Javascript 用于工具提示的Mousmove动画

我正在学习D3JS，并尝试了以下示例。不知何故，我通过删除非必需的代码，将其管理为单线图

现在，我想增强这个例子，一旦用户在较小的图表上画笔，无论画笔之间的范围是什么，它的线点应该每隔几秒设置工具提示的动画。但是我不能得到画笔的起点和终点

抱歉，代码太长

var main_margin = {top: 20, right: 80, bottom: 100, left: 40},
    mini_margin = {top: 430, right: 80, bottom: 20, left: 40},
    main_width = 960 - main_margin.left - main_margin.right,
    main_height = 500 - main_margin.top - main_margin.bottom,
    mini_height = 500 - mini_margin.top - mini_margin.bottom,
    start = 0,
    end = 100,
    focus;

var formatDate = d3.time.format("%H:%M"),
    parseDate = formatDate.parse,
    bisectDate = d3.bisector(function(d) { return d.Uhrzeit; }).left,
    formatOutput0 = function(d) { return formatDate(d.Uhrzeit) + " - " + d.Durchschn + " ms"; };

var main_x = d3.time.scale()
    .range([0, main_width]),
    mini_x = d3.time.scale()
    .range([0, main_width]);

var main_y0 = d3.scale.sqrt()
    .range([main_height, 0]),
    mini_y0 = d3.scale.sqrt()
    .range([mini_height, 0]);

var main_xAxis = d3.svg.axis()
    .scale(main_x)
    .tickFormat(d3.time.format("%H:%M"))
    .orient("bottom"),
    mini_xAxis = d3.svg.axis()
    .scale(mini_x)
    .tickFormat(d3.time.format("%H:%M"))
    .orient("bottom");

var main_yAxisLeft = d3.svg.axis()
    .scale(main_y0)
    .orient("left");

var brush = d3.svg.brush()
    .x(mini_x)
    .on("brushstart",function(){
        console.log(brush.extent()[0]);
    })
    .on("brush",brushMove)
    .on("brushend", function(){
        console.log(brush.extent()[1]);
    });

var main_line0 = d3.svg.line()
    .interpolate("cardinal")
    .x(function(d) { return main_x(d.Uhrzeit); })
    .y(function(d) { return main_y0(d.Durchschn); });

var mini_line0 = d3.svg.line()
    .x(function(d) { return mini_x(d.Uhrzeit); })
    .y(function(d) { return mini_y0(d.Durchschn); });

var svg = d3.select("body").append("svg")
    .attr("width", main_width + main_margin.left + main_margin.right)
    .attr("height", main_height + main_margin.top + main_margin.bottom);

    svg.append("defs").append("clipPath")
        .attr("id", "clip")
       .append("rect")
        .attr("width", main_width)
        .attr("height", main_height);

var main = svg.append("g")
    .attr("transform", "translate(" + main_margin.left + "," + main_margin.top + ")");

var mini = svg.append("g")
    .attr("transform", "translate(" + mini_margin.left + "," + mini_margin.top + ")");

d3.csv("data.txt", function(error, data) {
      data.forEach(function(d) {
        d.Uhrzeit = parseDate(d.Uhrzeit);
        d.Durchschn = +d.Durchschn;
      });

      data.sort(function(a, b) {
        return a.Uhrzeit - b.Uhrzeit;
      });

      main_x.domain([data[0].Uhrzeit, data[data.length - 1].Uhrzeit]);
      main_y0.domain(d3.extent(data, function(d) { return d.Durchschn; }));
      mini_x.domain(main_x.domain());
      mini_y0.domain(main_y0.domain());

      main.append("path")
          .datum(data)
          .attr("clip-path", "url(#clip)")
          .attr("class", "line line0")
          .attr("d", main_line0);

      main.append("g")
          .attr("class", "x axis")
          .attr("transform", "translate(0," + main_height + ")")
          .call(main_xAxis);

      main.append("g")
          .attr("class", "y axis axisLeft")
          .call(main_yAxisLeft)
        .append("text")
          .attr("transform", "rotate(-90)")
          .attr("y", 6)
          .attr("dy", ".71em")
          .style("text-anchor", "end")
          .text("Ø AWZ (ms)");

      mini.append("g")
          .attr("class", "x axis")
          .attr("transform", "translate(0," + mini_height + ")")
          .call(main_xAxis);

      mini.append("path")
          .datum(data)
          .attr("class", "line")
          .attr("d", mini_line0);

      mini.append("g")
          .attr("class", "x brush")
          .call(brush)
        .selectAll("rect")
          .attr("y", -6)
          .attr("height", mini_height + 7);

      focus = main.append("g")
          .attr("class", "focus")
          .style("display", "none");

      focus.append("line")
          .attr("class", "x")
          .attr("y1", main_y0(0) - 6)
          .attr("y2", main_y0(0) + 6)

      focus.append("line")
          .attr("class", "y0")
          .attr("x1", main_width - 6) // nach links
          .attr("x2", main_width + 6); // nach rechts

      focus.append("circle")
          .attr("class", "y0")
          .attr("r", 4);

      focus.append("text")
          .attr("class", "y0")
          .attr("dy", "-1em");

      main.append("rect")
          .attr("class", "overlay")
          .attr("width", main_width)
          .attr("height", main_height)
          .on("mouseover", showToolTip)
          .on("mouseout", hideToolTip)
          .on("mousemove", mousemove);

      function mousemove() {
        var x0 = main_x.invert(d3.mouse(this)[0]),
            i = bisectDate(data, x0, 1),
            d0 = data[i - 1],
            d1 = data[i],
            d = x0 - d0.Uhrzeit > d1.Uhrzeit - x0 ? i : (i-1);
            showToolTipForIndex(d);   
      }
      function showToolTipForIndex(i){
        var d = data[i];
        focus.select("circle.y0").attr("transform", "translate(" + main_x(d.Uhrzeit) + "," + main_y0(d.Durchschn) + ")");
        focus.select("text.y0").attr("transform", "translate(" + main_x(d.Uhrzeit) + "," + main_y0(d.Durchschn) + ")").text(formatOutput0(d));
        focus.select(".x").attr("transform", "translate(" + main_x(d.Uhrzeit) + ",0)");
        focus.select(".y0").attr("transform", "translate(" + main_width * -1 + ", " + main_y0(d.Durchschn) + ")").attr("x2", main_width + main_x(d.Uhrzeit));
      }
      // set default brush on mini xAxis
      defaultBrush(data,start,end);

      // bind event listeners
      document.getElementById('play').addEventListener('click',function(){
        if( !brush.empty() ){
        // here I want to get brush's start and end points.. I mean the range           
        }       
      });
});
function showToolTip(){
    focus.style("display", null);
}
function hideToolTip(){
    focus.style("display", "none"); 
}   
function defaultBrush(data,start,end){
    svg.select(".x.brush").call(brush.extent([data[start].Uhrzeit,data[end].Uhrzeit]));
    main_x.domain([data[start].Uhrzeit,data[end].Uhrzeit]);
    main.select(".line0").attr("d", main_line0);
    main.select(".x.axis").call(main_xAxis);
}
function brushMove() {
  main_x.domain(brush.empty() ? mini_x.domain() : brush.extent());
  main.select(".line0").attr("d", main_line0);
  main.select(".x.axis").call(main_xAxis);
}
function brushStart(){

}   
function brushEnd(){

}

});

---

所选区域的起点和终点包含在

brush.extent（）

中。此函数返回两个点（起点和终点）的数组。如果你想得到x坐标的起点和终点，你可以这样做

var extent = brush.extent(),
    start  = extent[0][0],
    end    = extent[1][0];