javascript - 在线条动画之后向折线图数据点添加工具提示

Question

我有一个包含两条线的基本折线图。当我单击一个按钮时，两条线之一将绘制在图形上。

我使用 stroke-dasharray 来绘制线条。

有谁知道如何将工具提示添加到我的行中？使用 stroke-dasharray 会使它更难吗？

这是我的代码。

var button=d3.select("#button");

//defines canvas (area in which graph is placed)    
var margin = {top: 30, right: 20, bottom: 50, left: 60},
width = 800 - margin.left - margin.right,
height = 700 - margin.top - margin.bottom;

var parseDate = d3.time.format("%d-%b-%y").parse;

//OUTPUT RANGE
var x = d3.time.scale()
    .range([0, width]);

//OUTPUT RANGE    
var y = d3.scale.linear()
    .range([height, 0]);

var xAxis = d3.svg.axis().scale(x)
    .orient("bottom")
    .ticks(5);

var yAxis = d3.svg.axis().scale(y)
    .orient("left")
    .ticks(5);

//assigns coordinates for each piece of data    
var valueline = d3.svg.line()
    .interpolate("interpolation")
    .x(function(d) { return x(d.date); })
    .y(function(d) { return y(d.close); });

//second line data
var valueline2 = d3.svg.line()
    .x(function(d) { return x(d.date); })
    .y(function(d) { return y(d.open); });

//create area for 'area' below line    
var area = d3.svg.area()
    .x(function(d) { return x(d.date); })
    .y0(height)
    .y1(function(d) { return y(d.close); });    

//creates area to draw graph    
var svg = d3.select("body")
    .append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
//groups content    
.append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

function make_x_axis() {
    return d3.svg.axis()
        .scale(x)
        .orient("bottom")
        .ticks(5)
}

function make_y_axis() {
    return d3.svg.axis()
        .scale(y)
        .orient("left")
        .ticks(30)
}

// csv callback function
d3.csv("myData3.csv", function(data) {

    data.forEach(function(d) {
        d.date = parseDate(d.date);
        d.close = +d.close;
        d.open = +d.open;
    });


//INPUT DOMAINS
//.extent() returns min and max values of argument
x.domain(d3.extent(data, function(d) { return d.date; }));
//returns max of whichever set of data is bigger
y.domain([0, d3.max(data, function(d) { return Math.max(d.close, d.open); })]);


 d3.select("#button1").on("click", function(){ 
      var path = svg.append("path")   // Add the valueline path. 
          .attr("class", "line")
          .attr("d", valueline(data))
          .attr("stroke", "steelblue")
          .attr("stroke-width", "5")
          .attr("fill", "none");

  var totalLength = path.node().getTotalLength();

  path
    .attr("stroke-dasharray", totalLength + "30" * 30)
    .attr("stroke-dashoffset", totalLength)
    .transition()
      .duration(2000)
      .ease("linear")
      .attr("stroke-dashoffset", 0);

     })

 d3.select("#button2").on("click", function(){ 
      var path2 = svg.append("path")        // Add the valueline path. 
          .attr("class", "line2")
          .attr("d", valueline2(data))
          .attr("stroke", "steelblue")
          .attr("stroke-width", "5")
          .attr("fill", "none");

  var totalLength = path2.node().getTotalLength();


  path2
    .attr("stroke-dasharray", totalLength + "30" * 30)
    .attr("stroke-dashoffset", totalLength)
    .transition()
      .duration(2000)
      .ease("linear")
      .attr("stroke-dashoffset", 0)
     })       


svg.append("g") // Add the X Axis
    .attr("class", "x axis")
    //moves x axis to bottom of graph
    .attr("transform", "translate(0," + height + ")")
    .call(xAxis);

//text label for x-axis    
svg.append("text") // text label for the x axis
    .attr("transform", "translate(" + (width / 2) + " ," + (height + margin.bottom - 5 ) + ")")
    .style("text-anchor", "middle")
    .text("Date");

svg.append("g") // Add the Y Axis
    .attr("class", "y axis")
    .call(yAxis);

//text label for y-axis    
svg.append("text")
    .attr("transform", "rotate(-90)")
    .attr("y", 0 - margin.left)
    .attr("x",0 - (height / 2))
    //adds extra left padding as original y pos = 0
    .attr("dy", "1em")
    .style("text-anchor", "middle")
    .text("Value");


//adding a title to the graph
svg.append("text")
    .attr("x", (width / 2))
    .attr("y", 0 - (margin.top / 2))
    .attr("text-anchor", "middle")
    .style("font-size", "16px")
    .style("text-decoration", "underline")
    .text("Graph");


//draw x axis grid    
svg.append("g")
    .attr("class", "grid")
    .attr("transform", "translate(0," + height + ")")
    .call(make_x_axis()
    .tickSize(-height, 0, 0)
    .tickFormat("")
)

//draw y axis grid
svg.append("g")
    .attr("class", "grid")
    .call(make_y_axis()
    .tickSize(-width, 0, 0)
    .tickFormat("")
)

});<!--d3.csv close-->​

提前致谢!

Answer 1

添加工具提示的最简单方法是将 svg:title 元素附加到您想要为其添加工具提示的元素。当您将鼠标悬停在元素上时，浏览器会自动显示它。它也适用于各种元素。

所以你的代码需要看起来像

var path = svg.append("path")   // Add the valueline path. 
      .attr("class", "line")
      .attr("d", valueline(data))
      .attr("stroke", "steelblue")
      .attr("stroke-width", "5")
      .attr("fill", "none")
      .append("title").text("whatever");

如果您需要更复杂的功能，您可以尝试例如 tipsy ，其工作方式类似。