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---
title: CanvasGradient.addColorStop()
slug: Web/API/CanvasGradient/addColorStop
translation_of: Web/API/CanvasGradient/addColorStop
---
<div>{{APIRef("Canvas")}}</div>
<p><code><strong>CanvasGradient</strong></code><strong><code>.addColorStop()</code></strong> 方法添加一个由<strong><code>偏移值</code></strong>和<strong><code>颜色值</code></strong>指定的断点到渐变。如果偏移值不在<code>0</code>到<code>1</code>之间，将抛出<code>INDEX_SIZE_ERR</code>错误，如果颜色值不能被解析为有效的CSS颜色值 {{cssxref("<color>")}}，将抛出<code>SYNTAX_ERR</code>错误。</p>
<h2 id="语法">语法</h2>
<pre class="syntaxbox">void <var><em>gradient</em>.addColorStop(offset, color);</var>
</pre>
<h3 id="参数">参数</h3>
<dl>
<dt>offset</dt>
<dd><code>0</code>到<code>1</code>之间的值，超出范围将抛出<code>INDEX_SIZE_ERR</code>错误</dd>
<dt>color</dt>
<dd>CSS颜色值 {{cssxref("<color>")}}。如果颜色值不能被解析为有效的CSS颜色值 <code><color></code>，将抛出<code>SYNTAX_ERR</code>错误。</dd>
</dl>
<h2 id="示例">示例</h2>
<h3 id="使用addColorStop方法">使用<code>addColorStop</code>方法</h3>
<p>一个使用{{domxref("CanvasGradient")}}对象的<code>addColorStop</code> 方法的简单例子</p>
<h4 id="HTML">HTML</h4>
<pre class="brush: html"> <canvas id="canvas"></canvas></pre>
<h4 id="JavaScript">JavaScript</h4>
<pre class="brush: js; highlight:[5,6]">var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var gradient = ctx.createLinearGradient(0,0,200,0);
gradient.addColorStop(0,"green");
gradient.addColorStop(1,"white");
ctx.fillStyle = gradient;
ctx.fillRect(10,10,200,100);
</pre>
<p>编辑以下代码可看到画布变化:</p>
<div class="hidden">
<h6 id="Playable_code">Playable code</h6>
<pre class="brush: html"><canvas id="canvas" width="400" height="200" class="playable-canvas"></canvas>
<div class="playable-buttons">
<input id="edit" type="button" value="Edit" />
<input id="reset" type="button" value="Reset" />
</div>
<textarea id="code" class="playable-code">
var gradient = ctx.createLinearGradient(0,0,200,0);
gradient.addColorStop(0,"green");
gradient.addColorStop(1,"white");
ctx.fillStyle = gradient;
ctx.fillRect(10,10,200,100);</textarea>
</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="标准">标准</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">标准</th>
<th scope="col">状态</th>
<th scope="col">备注</th>
</tr>
<tr>
<td>{{SpecName('HTML WHATWG', "scripting.html#dom-canvasgradient-addcolorstop", "CanvasGradient.addColorStop")}}</td>
<td>{{Spec2('HTML WHATWG')}}</td>
<td> </td>
</tr>
<tr>
<td>{{SpecName('HTML Canvas 2D Context W3C', "#dom-canvasgradient-addcolorstop", "CanvasGradient.addColorStop")}}</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>
{{Compat("api.CanvasGradient.addColorStop")}}
<h2 id="请参阅">请参阅</h2>
<ul>
<li>接口定义 {{domxref("CanvasGradient")}}</li>
<li>{{domxref("CanvasRenderingContext2D.createLinearGradient()")}}</li>
<li>{{domxref("CanvasRenderingContext2D.createRadialGradient()")}}</li>
</ul>
|
