Revision 830557 of <canvas>

<h2 id="Summary">Summary</h2>

<p><span style="background-color:rgb(250, 250, 250); color:rgb(43, 43, 43); font-family:arial,sans-serif">HTML &lt;帆布&gt;元素可以用来绘制图形通过脚本(通常JavaScript)。例如,它可以被用来绘制图形,使摄影作品,甚至执行动画。你可以(也应该)在&lt;帆布&gt;块提供替代内容。内容就会呈现在旧的浏览器不支持画布和浏览器禁用了JavaScript。</span></p>

<p>For more articles on canvas, see the <a href="/en-US/docs/HTML/Canvas" title="HTML/Canvas">canvas topic page</a>.</p>

<ul class="htmlelt">
 <li><dfn><a href="/en-US/docs/HTML/Content_categories" title="HTML/Content_categories">Content categories</a></dfn> <a href="/en-US/docs/HTML/Content_categories#Flow_content" title="HTML/Content categories#Flow content">Flow content</a>, <a href="/en-US/docs/HTML/Content_categories#Phrasing_content" title="HTML/Content categories#Phrasing content">phrasing content</a>, <a href="https://developer.mozilla.org/en-US/docs/HTML/Content_categories#Embedded_content" title="HTML/Content_categories#Embedded content">embedded content</a>, palpable content.</li>
 <li><dfn>Permitted content</dfn> Transparent but with no <a href="/en-US/docs/HTML/Content_categories#Interactive_content">interactive content</a> descendants except for {{HTMLElement("a")}} elements, {{HTMLElement("button")}} elements, {{HTMLElement("input")}} elements whose {{htmlattrxref("type", "input")}} attribute is <code>checkbox</code> or <code>radio</code>, and {{HTMLElement("input")}} elements whose {{htmlattrxref("type", "input")}} attribute is <code>button</code>.</li>
 <li><dfn>Tag omission</dfn> {{no_tag_omission}}</li>
 <li><dfn>Permitted parent elements</dfn> Any element that accepts <a href="/en-US/docs/HTML/Content_categories#Phrasing_content" title="HTML/Content_categories#Phrasing_content">phrasing_content</a>.</li>
 <li><dfn>DOM interface</dfn> {{domxref("HTMLCanvasElement")}}</li>
</ul>

<h2 id="Attributes">Attributes</h2>

<p><span style="line-height:21px">This element includes the&nbsp;</span><a href="https://developer.mozilla.org/en-US/docs/HTML/Global_attributes" style="line-height: 21px;" title="HTML/Global attributes">global attributes</a><span style="line-height:21px">.</span></p>

<dl>
 <dt>{{htmlattrdef("width")}}</dt>
 <dd>The width of the coordinate space in CSS pixels. Defaults to 300.</dd>
 <dt>{{htmlattrdef("height")}}</dt>
 <dd>The height of the coordinate space in CSS pixels. Defaults to 150.</dd>
</dl>

<p>{{Note("The displayed size of the canvas can be changed using a stylesheet. The image is scaled during rendering to fit the styled size.")}}</p>

<h2 id="Examples">Examples</h2>

<pre class="brush: html">
&lt;canvas id="canvas" width="300" height="300"&gt;
  Sorry, your browser doesn't support the &amp;lt;canvas&amp;gt; element.
&lt;/canvas&gt;
</pre>

<h2 id="Specifications" name="Specifications">Specifications</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{SpecName('HTML WHATWG', 'the-canvas-element.html#the-canvas-element', '&lt;canvas&gt;')}}</td>
   <td>{{Spec2('HTML WHATWG')}}</td>
   <td>&nbsp;</td>
  </tr>
  <tr>
   <td>{{SpecName('HTML5 W3C', 'the-canvas-element.html#the-canvas-element', '&lt;canvas&gt;')}}</td>
   <td>{{Spec2('HTML5 W3C')}}</td>
   <td>&nbsp;</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

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

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Firefox (Gecko)</th>
   <th>Chrome</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatGeckoDesktop("1.8")}}</td>
   <td>1.0</td>
   <td>9.0</td>
   <td><a href="https://www.opera.com/docs/changelogs/windows/900/">9.0</a></td>
   <td><a href="https://developer.apple.com/library/safari/#documentation/AudioVideo/Conceptual/HTML-canvas-guide/Introduction/Introduction.html">2.0</a></td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Android</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatGeckoMobile("1.8")}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>1.0</td>
  </tr>
 </tbody>
</table>
</div>

<h3 id="Browser-specific_notes">Browser-specific notes</h3>

<h4 id="Firefox_(Gecko)">Firefox (Gecko)</h4>

<ul>
 <li>Before Gecko 5.0 {{geckoRelease("5.0")}}, the canvas width and height were signed integers instead of unsigned integers.</li>
 <li>Prior to Gecko 6.0 {{geckoRelease("6.0")}}, a {{HTMLElement("canvas")}} element with a zero width or height would be rendered as if it had default dimensions.</li>
 <li>Before Gecko 12.0 {{geckoRelease("12.0")}}, if JavaScript is disabled, the <code>&lt;canvas&gt;</code> element was being rendered instead of showing the fallback content as per the <a href="https://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html">specification</a>. Now the fallback content is rendered instead.</li>
</ul>

<h2 id="See_also">See also</h2>

<ul>
 <li><a href="/en-US/docs/HTML/Canvas" title="https://developer.mozilla.org/en-US/docs/HTML/Canvas">MDN canvas portal</a></li>
 <li>A <a href="/en-US/docs/Canvas_tutorial" title="Canvas tutorial">canvas tutorial</a></li>
 <li><a href="https://blog.nihilogic.dk/2009/02/html5-canvas-cheat-sheet.html">Canvas cheat sheet</a></li>
 <li><a href="/en-US/demos/tag/tech:canvas" title="demos/tag/tech:canvas/">Canvas-related demos</a></li>
</ul>

<div>{{HTML:Element_Navigation}}</div>