area.

Arguments to the function

• Optionally you can specify a Path2D object to be clipped to. If not given the default path is clipped to.
  
  Clip to the default path:

  context.clip();

  Clip to the given Path2D object:

  context.clip(path);

An example

<script>
    window.onload = function ()
    {
        var canvas  = document.getElementById("cvs");
        var context = canvas.getContext('2d');
        
        context.save();
            
            context.beginPath();
            context.rect(50,50,50,50);
            context.clip();
    
            // Because the canvas is currently clipped only part of the rectangle is drawn on the canvas
            context.fillRect(0,0,600,250);
    
        context.restore();
    }
</script>