如何用D3js求平面矩形旋转后的x，y坐标？

var svg = d3.select("body")
            .append("svg")
            .attr("width", width)
            .attr("height", height);

var rect = svg.append("rect")
              .attr("x", rectX)
              .attr("y", rectY)
              .attr("width", rectWidth)
              .attr("height", rectHeight)
              .attr("fill", rectColor);

var rotation = d3.transform()
                 .rotate(angle, centerX, centerY);

rect.attr("transform", rotation);

var matrix = rotation.toString();
var transformedPoint = d3.transform(matrix).translate(rectX, rectY);
var rotatedX = transformedPoint.translate[0];
var rotatedY = transformedPoint.translate[1];