RenderTwoDimensionalViewport constructor

Implementation

RenderTwoDimensionalViewport({
  required ViewportOffset horizontalOffset,
  required AxisDirection horizontalAxisDirection,
  required ViewportOffset verticalOffset,
  required AxisDirection verticalAxisDirection,
  required TwoDimensionalChildDelegate delegate,
  required Axis mainAxis,
  required TwoDimensionalChildManager childManager,
  double? cacheExtent,
  Clip clipBehavior = Clip.hardEdge,
}) : assert(
       verticalAxisDirection == AxisDirection.down || verticalAxisDirection == AxisDirection.up,
       'TwoDimensionalViewport.verticalAxisDirection is not Axis.vertical.'
     ),
     assert(
       horizontalAxisDirection == AxisDirection.left || horizontalAxisDirection == AxisDirection.right,
       'TwoDimensionalViewport.horizontalAxisDirection is not Axis.horizontal.'
     ),
     _childManager = childManager,
     _horizontalOffset = horizontalOffset,
     _horizontalAxisDirection = horizontalAxisDirection,
     _verticalOffset = verticalOffset,
     _verticalAxisDirection = verticalAxisDirection,
     _delegate = delegate,
     _mainAxis = mainAxis,
     _cacheExtent = cacheExtent ?? RenderAbstractViewport.defaultCacheExtent,
     _clipBehavior = clipBehavior {
  assert(() {
    _debugDanglingKeepAlives = <RenderBox>[];
    return true;
  }());
}