问如何用变换旋转形状

EN

function createPoly(x, y)
{
    var width = 41;
    var height = 41;
    var centreX = width / 2;
    var centreY = height / 2;
    var shape = d3.select(this);
    var poly = svg.append("g")
            .classed("bpmnGateway", true)
            .append('svg:rect')
            .attr("type", "poly")
            .attr("x", (x - centreX))
            .attr("y", (y - centreY))
            .attr("width", 41)
            .attr("height", 41)
            .attr("transform", "rotate(-45)")
            .attr("stroke-width", "1.5px")
            .attr("stroke", "#7E7E7E")
            .style('cursor', 'move')
            .style("fill", "#FFED6B")
            .call(drag);
}

function drag()
{
    if (shape.attr('type') === 'poly')
    {
        translate = d3.transform(shape.attr("transform")).translate;
        var x = d3.event.dx + translate[0];
        var y = d3.event.dy + translate[1];
        shape.attr("transform", "rotate(-45)")
        shape.attr("transform", "translate(" + x + "," + y + ")");
    }
}