postrevealscene.dart

//Animation controller for showing animation after reveal
    _postRevealAnimationController =
        AnimationController(duration: Duration(milliseconds: 600), vsync: this);

 //Scale animation for showing center logo after reveal is completed
    _centerIconScale = Tween<double>(begin: 0, end: .5).animate(CurvedAnimation(
      parent: _postRevealAnimationController,
      curve: Curves.fastOutSlowIn,
    ));

//_centerIconScale animation used by FAB in the middle
 Positioned.fromRelativeRect(
        rect: _titleBaseLinePosTranslateAnim.value.shift(Offset(0, 18)),
        child: ScaleTransition(
            scale: _centerIconScale,
            child: FloatingActionButton(
                backgroundColor: Colors.white,
                elevation: 5,
                onPressed: null,
                child: Icon(Icons.monetization_on_outlined,
                    size: 100,
                    color: isLeftTabSelected
                        ? Colors.deepPurple
                        : Colors.pinkAccent))),
      ),

//Tab selection is done by "CurvePageSwitchIndicator" widget
Positioned(
      top: 0,
      bottom: _titleBaseLinePosTranslateAnim.value.bottom,
      left: 0,
      right: 0,
      child: CurvePageSwitchIndicator(widget.height, widget.width, arcHeight, 3,
          true, _onLeftTabSelectd, _onRightTabSelectd),
    );


//The build method of CurvePageSwitchIndicator consisting of "CurvePageSwitcher" CustomPainter to paint tab selection arc
//and Gesture detectors stacked on top to intercept left and right tap event.
///When the reveal scene is completed, left tab is selected and the tab selection fly
//towards from the left side of the screen
  @override
  Widget build(BuildContext context) {
    return Stack(children: [
      Transform(
          transform: Matrix4.identity()
            ..setEntry(0, 3, translationDxAnim.value)
            ..setEntry(1, 3, translationDyAnim.value)
            ..rotateZ(rotationAnim.value * 3.14 / 180),
          alignment: Alignment.bottomLeft,
          child: Container(
            height: double.infinity,
            width: double.infinity,
            child: CustomPaint(
              painter: CurvePageSwitcher(
                  widget.arcHeight,
                  widget.arcBottomOffset,
                  showLeftAsFirstPage,
                  pageTabAnimationController!),
            ),
          )),
      Row(
        crossAxisAlignment: CrossAxisAlignment.center,
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        children: [
          Expanded(
              child: Stack(children: [
            Positioned(
                left: 0,
                right: 20,
                bottom: 0,
                top: 90,
                child: Transform.rotate(
                    angle: -13 * 3.14 / 180,
                    child: Align(
                        alignment: Alignment.center,
                        child: Text(
                          "Login",
                          style: TextStyle(
                              color: showLeftAsFirstPage
                                  ? Colors.white
                                  : Colors.white60,
                              fontSize: 22,
                              fontWeight: FontWeight.w800),
                        )))),
            GestureDetector(onTap: _handleLeftTab,
              )
          ])),
          Expanded(
              child: Stack(children: [
            Positioned(
                left: 20,
                right: 0,
                bottom: 0,
                top: 90,
                child: Transform.rotate(
                    angle: 13 * 3.14 / 180,
                    child: Align(
                        alignment: Alignment.center,
                        child: Text("Signup",
                            style: TextStyle(
                                color: !showLeftAsFirstPage
                                    ? Colors.white
                                    : Colors.white60,
                                fontSize: 22,
                                fontWeight: FontWeight.w800))))),
                GestureDetector(onTap: _handleRightTab,
            )
          ])),
        ],
      ),
    ]);
  }