From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:40:17 -0500 Subject: initial commit --- .../canvasrenderingcontext2d/restore/index.html | 161 +++++++++++++++++++++ 1 file changed, 161 insertions(+) create mode 100644 files/zh-cn/web/api/canvasrenderingcontext2d/restore/index.html (limited to 'files/zh-cn/web/api/canvasrenderingcontext2d/restore/index.html') diff --git a/files/zh-cn/web/api/canvasrenderingcontext2d/restore/index.html b/files/zh-cn/web/api/canvasrenderingcontext2d/restore/index.html new file mode 100644 index 0000000000..c35d6ce849 --- /dev/null +++ b/files/zh-cn/web/api/canvasrenderingcontext2d/restore/index.html @@ -0,0 +1,161 @@ +--- +title: CanvasRenderingContext2D.restore() +slug: Web/API/CanvasRenderingContext2D/restore +translation_of: Web/API/CanvasRenderingContext2D/restore +--- +
{{APIRef}}
+ +

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 {{domxref("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);
+
+
+ +

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

+ +

规范描述

+ + + + + + + + + + + + + + +
SpecificationStatusComment
{{SpecName('HTML WHATWG', "scripting.html#dom-context-2d-restore", "CanvasRenderingContext2D.restore")}}{{Spec2('HTML WHATWG')}} 
+ +

浏览器兼容性

+ +

{{CompatibilityTable}}

+ +
+ + + + + + + + + + + + + + + + + + + +
FeatureChromeFirefox (Gecko)Internet ExplorerOperaSafari
Basic support{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}
+
+ +
+ + + + + + + + + + + + + + + + + + + + + +
FeatureAndroidChrome for AndroidFirefox Mobile (Gecko)IE MobileOpera MobileSafari Mobile
Basic support{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}
+
+ +

参见

+ + -- cgit v1.2.3-54-g00ecf