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CanvasRenderingContext2D.restore()

跳转到：
  1. 语法
  2. 示例
  3. 规范描述
  4. 浏览器兼容性
  5. 参见

CanvasRenderingContext2D.restore() 是 Canvas 2D API 通过在绘图状态栈中弹出顶端的状态，将 canvas 恢复到最近的保存状态的方法。 如果没有保存状态，此方法不做任何改变。

语法

void ctx.restore();

更多关于 drawing state 的信息， 请看 CanvasRenderingContext2D.save()。

示例

使用 restore 方法

这是一段简单的代码片段，使用 save() 方法保存默认的状态，使用 restore() 进行恢复。 所以，稍后你可以使用默认的状态绘制一个矩形。

HTML

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

JavaScript

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

ctx.save(); // save the default state

ctx.fillStyle = "green";
ctx.fillRect(10, 10, 100, 100);

ctx.restore(); // restore to the default state
ctx.fillRect(150, 75, 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.save();
ctx.fillStyle = "green";
ctx.fillRect(10, 10, 100, 100);
ctx.restore();
ctx.fillRect(150, 75, 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);

规范描述

Specification Status Comment
HTML Living Standard
CanvasRenderingContext2D.restore		 Living Standard  

浏览器兼容性

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

参见

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