你能帮我如何扩展 Chart.js v2.0。我需要在图表中绘制一些水平线,类似于:http: //jsfiddle.net/vsh6tcfd/3/
var originalLineDraw = Chart.controllers.bar.prototype.draw;
Chart.helpers.extend(Chart.controllers.bar.prototype, {
draw: function() {
originalLineDraw.apply(this, arguments);
var chart = this.chart;
var ctx = chart.chart.ctx;
var index = chart.config.data.lineAtIndex;
if (index) {
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.left);
ctx.strokeStyle = '#ff0000';
ctx.lineTo(xaxis.getPixelForValue(undefined, index), yaxis.right);
ctx.stroke();
ctx.restore();
}
}
});
var config = {
type: type,
data: jQuery.extend(true, {}, data),
options: this.chartdata.options,
lineAtIndex: 2
};
new Chart(ctx, config);