joint.all.js
function(x, y) {

            var svg = this.svg().node;
            
            var p = svg.createSVGPoint();
            p.x = x;
            p.y = y;

	    try {

		var globalPoint = p.matrixTransform(svg.getScreenCTM().inverse());
		var globalToLocalMatrix = this.node.getTransformToElement(svg).inverse();

	    } catch(e) {
		// IE9 throws an exception in odd cases. (`Unexpected call to method or property access`)
		// We have to make do with the original coordianates.
		return p;
	    }

            return globalPoint.matrixTransform(globalToLocalMatrix);
        }
function(x, y) {

            var svg = this.svg().node;
            
            var p = svg.createSVGPoint();
            p.x = x;
            p.y = y;

	    try {

		var globalPoint = p.matrixTransform(svg.getScreenCTM().inverse());
		var globalToLocalMatrix = this.node.getTransformToElement(svg).inverse();

	    } catch(e) {
		// IE9 throws an exception in odd cases. (`Unexpected call to method or property access`)
		// We have to make do with the original coordianates.
		return p;
	    }

            return globalPoint.matrixTransform(globalToLocalMatrix);
        }
Convert global point into the coordinate space of this element.