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CanvasRenderingContext2D.save()

CanvasRenderingContext2D.save() 是 Canvas 2D API 通过将当前状态放入栈中,保存 canvas 全部状态的方法。

语法

void ctx.save();

绘制状态

保存到栈中的绘制状态有下面部分组成:

示例

使用 save 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,这样,稍后你就可以使用默认的设置绘制一个矩形。

HTML

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

JavaScript

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

ctx.save(); // 保存默认的状态

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

ctx.restore(); // 还原到上次保存的默认状态
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.save
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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