详解利用exif.js解决ios手机上传竖拍照片旋转90度问题

HTML5+canvas进行移动端手机照片上传时,发现iOS手机上传竖拍照片会逆时针旋转90度,横拍照片无此问题;Android手机没这个问题。

因此解决这个问题的思路是:获取到照片拍摄的方向角,对非横拍的ios照片进行角度旋转修正。

利用exif.js读取照片的拍摄信息,这里主要用到Orientation属性。

Orientation属性说明如下:

下面就直接上代码了。

主要有html5页面和一个js,示例功能包含了图片压缩和旋转。

自己写的是uploadImage.js。

html5测试页面如下:

<!DOCTYPE html> 
<html> 
<head> 
  <meta charset="utf-8"> 
  <meta name="viewport" content="initial-scale=1.0, maximum-scale=1.0, user-scalable=no" /> 
  <title>图片上传</title> 
  <script type="text/javascript" src="js/jquery-1.8.3.js"></script> 
  <script type="text/javascript" src="js/uploadPicture/uploadImage.js" ></script> 
    <script type="text/javascript" src="js/exif.js" ></script> 
  <script> 
 
  </script> 
</head> 
<body> 
  <div style="height: 50px; line-height: 50px;text-align: center;border-bottom: 1px solid #171E28;"> 
      上传图片: 
      <input type="file" accept="image/*" id="uploadImage" capture="camera" onchange="selectFileImage(this);" /> 
    </div> 
    <div style="margin-top: 10px;"> 
      <img alt="preview" src="" id="myImage"/> 
    </div> 
</body> 
</html> 

uploadImage.js如下:

function selectFileImage(fileObj) { 
  var file = fileObj.files['0']; 
  //图片方向角 added by lzk 
  var Orientation = null; 
   
  if (file) { 
    console.log("正在上传,请稍后..."); 
    var rFilter = /^(image\/jpeg|image\/png)$/i; // 检查图片格式 
    if (!rFilter.test(file.type)) { 
      //showMyTips("请选择jpeg、png格式的图片", false); 
      return; 
    } 
    // var URL = URL || webkitURL; 
    //获取照片方向角属性,用户旋转控制 
    EXIF.getData(file, function() { 
      // alert(EXIF.pretty(this)); 
      EXIF.getAllTags(this);  
      //alert(EXIF.getTag(this, 'Orientation'));  
      Orientation = EXIF.getTag(this, 'Orientation'); 
      //return; 
    }); 
     
    var oReader = new FileReader(); 
    oReader.onload = function(e) { 
      //var blob = URL.createObjectURL(file); 
      //_compress(blob, file, basePath); 
      var image = new Image(); 
      image.src = e.target.result; 
      image.onload = function() { 
        var expectWidth = this.naturalWidth; 
        var expectHeight = this.naturalHeight; 
         
        if (this.naturalWidth > this.naturalHeight && this.naturalWidth > 800) { 
          expectWidth = 800; 
          expectHeight = expectWidth * this.naturalHeight / this.naturalWidth; 
        } else if (this.naturalHeight > this.naturalWidth && this.naturalHeight > 1200) { 
          expectHeight = 1200; 
          expectWidth = expectHeight * this.naturalWidth / this.naturalHeight; 
        } 
        var canvas = document.createElement("canvas"); 
        var ctx = canvas.getContext("2d"); 
        canvas.width = expectWidth; 
        canvas.height = expectHeight; 
        ctx.drawImage(this, 0, 0, expectWidth, expectHeight); 
        var base64 = null; 
        //修复ios 
        if (navigator.userAgent.match(/iphone/i)) { 
          console.log('iphone'); 
          //alert(expectWidth + ',' + expectHeight); 
          //如果方向角不为1,都需要进行旋转 added by lzk 
          if(Orientation != "" && Orientation != 1){ 
            alert('旋转处理'); 
            switch(Orientation){ 
              case 6://需要顺时针(向左)90度旋转 
                alert('需要顺时针(向左)90度旋转'); 
                rotateImg(this,'left',canvas); 
                break; 
              case 8://需要逆时针(向右)90度旋转 
                alert('需要顺时针(向右)90度旋转'); 
                rotateImg(this,'right',canvas); 
                break; 
              case 3://需要180度旋转 
                alert('需要180度旋转'); 
                rotateImg(this,'right',canvas);//转两次 
                rotateImg(this,'right',canvas); 
                break; 
            }     
          } 
           
          /*var mpImg = new MegaPixImage(image); 
          mpImg.render(canvas, { 
            maxWidth: 800, 
            maxHeight: 1200, 
            quality: 0.8, 
            orientation: 8 
          });*/ 
          base64 = canvas.toDataURL("image/jpeg", 0.8); 
        }else if (navigator.userAgent.match(/Android/i)) {// 修复android 
          var encoder = new JPEGEncoder(); 
          base64 = encoder.encode(ctx.getImageData(0, 0, expectWidth, expectHeight), 80); 
        }else{ 
          //alert(Orientation); 
          if(Orientation != "" && Orientation != 1){ 
            //alert('旋转处理'); 
            switch(Orientation){ 
              case 6://需要顺时针(向左)90度旋转 
                alert('需要顺时针(向左)90度旋转'); 
                rotateImg(this,'left',canvas); 
                break; 
              case 8://需要逆时针(向右)90度旋转 
                alert('需要顺时针(向右)90度旋转'); 
                rotateImg(this,'right',canvas); 
                break; 
              case 3://需要180度旋转 
                alert('需要180度旋转'); 
                rotateImg(this,'right',canvas);//转两次 
                rotateImg(this,'right',canvas); 
                break; 
            }     
          } 
           
          base64 = canvas.toDataURL("image/jpeg", 0.8); 
        } 
        //uploadImage(base64); 
        $("#myImage").attr("src", base64); 
      }; 
    }; 
    oReader.readAsDataURL(file); 
  } 
} 
 
//对图片旋转处理 added by lzk 
function rotateImg(img, direction,canvas) {  
    //alert(img); 
    //最小与最大旋转方向,图片旋转4次后回到原方向  
    var min_step = 0;  
    var max_step = 3;  
    //var img = document.getElementById(pid);  
    if (img == null)return;  
    //img的高度和宽度不能在img元素隐藏后获取,否则会出错  
    var height = img.height;  
    var width = img.width;  
    //var step = img.getAttribute('step');  
    var step = 2;  
    if (step == null) {  
      step = min_step;  
    }  
    if (direction == 'right') {  
      step++;  
      //旋转到原位置,即超过最大值  
      step > max_step && (step = min_step);  
    } else {  
      step--;  
      step < min_step && (step = max_step);  
    }  
    //img.setAttribute('step', step);  
    /*var canvas = document.getElementById('pic_' + pid);  
    if (canvas == null) {  
      img.style.display = 'none';  
      canvas = document.createElement('canvas');  
      canvas.setAttribute('id', 'pic_' + pid);  
      img.parentNode.appendChild(canvas);  
    } */ 
    //旋转角度以弧度值为参数  
    var degree = step * 90 * Math.PI / 180;  
    var ctx = canvas.getContext('2d');  
    switch (step) {  
      case 0:  
        canvas.width = width;  
        canvas.height = height;  
        ctx.drawImage(img, 0, 0);  
        break;  
      case 1:  
        canvas.width = height;  
        canvas.height = width;  
        ctx.rotate(degree);  
        ctx.drawImage(img, 0, -height);  
        break;  
      case 2:  
        canvas.width = width;  
        canvas.height = height;  
        ctx.rotate(degree);  
        ctx.drawImage(img, -width, -height);  
        break;  
      case 3:  
        canvas.width = height;  
        canvas.height = width;  
        ctx.rotate(degree);  
        ctx.drawImage(img, -width, 0);  
        break;  
    }  
  }  

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编程小技巧。

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