Here is a small example of creating an Image Navigator for big images in Flex.
The big image is loaded in Canvas and an Image navigator will have a small prototype of this image. A small rectangle in Navigator can be used to scroll image. Click and drag small rectangle to scroll image. This rectangle corresponds to visible area of image in Canvas.
This example demonstrates usage of:
Creating Sprite at runtime
Assigning Drag and drop functionality to sprite
Copying image using BitmapData
Controlling Scrollbar using ActionScript
Handling mouse events in Flex