Tab selection effect that runs when either of the tab is tapped

tabselectioneffect.dart

///The background for selected tab. On the basis of tab selected, the foreground container is translated away,
///revealing the underlying background container. If the screen state is just set to reveal, then in the
///initial state no foreground container is added which is signified by _tabSelectionAnimation set to null.
///_tabSelectionAnimation is only set when either of the tab is pressed.
  List<Widget> _getBgWidgets() {
    List<Widget> widgets = [];
    Color foreGroundColor;
    Color backgroundColor;
    if (isLeftTabSelected) {
      foreGroundColor = Colors.deepPurple;
      backgroundColor = Colors.pink;
    } else {
      foreGroundColor = Colors.pink;
      backgroundColor = Colors.deepPurple;
    }

    widgets.add(Positioned.fill(child: Container(color: foreGroundColor)));

    if (_tabSelectionAnimation != null)
      widgets.add(PositionedTransition(
          rect: _tabSelectionAnimation!,
          child: Container(
            decoration: BoxDecoration(
              color: backgroundColor
            ),
          )));
    
    widgets.add(Container(
      height: double.infinity,
      width: double.infinity,
      child: CustomPaint(
        painter: AmoebaBg(_amoebaOffsetAnimation),
      ),
    ));


    return widgets;
  }