安卓微信中长按base64图片无法保存的解决办法

遇到的问题:后端返回的是base64格式的图片,前端拿到返回体后进行拼接展示在img标签上,微信长按图片进行保存,发现苹果长按保存成功,安卓长按保存后相册中保存的图片时黑色的(且提示格式损坏)

解决办法,使用html2canvas插件进行重新绘制,根据设备来选择渲染方法

1.下载html2canvas

1 npm install --save html2canva

2.导入html2canvas

1 import html2canvas from 'html2canvas';

3.使用html2canvas

 1 this.imgUrl = "data:image/jpeg;base64," + res.content.base64_image;
 2             
 3             
 4             let ua = navigator.userAgent;
 5             let isAndroid = ua.indexOf("Android") > -1 || ua.indexOf("Linux") > -1; //判断设备是不是安卓
 6             if (isAndroid) { //如果是安卓,则使用html2canvas绘制
 7                 html2canvas(this.$refs.imageTofile, { //this.$refs.imageTofile是我的img的父盒子
 8                     backgroundColor: null,
 9                     useCORS: true, //解决跨域
10                     windowWidth: document.body.scrollWidth,
11                     windowHeight: document.body.scrollHeight,
12                     x: this.$refs.imageTofile.offsetLeft,
13                     y: this.$refs.imageTofile.offsetTop,
14                     scale: 6, // 这是分辨率倍数,一般是2,越高图片越大,越清晰
15                 }).then((canvas) => {
16                     let url = canvas.toDataURL('image/png');
17                     this.imgUrl = url
18                 })
19             }

解决办法2.使用原生canvas进行重新绘制,(优点:不用根据设备来选择渲染方法,ios/安卓都能兼容)

1.页面上创建一个canvas容器,设置其隐藏

1 <canvas v-show="false" ref="picture"></canvas>

2.使用canvas重新绘制并赋值

 1   this.imgUrl = "data:image/jpeg;base64," + res.content.base64_image;//这个路径只能苹果保存
 2 
 3   let img = new Image();
 4   img.src = this.imgUrl;
 5       this.$nextTick(() => {
 6           let canvas = this.$refs.picture; //获取到canvas的DOM
 7           let ctx = canvas.getContext('2d'); //使用2d绘图
 8           img.onload = () => {
 9           canvas.width = img.width; 
10           canvas.height = img.height;
11           ctx.drawImage(img, 0, 0, img.width, img.height); //完整的将this.imgUrl给裁剪下来
12           let canvasURL = canvas.toDataURL('image/jpeg'); 
13           this.imgUrl = canvasURL;
14           }
15      })