Wx. getImageInfo could not get base64 image information

preface

Wechat applet provides wx.getImageInfo(Object Object), but can only get pictures (network path, local path, code package path), not base64 format picture data.

The solution

Is a binary image file that converts base64 images to the local user path

• Base64 data is first converted to ArrayBuffer data using wx.Base64ToArrayBuffer
• Using FileSystemManager. WriteFile ArrayBuffer binary image file path for local users
• In this case, the image file path is in wx.env.USER_DATA_PATH, and the wx.getimageInfo interface can correctly obtain the image resource

Here is the base64src.js function code. Note that the base64 header is removed when the file is written:

const fsm = wx.getFileSystemManager();
const FILE_BASE_NAME = 'tmp_base64src';

const base64src = function(base64data) {
  return new Promise((resolve, reject) => {
    const [, format, bodyData] = /data:image\/(\w+);base64,(.*)/.exec(base64data) || [];
    if (!format) {
      reject(new Error('ERROR_BASE64SRC_PARSE'));
    }
    const filePath = `${wx.env.USER_DATA_PATH}/${FILE_BASE_NAME}.${format}`;
    const buffer = wx.base64ToArrayBuffer(bodyData);
    fsm.writeFile({
      filePath,
      data: buffer,
      encoding: 'binary',
      success() {
        resolve(filePath);
      },
      fail() {
        reject(new Error('ERROR_BASE64SRC_WRITE'));
      },
    });
  });
};

export default base64src;
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