Calculate scrollable properties for content-coordinate bounds and a separate layout offset.
public static void CalculateScrollable(Rect contentBounds, Point layoutOffset, Size borderSize, Matrix matrix, scoped out Size extent, scoped out Size viewport, scoped out Vector offset)
The effective bounds in content coordinates.
The layout position of the child inside the ZoomBorder.
The size of the ZoomBorder viewport.
The transform matrix.
The extent of the scrollable content.
The size of the viewport.
The current scroll offset.