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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