HTML5 Canvas实现360度全景图的示例代码

2024-09-05 07:22:21

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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.JavaScript中预加载所有照片，可以配合进度条显示加载精度
4.创建/获取Canvas对象，加上鼠标监听事件，当鼠标左右移动时候，适度的绘制不同帧。大致的原理就是这样，简单吧！

实现代码：

<!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 onclick="loaded()">Auto Play</button>  </body>  </html>

Demo演示文件下载地址-> fullview_jb51.rar

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。

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