GAE：如何获得blob-image高度 [英] GAE: How to get the blob-image height

问题描述

  avatar = db.BlobProperty（）
  

通过调用图像实例属性的高度或宽度（

  height 
 
 = profile.avatar.height 
  

引发以下错误：

AttributeError：'Blob'对象没有'height'属性

PIL如果图像存储在BlobProperty中，那么数据存储在数据存储中，如果<$ c $ c> profile 是您的实体，那么您可以以如下方式访问该高度：

  from google。 appengine.api import images 
 height = images.Image（image_data = profile.avatar）.height 
  

如果图像在t中他blobstore（数据存储区中的blobstore.BlobReferenceProperty），那么你有2种方法来实现它，更好的方法是复杂的，并且需要获取blob的读取器并将其提供给exif reader以获取大小。一个简单的方法是：如果 avatar = db.BlobReferenceProperty（）和 profile


/ code>是您的实体，那么：



  from google.appengine.api import images 
 img = images.Image（blob_key = str（profile.avatar.key（）））
 
＃我们必须执行一个变换来访问宽度/高度
 img.im_feeling_lucky（）＃做一个变换，否则GAE抱怨。 
 
＃将质量设置为1，如果图像很大，结果将适合1MB 
 img.execute_transforms（output_encoding = images.JPEG，quality = 1）
 
＃现在你可以访问img.height和img.width 
  




Given is the follwing model on GAE:

avatar = db.BlobProperty()

By calling the image instance properties height or width (see documentation) with:

height = profile.avatar.height

the following error is thrown:

AttributeError: 'Blob' object has no attribute 'height'

PIL is installed.

解决方案

If the image is stored in a BlobProperty, then the data is stored in the datastore, and if profile is your entity, then the height can be accessed as:

from google.appengine.api import images
height = images.Image(image_data=profile.avatar).height

If the image is in the blobstore, (blobstore.BlobReferenceProperty in the datastore), then you have 2 ways of doing it, the better way is complicated and requires getting a reader for the blob and feeding it to a exif reader to get the size. An easier way is:

if avatar = db.BlobReferenceProperty() and profile is your entity, then:

from google.appengine.api import images
img = images.Image(blob_key=str(profile.avatar.key()))

# we must execute a transform to access the width/height
img.im_feeling_lucky() # do a transform, otherwise GAE complains.

# set quality to 1 so the result will fit in 1MB if the image is huge
img.execute_transforms(output_encoding=images.JPEG,quality=1)

# now you can access img.height and img.width

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