javascript - d3 : tooltips on multi series line chart at each line when mouse hover event

Question

我在 Angular 2 应用程序中使用 d3 绘制图表。现在我有一个多系列折线图，所以我试图在将鼠标悬停在其垂直位置时在每条线上添加工具提示。

export class LineGraphDirective {
  private host;
  private svg;
  private margin;
  private width;
  private height;
  private xScale; // D3 scale in X
  private yScale; // D3 scale in Y
  private zScale; // D3 color scale
  private xAxis;
  private yAxis;
  private line;
  private htmlElement:HTMLElement;
  private parseDate;
  private ds;

  constructor(private element:ElementRef) {
    this.htmlElement = this.element.nativeElement;
    this.host = d3.select(this.element.nativeElement);
    this.parseDate = d3.timeParse('%Y-%m-%d');
    let data = [];
    this.ngOnChanges(data);
  }

  /**
   * Every time the @Input is updated, rebuild the chart
   **/
  ngOnChanges(data):void {
    this.setup(data);
    this.initData(data);
    this.buildSVG();
    this.scaleAxis(data);
    this.populate();
    this.drawXAxis();
    this.drawYAxis();
    this.zoomEventHandler();
    this.addVerticalLineTooltip();
  }

  private setup(data):void {}

  private initData(data) {}

  /**
   *  build  SVG element using the configurations
   **/
  private buildSVG():void {}

  private scaleAxis(data) {}


  /**
   * Create x axis
   **/
  private drawXAxis():void {}

  /**
   *create y axis
   **/
  private drawYAxis():void {}

  /**
   * Populate the graphs
   **/
  private populate():void {}

  private addVerticalLineTooltip() {
    // append a g for all the mouse over nonsense
    let mouseG = this.svg.append("g")
      .attr("class", "mouse-over-effects");

    // this is the vertical line
    mouseG.append("path")
      .attr("class", "mouse-line")
      .style("stroke", "black")
      .style("stroke-width", "1px")
      .style("opacity", "0");

    // keep a reference to all our lines
    let lines = document.getElementsByClassName('line');

    // here's a g for each circle and text on the line
    let mousePerLine = mouseG.selectAll('.mouse-per-line')
      .data(this.ds)
      .enter()
      .append("g")
      .attr("class", "mouse-per-line");

    // the circle
    mousePerLine.append("circle")
      .attr("r", 7)
      .style("stroke", (d) => {
        return this.zScale(d.name);
      })
      .style("fill", "none")
      .style("stroke-width", "1px")
      .style("opacity", "0");

    // the text
    mousePerLine.append("text")
      .attr("transform", "translate(10,3)");

    // rect to capture mouse movements
    mouseG.append('svg:rect')
      .attr('width', this.width)
      .attr('height', this.height)
      .attr('fill', 'none')
      .attr('pointer-events', 'all')
      .on('mouseout', () => { // on mouse out hide line, circles and text
        d3.select(".mouse-line")
          .style("opacity", "0");
        d3.selectAll(".mouse-per-line circle")
          .style("opacity", "0");
        d3.selectAll(".mouse-per-line text")
          .style("opacity", "0");
      })
      .on('mouseover', () => { // on mouse in show line, circles and text
        d3.select(".mouse-line")
          .style("opacity", "1");
        d3.selectAll(".mouse-per-line circle")
          .style("opacity", "1");
        d3.selectAll(".mouse-per-line text")
          .style("opacity", "1");
      })
      .on('mousemove', () => { // mouse moving over canvas
        let mouse = d3.mouse(d3.event.currentTarget);
        console.log(lines);

        // move the vertical line
        d3.select(".mouse-line")
          .attr("d", () => {
            let d = "M" + mouse[0] + "," + this.height;
            d += " " + mouse[0] + "," + 0;
            return d;
          });

        // position the circle and text
        d3.selectAll(".mouse-per-line")
          .attr("transform", (d, i) => {
            console.log(i);
            let beginning = 0,
              end = d3.select(lines[i]).node().getTotalLength(),
              target,
              pos;

            while (true) {
              target = Math.floor((beginning + end) / 2);
              pos = d3.select(lines[i]).node().getPointAtLength(target);
              if ((target === end || target === beginning) && pos.x !== mouse[0]) {
                break;
              }
              if (pos.x > mouse[0])      end = target;
              else if (pos.x < mouse[0]) beginning = target;
              else break; //position found
            }
            console.log(this.yScale.invert(pos.y).toFixed(2));

            // update the text with y value
            d3.select(this).select('text') // **Error this.querySelector is not a function
              .text(this.yScale.invert(pos.y).toFixed(2));

            // return position
            return "translate(" + mouse[0] + "," + pos.y + ")";
          });
      });
  }
}

现在它显示垂直线，每行都有圆圈，但不显示值(工具提示)。控制台日志中显示以下错误。

this.querySelector is not a function

console.log(this.yScale.invert(pos.y).toFixed(2));

上面的控制台日志在鼠标悬停事件时正确打印 Y 轴值。

任何建议。

谢谢!

Answer 1

我根据您的要求在多系列折线图上创建了工具提示，效果很好。

您需要对代码进行一些更改以设置来自以下示例链接的工具提示的位置

看这里的例子

Multi Series Line Chart with Tooltip