vue3 图片路径转base64 base64转file(二进制一般后台需要格式) file转base64

1.图片路径转64 

1.  
   function imageUrlToBase64(url) {
2.  
   let homeImage = new Image();
3.  
   // 解决跨域问题
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   homeImage.setAttribute("crossOrigin", "anonymous");
5.  
   homeImage.src = url;
6.  
   //homeImage.onload为异步加载
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   homeImage.onload = () => {
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   let canvas = document.createElement("canvas");
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   canvas.width = homeImage.width;
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    canvas.height = homeImage.height;
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    let context = canvas.getContext("2d");
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    context.drawImage(homeImage, 0, 0, homeImage.width, homeImage.height);
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    let quality = 0.8;
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    // 这里的dataurl就是base64类型
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    let dataURL = canvas.toDataURL("image/jpeg", quality);
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    console.log(dataURL);
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    // base64ToFile(dataURL, "moren"); // 这里是将base64转为file格式的方法
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    };
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    }

1.1图片转file

1.  
   function imageToBase64(homeImage) {
2.  
   let canvas = document.createElement("canvas");
3.  
   canvas.width = homeImage.width;
4.  
   canvas.height = homeImage.height;
5.  
   let ctx = canvas.getContext("2d");
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   ctx.drawImage(homeImage, 0, 0, homeImage.width, homeImage.height);
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   let ext = img.src.substring(homeImage.src.lastIndexOf(".") 1).toLowerCase();
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   let dataURL = canvas.toDataURL("image/jpeg" ext);
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   console.log(dataURL);
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    return dataURL;
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    };

2.base64转file 

1.  
   function base64ToFile(base64, fileName) {
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   let arr = base64.split(",");
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   let mime = arr[0].match(/:(.*?);/)[1];
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   let bytes = atob(arr[1]);
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   let n = bytes.length;
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   let ia = new Uint8Array(n);
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   while (n--) {
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   ia[n] = bytes.charCodeAt(n);
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   }
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    return new File([ia], fileName, { type: mime }); // 将值抛出去
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    }

3.file转base64

1.  
   function getBase64(file) {
2.  
   // 直接将处理结果返回
3.  
   return new Promise((resolve, reject) => {
4.  
   let reader = new FileReader();
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   let fileResult = "";
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   reader.readAsDataURL(file);
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   reader.onload = () => {
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   fileResult = reader.result.toString();
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   };
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    reader.onerror = (error) => {
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    reject(error);
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    };
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    reader.onloadend = () => {
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    resolve(fileResult);
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    };
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    });
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    }

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