原文：http://blog.csdn.net/jia20003/article/details/17172571
很多购物网站现在都支持360实物全景图像，可以360度任意选择查看样品，这样
对购买者来说是一个很好的消费体验，网上有很多这样的插件都是基于jQuery实现的
有收费的也有免费的，其实很好用的一个叫3deye.js的插件。该插件支持桌面与移动终
端iOS与Android， 它的demo程序：http://www.voidcanvas.com/demo/28823deye/
自己玩了玩这个Demo以后，照着它的思路，用HTML5 Canvas也实现了类似的功能。
所以先说一下它的360度全景图的原理
1. 首先需要对实物拍照，间隔是每张照片旋转15度，所以需要23张照片。
2. 照片准备好了以后，尽量选择JPG格式，裁剪到适当大小。
3. <a href="https://img.zhankr.net/ke40e4u1mgx38328.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 onclick=”loaded()”>Auto Play</button>
</body>
</html>
Demo演示文件下载地址->http://download.csdn.net/detail/jia20003/6670901
