Exif.js图片旋转修正

上传后图片旋转修正

测试流程

上传 -> base64展示 -> 获取旋转值 -> 修正 -> 修正后展示 -> 转换blobfile文件供其他功能调用


<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name='viewport' content='width=device-width,initial-scale=1.0'>
    <title>测试图片旋转title>
head>
<body>
<input type="file" id="test" onchange="upload(event)">
<hr>
图片展示:
<img src="" id="img">
<hr>
旋转值:
<div id="rotateval">div>
<hr>
canvas(旋转修正后):
<canvas id="canvas" width="100%" height="80%">canvas>
<script src="exif.js">script>
<script>
    function upload(e) {
        var file = e.target.files;

        var reader = new FileReader();
        reader.onload = function(e) {
            var res = reader.result;

            document.getElementById("img").setAttribute('src', res);

            EXIF.getData(file[0],
                function() {
                    var Orientation = EXIF.getTag(this, 'Orientation');

                    document.getElementById('rotateval').innerHTML = Orientation;

                    if (Orientation) {

                        var image = new Image();
                        image.src = res;
                        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.getElementById("canvas");
                            var ctx = canvas.getContext("2d");
                            canvas.width = "800px"; //expectWidth;
                            canvas.height = expectHeight;
                            ctx.drawImage(this, 0, 0, expectWidth, expectHeight);

                            switch (Orientation) {
                            case 6: //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
                                rotateImg(this, 'right', canvas);
                                break;
                            case 3: //需要180度旋转
                                rotateImg(this, 'right', canvas); //转两次
                                rotateImg(this, 'right', canvas);
                                break;
                            }

                            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);
                                }
                                //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;
                                }

                                uploadfile(canvas);
                            }

                        }
                    }

                });

        }
        reader.readAsDataURL(file[0]);

    }

    function uploadfile(canvas) {
        let src = canvas.toDataURL("image/png"); //这里转成的是base64的地址,直接用到img标签的src是可以显示图片的

        //转成Blob对象
        function dataURItoBlob(dataURI) { //图片转成Buffer

            //atob() 方法用于解码使用 base-64 编码的字符串。
            //base-64 编码使用方法是 btoa() 。
            var byteString = atob(dataURI.split(',')[1]);
            var mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0];
            var ab = new ArrayBuffer(byteString.length);
            var ia = new Uint8Array(ab);
            for (var i = 0; i < byteString.length; i++) {
                ia[i] = byteString.charCodeAt(i);
            }
            return new Blob([ab], { type: mimeString });
        }

        var blob = dataURItoBlob(src);

        console.log('二进制对象:');
        console.log(blob);

        //转成File对象
        function dataURLtoFile(dataurl, filename) {
            var arr = dataurl.split(','),
                mime = arr[0].match(/:(.*?);/)[1],
                bstr = atob(arr[1]),
                n = bstr.length,
                u8arr = new Uint8Array(n);
            while (n--) {
                u8arr[n] = bstr.charCodeAt(n);
            }
            return new File([u8arr], filename, { type: mime });
        }

        var file_b = dataURLtoFile(src, 'test.png');

        var formData = new FormData();
        var columnName = 'img';
        formData.append(columnName, file_b);
        formData.append("filetype", file_b.type);

        console.log('文件对象:');
        console.log(file_b);

    }
script>
body>
html>

解决图片自动旋转问题

exif.js

用于从图像文件中读取EXIF元数据的JavaScript库。

您可以在浏览器中的图像上使用它,从图像或文件输入元素。
检索EXIF和IPTC元数据。这个包也可以在AMD或CommonJS环境中使用。

注意:EXIF标准仅适用于.jpg.tiff图像。
这个包中的EXIF逻辑基于EXIF标准v2.2 (JEITA CP-3451,包含在这个repo中)。


<html>

<head>
    <meta charset="UTF-8">
    <title>title>
    <script src="./jquery-1.7.2.min.js">script>
    <script src="./exif.min.js">script>
head>

<body>

<img src="1.jpg" id="J-logo"/>
<script type="text/javascript">
    var getor = function() {
        EXIF.getData(document.getElementById("J-logo"),
            function() {
                var aaa = EXIF.getAllTags(this);
                var orp = EXIF.getTag(this, 'Orientation');
                if (orp == 1) {
                    $("#J-logo").css("transform", "rotate(0deg)");
                } else if (orp == 3) {
                    $("#J-logo").css("transform", "rotate(180deg)");
                } else if (orp == 6) {
                    $("#J-logo").css("transform", "rotate(90deg)");
                } else if (orp == 8) {
                    $("#J-logo").css("transform", "rotate(270deg)");
                }
            });
    }
    setTimeout('getor()', 1);
script>
body>

html>

你可能感兴趣的:(Html+Javascript)