HTML5 Canvas實(shí)現(xiàn)360度全景圖

發(fā)布時(shí)間：2020-07-22 12:15:07 來源：網(wǎng)絡(luò) 閱讀：799 作者：gloomyfish 欄目：移動(dòng)開發(fā)

很多購物網(wǎng)站現(xiàn)在都支持360實(shí)物全景圖像，可以360度任意選擇查看樣品，這樣

對(duì)購買者來說是一個(gè)很好的消費(fèi)體驗(yàn)，網(wǎng)上有很多這樣的插件都是基于JQuery實(shí)現(xiàn)的

有收費(fèi)的也有免費(fèi)的，其實(shí)很好用的一個(gè)叫3deye.js的插件。該插件支持桌面與移動(dòng)終

端iOS與Android，它的demo程序：http://www.voidcanvas.com/demo/28823deye/

自己玩了玩這個(gè)Demo以后，照著它的思路，用HTML5 Canvas也實(shí)現(xiàn)了類似的功能。

所以先說一下它的360度全景圖的原理

1. 首先需要對(duì)實(shí)物拍照，間隔是每張照片旋轉(zhuǎn)15度，所以需要23張照片。

2. 照片準(zhǔn)備好了以后，盡量選擇JPG格式，裁剪到適當(dāng)大小。

3. JAVASCRIPT中預(yù)加載所有照片，可以配合進(jìn)度條顯示加載精度

4. 創(chuàng)建/獲取Canvas對(duì)象，加上鼠標(biāo)監(jiān)聽事件，當(dāng)鼠標(biāo)左右移動(dòng)時(shí)候，適度的繪制不

同幀。大致的原理就是這樣，簡(jiǎn)單吧！

實(shí)現(xiàn)代碼：

<!DOCTYPE html> <html> <head>   <meta charset=utf-8">   <title>Full 360 degree View</title>   <script> 		var ctx = null; // global variable 2d context 		var frame = 1; // 23 		var width = 0; 		var height = 0; 		var started = false; 		var images = new Array(); 		var startedX = -1; 	  window.onload = function() { 		var canvas = document.getElementById("fullview_canvas"); 		canvas.width = 440;// window.innerWidth; 		canvas.height = 691;//window.innerHeight; 		width = canvas.width; 		height = canvas.height; 		var bar = document.getElementById('loadProgressBar'); 		for(var i=1; i<24; i++) 		{ 			bar.value = i; 			if(i<10) 			{ 				images[i] = new Image(); 				images[i].src = "0" + i + ".jpg"; 			} 			else  			{ 				images[i] = new Image(); 				images[i].src = i + ".jpg"; 			} 		} 		ctx = canvas.getContext("2d"); 		 		// mouse event 		canvas.addEventListener("mousedown", doMouseDown, false); 		canvas.addEventListener('mousemove', doMouseMove, false); 		canvas.addEventListener('mouseup',   doMouseUp, false); 		// loaded(); 		 		// frame = 1 		frame = 1; 		images[frame].onload = function() { 			redraw(); 			bar.style.display = 'none'; 		} 	} 	function doMouseDown(event) { 		var x = event.pageX; 		var y = event.pageY; 		var canvas = event.target; 		var loc = getPointOnCanvas(canvas, x, y); 		console.log("mouse down at point( x:" + loc.x + ", y:" + loc.y + ")"); 		startedX = loc.x; 		started = true; 	} 	 	function doMouseMove(event) { 		var x = event.pageX; 		var y = event.pageY; 		var canvas = event.target; 		var loc = getPointOnCanvas(canvas, x, y); 		if (started) { 			var count = Math.floor(Math.abs((startedX - loc.x)/30)); 			var frameIndex = Math.floor((startedX - loc.x)/30); 			while(count > 0) 			{				 				console.log("frameIndex = " + frameIndex); 				count--;	 				if(frameIndex > 0) 				{ 					frameIndex--; 					frame++; 				} else if(frameIndex < 0) 				{ 					frameIndex++; 					frame--; 				} 				else if(frameIndex == 0) 				{ 					break; 				} 								 				if(frame >= 24) 				{ 					frame = 1; 				} 				if(frame <= 0) 				{ 					frame = 23; 				} 				redraw(); 			} 		} 	} 	 	function doMouseUp(event) { 		console.log("mouse up now"); 		if (started) { 			doMouseMove(event); 			startedX = -1; 			started = false; 		} 	}  	function getPointOnCanvas(canvas, x, y) { 		var bbox = canvas.getBoundingClientRect(); 		return { x: x - bbox.left * (canvas.width  / bbox.width), 				y: y - bbox.top  * (canvas.height / bbox.height) 				}; 	} 	 	function loaded() { 		setTimeout( update, 1000/8); 	} 	function redraw() 	{ 		// var imageObj = document.createElement("img"); 		// var imageObj = new Image(); 		var imageObj = images[frame]; 		ctx.clearRect(0, 0, width, height) 		ctx.drawImage(imageObj, 0, 0, width, height); 	} 	function update() { 		redraw(); 		frame++; 		if (frame >= 23) frame = 1; 		setTimeout( update, 1000/8); 	}   </script> </head> <body> <progress id="loadProgressBar" value="0" max="23"></progress>  <canvas id="fullview_canvas"></canvas> <button  Play</button> </body> </html>

Demo演示文件下載地址->http://download.csdn.net/detail/jia20003/6670901

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HTML5 Canvas實(shí)現(xiàn)360度全景圖

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