--- 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"><canvas id="canvas"></canvas> </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"><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"> ctx.beginPath(); ctx.bezierCurveTo(50, 100, 180, 10, 20, 10); ctx.stroke();</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('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>