blocks|key|522861|text|​|type|unstyled|depth|inlineStyleRanges|entityRanges|data|522862|📷|atomic|offset|length|522863|522864|甜甜圈图在画布中居中，所以您可以像下面这样计算甜甜圈的中心：|522865|//+get+the+canvas+element+and+its+context
var+canvas+=+document.getElementById("myChart");
var+ctx+=+canvas.getContext("2d");

//+calculate+the+center+of+the+canvas+(cx,cy)
var+cx=canvas.width/2;
var+cy=canvas.height/2;|code-block|syntax|javascript|522866|然后，您可以告诉画布以cx为中心垂直和水平地绘制文本，cy如下所示：|522867|//+horizontally+align+text+around+the+specified+point+(cx)
ctx.textAlign='center';

//+vertically+align+text+around+the+specified+point+(cy)
ctx.textBaseline='middle';

//+draw+the+text
ctx.font='14px+verdana';
ctx.fillStyle='black';
ctx.fillText("Text+Here",cx,cy);|522868|但是，在绘制居中文本之前，必须等待任何动画的完成。|522869|要做到这一点，您必须告诉ChartJS，您希望在它完成动画时触发回调函数。可以通过设置图表选项的onAnimationComplete属性来设置回调：|style|CODE|522870|var+myDoughnutChart+=+new+Chart(ctx).Doughnut(data,+{
++++responsive+:+true,

++++//+when+ChartJS+has+completed+all+animations+then+call+the+addText+function
++++onAnimationComplete:+addText
});|522871|，这里有一个演示，把所有的东西组合在一起：|BOLD|522872|522873|var+doughnutData+=+[{
++++value:+300,
++++color:+"#F7464A",
++++highlight:+"#FF5A5E",
++++label:+"Red"
++},+{
++++value:+50,
++++color:+"#46BFBD",
++++highlight:+"#5AD3D1",
++++label:+"Green"
++},+{
++++value:+100,
++++color:+"#FDB45C",
++++highlight:+"#FFC870",
++++label:+"Yellow"
++},+{
++++value:+40,
++++color:+"#949FB1",
++++highlight:+"#A8B3C5",
++++label:+"Grey"
++},+{
++++value:+120,
++++color:+"#4D5360",
++++highlight:+"#616774",
++++label:+"Dark+Grey"
++}

];

window.onload+=+function()+{
++var+canvas+=+document.getElementById("chart-area");
++var+ctx+=+document.getElementById("chart-area").getContext("2d");
++window.myDoughnut+=+new+Chart(ctx).Doughnut(doughnutData,+{
++++responsive:+true,
++++onAnimationComplete:+addText
++});

};

var+myDoughnutChart+=+new+Chart(ctx).Doughnut(data);
var+myDoughnutChart+=+new+Chart(ctx).Doughnut(doughnutData,+{
++responsive:+true,
++onAnimationComplete:+addText
});


function+addText()+{

++var+canvas+=+document.getElementById("chart-area");
++var+ctx+=+document.getElementById("chart-area").getContext("2d");

++var+cx+=+canvas.width+/+2;
++var+cy+=+canvas.height+/+2;

++ctx.textAlign+=+'center';
++ctx.textBaseline+=+'middle';
++ctx.font+=+'14px+verdana';
++ctx.fillStyle+=+'black';
++ctx.fillText("Text+Here",+cx,+cy);

}|522874|body+{
++padding:+10px;
++margin:+0;
}
#canvas-holder+{
++width:+30%25;
}
canvas+{
++border:+1px+solid+red;
}|522875|<script+src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/1.0.1/Chart.min.js"></script>
<div+id="canvas-holder">
++<canvas+id="chart-area"+width="500"+height="500"+/>
</div>|522876|522877|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://developer.qcloudimg.com/http-save/yehe-900000/eff0d13a39de1d84bef47931b096508b.png|imageAlt^0|0|0|1|0|0|0|0|0|0|0|0|1C|J|0|0|0|L|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1L|8|@]|9|@$E|1M|F|1N|1|1O]]|A|$]]|$1|G|3|4|5|6|7|1P|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|1Q|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|1R|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|1S|8|@]|9|@]|A|$]]|$1|Q|3|R|5|L|7|1T|8|@]|9|@]|A|$M|N]]|$1|S|3|T|5|6|7|1U|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|1V|8|@$E|1W|F|1X|W|X]]|9|@]|A|$]]|$1|Y|3|Z|5|L|7|1Y|8|@]|9|@]|A|$M|N]]|$1|10|3|11|5|6|7|1Z|8|@$E|20|F|21|W|12]]|9|@]|A|$]]|$1|13|3|4|5|6|7|22|8|@]|9|@]|A|$]]|$1|14|3|15|5|L|7|23|8|@]|9|@]|A|$M|N]]|$1|16|3|17|5|L|7|24|8|@]|9|@]|A|$M|N]]|$1|18|3|19|5|L|7|25|8|@]|9|@]|A|$M|N]]|$1|1A|3|4|5|6|7|26|8|@]|9|@]|A|$]]|$1|1B|3|-4|5|6|7|27|8|@]|9|@]|A|$]]]|1C|$1D|$5|1E|1F|1G|A|$1H|1I|1J|-4]]]]

<p><img src="https://i.stack.imgur.com/yHvGm.png" alt="enter image description here"></p>

<p>The donut chart is centered in the canvas, so you can calculate the center of the donut like this:</p>

<pre><code>// get the canvas element and its context
var canvas = document.getElementById("myChart");
var ctx = canvas.getContext("2d");

// calculate the center of the canvas (cx,cy)
var cx=canvas.width/2;
var cy=canvas.height/2;
</code></pre>

<p>Then you can tell canvas to draw text vertically &amp; horizontally centered around cx,cy like this:</p>

<pre><code>// horizontally align text around the specified point (cx)
ctx.textAlign='center';

// vertically align text around the specified point (cy)
ctx.textBaseline='middle';

// draw the text
ctx.font='14px verdana';
ctx.fillStyle='black';
ctx.fillText("Text Here",cx,cy);
</code></pre>

<p>But you must wait for any animations to complete before drawing your centered text.</p>

<p>To do that you must tell ChartJS that you want a callback function triggered when it completes its animation. You can set the callback by setting the <code>onAnimationComplete</code> property of the chart options:</p>

<pre><code>var myDoughnutChart = new Chart(ctx).Doughnut(data, {
    responsive : true,

    // when ChartJS has completed all animations then call the addText function
    onAnimationComplete: addText
});
</code></pre>

<p><strong>Here's a demo putting it all together:</strong></p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="false" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>var doughnutData = [{
    value: 300,
    color: "#F7464A",
    highlight: "#FF5A5E",
    label: "Red"
  }, {
    value: 50,
    color: "#46BFBD",
    highlight: "#5AD3D1",
    label: "Green"
  }, {
    value: 100,
    color: "#FDB45C",
    highlight: "#FFC870",
    label: "Yellow"
  }, {
    value: 40,
    color: "#949FB1",
    highlight: "#A8B3C5",
    label: "Grey"
  }, {
    value: 120,
    color: "#4D5360",
    highlight: "#616774",
    label: "Dark Grey"
  }

];

window.onload = function() {
  var canvas = document.getElementById("chart-area");
  var ctx = document.getElementById("chart-area").getContext("2d");
  window.myDoughnut = new Chart(ctx).Doughnut(doughnutData, {
    responsive: true,
    onAnimationComplete: addText
  });

};

var myDoughnutChart = new Chart(ctx).Doughnut(data);
var myDoughnutChart = new Chart(ctx).Doughnut(doughnutData, {
  responsive: true,
  onAnimationComplete: addText
});


function addText() {

  var canvas = document.getElementById("chart-area");
  var ctx = document.getElementById("chart-area").getContext("2d");

  var cx = canvas.width / 2;
  var cy = canvas.height / 2;

  ctx.textAlign = 'center';
  ctx.textBaseline = 'middle';
  ctx.font = '14px verdana';
  ctx.fillStyle = 'black';
  ctx.fillText("Text Here", cx, cy);

}</code></pre>
<pre class="snippet-code-css lang-css prettyprint-override"><code>body {
  padding: 10px;
  margin: 0;
}
#canvas-holder {
  width: 30%;
}
canvas {
  border: 1px solid red;
}</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/1.0.1/Chart.min.js"&gt;&lt;/script&gt;
&lt;div id="canvas-holder"&gt;
  &lt;canvas id="chart-area" width="500" height="500" /&gt;
&lt;/div&gt;</code></pre>
</div>
</div>
</p>


blocks|key|522921|text|“绘制”方法为图表创建画布。在悬停时，调用绘图方法来重新创建图表并显示工具提示。文本消失是因为在API之外手动添加文本时，没有代码可以在绘制方法中显示文本。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|522922|您可以通过扩展图表来实现这一点。跟着文档来。|offset|length|522923|下面是在甜甜圈图中心添加总记录的示例。|blockquote|522924|Chart.defaults.derivedDoughnut+=+Chart.defaults.doughnut;
var+customDoughnut+=+Chart.controllers.doughnut.extend({
++draw:+function(ease)+{
++++Chart.controllers.doughnut.prototype.draw.apply(this,+[ease]);
++++var+width+=+this.chart.chart.width,
++++++height+=+this.chart.chart.height;
++++var+total+=+this.getMeta().total;
++++var+fontSize+=+(height+/+114).toFixed(2);
++++var+ctx+=+this.chart.chart.ctx;
++++ctx.font+=+fontSize+%2B+"em+Verdana";
++++ctx.textBaseline+=+"middle";
++++var+text+=+total,
++++++textX+=+Math.round((width+-+ctx.measureText(text).width)+/+2),
++++++textY+=+height+/+2;

++++ctx.fillText(text,+textX,+textY);
++}
});
Chart.controllers.derivedDoughnut+=+customDoughnut;|code-block|syntax|javascript|522925|示例：小提琴|522926|entityMap|0|LINK|mutability|MUTABLE|url|http://www.chartjs.org/docs/latest/developers/charts.html#extending-existing-chart-types|1|https://jsfiddle.net/imdebasis/f2q86npk^0|0|I|2|0|0|0|0|3|3|1|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|10|8|@]|9|@$D|11|E|12|1|13]]|A|$]]|$1|F|3|G|5|H|7|14|8|@]|9|@]|A|$]]|$1|I|3|J|5|K|7|15|8|@]|9|@]|A|$L|M]]|$1|N|3|O|5|6|7|16|8|@]|9|@$D|17|E|18|1|19]]|A|$]]|$1|P|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|Q|$R|$5|S|T|U|A|$V|W]]|X|$5|S|T|U|A|$V|Y]]]]

<p>Draw method creates the canvas for chart. On hover draw method is called to re-create the chart and show the tool-tip. Text disappears because there is no code to show text inside draw method as we are adding text manually outside of API. </p>

<p>You can achieve this by extending the chart. Follow <a href="http://www.chartjs.org/docs/latest/developers/charts.html#extending-existing-chart-types" rel="nofollow noreferrer">Docs</a> here.</p>

<blockquote>
  <p>Following is the example of adding total records at the centre of the
  doughnut chart.</p>
</blockquote>

<pre><code>Chart.defaults.derivedDoughnut = Chart.defaults.doughnut;
var customDoughnut = Chart.controllers.doughnut.extend({
  draw: function(ease) {
    Chart.controllers.doughnut.prototype.draw.apply(this, [ease]);
    var width = this.chart.chart.width,
      height = this.chart.chart.height;
    var total = this.getMeta().total;
    var fontSize = (height / 114).toFixed(2);
    var ctx = this.chart.chart.ctx;
    ctx.font = fontSize + "em Verdana";
    ctx.textBaseline = "middle";
    var text = total,
      textX = Math.round((width - ctx.measureText(text).width) / 2),
      textY = height / 2;

    ctx.fillText(text, textX, textY);
  }
});
Chart.controllers.derivedDoughnut = customDoughnut;
</code></pre>

<p>Example: <a href="https://jsfiddle.net/imdebasis/f2q86npk" rel="nofollow noreferrer">jsfiddle</a></p>


blocks|key|522950|text|纯css解决方案|type|unstyled|depth|inlineStyleRanges|entityRanges|data|522951|.overview-total+{
++position:+relative;

++.overview-num{
++++position:+absolute;
++++left:+50%25;
++++top:+50%25;
++++transform:+translate(-50%25,+-50%25);
++}
}|code-block|syntax|javascript|522952|Html|522953|<div+class="overview-total">
+++<span+class="overview-num">140</span>
+++<canvas+baseChart+class="chart-size"+width="300"+height="180"
++++++++++++++++++++++[plugins]="doughnutChartPluginsSo"
++++++++++++++++++++++[colors]="doughnutChartColorsSo"
++++++++++++++++++++++[data]="doughnutChartDataSo"
++++++++++++++++++++++[labels]="doughnutChartLabelsSo"
++++++++++++++++++++++[chartType]="doughnutChartTypeSo"
++++++++++++++++++++++[options]="doughnutChartOptionsSo"></canvas>
</div>|522954|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<p>A pure css solution</p>

<pre><code>.overview-total {
  position: relative;

  .overview-num{
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
  }
}
</code></pre>

<p>Html</p>

<pre><code>&lt;div class="overview-total"&gt;
   &lt;span class="overview-num"&gt;140&lt;/span&gt;
   &lt;canvas baseChart class="chart-size" width="300" height="180"
                      [plugins]="doughnutChartPluginsSo"
                      [colors]="doughnutChartColorsSo"
                      [data]="doughnutChartDataSo"
                      [labels]="doughnutChartLabelsSo"
                      [chartType]="doughnutChartTypeSo"
                      [options]="doughnutChartOptionsSo"&gt;&lt;/canvas&gt;
&lt;/div&gt;
</code></pre>


blocks|key|1820723|text|我认为接受的答案是行不通的，至少对我来说是这样。这是我的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1820724|let+canvas+=+document.getElementById('chart-area');
let+ctx+=+canvas.getContext('2d');
let+perc+=+25;

const+config+=+{
++++type:+'doughnut',
++++data:+{
++++++++datasets:+[{
++++++++++++data:+[
++++++++++++++++perc,
++++++++++++++++100-perc
++++++++++++],
++++++++++++backgroundColor:+[
++++++++++++++++window.chartColors.green,
++++++++++++++++window.chartColors.gray
++++++++++++]
++++++++}]
++++},
++++options:+{
++++++++responsive:+true,
++++++++animation:+{
++++++++++++animateScale:+true,
++++++++++++animateRotate:+true,
++++++++++++onComplete+:+function()+{
++++++++++++++++var+cx+=+canvas.width+/+2;
++++++++++++++++var+cy+=+canvas.height+/+2;
++++++++++++++++ctx.textAlign+=+'center';
++++++++++++++++ctx.textBaseline+=+'middle';
++++++++++++++++ctx.font+=+'16px+verdana';
++++++++++++++++ctx.fillStyle+=+'black';
++++++++++++++++ctx.fillText(perc%2B"%25",+cx,+cy);
++++++++++++}
++++++++},
++++}
};

new+Chart(ctx,+config);|code-block|syntax|javascript|1820725|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

<p>I think the accepted answer does not work, at least for me. Here is my solution:</p>

<pre><code>let canvas = document.getElementById('chart-area');
let ctx = canvas.getContext('2d');
let perc = 25;

const config = {
    type: 'doughnut',
    data: {
        datasets: [{
            data: [
                perc,
                100-perc
            ],
            backgroundColor: [
                window.chartColors.green,
                window.chartColors.gray
            ]
        }]
    },
    options: {
        responsive: true,
        animation: {
            animateScale: true,
            animateRotate: true,
            onComplete : function() {
                var cx = canvas.width / 2;
                var cy = canvas.height / 2;
                ctx.textAlign = 'center';
                ctx.textBaseline = 'middle';
                ctx.font = '16px verdana';
                ctx.fillStyle = 'black';
                ctx.fillText(perc+"%", cx, cy);
            }
        },
    }
};

new Chart(ctx, config);
</code></pre>


<p>i'm, using charts.js librarie and would like to know how could I add some mark to the hole of a doughnut chart (sth like a percentage)- </p>

<p><img src="https://i.stack.imgur.com/NetDw.png" alt="enter image description here"></p>

<p>My js </p>

<pre><code> jQuery(document).ready(function(){

var data = [
            {
                value: 5,
                color:"#A1638C",
                highlight: "#BF7AAF",
                label: "Días Completados 1/21"
            },
            {
                value: 95,
                color: "#07659A",
                highlight: "#4190BA",
                label: "Días pendientes 20/21"
            },

        ]


 var ctx = jQuery("#myChart").get(0).getContext("2d");
 var myDoughnutChart = new Chart(ctx).Doughnut(data);





});
</code></pre>

<p>My canvas:</p>

<pre><code>&lt;canvas id="myChart" width="264px"&gt;&lt;/canvas&gt;
</code></pre>


Inserting percentage charts.js doughnut

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在使用charts.js图书馆，我想知道我怎样才能在甜甜圈图的孔上加上一些标记(比如百分比)-​​我的js jQuery(document).ready(function(){var data = [            {                value: 5,                colo...

问插入率charts.js甜甜圈
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