packages/flutter/lib/src/material/page_transitions_theme.dart - mirrors/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'package:flutter/cupertino.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';

 import 'colors.dart';
 import 'theme.dart';

 // Slides the page upwards and fades it in, starting from 1/4 screen
 // below the top.
 class _FadeUpwardsPageTransition extends StatelessWidget {
   _FadeUpwardsPageTransition({
     Key key,
     @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),
        super(key: key);

   // Fractional offset from 1/4 screen below the top to fully on screen.
   static final Tween<Offset> _bottomUpTween = Tween<Offset>(
     begin: const Offset(0.0, 0.25),
     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 SlideTransition(
       position: _positionAnimation,
       // TODO(ianh): tell the transform to be un-transformed for hit testing
       child: FadeTransition(
         opacity: _opacityAnimation,
         child: child,
       ),
     );
   }
 }

 // This transition is intended to match the default for Android P.
 class _OpenUpwardsPageTransition extends StatelessWidget {
   const _OpenUpwardsPageTransition({
     Key key,
     this.animation,
     this.secondaryAnimation,
     this.child,
   }) : super(key: key);

   // The new page slides upwards just a little as its clip
   // rectangle exposes the page from bottom to top.
   static final Tween<Offset> _primaryTranslationTween = Tween<Offset>(
     begin: const Offset(0.0, 0.05),
     end: Offset.zero,
   );

   // The old page slides upwards a little as the new page appears.
   static final Tween<Offset> _secondaryTranslationTween = Tween<Offset>(
     begin: Offset.zero,
     end: const Offset(0.0, -0.025),
   );

   // The scrim obscures the old page by becoming increasingly opaque.
   static final Tween<double> _scrimOpacityTween = Tween<double>(
     begin: 0.0,
     end: 0.25,
   );

   // Used by all of the transition animations.
   static const Curve _transitionCurve = Cubic(0.20, 0.00, 0.00, 1.00);

   final Animation<double> animation;
   final Animation<double> secondaryAnimation;
   final Widget child;

   @override
   Widget build(BuildContext context) {
     return LayoutBuilder(
       builder: (BuildContext context, BoxConstraints constraints) {
         final Size size = constraints.biggest;

         final CurvedAnimation primaryAnimation = CurvedAnimation(
           parent: animation,
           curve: _transitionCurve,
           reverseCurve: _transitionCurve.flipped,
         );

         // Gradually expose the new page from bottom to top.
         final Animation<double> clipAnimation = Tween<double>(
           begin: 0.0,
           end: size.height,
         ).animate(primaryAnimation);

         final Animation<double> opacityAnimation = _scrimOpacityTween.animate(primaryAnimation);
         final Animation<Offset> primaryTranslationAnimation = _primaryTranslationTween.animate(primaryAnimation);

         final Animation<Offset> secondaryTranslationAnimation = _secondaryTranslationTween.animate(
           CurvedAnimation(
             parent: secondaryAnimation,
             curve: _transitionCurve,
             reverseCurve: _transitionCurve.flipped,
           ),
         );

         return AnimatedBuilder(
           animation: animation,
           builder: (BuildContext context, Widget child) {
             return Container(
               color: Colors.black.withOpacity(opacityAnimation.value),
               alignment: Alignment.bottomLeft,
               child: ClipRect(
                 child: SizedBox(
                   height: clipAnimation.value,
                   child: OverflowBox(
                     alignment: Alignment.bottomLeft,
                     maxHeight: size.height,
                     child: child,
                   ),
                 ),
               ),
             );
           },
           child: AnimatedBuilder(
             animation: secondaryAnimation,
             child: FractionalTranslation(
               translation: primaryTranslationAnimation.value,
               child: child,
             ),
             builder: (BuildContext context, Widget child) {
               return FractionalTranslation(
                 translation: secondaryTranslationAnimation.value,
                 child: child,
               );
             },
           ),
         );
       },
     );
   }
 }

 // Zooms and fades a new page in, zooming out the previous page. This transition
 // is designed to match the Android 10 activity transition.
 class _ZoomPageTransition extends StatefulWidget {
   const _ZoomPageTransition({
     Key key,
     this.animation,
     this.secondaryAnimation,
     this.child,
   }) : super(key: key);

   // The scrim obscures the old page by becoming increasingly opaque.
   static final Tween<double> _scrimOpacityTween = Tween<double>(
     begin: 0.0,
     end: 0.60,
   );

   // A curve sequence that is similar to the 'fastOutExtraSlowIn' curve used in
   // the native transition.
   static final List<TweenSequenceItem<double>> fastOutExtraSlowInTweenSequenceItems = <TweenSequenceItem<double>>[
     TweenSequenceItem<double>(
       tween: Tween<double>(begin: 0.0, end: 0.4)
         .chain(CurveTween(curve: const Cubic(0.05, 0.0, 0.133333, 0.06))),
       weight: 0.166666,
     ),
     TweenSequenceItem<double>(
       tween: Tween<double>(begin: 0.4, end: 1.0)
         .chain(CurveTween(curve: const Cubic(0.208333, 0.82, 0.25, 1.0))),
       weight: 1.0 - 0.166666,
     ),
   ];
   static final TweenSequence<double> _scaleCurveSequence = TweenSequence<double>(fastOutExtraSlowInTweenSequenceItems);
   static final FlippedTweenSequence _flippedScaleCurveSequence = FlippedTweenSequence(fastOutExtraSlowInTweenSequenceItems);

   final Animation<double> animation;
   final Animation<double> secondaryAnimation;
   final Widget child;

   @override
   __ZoomPageTransitionState createState() => __ZoomPageTransitionState();
 }

 class __ZoomPageTransitionState extends State<_ZoomPageTransition> {
   AnimationStatus _currentAnimationStatus;
   AnimationStatus _lastAnimationStatus;

   @override
   void initState() {
     super.initState();
     widget.animation.addStatusListener((AnimationStatus animationStatus) {
       _lastAnimationStatus = _currentAnimationStatus;
       _currentAnimationStatus = animationStatus;
     });
   }

   // This check ensures that the animation reverses the original animation if
   // the transition were interruped midway. This prevents a disjointed
   // experience since the reverse animation uses different fade and scaling
   // curves.
   bool get _transitionWasInterrupted {
     bool wasInProgress = false;
     bool isInProgress = false;

     switch (_currentAnimationStatus) {
       case AnimationStatus.completed:
       case AnimationStatus.dismissed:
         isInProgress = false;
         break;
       case AnimationStatus.forward:
       case AnimationStatus.reverse:
         isInProgress = true;
         break;
     }
     switch (_lastAnimationStatus) {
       case AnimationStatus.completed:
       case AnimationStatus.dismissed:
         wasInProgress = false;
         break;
       case AnimationStatus.forward:
       case AnimationStatus.reverse:
         wasInProgress = true;
         break;
     }
     return wasInProgress && isInProgress;
   }

   @override
   Widget build(BuildContext context) {
     final Animation<double> _forwardScrimOpacityAnimation = widget.animation.drive(
       _ZoomPageTransition._scrimOpacityTween
         .chain(CurveTween(curve: const Interval(0.2075, 0.4175))));

     final Animation<double> _forwardEndScreenScaleTransition = widget.animation.drive(
       Tween<double>(begin: 0.85, end: 1.00)
         .chain(_ZoomPageTransition._scaleCurveSequence));

     final Animation<double> _forwardStartScreenScaleTransition = widget.secondaryAnimation.drive(
       Tween<double>(begin: 1.00, end: 1.05)
         .chain(_ZoomPageTransition._scaleCurveSequence));

     final Animation<double> _forwardEndScreenFadeTransition = widget.animation.drive(
       Tween<double>(begin: 0.0, end: 1.00)
         .chain(CurveTween(curve: const Interval(0.125, 0.250))));

     final Animation<double> _reverseEndScreenScaleTransition = widget.secondaryAnimation.drive(
       Tween<double>(begin: 1.00, end: 1.10)
         .chain(_ZoomPageTransition._flippedScaleCurveSequence));

     final Animation<double> _reverseStartScreenScaleTransition = widget.animation.drive(
       Tween<double>(begin: 0.9, end: 1.0)
         .chain(_ZoomPageTransition._flippedScaleCurveSequence));

     final Animation<double> _reverseStartScreenFadeTransition = widget.animation.drive(
       Tween<double>(begin: 0.0, end: 1.00)
         .chain(CurveTween(curve: const Interval(1 - 0.2075, 1 - 0.0825))));

     return AnimatedBuilder(
       animation: widget.animation,
       builder: (BuildContext context, Widget child) {
         if (widget.animation.status == AnimationStatus.forward || _transitionWasInterrupted) {
           return Container(
             color: Colors.black.withOpacity(_forwardScrimOpacityAnimation.value),
             child: FadeTransition(
               opacity: _forwardEndScreenFadeTransition,
               child: ScaleTransition(
                 scale: _forwardEndScreenScaleTransition,
                 child: child,
               ),
             ),
           );
         } else if (widget.animation.status == AnimationStatus.reverse) {
           return ScaleTransition(
             scale: _reverseStartScreenScaleTransition,
             child: FadeTransition(
               opacity: _reverseStartScreenFadeTransition,
               child: child,
             ),
           );
         }
         return child;
       },
       child: AnimatedBuilder(
         animation: widget.secondaryAnimation,
         builder: (BuildContext context, Widget child) {
           if (widget.secondaryAnimation.status == AnimationStatus.forward || _transitionWasInterrupted) {
             return ScaleTransition(
               scale: _forwardStartScreenScaleTransition,
               child: child,
             );
           } else if (widget.secondaryAnimation.status == AnimationStatus.reverse) {
             return ScaleTransition(
               scale: _reverseEndScreenScaleTransition,
               child: child,
             );
           }
           return child;
         },
         child: widget.child,
       ),
     );
   }
 }

 /// Used by [PageTransitionsTheme] to define a [MaterialPageRoute] page
 /// transition animation.
 ///
 /// Apps can configure the map of builders for [ThemeData.pageTransitionsTheme]
 /// to customize the default [MaterialPageRoute] page transition animation
 /// for different platforms.
 ///
 /// See also:
 ///
 ///  * [FadeUpwardsPageTransitionsBuilder], which defines a default page transition.
 ///  * [OpenUpwardsPageTransitionsBuilder], which defines a page transition
 ///    that's similar to the one provided by Android P.
 ///  * [ZoomPageTransitionsBuilder], which defines a page transition similar
 ///    to the one provided in Android 10.
 ///  * [CupertinoPageTransitionsBuilder], which defines a horizontal page
 ///    transition that matches native iOS page transitions.
 abstract class PageTransitionsBuilder {
   /// Abstract const constructor. This constructor enables subclasses to provide
   /// const constructors so that they can be used in const expressions.
   const PageTransitionsBuilder();

   /// Wraps the child with one or more transition widgets which define how [route]
   /// arrives on and leaves the screen.
   ///
   /// The [MaterialPageRoute.buildTransitions] method looks up the current
   /// current [PageTransitionsTheme] with `Theme.of(context).pageTransitionsTheme`
   /// and delegates to this method with a [PageTransitionsBuilder] based
   /// on the theme's [ThemeData.platform].
   Widget buildTransitions<T>(
     PageRoute<T> route,
     BuildContext context,
     Animation<double> animation,
     Animation<double> secondaryAnimation,
     Widget child,
   );
 }

 /// Used by [PageTransitionsTheme] to define a default [MaterialPageRoute] page
 /// transition animation.
 ///
 /// The default animation fades the new page in while translating it upwards,
 /// starting from about 25% below the top of the screen.
 ///
 /// See also:
 ///
 ///  * [OpenUpwardsPageTransitionsBuilder], which defines a page transition
 ///    that's similar to the one provided by Android P.
 ///  * [ZoomPageTransitionsBuilder], which defines a page transition similar
 ///    to the one provided in Android 10.
 ///  * [CupertinoPageTransitionsBuilder], which defines a horizontal page
 ///    transition that matches native iOS page transitions.
 class FadeUpwardsPageTransitionsBuilder extends PageTransitionsBuilder {
   /// Construct a [FadeUpwardsPageTransitionsBuilder].
   const FadeUpwardsPageTransitionsBuilder();

   @override
   Widget buildTransitions<T>(
     PageRoute<T> route,
     BuildContext context,
     Animation<double> animation,
     Animation<double> secondaryAnimation,
     Widget child,
   ) {
     return _FadeUpwardsPageTransition(routeAnimation: animation, child: child);
   }
 }

 /// Used by [PageTransitionsTheme] to define a vertical [MaterialPageRoute] page
 /// transition animation that looks like the default page transition
 /// used on Android P.
 ///
 /// See also:
 ///
 ///  * [FadeUpwardsPageTransitionsBuilder], which defines a default page transition.
 ///  * [ZoomPageTransitionsBuilder], which defines a page transition similar
 ///    to the one provided in Android 10.
 ///  * [CupertinoPageTransitionsBuilder], which defines a horizontal page
 ///    transition that matches native iOS page transitions.
 class OpenUpwardsPageTransitionsBuilder extends PageTransitionsBuilder {
   /// Construct a [OpenUpwardsPageTransitionsBuilder].
   const OpenUpwardsPageTransitionsBuilder();

   @override
   Widget buildTransitions<T>(
     PageRoute<T> route,
     BuildContext context,
     Animation<double> animation,
     Animation<double> secondaryAnimation,
     Widget child,
   ) {
     return _OpenUpwardsPageTransition(
       animation: animation,
       secondaryAnimation: secondaryAnimation,
       child: child,
     );
   }
 }

 /// Used by [PageTransitionsTheme] to define a zooming [MaterialPageRoute] page
 /// transition animation that looks like the default page transition used on
 /// Android 10.
 ///
 /// See also:
 ///
 ///  * [FadeUpwardsPageTransitionsBuilder], which defines a default page transition.
 ///  * [OpenUpwardsPageTransitionsBuilder], which defines a page transition
 ///    similar to the one provided by Android P.
 ///  * [CupertinoPageTransitionsBuilder], which defines a horizontal page
 ///    transition that matches native iOS page transitions.
 class ZoomPageTransitionsBuilder extends PageTransitionsBuilder {
   /// Construct a [ZoomPageTransitionsBuilder].
   const ZoomPageTransitionsBuilder();

   @override
   Widget buildTransitions<T>(
     PageRoute<T> route,
     BuildContext context,
     Animation<double> animation,
     Animation<double> secondaryAnimation,
     Widget child,
   ) {
     return _ZoomPageTransition(
       animation: animation,
       secondaryAnimation: secondaryAnimation,
       child: child,
     );
   }
 }

 /// Used by [PageTransitionsTheme] to define a horizontal [MaterialPageRoute]
 /// page transition animation that matches native iOS page transitions.
 ///
 /// See also:
 ///
 ///  * [FadeUpwardsPageTransitionsBuilder], which defines a default page transition.
 ///  * [OpenUpwardsPageTransitionsBuilder], which defines a page transition
 ///    that's similar to the one provided by Android P.
 ///  * [ZoomPageTransitionsBuilder], which defines a page transition similar
 ///    to the one provided in Android 10.
 class CupertinoPageTransitionsBuilder extends PageTransitionsBuilder {
   /// Construct a [CupertinoPageTransitionsBuilder].
   const CupertinoPageTransitionsBuilder();

   @override
   Widget buildTransitions<T>(
     PageRoute<T> route,
     BuildContext context,
     Animation<double> animation,
     Animation<double> secondaryAnimation,
     Widget child,
   ) {
     return CupertinoPageRoute.buildPageTransitions<T>(route, context, animation, secondaryAnimation, child);
   }
 }

 /// Defines the page transition animations used by [MaterialPageRoute]
 /// for different [TargetPlatform]s.
 ///
 /// The [MaterialPageRoute.buildTransitions] method looks up the current
 /// current [PageTransitionsTheme] with `Theme.of(context).pageTransitionsTheme`
 /// and delegates to [buildTransitions].
 ///
 /// If a builder with a matching platform is not found, then the
 /// [FadeUpwardsPageTransitionsBuilder] is used.
 ///
 /// See also:
 ///
 ///  * [ThemeData.pageTransitionsTheme], which defines the default page
 ///    transitions for the overall theme.
 ///  * [FadeUpwardsPageTransitionsBuilder], which defines a default page transition.
 ///  * [OpenUpwardsPageTransitionsBuilder], which defines a page transition
 ///    that's similar to the one provided by Android P.
 ///  * [CupertinoPageTransitionsBuilder], which defines a horizontal page
 ///    transition that matches native iOS page transitions.
 @immutable
 class PageTransitionsTheme with Diagnosticable {
   /// Construct a PageTransitionsTheme.
   ///
   /// By default the list of builders is: [FadeUpwardsPageTransitionsBuilder]
   /// for [TargetPlatform.android], and [CupertinoPageTransitionsBuilder] for
   /// [TargetPlatform.iOS] and [TargetPlatform.macOS].
   const PageTransitionsTheme({ Map<TargetPlatform, PageTransitionsBuilder> builders }) : _builders = builders;

   static const Map<TargetPlatform, PageTransitionsBuilder> _defaultBuilders = <TargetPlatform, PageTransitionsBuilder>{
     TargetPlatform.android: FadeUpwardsPageTransitionsBuilder(),
     TargetPlatform.iOS: CupertinoPageTransitionsBuilder(),
     TargetPlatform.linux: FadeUpwardsPageTransitionsBuilder(),
     TargetPlatform.macOS: CupertinoPageTransitionsBuilder(),
     TargetPlatform.windows: FadeUpwardsPageTransitionsBuilder(),
   };

   /// The [PageTransitionsBuilder]s supported by this theme.
   Map<TargetPlatform, PageTransitionsBuilder> get builders => _builders ?? _defaultBuilders;
   final Map<TargetPlatform, PageTransitionsBuilder> _builders;

   /// Delegates to the builder for the current [ThemeData.platform]
   /// or [FadeUpwardsPageTransitionsBuilder].
   ///
   /// [MaterialPageRoute.buildTransitions] delegates to this method.
   Widget buildTransitions<T>(
     PageRoute<T> route,
     BuildContext context,
     Animation<double> animation,
     Animation<double> secondaryAnimation,
     Widget child,
   ) {
     TargetPlatform platform = Theme.of(context).platform;

     if (CupertinoPageRoute.isPopGestureInProgress(route))
       platform = TargetPlatform.iOS;

     final PageTransitionsBuilder matchingBuilder =
       builders[platform] ?? const FadeUpwardsPageTransitionsBuilder();
     return matchingBuilder.buildTransitions<T>(route, context, animation, secondaryAnimation, child);
   }

   // Just used to the builders Map to a list with one PageTransitionsBuilder per platform
   // for the operator == overload.
   List<PageTransitionsBuilder> _all(Map<TargetPlatform, PageTransitionsBuilder> builders) {
     return TargetPlatform.values.map((TargetPlatform platform) => builders[platform]).toList();
   }

   @override
   bool operator ==(Object other) {
     if (identical(this, other))
       return true;
     if (other.runtimeType != runtimeType)
       return false;
     if (other is PageTransitionsTheme && identical(builders, other.builders))
       return true;
     return other is PageTransitionsTheme
         && listEquals<PageTransitionsBuilder>(_all(other.builders), _all(builders));
   }

   @override
   int get hashCode => hashList(_all(builders));

   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
     properties.add(
       DiagnosticsProperty<Map<TargetPlatform, PageTransitionsBuilder>>(
         'builders',
         builders,
         defaultValue: PageTransitionsTheme._defaultBuilders,
       ),
     );
   }
 }
	// Copyright 2014 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'package:flutter/cupertino.dart';
	import 'package:flutter/foundation.dart';
	import 'package:flutter/widgets.dart';

	import 'colors.dart';
	import 'theme.dart';

	// Slides the page upwards and fades it in, starting from 1/4 screen
	// below the top.
	class _FadeUpwardsPageTransition extends StatelessWidget {
	_FadeUpwardsPageTransition({
	Key key,
	@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),
	super(key: key);

	// Fractional offset from 1/4 screen below the top to fully on screen.
	static final Tween<Offset> _bottomUpTween = Tween<Offset>(
	begin: const Offset(0.0, 0.25),
	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 SlideTransition(
	position: _positionAnimation,
	// TODO(ianh): tell the transform to be un-transformed for hit testing
	child: FadeTransition(
	opacity: _opacityAnimation,
	child: child,
	),
	);
	}
	}

	// This transition is intended to match the default for Android P.
	class _OpenUpwardsPageTransition extends StatelessWidget {
	const _OpenUpwardsPageTransition({
	Key key,
	this.animation,
	this.secondaryAnimation,
	this.child,
	}) : super(key: key);

	// The new page slides upwards just a little as its clip
	// rectangle exposes the page from bottom to top.
	static final Tween<Offset> _primaryTranslationTween = Tween<Offset>(
	begin: const Offset(0.0, 0.05),
	end: Offset.zero,
	);

	// The old page slides upwards a little as the new page appears.
	static final Tween<Offset> _secondaryTranslationTween = Tween<Offset>(
	begin: Offset.zero,
	end: const Offset(0.0, -0.025),
	);

	// The scrim obscures the old page by becoming increasingly opaque.
	static final Tween<double> _scrimOpacityTween = Tween<double>(
	begin: 0.0,
	end: 0.25,
	);

	// Used by all of the transition animations.
	static const Curve _transitionCurve = Cubic(0.20, 0.00, 0.00, 1.00);

	final Animation<double> animation;
	final Animation<double> secondaryAnimation;
	final Widget child;

	@override
	Widget build(BuildContext context) {
	return LayoutBuilder(
	builder: (BuildContext context, BoxConstraints constraints) {
	final Size size = constraints.biggest;

	final CurvedAnimation primaryAnimation = CurvedAnimation(
	parent: animation,
	curve: _transitionCurve,
	reverseCurve: _transitionCurve.flipped,
	);

	// Gradually expose the new page from bottom to top.
	final Animation<double> clipAnimation = Tween<double>(
	begin: 0.0,
	end: size.height,
	).animate(primaryAnimation);

	final Animation<double> opacityAnimation = _scrimOpacityTween.animate(primaryAnimation);
	final Animation<Offset> primaryTranslationAnimation = _primaryTranslationTween.animate(primaryAnimation);

	final Animation<Offset> secondaryTranslationAnimation = _secondaryTranslationTween.animate(
	CurvedAnimation(
	parent: secondaryAnimation,
	curve: _transitionCurve,
	reverseCurve: _transitionCurve.flipped,
	),
	);

	return AnimatedBuilder(
	animation: animation,
	builder: (BuildContext context, Widget child) {
	return Container(
	color: Colors.black.withOpacity(opacityAnimation.value),
	alignment: Alignment.bottomLeft,
	child: ClipRect(
	child: SizedBox(
	height: clipAnimation.value,
	child: OverflowBox(
	alignment: Alignment.bottomLeft,
	maxHeight: size.height,
	child: child,
	),
	),
	),
	);
	},
	child: AnimatedBuilder(
	animation: secondaryAnimation,
	child: FractionalTranslation(
	translation: primaryTranslationAnimation.value,
	child: child,
	),
	builder: (BuildContext context, Widget child) {
	return FractionalTranslation(
	translation: secondaryTranslationAnimation.value,
	child: child,
	);
	},
	),
	);
	},
	);
	}
	}

	// Zooms and fades a new page in, zooming out the previous page. This transition
	// is designed to match the Android 10 activity transition.
	class _ZoomPageTransition extends StatefulWidget {
	const _ZoomPageTransition({
	Key key,
	this.animation,
	this.secondaryAnimation,
	this.child,
	}) : super(key: key);

	// The scrim obscures the old page by becoming increasingly opaque.
	static final Tween<double> _scrimOpacityTween = Tween<double>(
	begin: 0.0,
	end: 0.60,
	);

	// A curve sequence that is similar to the 'fastOutExtraSlowIn' curve used in
	// the native transition.
	static final List<TweenSequenceItem<double>> fastOutExtraSlowInTweenSequenceItems = <TweenSequenceItem<double>>[
	TweenSequenceItem<double>(
	tween: Tween<double>(begin: 0.0, end: 0.4)
	.chain(CurveTween(curve: const Cubic(0.05, 0.0, 0.133333, 0.06))),
	weight: 0.166666,
	),
	TweenSequenceItem<double>(
	tween: Tween<double>(begin: 0.4, end: 1.0)
	.chain(CurveTween(curve: const Cubic(0.208333, 0.82, 0.25, 1.0))),
	weight: 1.0 - 0.166666,
	),
	];
	static final TweenSequence<double> _scaleCurveSequence = TweenSequence<double>(fastOutExtraSlowInTweenSequenceItems);
	static final FlippedTweenSequence _flippedScaleCurveSequence = FlippedTweenSequence(fastOutExtraSlowInTweenSequenceItems);

	final Animation<double> animation;
	final Animation<double> secondaryAnimation;
	final Widget child;

	@override
	__ZoomPageTransitionState createState() => __ZoomPageTransitionState();
	}

	class __ZoomPageTransitionState extends State<_ZoomPageTransition> {
	AnimationStatus _currentAnimationStatus;
	AnimationStatus _lastAnimationStatus;

	@override
	void initState() {
	super.initState();
	widget.animation.addStatusListener((AnimationStatus animationStatus) {
	_lastAnimationStatus = _currentAnimationStatus;
	_currentAnimationStatus = animationStatus;
	});
	}

	// This check ensures that the animation reverses the original animation if
	// the transition were interruped midway. This prevents a disjointed
	// experience since the reverse animation uses different fade and scaling
	// curves.
	bool get _transitionWasInterrupted {
	bool wasInProgress = false;
	bool isInProgress = false;

	switch (_currentAnimationStatus) {
	case AnimationStatus.completed:
	case AnimationStatus.dismissed:
	isInProgress = false;
	break;
	case AnimationStatus.forward:
	case AnimationStatus.reverse:
	isInProgress = true;
	break;
	}
	switch (_lastAnimationStatus) {
	case AnimationStatus.completed:
	case AnimationStatus.dismissed:
	wasInProgress = false;
	break;
	case AnimationStatus.forward:
	case AnimationStatus.reverse:
	wasInProgress = true;
	break;
	}
	return wasInProgress && isInProgress;
	}

	@override
	Widget build(BuildContext context) {
	final Animation<double> _forwardScrimOpacityAnimation = widget.animation.drive(
	_ZoomPageTransition._scrimOpacityTween
	.chain(CurveTween(curve: const Interval(0.2075, 0.4175))));

	final Animation<double> _forwardEndScreenScaleTransition = widget.animation.drive(
	Tween<double>(begin: 0.85, end: 1.00)
	.chain(_ZoomPageTransition._scaleCurveSequence));

	final Animation<double> _forwardStartScreenScaleTransition = widget.secondaryAnimation.drive(
	Tween<double>(begin: 1.00, end: 1.05)
	.chain(_ZoomPageTransition._scaleCurveSequence));

	final Animation<double> _forwardEndScreenFadeTransition = widget.animation.drive(
	Tween<double>(begin: 0.0, end: 1.00)
	.chain(CurveTween(curve: const Interval(0.125, 0.250))));

	final Animation<double> _reverseEndScreenScaleTransition = widget.secondaryAnimation.drive(
	Tween<double>(begin: 1.00, end: 1.10)
	.chain(_ZoomPageTransition._flippedScaleCurveSequence));

	final Animation<double> _reverseStartScreenScaleTransition = widget.animation.drive(
	Tween<double>(begin: 0.9, end: 1.0)
	.chain(_ZoomPageTransition._flippedScaleCurveSequence));

	final Animation<double> _reverseStartScreenFadeTransition = widget.animation.drive(
	Tween<double>(begin: 0.0, end: 1.00)
	.chain(CurveTween(curve: const Interval(1 - 0.2075, 1 - 0.0825))));

	return AnimatedBuilder(
	animation: widget.animation,
	builder: (BuildContext context, Widget child) {
	if (widget.animation.status == AnimationStatus.forward \|\| _transitionWasInterrupted) {
	return Container(
	color: Colors.black.withOpacity(_forwardScrimOpacityAnimation.value),
	child: FadeTransition(
	opacity: _forwardEndScreenFadeTransition,
	child: ScaleTransition(
	scale: _forwardEndScreenScaleTransition,
	child: child,
	),
	),
	);
	} else if (widget.animation.status == AnimationStatus.reverse) {
	return ScaleTransition(
	scale: _reverseStartScreenScaleTransition,
	child: FadeTransition(
	opacity: _reverseStartScreenFadeTransition,
	child: child,
	),
	);
	}
	return child;
	},
	child: AnimatedBuilder(
	animation: widget.secondaryAnimation,
	builder: (BuildContext context, Widget child) {
	if (widget.secondaryAnimation.status == AnimationStatus.forward \|\| _transitionWasInterrupted) {
	return ScaleTransition(
	scale: _forwardStartScreenScaleTransition,
	child: child,
	);
	} else if (widget.secondaryAnimation.status == AnimationStatus.reverse) {
	return ScaleTransition(
	scale: _reverseEndScreenScaleTransition,
	child: child,
	);
	}
	return child;
	},
	child: widget.child,
	),
	);
	}
	}

	/// Used by [PageTransitionsTheme] to define a [MaterialPageRoute] page
	/// transition animation.
	///
	/// Apps can configure the map of builders for [ThemeData.pageTransitionsTheme]
	/// to customize the default [MaterialPageRoute] page transition animation
	/// for different platforms.
	///
	/// See also:
	///
	/// * [FadeUpwardsPageTransitionsBuilder], which defines a default page transition.
	/// * [OpenUpwardsPageTransitionsBuilder], which defines a page transition
	/// that's similar to the one provided by Android P.
	/// * [ZoomPageTransitionsBuilder], which defines a page transition similar
	/// to the one provided in Android 10.
	/// * [CupertinoPageTransitionsBuilder], which defines a horizontal page
	/// transition that matches native iOS page transitions.
	abstract class PageTransitionsBuilder {
	/// Abstract const constructor. This constructor enables subclasses to provide
	/// const constructors so that they can be used in const expressions.
	const PageTransitionsBuilder();

	/// Wraps the child with one or more transition widgets which define how [route]
	/// arrives on and leaves the screen.
	///
	/// The [MaterialPageRoute.buildTransitions] method looks up the current
	/// current [PageTransitionsTheme] with `Theme.of(context).pageTransitionsTheme`
	/// and delegates to this method with a [PageTransitionsBuilder] based
	/// on the theme's [ThemeData.platform].
	Widget buildTransitions<T>(
	PageRoute<T> route,
	BuildContext context,
	Animation<double> animation,
	Animation<double> secondaryAnimation,
	Widget child,
	);
	}

	/// Used by [PageTransitionsTheme] to define a default [MaterialPageRoute] page
	/// transition animation.
	///
	/// The default animation fades the new page in while translating it upwards,
	/// starting from about 25% below the top of the screen.
	///
	/// See also:
	///
	/// * [OpenUpwardsPageTransitionsBuilder], which defines a page transition
	/// that's similar to the one provided by Android P.
	/// * [ZoomPageTransitionsBuilder], which defines a page transition similar
	/// to the one provided in Android 10.
	/// * [CupertinoPageTransitionsBuilder], which defines a horizontal page
	/// transition that matches native iOS page transitions.
	class FadeUpwardsPageTransitionsBuilder extends PageTransitionsBuilder {
	/// Construct a [FadeUpwardsPageTransitionsBuilder].
	const FadeUpwardsPageTransitionsBuilder();

	@override
	Widget buildTransitions<T>(
	PageRoute<T> route,
	BuildContext context,
	Animation<double> animation,
	Animation<double> secondaryAnimation,
	Widget child,
	) {
	return _FadeUpwardsPageTransition(routeAnimation: animation, child: child);
	}
	}

	/// Used by [PageTransitionsTheme] to define a vertical [MaterialPageRoute] page
	/// transition animation that looks like the default page transition
	/// used on Android P.
	///
	/// See also:
	///
	/// * [FadeUpwardsPageTransitionsBuilder], which defines a default page transition.
	/// * [ZoomPageTransitionsBuilder], which defines a page transition similar
	/// to the one provided in Android 10.
	/// * [CupertinoPageTransitionsBuilder], which defines a horizontal page
	/// transition that matches native iOS page transitions.
	class OpenUpwardsPageTransitionsBuilder extends PageTransitionsBuilder {
	/// Construct a [OpenUpwardsPageTransitionsBuilder].
	const OpenUpwardsPageTransitionsBuilder();

	@override
	Widget buildTransitions<T>(
	PageRoute<T> route,
	BuildContext context,
	Animation<double> animation,
	Animation<double> secondaryAnimation,
	Widget child,
	) {
	return _OpenUpwardsPageTransition(
	animation: animation,
	secondaryAnimation: secondaryAnimation,
	child: child,
	);
	}
	}

	/// Used by [PageTransitionsTheme] to define a zooming [MaterialPageRoute] page
	/// transition animation that looks like the default page transition used on
	/// Android 10.
	///
	/// See also:
	///
	/// * [FadeUpwardsPageTransitionsBuilder], which defines a default page transition.
	/// * [OpenUpwardsPageTransitionsBuilder], which defines a page transition
	/// similar to the one provided by Android P.
	/// * [CupertinoPageTransitionsBuilder], which defines a horizontal page
	/// transition that matches native iOS page transitions.
	class ZoomPageTransitionsBuilder extends PageTransitionsBuilder {
	/// Construct a [ZoomPageTransitionsBuilder].
	const ZoomPageTransitionsBuilder();

	@override
	Widget buildTransitions<T>(
	PageRoute<T> route,
	BuildContext context,
	Animation<double> animation,
	Animation<double> secondaryAnimation,
	Widget child,
	) {
	return _ZoomPageTransition(
	animation: animation,
	secondaryAnimation: secondaryAnimation,
	child: child,
	);
	}
	}

	/// Used by [PageTransitionsTheme] to define a horizontal [MaterialPageRoute]
	/// page transition animation that matches native iOS page transitions.
	///
	/// See also:
	///
	/// * [FadeUpwardsPageTransitionsBuilder], which defines a default page transition.
	/// * [OpenUpwardsPageTransitionsBuilder], which defines a page transition
	/// that's similar to the one provided by Android P.
	/// * [ZoomPageTransitionsBuilder], which defines a page transition similar
	/// to the one provided in Android 10.
	class CupertinoPageTransitionsBuilder extends PageTransitionsBuilder {
	/// Construct a [CupertinoPageTransitionsBuilder].
	const CupertinoPageTransitionsBuilder();

	@override
	Widget buildTransitions<T>(
	PageRoute<T> route,
	BuildContext context,
	Animation<double> animation,
	Animation<double> secondaryAnimation,
	Widget child,
	) {
	return CupertinoPageRoute.buildPageTransitions<T>(route, context, animation, secondaryAnimation, child);
	}
	}

	/// Defines the page transition animations used by [MaterialPageRoute]
	/// for different [TargetPlatform]s.
	///
	/// The [MaterialPageRoute.buildTransitions] method looks up the current
	/// current [PageTransitionsTheme] with `Theme.of(context).pageTransitionsTheme`
	/// and delegates to [buildTransitions].
	///
	/// If a builder with a matching platform is not found, then the
	/// [FadeUpwardsPageTransitionsBuilder] is used.
	///
	/// See also:
	///
	/// * [ThemeData.pageTransitionsTheme], which defines the default page
	/// transitions for the overall theme.
	/// * [FadeUpwardsPageTransitionsBuilder], which defines a default page transition.
	/// * [OpenUpwardsPageTransitionsBuilder], which defines a page transition
	/// that's similar to the one provided by Android P.
	/// * [CupertinoPageTransitionsBuilder], which defines a horizontal page
	/// transition that matches native iOS page transitions.
	@immutable
	class PageTransitionsTheme with Diagnosticable {
	/// Construct a PageTransitionsTheme.
	///
	/// By default the list of builders is: [FadeUpwardsPageTransitionsBuilder]
	/// for [TargetPlatform.android], and [CupertinoPageTransitionsBuilder] for
	/// [TargetPlatform.iOS] and [TargetPlatform.macOS].
	const PageTransitionsTheme({ Map<TargetPlatform, PageTransitionsBuilder> builders }) : _builders = builders;

	static const Map<TargetPlatform, PageTransitionsBuilder> _defaultBuilders = <TargetPlatform, PageTransitionsBuilder>{
	TargetPlatform.android: FadeUpwardsPageTransitionsBuilder(),
	TargetPlatform.iOS: CupertinoPageTransitionsBuilder(),
	TargetPlatform.linux: FadeUpwardsPageTransitionsBuilder(),
	TargetPlatform.macOS: CupertinoPageTransitionsBuilder(),
	TargetPlatform.windows: FadeUpwardsPageTransitionsBuilder(),
	};

	/// The [PageTransitionsBuilder]s supported by this theme.
	Map<TargetPlatform, PageTransitionsBuilder> get builders => _builders ?? _defaultBuilders;
	final Map<TargetPlatform, PageTransitionsBuilder> _builders;

	/// Delegates to the builder for the current [ThemeData.platform]
	/// or [FadeUpwardsPageTransitionsBuilder].
	///
	/// [MaterialPageRoute.buildTransitions] delegates to this method.
	Widget buildTransitions<T>(
	PageRoute<T> route,
	BuildContext context,
	Animation<double> animation,
	Animation<double> secondaryAnimation,
	Widget child,
	) {
	TargetPlatform platform = Theme.of(context).platform;

	if (CupertinoPageRoute.isPopGestureInProgress(route))
	platform = TargetPlatform.iOS;

	final PageTransitionsBuilder matchingBuilder =
	builders[platform] ?? const FadeUpwardsPageTransitionsBuilder();
	return matchingBuilder.buildTransitions<T>(route, context, animation, secondaryAnimation, child);
	}

	// Just used to the builders Map to a list with one PageTransitionsBuilder per platform
	// for the operator == overload.
	List<PageTransitionsBuilder> _all(Map<TargetPlatform, PageTransitionsBuilder> builders) {
	return TargetPlatform.values.map((TargetPlatform platform) => builders[platform]).toList();
	}

	@override
	bool operator ==(Object other) {
	if (identical(this, other))
	return true;
	if (other.runtimeType != runtimeType)
	return false;
	if (other is PageTransitionsTheme && identical(builders, other.builders))
	return true;
	return other is PageTransitionsTheme
	&& listEquals<PageTransitionsBuilder>(_all(other.builders), _all(builders));
	}

	@override
	int get hashCode => hashList(_all(builders));

	@override
	void debugFillProperties(DiagnosticPropertiesBuilder properties) {
	super.debugFillProperties(properties);
	properties.add(
	DiagnosticsProperty<Map<TargetPlatform, PageTransitionsBuilder>>(
	'builders',
	builders,
	defaultValue: PageTransitionsTheme._defaultBuilders,
	),
	);
	}
	}