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lib/13/02_/transition/fade_transition.dart

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+
+
+
+
+import 'package:flutter/material.dart';
+
+
+class FadeTransitionsBuilder extends PageTransitionsBuilder {
+  /// Constructs a page transition animation that slides the page up.
+  const FadeTransitionsBuilder();
+
+  @override
+  Widget buildTransitions<T>(
+      PageRoute<T>? route,
+      BuildContext? context,
+      Animation<double> animation,
+      Animation<double>? secondaryAnimation,
+      Widget child,
+      ) {
+    return _FadeUpwardsPageTransition(routeAnimation: animation, child: child);
+  }
+}
+
+class _FadeUpwardsPageTransition extends StatelessWidget {
+  _FadeUpwardsPageTransition({
+    required Animation<double> routeAnimation, // The route's linear 0.0 - 1.0 animation.
+    required this.child,
+  }) : _positionAnimation = routeAnimation.drive(_bottomUpTween.chain(_fastOutSlowInTween)),
+        _opacityAnimation = routeAnimation.drive(_easeInTween);
+
+  // Fractional offset from 1/4 screen below the top to fully on screen.
+  static final Tween<Offset> _bottomUpTween = Tween<Offset>(
+    begin: const Offset(0.25,0),
+    end: Offset.zero,
+  );
+  static final Animatable<double> _fastOutSlowInTween = CurveTween(curve: Curves.fastOutSlowIn);
+  static final Animatable<double> _easeInTween = CurveTween(curve: Curves.easeIn);
+
+  final Animation<Offset> _positionAnimation;
+  final Animation<double> _opacityAnimation;
+  final Widget child;
+
+  @override
+  Widget build(BuildContext context) {
+    // return FadeTransition(
+    //   opacity: _opacityAnimation,
+    //   child: child,
+    // );
+
+    return SlideTransition(
+      position: _positionAnimation,
+      child: FadeTransition(
+        opacity: _opacityAnimation,
+        child: child,
+      ),
+    );
+  }
+}