path: root/files/zh-cn/web/api/canvasrenderingcontext2d/createpattern/index.html

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

<p><code><strong>CanvasRenderingContext2D</strong></code><strong><code>.createPattern() </code></strong>是 Canvas 2D API 使用指定的图像 ({{domxref("CanvasImageSource")}})创建模式的方法。 它通过repetition参数在指定的方向上重复元图像。此方法返回一个{{domxref("CanvasPattern")}}对象。</p>

<h2 id="语法">语法</h2>

<pre class="syntaxbox">CanvasPattern <var><em>ctx</em>.createPattern(image, repetition);</var>
</pre>

<h3 id="参数">参数</h3>

<dl>
 <dt><code>image</code></dt>
 <dd>作为重复图像源的 {{domxref("CanvasImageSource")}} 对象。可以是下列之一：
 <ul>
  <li>{{domxref("HTMLImageElement")}} ({{HTMLElement("img")}}),</li>
  <li>{{domxref("HTMLVideoElement")}} ({{HTMLElement("video")}}),</li>
  <li>{{domxref("HTMLCanvasElement")}} ({{HTMLElement("canvas")}}),</li>
  <li>{{domxref("CanvasRenderingContext2D")}},</li>
  <li>{{domxref("ImageBitmap")}},</li>
  <li>{{domxref("ImageData")}},</li>
  <li>{{domxref("Blob")}}.</li>
 </ul>
 </dd>
 <dt><code>repetition</code></dt>
 <dd>{{domxref("DOMString")}}，指定如何重复图像。允许的值有：
 <ul>
  <li><code>"repeat"</code> (both directions),</li>
  <li><code>"repeat-x"</code> (horizontal only),</li>
  <li><code>"repeat-y"</code> (vertical only), </li>
  <li><code>"no-repeat"</code> (neither).</li>
 </ul>
 如果为空字符串 (<code>''</code>) 或 {{jsxref("null")}} (但不是 {{jsxref("undefined")}})，repetition将被当作"repeat"。</dd>
</dl>

<h3 id="返回值">返回值</h3>

<dl>
 <dt>{{domxref("CanvasPattern")}}</dt>
 <dd>描述模式的不透明对象</dd>
</dl>

<h2 id="示例">示例</h2>

<h3 id="使用createPattern方法">使用<code>createPattern</code>方法</h3>

<p>这是一段简单的代码片段，使用 <span style="font-family: consolas,monaco,andale mono,monospace;">createPattern 方法创建一个指定图像和重复的</span>{{domxref("CanvasPattern")}} 对象。创建完成后，可以使用{{domxref("CanvasPattern.setTransform()")}}方法对图案进行变形。如示例所示，你可以把此模式赋值给当前的{{domxref("CanvasRenderingContext2D.fillStyle", "fillStyle")}}，当你使用{{domxref("CanvasRenderingContext2D.fillRect", "fillRect()")}} 方法时，会在 canvas 上绘制出效果。</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:[7]">var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");

var img = new Image();
img.src = 'https://mdn.mozillademos.org/files/222/Canvas_createpattern.png';
img.onload = function() {
  var pattern = ctx.createPattern(img, 'repeat');
  ctx.fillStyle = pattern;
  ctx.fillRect(0,0,400,400);
};
</pre>

<p>编辑以下代码并在线查看canvas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" style="height:120px"&gt;
var img = new Image();
img.src = 'https://mdn.mozillademos.org/files/222/Canvas_createpattern.png';
img.onload = function() {
  var pattern = ctx.createPattern(img, 'repeat');
  ctx.fillStyle = pattern;
  ctx.fillRect(0,0,400,400);
};&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, 380) }}</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-createpattern", "CanvasRenderingContext2D.createPattern")}}</td>
   <td>{{Spec2('HTML WHATWG')}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName('HTML Canvas 2D Context W3C', "#dom-context-2d-createpattern", "CanvasRenderingContext2D.createPattern")}}</td>
   <td>{{Spec2('HTML5 W3C')}}</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("CanvasPattern")}}</li>
</ul>