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拍照或从文件夹里上传图片(重复上传同一张图片失效的解决办法)

拍照或从文件夹里上传图片(重复上传同一张图片失效的解决办法)

作者: 爱笑的小白菜 | 来源:发表于2018-09-20 10:30 被阅读0次

HTML:

<!--添加-->

<div  class="dianji" @click="triggerUpload">添加图片</div>

<input type="file" id="upload" accept="image/*;capture=camera" value="" @change="upload">

JS:

triggerUpload() { //触发input的点击事件,用户选择图片进行上传

    document.getElementById("upload").click();

},

//上传图片

upload(e) {

let self = this;

let file = e.target.files[0] || e.dataTransfer.files[0];

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;

e.target.value='';//input file 重复上传同一张图片失效的解决办法

let uploadImagesItem = {

msrc: this.result,

src: this.result,

Attachmentid: 0,

Newfilename: this.result

};

//现在是判断图片是否大于250k,是就直接上传,反之压缩图片

if(this.result.length <= (250 * 1024)) {

self.uploadImages.push(uploadImagesItem);

self.postImg(this.result); //提交图片到后台

} else {

img.onload = function() {

uploadImagesItem = {

msrc: self.compress(img, Orientation),

src: self.compress(img, Orientation),

Attachmentid: 0,

Newfilename: self.compress(img, Orientation)

};

self.uploadImages.push(uploadImagesItem);

let data = self.compress(img, Orientation);

self.postImg(data);

}

}

}

}

},

postImg() {

//这里写接口

},

//旋转照片, 利用exif.js解决ios手机上传竖拍照片旋转90度问题

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;

}

},

//压缩图片

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;

},

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      本文标题:拍照或从文件夹里上传图片(重复上传同一张图片失效的解决办法)

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