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

<p><code><strong>CanvasRenderingContext2D</strong></code><strong><code>.shadowOffsetX</code></strong> 是 Canvas 2D API 描述阴影水平偏移距离的属性。</p>

<h2 id="Syntax">Syntax</h2>

<pre class="syntaxbox"><var><em>ctx</em>.shadowOffsetX = offset;</var>
</pre>

<dl>
 <dt><code>offset</code></dt>
 <dd>阴影水平偏移距离的float类型的值。默认值是 0。  {{jsxref("Infinity")}} 或者{{jsxref("NaN")}}都会被忽略。</dd>
</dl>

<h2 id="示例">示例</h2>

<h3 id="Using_the_shadowOffsetX_property" name="Using_the_shadowOffsetX_property">使用 <code>shadowOffsetX</code> 属性</h3>

<p>这是一段简单的代码片段，使用 <code>shadowOffsetX</code> 属性设置阴影的水平偏移量。注意：将shadowColor属性设置成不透明，阴影才会被绘制。</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">var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");

ctx.shadowColor = "black";
ctx.shadowOffsetX = 10;
ctx.shadowBlur = 10;

ctx.fillStyle = "green";
ctx.fillRect(10, 10, 100, 100);
</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" 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.shadowColor = "black";
ctx.shadowOffsetX = 10;
ctx.shadowBlur = 10;
ctx.fillStyle = "green";
ctx.fillRect(10, 10, 100, 100);&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-shadowoffsetx", "CanvasRenderingContext2D.shadowOffsetX")}}</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.shadowOffsetY")}}</li>
 <li>{{domxref("CanvasRenderingContext2D.shadowColor")}}</li>
 <li>{{domxref("CanvasRenderingContext2D.shadowBlur")}}</li>
</ul>