Latest gtk2 version: gtkimageviewer-0.9.3.tar.gz | ChangeLog
Documentation: Tutorial
Considerable emphasis has been put into the speed and the memory requirements of the widget. While panning only the exposed areas are redrawn, and the zoomed up image outside the display area is never kept in memory.
The GtkImageViewer is perfectly suited to be used by any photo display program and will provide a uniform interface for interacting with images.