---
title: CanvasRenderingContext2D.bezierCurveTo()
slug: Web/API/CanvasRenderingContext2D/bezierCurveTo
tags:
  - API
  - Canvas
  - CanvasRenderingContext2D
  - Method
  - Reference
translation_of: Web/API/CanvasRenderingContext2D/bezierCurveTo
---
<div>{{APIRef}}</div>

<p><code><strong>CanvasRenderingContext2D</strong></code><strong><code>.bezierCurveTo()</code></strong> 是 Canvas 2D API 绘制三次贝赛尔曲线路径的方法。 该方法需要三个点。 第一、第二个点是控制点,第三个点是结束点。起始点是当前路径的最后一个点,绘制贝赛尔曲线前,可以通过调用 <code>moveTo()</code> 进行修改。</p>

<h2 id="语法">语法</h2>

<pre class="syntaxbox">void <var><em>ctx</em>.bezierCurveTo(cp1x, cp1y, cp2x, cp2y, x, y);</var>
</pre>

<h3 id="参数">参数</h3>

<dl>
 <dt><code>cp1x</code></dt>
 <dd>第一个控制点的 x 轴坐标。</dd>
 <dt><code>cp1y</code></dt>
 <dd>第一个控制点的 y 轴坐标。</dd>
 <dt><code>cp2x</code></dt>
 <dd>第二个控制点的 x 轴坐标。</dd>
 <dt><code>cp2y</code></dt>
 <dd>第二个控制点的 y 轴坐标。</dd>
 <dt><code>x</code></dt>
 <dd>结束点的 x 轴坐标。</dd>
 <dt><code>y</code></dt>
 <dd>结束点的 y 轴坐标。</dd>
</dl>

<h2 id="示例">示例</h2>

<h3 id="使用_bezierCurveTo_方法">使用 <code>bezierCurveTo</code> 方法</h3>

<p>这是一段绘制贝赛尔曲线的简单的代码片段。  <span style="color: red;">控制点是红色的</span>,<span style="color: blue;"> 开始和结束点是蓝色的。</span></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:[6]">var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");

ctx.beginPath();
ctx.moveTo(50,20);
ctx.bezierCurveTo(230, 30, 150, 60, 50, 100);
ctx.stroke();

ctx.fillStyle = 'blue';
// start point
ctx.fillRect(50, 20, 10, 10);
// end point
ctx.fillRect(50, 100, 10, 10);

ctx.fillStyle = 'red';
// control point one
ctx.fillRect(230, 30, 10, 10);
// control point two
ctx.fillRect(150, 70, 10, 10);</pre>

<p>{{ EmbedLiveSample('使用_bezierCurveTo_方法', 315, 165) }}</p>

<h3 id="尝试_bezierCurveTo_参数">尝试 <code>bezierCurveTo</code> 参数</h3>

<p>修改下面的代码并在线查看 canvas 的变化:</p>

<div class="hidden">
<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.beginPath();
ctx.bezierCurveTo(50, 100, 180, 10, 20, 10);
ctx.stroke();&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('尝试_bezierCurveTo_参数', 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-beziercurveto", "CanvasRenderingContext2D.beziercurveto")}}</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>

{{Compat("api.CanvasRenderingContext2D.bezierCurveTo")}}

<h2 id="参见">参见</h2>

<ul>
 <li>接口定义, {{domxref("CanvasRenderingContext2D")}}</li>
 <li><a href="http://en.wikipedia.org/wiki/B%C3%A9zier_curve">维基百科关于贝赛尔曲线</a>。</li>
</ul>