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

<p><code><strong>CanvasRenderingContext2D</strong></code><strong><code>.rect()</code></strong> 是 Canvas 2D API 创建矩形路径的方法，矩形的起点位置是 <em>(x, y) </em>，尺寸为 <em>width</em> 和 <em>height</em>。矩形的4个点通过直线连接，子路径做为闭合的标记，所以你可以填充或者描边矩形。</p>

<h2 id="语法">语法</h2>

<pre class="syntaxbox">void <var><em>ctx</em>.rect(x, y, width, height);</var>
</pre>

<h3 id="参数">参数</h3>

<dl>
 <dt><code>x</code></dt>
 <dd>矩形起点的 x 轴坐标。</dd>
 <dt><code>y</code></dt>
 <dd>矩形起点的 y 轴坐标。</dd>
 <dt><code>width</code></dt>
 <dd>矩形的宽度。</dd>
 <dt><code>height</code></dt>
 <dd>矩形的高度。</dd>
</dl>

<h2 id="示例">示例</h2>

<h3 id="使用_rect_方法">使用 <code>rect</code> 方法</h3>

<p>这是一段简单的代码片段，使用 <code>rect </code>方法创建一条路径。 实际上，在 canvas 中绘制矩形路径， 你可以使用 {{domxref("CanvasRenderingContext2D.fill", "fill()")}} 或者 {{domxref("CanvasRenderingContext2D.stroke", "stroke()")}} 方法。 参见 {{domxref("CanvasRenderingContext2D.fillRect", "fillRect()")}} 和{{domxref("CanvasRenderingContext2D.strokeRect", "strokeRect()")}} 方法， 只需一步即可绘制。</p>

<h4 id="HTML">HTML</h4>

<pre class="brush: html">&lt;canvas id="canvas"&gt;&lt;/canvas&gt;
</pre>

<h4 id="JavaScript">JavaScript</h4>

<pre class="brush: js; highlight:[3]">var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
ctx.rect(10, 10, 100, 100);
ctx.fill();
</pre>

<p>修改下面的代码并在线查看 canvas 的变化：</p>

<div class="hidden">
<h6 id="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.rect(10, 10, 100, 100);
ctx.fill();&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('Playable_code', 700, 360) }}</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-rect", "CanvasRenderingContext2D.rect")}}</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>

<h2 id="参见">参见</h2>

<ul>
 <li>接口定义， {{domxref("CanvasRenderingContext2D")}}</li>
 <li>{{domxref("CanvasRenderingContext2D.fillRect")}}</li>
 <li>{{domxref("CanvasRenderingContext2D.strokeRect()")}}</li>
 <li>{{domxref("CanvasRenderingContext2D.fill()")}}</li>
 <li>{{domxref("CanvasRenderingContext2D.stroke()")}}</li>
</ul>