vue实现头像上传

Posted 2020-09-14 wings_lhw

<template>
    <div>
        <div style="padding:20px;">
            <div class="show">
                <div class="picture" :style="‘backgroundImage:url(‘+headerImage+‘)‘"></div>
            </div>
            <div style="margin-top:20px;">
                <input type="file" id="upload" accept="image" @change="upload">
                <label for="upload"></label>
            </div>
        </div>
    </div>
</template>

<script>
    import Exif from ‘exif-js‘

    export default {
        data () {
            return {
                headerImage:‘‘,picValue:‘‘
            }
        },
        mounted () {
        },
        methods: {
            upload (e) {
                let files = e.target.files || e.dataTransfer.files;
                if (!files.length) return;
                this.picValue = files[0];
                this.imgPreview(this.picValue);
            },
            imgPreview (file) {
                let self = this;
                let Orientation;
                //去获取拍照时的信息，解决拍出来的照片旋转问题
                Exif.getData(file, function(){
                    Orientation = Exif.getTag(this, ‘Orientation‘);
                });
                // 看支持不支持FileReader
                if (!file || !window.FileReader) return;

                if (/^image/.test(file.type)) {
                    // 创建一个reader
                    let reader = new FileReader();
                    // 将图片2将转成 base64 格式
                    reader.readAsDataURL(file);
                    // 读取成功后的回调
                    reader.onloadend = function () {
                        let result = this.result;
                        let img = new Image();
                        img.src = result;
                        //判断图片是否大于100K,是就直接上传，反之压缩图片
                        if (this.result.length <= (100 * 1024)) {
                            self.headerImage = this.result;

                            self.picValue = this.result.split(",")[1];


                            self.postImg();
                        }else {
                            img.onload = function () {
                                let data = self.compress(img,Orientation);
                                self.headerImage = data;

                                self.picValue = data.split(",")[1];
                                
                                self.postImg();
                            }
                        }
                    }
                }
            },
            postImg () {
                //这里写接口
                console.log(this)
                this.$http.post("http://192.168.40.188:8089/yoho/uploadimg",{imgs:this.picValue},{emulateJSON:true}).then(
                    function (res) {
                        // 处理成功的结果
                        alert("图片上传成功");
                    },function (res) {
                        // 处理失败的结果
                        alert("图片上传失败")
                    }
                );
            },
            rotateImg (img, direction,canvas) {
                //最小与最大旋转方向，图片旋转4次后回到原方向
                const min_step = 0;
                const max_step = 3;
                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
                let height = img.height;
                let width = img.width;
                let 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
                let degree = step * 90 * Math.PI / 180;
                let 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;
                }
            },
            compress(img,Orientation) {
                let canvas = document.createElement("canvas");
                let ctx = canvas.getContext(‘2d‘);
                //瓦片canvas
                let tCanvas = document.createElement("canvas");
                let tctx = tCanvas.getContext("2d");
                let initSize = img.src.length;
                let width = img.width;
                let height = img.height;
                //如果图片大于四百万像素，计算压缩比并将大小压至400万以下
                let ratio;
                if ((ratio = width * height / 4000000) > 1) {
                    console.log("大于400万像素")
                    ratio = Math.sqrt(ratio);
                    width /= ratio;
                    height /= ratio;
                } else {
                    ratio = 1;
                }
                canvas.width = width;
                canvas.height = height;
                //        铺底色
                ctx.fillStyle = "#fff";
                ctx.fillRect(0, 0, canvas.width, canvas.height);
                //如果图片像素大于100万则使用瓦片绘制
                let count;
                if ((count = width * height / 1000000) > 1) {
                    console.log("超过100W像素");
                    count = ~~(Math.sqrt(count) + 1); //计算要分成多少块瓦片
                    //            计算每块瓦片的宽和高
                    let nw = ~~(width / count);
                    let nh = ~~(height / count);
                    tCanvas.width = nw;
                    tCanvas.height = nh;
                    for (let i = 0; i < count; i++) {
                        for (let j = 0; j < count; j++) {
                            tctx.drawImage(img, i * nw * ratio, j * nh * ratio, nw * ratio, nh * ratio, 0, 0, nw, nh);
                            ctx.drawImage(tCanvas, i * nw, j * nh, nw, nh);
                        }
                    }
                } else {
                    ctx.drawImage(img, 0, 0, width, height);
                }
                //修复ios上传图片的时候 被旋转的问题
                if(Orientation != "" && Orientation != 1){
                    switch(Orientation){
                        case 6://需要顺时针（向左）90度旋转
                            this.rotateImg(img,‘left‘,canvas);
                            break;
                        case 8://需要逆时针（向右）90度旋转
                            this.rotateImg(img,‘right‘,canvas);
                            break;
                        case 3://需要180度旋转
                            this.rotateImg(img,‘right‘,canvas);//转两次
                            this.rotateImg(img,‘right‘,canvas);
                            break;
                    }
                }
                //进行最小压缩
                let ndata = canvas.toDataURL(‘image/jpeg‘, 0.1);
                console.log(‘压缩前：‘ + initSize);
                console.log(‘压缩后：‘ + ndata.length);
                console.log(‘压缩率：‘ + ~~(100 * (initSize - ndata.length) / initSize) + "%");
                tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0;
                return ndata;
            }, convertBase64UrlToBlob(urlData){
                var bytes=window.atob(urlData.split(‘,‘)[1]);        //去掉url的头，并转换为byte

                //处理异常,将ascii码小于0的转换为大于0
                var ab = new ArrayBuffer(bytes.length);
                var ia = new Uint8Array(ab);
                for (var i = 0; i < bytes.length; i++) {
                    ia[i] = bytes.charCodeAt(i);
                }

                return new Blob( [ab] , {type : ‘image/png‘});
            }
        }
    }
</script>

<style>
    *{
        margin: 0;
        padding: 0;
    }
    .show {
        width: 100px;
        height: 100px;
        overflow: hidden;
        position: relative;
        border-radius: 50%;
        border: 1px solid #d5d5d5;
    }
    .picture {
        width: 100%;
        height: 100%;
        overflow: hidden;
        background-position: center center;
        background-repeat: no-repeat;
        background-size: cover;
    }
</style>