Get bounding box off all objects on a fabric canvas

bounding_box_fabricjs.js

getBoardBoundingBox: function(canvas) {

            var minX = Number.MAX_VALUE;
            var maxX = Number.MIN_VALUE;
            var minY = Number.MAX_VALUE;
            var maxY = Number.MIN_VALUE;

            canvas.forEachObject(function(o){
                var rad = o.angle * Math.PI/180;
                var w = o.width * o.scaleX;
                var h = o.height * o.scaleY;
                // xmax = x * w/2 * |cos(theta)| + h/2 * |sin(theta)|
                var omaxX = o.left +((w/2) * Math.abs(Math.cos(rad))) + ((h/2) * Math.abs(Math.sin(rad)));
                var ominX = o.left - (omaxX - o.left);
                // ymax = y * w/2 * |sin(theta)| + h/2 * |cos(theta)|
                var omaxY = o.top + ((w/2) * Math.abs(Math.sin(rad))) + ((h/2) * Math.abs(Math.cos(rad)));
                var ominY = o.top - (omaxY - o.top);

                if (ominX < minX)
                    minX = ominX;
                if (omaxX > maxX)
                    maxX = omaxX;
                if (ominY < minY)
                    minY = ominY;
                if (omaxY > maxY)
                    maxY = omaxY;
            
            });
            var box = {
                "x": minX,
                "y": minY,
                "w": maxX - minX,
                "h": maxY - minY
            };
            return box;
        }
    });