void ExtentsChangedCallback(double contentExtent, double containerExtent)

Signature for reporting the interior and exterior dimensions of a viewport.

  • The contentExtent is the interior dimension of the viewport (i.e., the size of the thing that's being viewed through the viewport).
  • The containerExtent is the exterior dimension of the viewport (i.e., the amount of the thing inside the viewport that is visible from outside the viewport).

Used by ScrollableGrid.onExtentsChanged, ScrollableList.onExtentsChanged, etc.

Source 

typedef void ExtentsChangedCallback(double contentExtent, double containerExtent);