Chart.js 阴影区域 [英] Chart.js shaded regions

问题描述

Chart.js (

或

<小时>

脚本

Chart.types.Line.extend({name: "LineAlt",初始化:函数(数据){Chart.types.Line.prototype.initialize.apply(this, arguments);变量范围 = [{开始:100，结束: 75,颜色:'RGBA(250,0,0,0.5)'},{开始:75，结束: 50,颜色:'RGBA(0,250,0,0.5)'},{开始:50，结束: 25,颜色:'RGBA(0,0,250,0.5)'},{开始:25，结束: 0,颜色:'RGBA(250,250,0,0.5)'}];var scale = this.scale;var rangeStart = scale.calculateY(ranges[0].start);var rangeEnd = scale.calculateY(ranges[ranges.length - 1].end);var梯度 = this.chart.ctx.createLinearGradient(0, rangeStart, 0, rangeEnd);range.forEach(函数(范围){gradient.addColorStop((scale.calculateY(range.start) -rangesStart)/(rangesEnd -rangesStart), range.color);gradient.addColorStop((scale.calculateY(range.end) -rangesStart)/(rangesEnd -rangesStart), range.color);})this.datasets[0].fillColor = 渐变；}});

然后

<代码>...新图表(ctx).LineAlt(数据)；

<小时>

如果你想对整个背景进行着色，请使用

var originalDraw = scale.draw;scale.draw = 函数(){originalDraw.apply(this, arguments);ctx.save();ctx.fillStyle = 渐变；ctx.fillRect(scale.calculateX(0), scale.startPoint, scale.width, scale.endPoint - scale.startPoint);ctx.restore();}

代替this.datasets[0].fillColor = gradient;

<小时>

小提琴(下线) - http://jsfiddle.net/61vg048r/

小提琴(整个背景) - http://jsfiddle.net/u4Lk7xns/

Chart.js (http://www.chartjs.org/docs/) can fill the color below line charts using the "fillColor" attribute (filling the region between the line chart itself and the x-axis).

What I'd like to know is whether Chart.js can be configured to create shaded regions such as the one shown below:

http://peltiertech.com/Excel/pix5/HorizBands09.png

Thank you.

解决方案

Shaded Regions for Line Charts

You can extend the chart to do this.

---

Preview

or

---

Script

Chart.types.Line.extend({
    name: "LineAlt",
    initialize: function (data) {
        Chart.types.Line.prototype.initialize.apply(this, arguments);

        var ranges = [
            {
                start: 100,
                end: 75,
                color: 'rgba(250,0,0,0.5)'
            },
            {
                start: 75,
                end: 50,
                color: 'rgba(0,250,0,0.5)'
            },
            {
                start: 50,
                end: 25,
                color: 'rgba(0,0,250,0.5)'
            },
            {
                start: 25,
                end: 0,
                color: 'rgba(250,250,0,0.5)'
            }
        ];

        var scale = this.scale;
        var rangesStart = scale.calculateY(ranges[0].start);
        var rangesEnd = scale.calculateY(ranges[ranges.length - 1].end);
        var gradient = this.chart.ctx.createLinearGradient(0, rangesStart, 0, rangesEnd);

        ranges.forEach(function (range) {
            gradient.addColorStop((scale.calculateY(range.start) - rangesStart) / (rangesEnd - rangesStart), range.color);
            gradient.addColorStop((scale.calculateY(range.end) - rangesStart) / (rangesEnd - rangesStart), range.color);
        })

        this.datasets[0].fillColor = gradient;
    }
});

and then

...
new Chart(ctx).LineAlt(data);

---

If you want to shade the whole background use

var originalDraw = scale.draw;
scale.draw = function() {
    originalDraw.apply(this, arguments);

  ctx.save();
  ctx.fillStyle = gradient;
  ctx.fillRect(scale.calculateX(0), scale.startPoint, scale.width, scale.endPoint - scale.startPoint);
  ctx.restore();
}

instead of this.datasets[0].fillColor = gradient;

---

Fiddle (below line) - http://jsfiddle.net/61vg048r/

Fiddle (whole background) - http://jsfiddle.net/u4Lk7xns/

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