edgePadding property
Distance from each viewport edge (in screen pixels) where autopan activates.
When the pointer enters any of these zones during a drag, autopan begins. Larger values make it easier to trigger autopan but reduce the usable drag area. Typical values range from 30 to 80 pixels per edge.
Use EdgeInsets.all for uniform padding, EdgeInsets.symmetric for horizontal/vertical control, or EdgeInsets.only for per-edge values.
Implementation
final EdgeInsets edgePadding;