ScaleUpdateDetails constructor

ScaleUpdateDetails({Offset focalPoint: Offset.zero, double scale: 1.0, double rotation: 0.0 })

Creates details for GestureScaleUpdateCallback.

The focalPoint, scale, rotation arguments must not be null. The scale argument must be greater than or equal to zero.

Implementation 

ScaleUpdateDetails({
  this.focalPoint = Offset.zero,
  this.scale = 1.0,
  this.rotation = 0.0,
}) : assert(focalPoint != null),
     assert(scale != null && scale >= 0.0),
     assert(rotation != null);