使用d3.js的时候，如何用zoom translate scale限制拖拽范围

红色代表需要改写的代码

1.添加定义图像大小和容器的大小及坐标

d3.behavior.zoom = function () {

      var moveCanvas={

          width: , height: ,

          cx:,cy:,cwidth:,cheight:

      };

    var view = {

      x: ,

      y: ,

      k: 

    }, translate0, center0, center, size = [ ,  ], scaleExtent = d3_behavior_zoomInfinity, duration = , zooming = , mousedown = "mousedown.zoom", mousemove = "mousemove.zoom", mouseup = "mouseup.zoom", mousewheelTimer, touchstart = "touchstart.zoom", touchtime, event = d3_eventDispatch(zoom, "zoomstart", "zoom", "zoomend"), x0, x1, y0, y1;

    if (!d3_behavior_zoomWheel) {

      d3_behavior_zoomWheel = "onwheel" in d3_document ? (d3_behavior_zoomDelta = function() {

        return -d3.event.deltaY * (d3.event.deltaMode ?  : );

      }, "wheel") : "onmousewheel" in d3_document ? (d3_behavior_zoomDelta = function() {

        return d3.event.wheelDelta;

      }, "mousewheel") : (d3_behavior_zoomDelta = function() {

        return -d3.event.detail;

      }, "MozMousePixelScroll");

    }

2.添加定义设置参数方法

zoom.y = function(z) {

      if (!arguments.length) return y1;

      y1 = z;

      y0 = z.copy();

      view = {

        x: ,

        y: ,

        k: 

      };

      return zoom;

    };

 zoom.moveCanvas = function (_) {

        if (!arguments.length) return [moveCanvas.width, moveCanvas.height, moveCanvas.cx, moveCanvas.cy, moveCanvas.cwidth, moveCanvas.cheight];

        moveCanvas = {

            width: +_[],//图像宽度

            height: +_[],//图像高度

            cx: +_[],//容器坐标x

            cy: +_[],//容器坐标y

            cwidth: +_[],//容器宽度

            cheight: +_[],//容器高度

        };

        return zoom;

    };

3.重写translateTo方法

    function scaleTo(s) {

      view.k = Math.max(scaleExtent[], Math.min(scaleExtent[], s));

    }

    function translateTo(p, l) {

      l = point(l);

      view.x += p[] - l[];

      view.y += p[] - l[];

      var minx = moveCanvas.cx - view.k * moveCanvas.width / ;//图像的一半

      var maxx = moveCanvas.cx + moveCanvas.cwidth - moveCanvas.width / *view.k;

      var miny = moveCanvas.cy - view.k * moveCanvas.height / ;//图像的一半

      var maxy = moveCanvas.cy + moveCanvas.cheight - moveCanvas.height / *view.k;

      if (view.x < minx) view.x = minx;

      if (view.y < miny) view.y = miny;

      if (view.x > maxx) view.x = maxx;

      if (view.y > maxy) view.y = maxy;

    }

4.页面调用

 var zoom = d3.behavior.zoom()

                                    .scaleExtent([0.5, ])

                                    .moveCanvas([svgWidth,svgHeight,,,divWidth,divHeight])

                                    .on("zoom", function (d) {

                                        sval = d3.event.scale;

                                        console.info("transform");

                                        gMap.attr("transform", "translate(" + d3.event.translate + ")" + "scale(" + d3.event.scale + ")")

                                    });