如何在 Chart.js 的饼图中（顶部）添加切片的大小？
[英]How add the sizes of the slices in the pie chart (at the top) in Chart.js?
问题描述
I am starting to learn the chart.js library.
我开始学习 chart.js 库。
I drew a pie chart (like "pie").我画了一个饼图（比如“饼”）。 When you hover over the slices of the diagram, a number appears in the pop-up window that sets the size of the sector.当您将鼠标悬停在图表的切片上时，弹出窗口中会出现一个数字，用于设置扇区的大小。
new chart(
document.getElementById('diagram_1').getContext('2d'), {
type: 'pie',
data: {
labels: [
'Завершенная задача',
'Новая задача',
'Ошибка выполнения'
],
datasets: [{
label: '# of Votes',
data: [@successful_tasks, @new_tasks, @error_tasks],
backgroundColor: [
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(255, 99, 132, 0.2)'
],
borderColor: [
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(255, 99, 132, 1)'
],
borderWidth: 1
}]
},
options: {
scales: {
y: {
beginAtZero: true
}
},
responsive: false
}
}
)
How can you make this number still displayed at the top, where the sectors are listed (I marked this place with a red circle in the picture)?你怎么能让这个数字仍然显示在顶部，列出扇区（我在图中用红色圆圈标记了这个地方）？
I can add the required number to the labels array我可以将所需的数字添加到标签数组
...
data: {
labels: [
'Завершенная задача: ' + @successful_tasks,
'Новая задача: ' + @new_tasks,
'Ошибка выполнения: ' + @error_tasks
],
...
But then this number will appear twice in the tooltip但是这个数字会在工具提示中出现两次
2 个解决方案
解决方案1
0 2021-10-25 10:49:47
You can use the plugin system for this:您可以为此使用插件系统：
var options = { type: 'pie', data: { labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"], datasets: [{ label: '# of Votes', data: [12, 19, 3, 5, 2, 3], backgroundColor: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"] }] }, options: { plugins: { customNumber: { textColor: 'red', xOffset: 10, yOffset: 0, font: '24px Comic Sans MS' } } }, plugins: [{ id: 'customNumber', afterDraw: (chart, args, opts) => { const hoveredSlice = chart._active[0]; const { ctx, chartArea: { right } } = chart; if (!hoveredSlice) { return; } ctx.font = opts.font || '24px verdana, sans-serif' ctx.fillStyle = opts.textColor || 'black' const val = chart.data.datasets[hoveredSlice.datasetIndex].data[hoveredSlice.index]; const meassures = ctx.measureText(val); const height = ctx.measureText('M').width; ctx.fillText(val, (right - meassures.width - (opts.xOffset || 0)), height + (opts.yOffset || 0)) } }] } var ctx = document.getElementById('chartJSContainer').getContext('2d'); new Chart(ctx, options);
<body> <canvas id="chartJSContainer" width="600" height="400"></canvas> <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.6.0/chart.js"></script> </body>
解决方案2
0 2021-10-26 11:40:01
I found the answer.我找到了答案。 My project is written in CoffeeScript, but I think it would be more useful for the StackOverflow community to post the code in JS.我的项目是用 CoffeeScript 写的，但是我觉得 StackOverflow 社区用 JS 发布代码会更有用。
options: {
legend: {
labels: {
generateLabels: function(chart) {
var data = chart.data;
if (data.labels.length && data.datasets.length) {
return data.labels.map(function(label, i) {
var meta = chart.getDatasetMeta(0);
var ds = data.datasets[0];
var arc = meta.data[i];
var custom = arc && arc.custom || {};
var getValueAtIndexOrDefault = Chart.helpers.getValueAtIndexOrDefault;
var arcOpts = chart.options.elements.arc;
var fill = custom.backgroundColor ? custom.backgroundColor : getValueAtIndexOrDefault(ds.backgroundColor, i, arcOpts.backgroundColor);
var stroke = custom.borderColor ? custom.borderColor : getValueAtIndexOrDefault(ds.borderColor, i, arcOpts.borderColor);
var bw = custom.borderWidth ? custom.borderWidth : getValueAtIndexOrDefault(ds.borderWidth, i, arcOpts.borderWidth);
var value = chart.config.data.datasets[arc._datasetIndex].data[arc._index];
return {
text: label + ": " + value,
fillStyle: fill,
strokeStyle: stroke,
lineWidth: bw,
hidden: isNaN(ds.data[i]) || meta.data[i].hidden,
index: i
};
});
} else {
return [];
}
}
}
}
}
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