javascript - Chart.js(雷达图)每个 scaleLine 的不同 scaleLineColor

Question

我想尝试使用 Chart.js 创建一个雷达图，每个 scaleLine 都有不同的颜色，或者在 scaleLine 之间有颜色。我想知道这是否可能？

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我目前有一个工作图，但似乎没有改变个别比例线的方法。

亲切的问候利

Answer 1

你可以像这样扩展雷达图类型来做到这一点

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

        var originalScaleDraw = this.scale.draw;
        var ctx = this.chart.ctx;
        this.scale.draw = function () {
            var lineWidth = this.lineWidth;
            // this bypasses the line drawing in originalScaleDraw
            this.lineWidth = lineWidth;

            originalScaleDraw.apply(this, arguments);

            ctx.lineWidth = this.lineWidth;
            var scale = this;
            // now we draw
            Chart.helpers.each(scale.yLabels, function (label, index) {
                // color of each radial line - you could replace this by an array lookup (if you limit your scaleSteps)
                ctx.strokeStyle = "hsl(" + index / scale.yLabels.length * 360 + ", 80%, 70%)";

                // copy of the chart.js code
                ctx.beginPath();
                for (var i = 0; i < scale.valuesCount; i++) {
                    pointPosition = scale.getPointPosition(i, scale.calculateCenterOffset(scale.min + (index * scale.stepValue)));
                    if (i === 0) {
                        ctx.moveTo(pointPosition.x, pointPosition.y);
                    } else {
                        ctx.lineTo(pointPosition.x, pointPosition.y);
                    }
                }
                ctx.closePath();
                ctx.stroke();
            });
        }
    }
});

然后像这样调用它

var ctx = document.getElementById("myChart").getContext("2d");
var myRadarChart = new Chart(ctx).RadarAlt(data, {
    scaleLineWidth: 10
});

// this is requried if you have animation: false
// myRadarChart.update();

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fiddle - http://jsfiddle.net/x3ftqx5r/

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当然，明智的做法是更改亮度值而不是色相值:-)