trackBrush
Optional gradient brush for the track. If not null, this brush will be used instead of a solid color.
Return
A Brush for the track, or null if not used.
Parameters
slideFraction
The current progress of the swipe.
Optional gradient brush for the track. If not null, this brush will be used instead of a solid color.
A Brush for the track, or null if not used.
The current progress of the swipe.