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js解决ios手机上传竖拍照片旋转90度问题

03th of May 2017 Javascript JS 1539

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,详见  http://code.ciaoca.com/javascript/exif-js/

这里主要用到Orientation属性。

Orientation属性说明如下:

旋转角度 参数

1

顺时针90°  6

逆时针90°  8

180°    3


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="http://form1.cn/public/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;    
        }    
    }

最终会以base64的方式显示图片