d3：鼠标悬停事件时每行的多系列折线图上的工具提示 [英] d3: tooltips on multi series line chart at each line when mouse hover event

问题描述

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，所以我试图在悬停其垂直位置时在每一行添加工具提示。

I am drawing charts with d3 in my Angular 2 application. Now I have a multi series line chart so I am trying to add tool tips at each line when hover its' vertical position.

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，每行有圆圈但是它不显示值（工具提示）。控制台日志中显示以下错误。

Now it shows vertical line with circles at each line but it doesn't show the values (tooltips). Following error is displaying on console log.

this.querySelector is not a function

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

控制台日志上方在鼠标悬停事件中正确打印Y轴值。

Above console log prints Y-axis values correctly on mouse hover event.

任何建议。

谢谢！

推荐答案

你可以这样做

d3.selectAll(".mouse-per-line")
      .attr("transform", (d, i, f) => {
        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(f[i]).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 + ")";
      });

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