--- title: CanvasRenderingContext2D.clip() slug: Web/API/CanvasRenderingContext2D/clip translation_of: Web/API/CanvasRenderingContext2D/clip ---
{{APIRef}}

CanvasRenderingContext2D.clip() 是 Canvas 2D API 将当前创建的路径设置为当前剪切路径的方法。

语法

void ctx.clip();
void ctx.clip(fillRule);
void ctx.clip(path, fillRule);

参数

fillRule
这个算法判断一个点是在路径内还是在路径外。
允许的值：
path
需要剪切的 {{domxref("Path2D")}} 路径。

示例

使用 clip 方法

这是一段简单的代码片段，使用 clip 方法创建剪切区域。

HTML

<canvas id="canvas"></canvas>

JavaScript

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");

// Create clipping region
ctx.arc(100, 100, 75, 0, Math.PI*2, false);
ctx.clip();

ctx.fillRect(0, 0, 100,100);

修改下面的代码并在线查看 canvas 的变化：

Playable code
<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.arc(100, 100, 75, 0, Math.PI*2, false);
ctx.clip();
ctx.fillRect(0, 0, 100,100);</textarea>

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);

{{ EmbedLiveSample('Playable_code', 700, 360) }}

规范描述

Specification Status Comment
{{SpecName('HTML WHATWG', "scripting.html#dom-context-2d-clip", "CanvasRenderingContext2D.clip")}} {{Spec2('HTML WHATWG')}}  

浏览器兼容性

{{CompatibilityTable}}

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}}
Path parameter {{CompatUnknown}} {{ CompatGeckoDesktop(31) }} {{ CompatNo }} {{CompatUnknown}} {{ CompatNo }}
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}}
Path parameter {{CompatUnknown}} {{CompatUnknown}} {{ CompatGeckoMobile(31) }} {{CompatUnknown}} {{CompatUnknown}} {{CompatUnknown}}

参见