使用JS和canvas實現gif動圖的停止和播放代碼

<img id="testImg" src="xxx.gif" width="224" height="126">
<p><input type="button" id="testBtn" value="停止"></p>

if ('getContext' in document.createElement('canvas')) {
 HTMLImageElement.prototype.play = function() {
 if (this.storeCanvas) {
 // 移除存儲的canvas
 this.storeCanvas.parentElement.removeChild(this.storeCanvas);
 this.storeCanvas = null;
 // 透明度還原
 image.style.opacity = '';
 }
 if (this.storeUrl) {
 this.src = this.storeUrl; 
 }
 };
 HTMLImageElement.prototype.stop = function() {
 var canvas = document.createElement('canvas');
 // 尺寸
 var width = this.width, height = this.height;
 if (width && height) {
 // 存儲之前的地址
 if (!this.storeUrl) {
 this.storeUrl = this.src;
 }
 // canvas大小
 canvas.width = width;
 canvas.height = height;
 // 繪制圖片幀（第一幀）
 canvas.getContext('2d').drawImage(this, 0, 0, width, height);
 // 重置當前圖片
 try {
 this.src = canvas.toDataURL("image/gif");
 } catch(e) {
 // 跨域
 this.removeAttribute('src');
 // 載入canvas元素
 canvas.style.position = 'absolute';
 // 前面插入圖片
 this.parentElement.insertBefore(canvas, this);
 // 隱藏原圖
 this.style.opacity = '0';
 // 存儲canvas
 this.storeCanvas = canvas;
 }
 }
 };
}
 
var image = document.getElementById("testImg"), 
 button = document.getElementById("testBtn");
 
if (image && button) {
 button.onclick = function() {
 if (this.value == '停止') {
 image.stop();
 this.value = '播放';
 } else {
 image.play();
 this.value = '停止';
 }
 };
}