Can my app integrate with the default android Gallery - Like Picasa?

I'm writing an app that involves some media syncing. I really love the way Picasa integrates int开发者_JAVA百科o the default gallery - mainly the Picasa icon on the folder and the thumbnail mechanism (i.e. it loads a thumbnail at first and only if you open the picture it actually gets the full size from the web).

I know an application can show custom data in the native contacts' app for instance, using sync adapters. So I'm looking for ways to do something similar but in the native gallery app - without developing a new gallery of course. I guess the question is whether the Gallery app is open for addons/plugins or custom behaviors etc.

From what I gather this is impossible - but maybe I'm missing something. Thanks.

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It looks like Picasa is built right into the Android Gallery:

http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android-apps/4.2.2_r1/com/android/gallery3d/picasasource/PicasaSource.java?av=f

You could try to rebuild the gallery from the source with your photo source included like PicasaSource but it doesn't look like you can modify the behavior of the stock Android Gallery.