问题描述

我实际上是在使用 Chart JS 2.0.1 在页面上绘制图表.

I'm actualy using Chart JS 2.0.1 to draw charts on a page.

我的客户要求我在条形图中添加一条线，以便他们可以看到无法超过的限制.像这样:y轴上的条形图

My customers asked me to add a line in a bar chart so that they can see the limit they can't go over. Like that: Bar chart with line on y axes

因此，我正在尝试将条形图扩展为一个新的条形图，该条形图采用一个名为 lineAtValue 的参数，该参数提供该线的 y 值.

So, I'm trying to extend the Bar Chart into a new one which takes a parameter called lineAtValue which provides the y value for the line.

我成功扩展了条形图，但它覆盖了页面中显示的其他条形图，而我在其他条形图中不需要它.

I succeeded in extending the bar chart but it overrides the others bar charts displayed in the page and I don't need that in the other Bar Charts.

这是我所做的:http://jsfiddle.net/d5ye1xpe/

我希望能够有这样的东西:jsfiddle.net/L3uhpvd5/(对不起，我不能上传两个以上的链接)

And I'd like to be able to have something like this one : jsfiddle.net/L3uhpvd5/ (sorry I can't upload more than two links) with the

Chart.barWithLine(ctx,config);

但是使用 Chart JS 的 2.0.1 版本

But with the version 2.0.1 of Chart JS

谢谢，

普图尔内姆

推荐答案

这很有帮助，但我发现它并没有针对实际上不是数据的行添加新数据集进行优化.

This is helpful but I found it not that optimized to add new Dataset just for a line that is actually not a data.

我终于成功地创建了扩展 bar 类型的新类型，如果提供了值，则添加一行.

I finally suceeded in creating the new type that extend the bar type and add a line if the value is provided.

// Store the original Draw function
var originalLineDraw = Chart.controllers.bar.prototype.draw;
// extend the new type
Chart.helpers.extend(Chart.controllers.bar.prototype, {
    draw: function () {
    // use the base draw function
    originalLineDraw.apply(this, arguments);

    // get chart and context
    var chart = this.chart;
    var ctx = chart.chart.ctx;

    // get lineAtValue value
    var value = chart.config.lineAtValue;

    // stop if it doesn't exist
    if (typeof value === "undefined") {
        return;
    }

    // draw the line
    var xaxis = chart.scales['x-axis-0'];
    var yaxis = chart.scales['y-axis-0'];
    ctx.save();
    ctx.beginPath();
    ctx.moveTo(xaxis.left, yaxis.getPixelForValue(value));
    ctx.strokeStyle = '#ff0000';
    ctx.lineTo(xaxis.right, yaxis.getPixelForValue(value));
    ctx.stroke();
    ctx.restore();

    }
});

但感谢您的帮助 =)

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