Chart.js - 绘制任意垂直线 [英] Chart.js — drawing an arbitrary vertical line

问题描述

如何使用Chart.js在x轴上的特定点绘制垂直线？

特别是，我想画一条线来表示LineChart上的当天。这是图表的模型：

解决方案

更新 - 这个答案适用于Chart.js 1.x，如果您正在寻找2.x答案，请查看评论和其他答案。

您可以扩展折线图并包含用于在绘图功能中绘制线条的逻辑。

---

预览

---

HTML

 < div> 
< canvas id =LineWithLinewidth =600height =400>< / canvas> 
< / div> 
  

脚本

  var data = {
 labels：[JAN，FEB，MAR，APR，MAY，JUN，JUL， AUG，SEP，OCT，NOV，DEC]，
数据集：[{
数据：[12,3,2,1,8,8,2， 2,3,5,7,1] 
}] 
}; 
 
 var ctx = document.getElementById（LineWithLine）。getContext（2d）; 
 
 Chart.types.Line.extend（{
 name：LineWithLine，
 draw：function（）{
 Chart.types.Line.prototype.draw .apply（this，arguments）; 
 
 var point = this.datasets [0] .points [this.options.lineAtIndex] 
 var scale = this.scale 
 
 //绘制线
 this.chart.ctx.beginPath（）; 
 this.chart.ctx.moveTo（point.x，scale.startPoint + 24）; 
 this.chart .ctx.strokeStyle ='＃ff0000'; 
 this.chart.ctx.lineTo（point.x，scale.endPoint）; 
 this.chart.ctx.stroke（）; 
 
 //写TODAY 
 this.chart.ctx.textAlign ='center'; 
 this.chart.ctx.fillText（TODAY，point.x，scale.startPoint + 12）; 
} 
}）; 
 
 new Chart（ctx）.LineWithLine（data，{
 datasetFill：false，
 lineAtIndex：2 
}）; 
  

选项属性lineAtIndex控制在哪一点画线。

小提琴 - http://jsfiddle.net/dbyze2ga/14/ / p>

How can I draw an vertical line at a particular point on the x-axis using Chart.js?

In particular, I want to draw a line to indicate the current day on a LineChart. Here's a mockup of the chart: http://i.stack.imgur.com/VQDWR.png

解决方案

Update - this answer is for Chart.js 1.x, if you are looking for a 2.x answer check the comments and other answers.

You extend the line chart and include logic for drawing the line in the draw function.

---

Preview

---

HTML

<div>
    <canvas id="LineWithLine" width="600" height="400"></canvas>
</div>

Script

var data = {
    labels: ["JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP", "OCT", "NOV", "DEC"],
    datasets: [{
        data: [12, 3, 2, 1, 8, 8, 2, 2, 3, 5, 7, 1]
    }]
};

var ctx = document.getElementById("LineWithLine").getContext("2d");

Chart.types.Line.extend({
    name: "LineWithLine",
    draw: function () {
        Chart.types.Line.prototype.draw.apply(this, arguments);

        var point = this.datasets[0].points[this.options.lineAtIndex]
        var scale = this.scale

        // draw line
        this.chart.ctx.beginPath();
        this.chart.ctx.moveTo(point.x, scale.startPoint + 24);
        this.chart.ctx.strokeStyle = '#ff0000';
        this.chart.ctx.lineTo(point.x, scale.endPoint);
        this.chart.ctx.stroke();

        // write TODAY
        this.chart.ctx.textAlign = 'center';
        this.chart.ctx.fillText("TODAY", point.x, scale.startPoint + 12);
    }
});

new Chart(ctx).LineWithLine(data, {
    datasetFill : false,
    lineAtIndex: 2
});

The option property lineAtIndex controls which point to draw the line at.

Fiddle - http://jsfiddle.net/dbyze2ga/14/

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