Asus Eee PC 1004DN - Manual (Page 20)

Chapter 1: Knowing the Parts 1-12
Touchpad Usage
Multi-finger gesture input
Finger gesture Applications
Two-finger zooming in/out Impress, Adobe reader, Photomanager
Two-finger zooming in/out - Moving two fingertips apart or together on
the touchpad to zoom in or zoom out. This is convenient when viewing
photos or reading documents.
Zoom in Zoom out