mirror of
https://github.com/chartjs/Chart.js.git
synced 2024-10-08 21:29:07 +02:00
6f7e09540c
Changed var to const/let in the docs
117 lines
2.7 KiB
Markdown
117 lines
2.7 KiB
Markdown
# Radial Gradient
|
|
|
|
```js chart-editor
|
|
// <block:setup:3>
|
|
const DATA_COUNT = 5;
|
|
Utils.srand(110);
|
|
|
|
const chartColors = Utils.CHART_COLORS;
|
|
const colors = [chartColors.red, chartColors.orange, chartColors.yellow, chartColors.green, chartColors.blue];
|
|
|
|
const cache = new Map();
|
|
let width = null;
|
|
let height = null;
|
|
|
|
const actions = [
|
|
{
|
|
name: 'Randomize',
|
|
handler(chart) {
|
|
chart.data.datasets.forEach(dataset => {
|
|
dataset.data = generateData();
|
|
});
|
|
chart.update();
|
|
}
|
|
},
|
|
];
|
|
// </block:setup>
|
|
|
|
// <block:createRadialGradient3:0>
|
|
function createRadialGradient3(context, c1, c2, c3) {
|
|
const chartArea = context.chart.chartArea;
|
|
if (!chartArea) {
|
|
// This case happens on initial chart load
|
|
return;
|
|
}
|
|
|
|
const chartWidth = chartArea.right - chartArea.left;
|
|
const chartHeight = chartArea.bottom - chartArea.top;
|
|
if (width !== chartWidth || height !== chartHeight) {
|
|
cache.clear();
|
|
}
|
|
let gradient = cache.get(c1 + c2 + c3);
|
|
if (!gradient) {
|
|
// Create the gradient because this is either the first render
|
|
// or the size of the chart has changed
|
|
width = chartWidth;
|
|
height = chartHeight;
|
|
const centerX = (chartArea.left + chartArea.right) / 2;
|
|
const centerY = (chartArea.top + chartArea.bottom) / 2;
|
|
const r = Math.min(
|
|
(chartArea.right - chartArea.left) / 2,
|
|
(chartArea.bottom - chartArea.top) / 2
|
|
);
|
|
const ctx = context.chart.ctx;
|
|
gradient = ctx.createRadialGradient(centerX, centerY, 0, centerX, centerY, r);
|
|
gradient.addColorStop(0, c1);
|
|
gradient.addColorStop(0.5, c2);
|
|
gradient.addColorStop(1, c3);
|
|
cache.set(c1 + c2 + c3, gradient);
|
|
}
|
|
|
|
return gradient;
|
|
}
|
|
// </block:createRadialGradient3>
|
|
|
|
// <block:data:2>
|
|
function generateData() {
|
|
return Utils.numbers({
|
|
count: DATA_COUNT,
|
|
min: 0,
|
|
max: 100
|
|
});
|
|
}
|
|
|
|
const data = {
|
|
labels: Utils.months({count: DATA_COUNT}),
|
|
datasets: [{
|
|
data: generateData()
|
|
}]
|
|
};
|
|
// </block:data>
|
|
|
|
// <block:config:1>
|
|
const config = {
|
|
type: 'polarArea',
|
|
data: data,
|
|
options: {
|
|
plugins: {
|
|
legend: false,
|
|
tooltip: false,
|
|
},
|
|
elements: {
|
|
arc: {
|
|
backgroundColor: function(context) {
|
|
let c = colors[context.dataIndex];
|
|
if (!c) {
|
|
return;
|
|
}
|
|
if (context.active) {
|
|
c = helpers.getHoverColor(c);
|
|
}
|
|
const mid = helpers.color(c).desaturate(0.2).darken(0.2).rgbString();
|
|
const start = helpers.color(c).lighten(0.2).rotate(270).rgbString();
|
|
const end = helpers.color(c).lighten(0.1).rgbString();
|
|
return createRadialGradient3(context, start, mid, end);
|
|
},
|
|
}
|
|
}
|
|
}
|
|
};
|
|
// </block:config>
|
|
|
|
module.exports = {
|
|
actions,
|
|
config,
|
|
};
|
|
```
|