在firebase云函数中创建方形缩略图

 const fileBucket = object.bucket;

 const filePath = object.name;

 const contentType = object.contentType;

 const fileName = filePath.split('/').pop();

 const bucket = admin.storage().bucket(fileBucket);

 const tempFilePath = `/tmp/${fileName}`;

 if (!contentType.startsWith('image/')) {

   console.log('This is not an image.');

   return null;

 }

 if (fileName.startsWith('thumb_')) {

   console.log('Already a Thumbnail.');

   return null;

 }

 await bucket.file(filePath).download({

   destination: tempFilePath,

 });

 const thumbFileName = `thumb_${fileName}`;

 const thumbFilePath = filePath.replace(fileName, thumbFileName);

 const thumbFileBucket = bucket.file(thumbFilePath);

 await sharp(tempFilePath)

   .resize(200, 200)

   .toFile(tempFilePath);

 await bucket.upload(tempFilePath, {

   destination: thumbFilePath,

   metadata: {

     contentType: contentType,

   },

 });

 return thumbFileBucket.makePublic();