The following assertion was thrown while handling a gesture:
No MediaQuery widget ancestor found.

PhotoApp widgets require a MediaQuery widget ancestor.
The specific widget that could not find a MediaQuery ancestor was: PhotoApp
state: _PhotoAppState#b0ee5
The ownership chain for the affected widget is: “PhotoApp ← [root]”

No MediaQuery ancestor could be found starting from the context that was passed to MediaQuery.of(). This can happen because you have not added a WidgetsApp, CupertinoApp, or MaterialApp widget (those widgets introduce a MediaQuery), or it can happen if the context you use comes from a widget above those widgets.