V.transformRect(r, matrix)

Transform a rectangle specified by r (an object with x, y, width and height properties) by an SVG transformation represented by matrix. This function is used internally in the V.prototype.bbox method to return a bounding box of an SVG element relative to another SVG parent element. However, this can be used elsewhere too, that's why it is publicly exposed. Whenever you need to transform a bounding box to a coordinate system of another element, use this function. To get the transformation matrix of the target element relative to which you want to tranform your rectangle, use e.g. the native SVG method: var matrix = svgSourceElement.getTransformToElement(svgTargetElement).