根据 jpeg、png File 文件对象，获取 webp 格式的 File 文件对象

2024/7/15·1 views
html 复制代码
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>根据 jpeg、png File 文件对象，获取 webp 格式的 File 文件对象</title>
</head>
<body>
  <input type="file" id="inputimg">
  <button type="button" id="toW">To Webp</button>
  <script>
    /**
     * 根据 jpeg、png File 文件对象，获取 webp 格式的 File 文件对象
     * @param {File} imageFile jpeg、png图片文件对象
     * @returns image/webp File
     */
    const getWebpFileByImageFile = imageFile => {
      const base64ToFile = (base64, fileName) => {
        let arr = base64.split(','),
          type = arr[0].match(/:(.*?);/)[1],
          bstr = atob(arr[1]),
          n = bstr.length,
          u8arr = new Uint8Array(n);
        while (n--) {
          u8arr[n] = bstr.charCodeAt(n);
        }
        return new File([u8arr], fileName, {
          type
        });
      };
      return new Promise((resolve, reject) => {
        const imageFileReader = new FileReader();
        imageFileReader.onload = function (e) {
          const image = new Image();
          image.src = e.target.result;
          image.onload = function () {
            const canvas = document.createElement("canvas");
            canvas.width = image.width;
            canvas.height = image.height;
            canvas.getContext("2d").drawImage(image, 0, 0);

            resolve(base64ToFile(canvas.toDataURL("image/webp"), imageFile.name))
          }
        }
        imageFileReader.readAsDataURL(imageFile)
      });
    }
    // 使用示例
    document.getElementById('toW').addEventListener('click', async function () {
      const file = document.getElementById('inputimg').files[0];
      const wfile = await getWebpFileByImageFile(file);
      console.log(file, wfile);
    });
  </script>
</body>
</html>
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