具有区域范围的 Chart.js 折线图

Question

我想向Chart.js 折线图添加另一个维度，类似于下面的图表，或this Highcharts example。考虑到 Chart.js 的无数扩展选项，我很难理解在哪里可以实现这样的功能。

理想情况下，我可以提供一个数据集，其字段类似于data，指定某一点的线宽。

Answer 1

您可以从折线图类型创建新的图表类型来执行此操作

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预览

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脚本

Chart.defaults.stripe = Chart.helpers.clone(Chart.defaults.line);
Chart.controllers.stripe = Chart.controllers.line.extend({
  draw: function(ease) {
    var result = Chart.controllers.line.prototype.draw.apply(this, arguments);

    // don't render the stripes till we've finished animating
    if (!this.rendered && ease !== 1)
      return;
    this.rendered = true;


    var helpers = Chart.helpers;
    var meta = this.getMeta();
    var yScale = this.getScaleForId(meta.yAxisID);
    var yScaleZeroPixel = yScale.getPixelForValue(0);
    var widths = this.getDataset().width;
    var ctx = this.chart.chart.ctx;

    ctx.save();
    ctx.fillStyle = this.getDataset().backgroundColor;
    ctx.lineWidth = 1;
    ctx.beginPath();

    // initialize the data and bezier control points for the top of the stripe
    helpers.each(meta.data, function(point, index) {
      point._view.y += (yScale.getPixelForValue(widths[index]) - yScaleZeroPixel);
    });
    Chart.controllers.line.prototype.updateBezierControlPoints.apply(this);

    // draw the top of the stripe
    helpers.each(meta.data, function(point, index) {
      if (index === 0)
        ctx.moveTo(point._view.x, point._view.y);
      else {
        var previous = helpers.previousItem(meta.data, index);
        var next = helpers.nextItem(meta.data, index);

        Chart.elements.Line.prototype.lineToNextPoint.apply({
          _chart: {
            ctx: ctx
          }
        }, [previous, point, next, null, null])
      }
    });

    // revert the data for the top of the stripe
    // initialize the data and bezier control points for the bottom of the stripe
    helpers.each(meta.data, function(point, index) {
      point._view.y -= 2 * (yScale.getPixelForValue(widths[index]) - yScaleZeroPixel);
    });
    // we are drawing the points in the reverse direction
    meta.data.reverse();
    Chart.controllers.line.prototype.updateBezierControlPoints.apply(this);

    // draw the bottom of the stripe
    helpers.each(meta.data, function(point, index) {
      if (index === 0)
        ctx.lineTo(point._view.x, point._view.y);
      else {
        var previous = helpers.previousItem(meta.data, index);
        var next = helpers.nextItem(meta.data, index);

        Chart.elements.Line.prototype.lineToNextPoint.apply({
          _chart: {
            ctx: ctx
          }
        }, [previous, point, next, null, null])
      }

    });

    // revert the data for the bottom of the stripe
    meta.data.reverse();
    helpers.each(meta.data, function(point, index) {
      point._view.y += (yScale.getPixelForValue(widths[index]) - yScaleZeroPixel);
    });
    Chart.controllers.line.prototype.updateBezierControlPoints.apply(this);

    ctx.stroke();
    ctx.closePath();
    ctx.fill();
    ctx.restore();

    return result;
  }
});

然后

...
data: ...,
width: [12, 4, 5, 13, 12, 2, 19],
...

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小提琴 - http://jsfiddle.net/u20cfpcd/

注意： 乐队似乎存在间歇性问题，没有出现。评论 if (!this.rendered && ease !== 1) return 似乎可以解决这个问题。感谢@ClaudeBrisson 找出问题和解决方案！