---
title: CanvasRenderingContext2D.miterLimit
slug: Web/API/CanvasRenderingContext2D/miterLimit
translation_of: Web/API/CanvasRenderingContext2D/miterLimit
---
<div>{{APIRef}}</div>

<p>The <code><strong>CanvasRenderingContext2D.miterLimit</strong></code> 是 Canvas 2D API 设置斜接面限制比例的属性。 当获取属性值时， 会返回当前的值（默认值是<code>10.0</code> ）。当给属性赋值时， 0、负数、 {{jsxref("Infinity")}} 和 {{jsxref("NaN")}} 都会被忽略；除此之外都会被赋予一个新值。</p>

<p>参见 <a href="/en-US/docs/Web/API/Canvas_API/Tutorial">Canvas Tutorial</a> 中的 <a href="/en-US/docs/Web/API/Canvas_API/Tutorial/Applying_styles_and_colors">Applying styles and color</a> 章节。</p>

<h2 id="语法">语法</h2>

<pre class="syntaxbox"><var><em>ctx</em>.miterLimit = value;</var></pre>

<h3 id="选项">选项</h3>

<dl>
 <dt><code>value</code></dt>
 <dd>斜接面限制比例的的数字。 0、负数、{{jsxref("Infinity")}} 和 {{jsxref("NaN")}} 都会被忽略。</dd>
</dl>

<h2 id="简释">简释</h2>

<pre>ctx.lineJoin = "miter"  // "miter" &gt;   "round" )   "bevel" ]  </pre>

<p>只有当 lineJoin 显示为 "&gt;"  时，miterLimit 才有效。边角的角度越小，斜接长度就会越大。为了避免斜接长度过长，我们可以使用 miterLimit 属性。如果斜接长度超过 miterLimit 的值，边角会以 lineJoin 的 " ] " 类型来显示</p>

<h2 id="示例">示例</h2>

<h3 id="Using_the_lineWidth_property" name="Using_the_lineWidth_property">使用 <code>miterLimit</code> 属性</h3>

<p>查看 <a href="/en-US/docs/Web/API/Canvas_API/Tutorial">Canvas Tutorial</a> 中的 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Applying_styles_and_colors#A_demo_of_the_miterLimit_property">Applying styles and color</a> 章节，获取更多信息。</p>

<div class="hidden">
<h6 id="Playable_code" name="Playable_code">Playable code</h6>

<pre class="brush: html">&lt;canvas id="canvas" width="400" height="200" class="playable-canvas"&gt;&lt;/canvas&gt;
&lt;div class="playable-buttons"&gt;
  &lt;input id="edit" type="button" value="Edit" /&gt;
  &lt;input id="reset" type="button" value="Reset" /&gt;
&lt;/div&gt;
&lt;textarea id="code" class="playable-code"&gt;
ctx.beginPath();
ctx.moveTo(0,0);
ctx.lineWidth = 15;
ctx.lineTo(100, 100);
ctx.stroke();&lt;/textarea&gt;
</pre>

<pre class="brush: js">var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var textarea = document.getElementById("code");
var reset = document.getElementById("reset");
var edit = document.getElementById("edit");
var code = textarea.value;

function drawCanvas() {
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  eval(textarea.value);
}

reset.addEventListener("click", function() {
  textarea.value = code;
  drawCanvas();
});

edit.addEventListener("click", function() {
  textarea.focus();
})

textarea.addEventListener("input", drawCanvas);
window.addEventListener("load", drawCanvas);
</pre>
</div>

<p>{{EmbedLiveSample("A_demo_of_the_miterLimit_property", "400", "180", "https://mdn.mozillademos.org/files/240/Canvas_miterlimit.png", "Web/API/Canvas_API/Tutorial/Applying_styles_and_colors")}}</p>

<h2 id="规范描述">规范描述</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('HTML WHATWG', "scripting.html#dom-context-2d-miterlimit", "CanvasRenderingContext2D.miterLimit")}}</td>
   <td>{{Spec2('HTML WHATWG')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<p>{{CompatibilityTable}}</p>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Chrome for Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<h3 id="WebKitBlink-specific_注解">WebKit/Blink-specific 注解</h3>

<ul>
 <li>在基与 WebKit- 和 Blink- 的浏览器中，除了此属性外，还实现了一个不标准的并且不赞成使用的方法 <code>ctx.setMiterLimit()</code> 。</li>
</ul>

<h3 id="Gecko-specific_注解">Gecko-specific 注解</h3>

<ul>
 <li>从 Gecko 2.0 {{geckoRelease("2.0")}}版本开始， 给 <code>miterLimit</code> 设置负数不再抛出异常，所有的非正数都会被忽略。</li>
</ul>

<h2 id="参见">参见</h2>

<ul>
 <li>接口定义， {{domxref("CanvasRenderingContext2D")}}</li>
 <li>{{domxref("CanvasRenderingContext2D.lineCap")}}</li>
 <li>{{domxref("CanvasRenderingContext2D.lineJoin")}}</li>
</ul>