Question

因此，在查看Chart.js的一些代码示例时，我遇到了以下JSFiddle（http://jsfiddle.net/dbyze2ga/14/）。当我把它处理到我的IDE（bracket.io）时，它才起作用，直到我意识到这个jsfiddle使用chart.js 1.x.x.

使用v2.0扩展图表的当前语法是什么？我试过检查文档;但它真的让我更加困惑。没有帮助，至少在Brackets的情况下，它不会显示图表的任何真正有用的点完成。

有问题的JS代码是：

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
});

Answer 1

2.0更改在documentation中解释：

var myLineExtend = Chart.controllers.line.prototype.draw;

var ctx = document.getElementById("LineWithLine").getContext("2d");

var config = {
  type: 'line',
  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]
    }],
    datasetFill : false,
    lineAtIndex: 2
  }
};

Chart.helpers.extend(Chart.controllers.line.prototype, {
    draw: function () {
    
      myLineExtend.apply(this, arguments);   

      var chart = this.chart;
      var ctx = chart.chart.ctx;

      var index = chart.config.data.lineAtIndex;
      var xaxis = chart.scales['x-axis-0'];
      var yaxis = chart.scales['y-axis-0'];

      ctx.save();
      ctx.beginPath();
      ctx.moveTo(xaxis.getPixelForValue(undefined, index), yaxis.top + 24);
      ctx.strokeStyle = '#ff0000';
      ctx.lineTo(xaxis.getPixelForValue(undefined, index), yaxis.bottom);
      ctx.stroke();
      ctx.restore();

      ctx.textAlign = 'center';
      ctx.fillText("TODAY", xaxis.getPixelForValue(undefined, index), yaxis.top + 12);

    }
});

new Chart(ctx, config);

<script src="https://github.com/chartjs/Chart.js/releases/download/v2.6.0/Chart.bundle.min.js"></script>
<canvas id="LineWithLine"></canvas>

Chart.js扩展的新语法是什么？

1 个答案: