blob: bfa338d64d0efd38a717a7be3f878ac65fd33cfd [file] [log] [blame]
// Copyright 2015 The Chromium 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 'dart:async';
import 'package:flutter/foundation.dart';
import 'basic.dart';
import 'focus_manager.dart';
import 'focus_scope.dart';
import 'framework.dart';
import 'modal_barrier.dart';
import 'navigator.dart';
import 'overlay.dart';
import 'page_storage.dart';
import 'transitions.dart';
const Color _kTransparent = const Color(0x00000000);
/// A route that displays widgets in the [Navigator]'s [Overlay].
abstract class OverlayRoute<T> extends Route<T> {
/// Creates a route that knows how to interact with an [Overlay].
OverlayRoute({
RouteSettings settings,
}) : super(settings: settings);
/// Subclasses should override this getter to return the builders for the overlay.
Iterable<OverlayEntry> createOverlayEntries();
/// The entries this route has placed in the overlay.
@override
List<OverlayEntry> get overlayEntries => _overlayEntries;
final List<OverlayEntry> _overlayEntries = <OverlayEntry>[];
@override
void install(OverlayEntry insertionPoint) {
assert(_overlayEntries.isEmpty);
_overlayEntries.addAll(createOverlayEntries());
navigator.overlay?.insertAll(_overlayEntries, above: insertionPoint);
super.install(insertionPoint);
}
/// Controls whether [didPop] calls [NavigatorState.finalizeRoute].
///
/// If true, this route removes its overlay entries during [didPop].
/// Subclasses can override this getter if they want to delay finalization
/// (for example to animate the route's exit before removing it from the
/// overlay).
///
/// Subclasses that return false from [finishedWhenPopped] are responsible for
/// calling [NavigatorState.finalizeRoute] themselves.
@protected
bool get finishedWhenPopped => true;
@override
bool didPop(T result) {
final bool returnValue = super.didPop(result);
assert(returnValue);
if (finishedWhenPopped)
navigator.finalizeRoute(this);
return returnValue;
}
@override
void dispose() {
for (OverlayEntry entry in _overlayEntries)
entry.remove();
_overlayEntries.clear();
super.dispose();
}
}
/// A route with entrance and exit transitions.
abstract class TransitionRoute<T> extends OverlayRoute<T> {
/// Creates a route that animates itself when it is pushed or popped.
TransitionRoute({
RouteSettings settings,
}) : super(settings: settings);
// TODO(ianh): once https://github.com/dart-lang/sdk/issues/31543 is fixed,
// this should be removed.
TransitionRoute._settings(RouteSettings settings) : super(settings: settings);
/// This future completes only once the transition itself has finished, after
/// the overlay entries have been removed from the navigator's overlay.
///
/// This future completes once the animation has been dismissed. That will be
/// after [popped], because [popped] typically completes before the animation
/// even starts, as soon as the route is popped.
Future<T> get completed => _transitionCompleter.future;
final Completer<T> _transitionCompleter = new Completer<T>();
/// The duration the transition lasts.
Duration get transitionDuration;
/// Whether the route obscures previous routes when the transition is complete.
///
/// When an opaque route's entrance transition is complete, the routes behind
/// the opaque route will not be built to save resources.
bool get opaque;
@override
bool get finishedWhenPopped => _controller.status == AnimationStatus.dismissed;
/// The animation that drives the route's transition and the previous route's
/// forward transition.
Animation<double> get animation => _animation;
Animation<double> _animation;
/// The animation controller that the route uses to drive the transitions.
///
/// The animation itself is exposed by the [animation] property.
@protected
AnimationController get controller => _controller;
AnimationController _controller;
/// Called to create the animation controller that will drive the transitions to
/// this route from the previous one, and back to the previous route from this
/// one.
AnimationController createAnimationController() {
assert(!_transitionCompleter.isCompleted, 'Cannot reuse a $runtimeType after disposing it.');
final Duration duration = transitionDuration;
assert(duration != null && duration >= Duration.zero);
return new AnimationController(
duration: duration,
debugLabel: debugLabel,
vsync: navigator,
);
}
/// Called to create the animation that exposes the current progress of
/// the transition controlled by the animation controller created by
/// [createAnimationController()].
Animation<double> createAnimation() {
assert(!_transitionCompleter.isCompleted, 'Cannot reuse a $runtimeType after disposing it.');
assert(_controller != null);
return _controller.view;
}
T _result;
void _handleStatusChanged(AnimationStatus status) {
switch (status) {
case AnimationStatus.completed:
if (overlayEntries.isNotEmpty)
overlayEntries.first.opaque = opaque;
break;
case AnimationStatus.forward:
case AnimationStatus.reverse:
if (overlayEntries.isNotEmpty)
overlayEntries.first.opaque = false;
break;
case AnimationStatus.dismissed:
assert(!overlayEntries.first.opaque);
// We might still be the current route if a subclass is controlling the
// the transition and hits the dismissed status. For example, the iOS
// back gesture drives this animation to the dismissed status before
// popping the navigator.
if (!isCurrent) {
navigator.finalizeRoute(this);
assert(overlayEntries.isEmpty);
}
break;
}
changedInternalState();
}
/// The animation for the route being pushed on top of this route. This
/// animation lets this route coordinate with the entrance and exit transition
/// of routes pushed on top of this route.
Animation<double> get secondaryAnimation => _secondaryAnimation;
final ProxyAnimation _secondaryAnimation = new ProxyAnimation(kAlwaysDismissedAnimation);
@override
void install(OverlayEntry insertionPoint) {
assert(!_transitionCompleter.isCompleted, 'Cannot install a $runtimeType after disposing it.');
_controller = createAnimationController();
assert(_controller != null, '$runtimeType.createAnimationController() returned null.');
_animation = createAnimation();
assert(_animation != null, '$runtimeType.createAnimation() returned null.');
super.install(insertionPoint);
}
@override
TickerFuture didPush() {
assert(_controller != null, '$runtimeType.didPush called before calling install() or after calling dispose().');
assert(!_transitionCompleter.isCompleted, 'Cannot reuse a $runtimeType after disposing it.');
_animation.addStatusListener(_handleStatusChanged);
return _controller.forward();
}
@override
void didReplace(Route<dynamic> oldRoute) {
assert(_controller != null, '$runtimeType.didReplace called before calling install() or after calling dispose().');
assert(!_transitionCompleter.isCompleted, 'Cannot reuse a $runtimeType after disposing it.');
if (oldRoute is TransitionRoute)
_controller.value = oldRoute._controller.value;
_animation.addStatusListener(_handleStatusChanged);
super.didReplace(oldRoute);
}
@override
bool didPop(T result) {
assert(_controller != null, '$runtimeType.didPop called before calling install() or after calling dispose().');
assert(!_transitionCompleter.isCompleted, 'Cannot reuse a $runtimeType after disposing it.');
_result = result;
_controller.reverse();
return super.didPop(result);
}
@override
void didPopNext(Route<dynamic> nextRoute) {
assert(_controller != null, '$runtimeType.didPopNext called before calling install() or after calling dispose().');
assert(!_transitionCompleter.isCompleted, 'Cannot reuse a $runtimeType after disposing it.');
_updateSecondaryAnimation(nextRoute);
super.didPopNext(nextRoute);
}
@override
void didChangeNext(Route<dynamic> nextRoute) {
assert(_controller != null, '$runtimeType.didChangeNext called before calling install() or after calling dispose().');
assert(!_transitionCompleter.isCompleted, 'Cannot reuse a $runtimeType after disposing it.');
_updateSecondaryAnimation(nextRoute);
super.didChangeNext(nextRoute);
}
void _updateSecondaryAnimation(Route<dynamic> nextRoute) {
if (nextRoute is TransitionRoute<dynamic> && canTransitionTo(nextRoute) && nextRoute.canTransitionFrom(this)) {
final Animation<double> current = _secondaryAnimation.parent;
if (current != null) {
if (current is TrainHoppingAnimation) {
TrainHoppingAnimation newAnimation;
newAnimation = new TrainHoppingAnimation(
current.currentTrain,
nextRoute._animation,
onSwitchedTrain: () {
assert(_secondaryAnimation.parent == newAnimation);
assert(newAnimation.currentTrain == nextRoute._animation);
_secondaryAnimation.parent = newAnimation.currentTrain;
newAnimation.dispose();
}
);
_secondaryAnimation.parent = newAnimation;
current.dispose();
} else {
_secondaryAnimation.parent = new TrainHoppingAnimation(current, nextRoute._animation);
}
} else {
_secondaryAnimation.parent = nextRoute._animation;
}
} else {
_secondaryAnimation.parent = kAlwaysDismissedAnimation;
}
}
/// Whether this route can perform a transition to the given route.
///
/// Subclasses can override this method to restrict the set of routes they
/// need to coordinate transitions with.
bool canTransitionTo(TransitionRoute<dynamic> nextRoute) => true;
/// Whether this route can perform a transition from the given route.
///
/// Subclasses can override this method to restrict the set of routes they
/// need to coordinate transitions with.
bool canTransitionFrom(TransitionRoute<dynamic> previousRoute) => true;
@override
void dispose() {
assert(!_transitionCompleter.isCompleted, 'Cannot dispose a $runtimeType twice.');
_controller?.dispose();
_transitionCompleter.complete(_result);
super.dispose();
}
/// A short description of this route useful for debugging.
String get debugLabel => '$runtimeType';
@override
String toString() => '$runtimeType(animation: $_controller)';
}
/// An entry in the history of a [LocalHistoryRoute].
class LocalHistoryEntry {
/// Creates an entry in the history of a [LocalHistoryRoute].
LocalHistoryEntry({ this.onRemove });
/// Called when this entry is removed from the history of its associated [LocalHistoryRoute].
final VoidCallback onRemove;
LocalHistoryRoute<dynamic> _owner;
/// Remove this entry from the history of its associated [LocalHistoryRoute].
void remove() {
_owner.removeLocalHistoryEntry(this);
assert(_owner == null);
}
void _notifyRemoved() {
if (onRemove != null)
onRemove();
}
}
/// A route that can handle back navigations internally by popping a list.
///
/// When a [Navigator] is instructed to pop, the current route is given an
/// opportunity to handle the pop internally. A LocalHistoryRoute handles the
/// pop internally if its list of local history entries is non-empty. Rather
/// than being removed as the current route, the most recent [LocalHistoryEntry]
/// is removed from the list and its [LocalHistoryEntry.onRemove] is called.
///
/// This class is typically used as a mixin.
abstract class LocalHistoryRoute<T> extends Route<T> {
List<LocalHistoryEntry> _localHistory;
/// Adds a local history entry to this route.
///
/// When asked to pop, if this route has any local history entries, this route
/// will handle the pop internally by removing the most recently added local
/// history entry.
///
/// The given local history entry must not already be part of another local
/// history route.
void addLocalHistoryEntry(LocalHistoryEntry entry) {
assert(entry._owner == null);
entry._owner = this;
_localHistory ??= <LocalHistoryEntry>[];
final bool wasEmpty = _localHistory.isEmpty;
_localHistory.add(entry);
if (wasEmpty)
changedInternalState();
}
/// Remove a local history entry from this route.
///
/// The entry's [LocalHistoryEntry.onRemove] callback, if any, will be called
/// synchronously.
void removeLocalHistoryEntry(LocalHistoryEntry entry) {
assert(entry != null);
assert(entry._owner == this);
assert(_localHistory.contains(entry));
_localHistory.remove(entry);
entry._owner = null;
entry._notifyRemoved();
if (_localHistory.isEmpty)
changedInternalState();
}
@override
Future<RoutePopDisposition> willPop() async {
if (willHandlePopInternally)
return RoutePopDisposition.pop;
return await super.willPop();
}
@override
bool didPop(T result) {
if (_localHistory != null && _localHistory.isNotEmpty) {
final LocalHistoryEntry entry = _localHistory.removeLast();
assert(entry._owner == this);
entry._owner = null;
entry._notifyRemoved();
if (_localHistory.isEmpty)
changedInternalState();
return false;
}
return super.didPop(result);
}
@override
bool get willHandlePopInternally {
return _localHistory != null && _localHistory.isNotEmpty;
}
}
class _ModalScopeStatus extends InheritedWidget {
const _ModalScopeStatus({
Key key,
@required this.isCurrent,
@required this.canPop,
@required this.route,
@required Widget child
}) : assert(isCurrent != null),
assert(canPop != null),
assert(route != null),
assert(child != null),
super(key: key, child: child);
final bool isCurrent;
final bool canPop;
final Route<dynamic> route;
@override
bool updateShouldNotify(_ModalScopeStatus old) {
return isCurrent != old.isCurrent ||
canPop != old.canPop ||
route != old.route;
}
@override
void debugFillProperties(DiagnosticPropertiesBuilder description) {
super.debugFillProperties(description);
description.add(new FlagProperty('isCurrent', value: isCurrent, ifTrue: 'active', ifFalse: 'inactive'));
description.add(new FlagProperty('canPop', value: canPop, ifTrue: 'can pop'));
}
}
class _ModalScope<T> extends StatefulWidget {
const _ModalScope({
Key key,
this.route,
}) : super(key: key);
final ModalRoute<T> route;
@override
_ModalScopeState<T> createState() => new _ModalScopeState<T>();
}
class _ModalScopeState<T> extends State<_ModalScope<T>> {
// We cache the result of calling the route's buildPage, and clear the cache
// whenever the dependencies change. This implements the contract described in
// the documentation for buildPage, namely that it gets called once, unless
// something like a ModalRoute.of() dependency triggers an update.
Widget _page;
// This is the combination of the two animations for the route.
Listenable _listenable;
@override
void initState() {
super.initState();
final List<Listenable> animations = <Listenable>[];
if (widget.route.animation != null)
animations.add(widget.route.animation);
if (widget.route.secondaryAnimation != null)
animations.add(widget.route.secondaryAnimation);
_listenable = new Listenable.merge(animations);
}
@override
void didUpdateWidget(_ModalScope<T> oldWidget) {
super.didUpdateWidget(oldWidget);
assert(widget.route == oldWidget.route);
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
_page = null;
}
void _forceRebuildPage() {
setState(() {
_page = null;
});
}
// This should be called to wrap any changes to route.isCurrent, route.canPop,
// and route.offstage.
void _routeSetState(VoidCallback fn) {
setState(fn);
}
@override
Widget build(BuildContext context) {
return new _ModalScopeStatus(
route: widget.route,
isCurrent: widget.route.isCurrent, // _routeSetState is called if this updates
canPop: widget.route.canPop, // _routeSetState is called if this updates
child: new Offstage(
offstage: widget.route.offstage, // _routeSetState is called if this updates
child: new PageStorage(
bucket: widget.route._storageBucket, // immutable
child: new FocusScope(
node: widget.route.focusScopeNode, // immutable
child: new RepaintBoundary(
child: new AnimatedBuilder(
animation: _listenable, // immutable
builder: (BuildContext context, Widget child) {
return widget.route.buildTransitions(
context,
widget.route.animation,
widget.route.secondaryAnimation,
new IgnorePointer(
ignoring: widget.route.animation?.status == AnimationStatus.reverse,
child: child,
),
);
},
child: _page ??= new RepaintBoundary(
key: widget.route._subtreeKey, // immutable
child: new Builder(
builder: (BuildContext context) {
return widget.route.buildPage(
context,
widget.route.animation,
widget.route.secondaryAnimation,
);
},
),
),
),
),
),
),
),
);
}
}
/// A route that blocks interaction with previous routes.
///
/// [ModalRoute]s cover the entire [Navigator]. They are not necessarily
/// [opaque], however; for example, a pop-up menu uses a [ModalRoute] but only
/// shows the menu in a small box overlapping the previous route.
///
/// The `T` type argument is the return value of the route. If there is no
/// return value, consider using `void` as the return value.
abstract class ModalRoute<T> extends TransitionRoute<T> with LocalHistoryRoute<T> {
/// Creates a route that blocks interaction with previous routes.
ModalRoute({
RouteSettings settings,
}) : super._settings(settings);
// The API for general users of this class
/// Returns the modal route most closely associated with the given context.
///
/// Returns null if the given context is not associated with a modal route.
///
/// Typical usage is as follows:
///
/// ```dart
/// ModalRoute route = ModalRoute.of(context);
/// ```
///
/// The given [BuildContext] will be rebuilt if the state of the route changes
/// (specifically, if [isCurrent] or [canPop] change value).
static ModalRoute<T> of<T extends Object>(BuildContext context) {
final _ModalScopeStatus widget = context.inheritFromWidgetOfExactType(_ModalScopeStatus);
return widget?.route;
}
/// Schedule a call to [buildTransitions].
///
/// Whenever you need to change internal state for a [ModalRoute] object, make
/// the change in a function that you pass to [setState], as in:
///
/// ```dart
/// setState(() { myState = newValue });
/// ```
///
/// If you just change the state directly without calling [setState], then the
/// route will not be scheduled for rebuilding, meaning that its rendering
/// will not be updated.
@protected
void setState(VoidCallback fn) {
if (_scopeKey.currentState != null) {
_scopeKey.currentState._routeSetState(fn);
} else {
// The route isn't currently visible, so we don't have to call its setState
// method, but we do still need to call the fn callback, otherwise the state
// in the route won't be updated!
fn();
}
}
/// Returns a predicate that's true if the route has the specified name and if
/// popping the route will not yield the same route, i.e. if the route's
/// [willHandlePopInternally] property is false.
///
/// This function is typically used with [Navigator.popUntil()].
static RoutePredicate withName(String name) {
return (Route<dynamic> route) {
return !route.willHandlePopInternally
&& route is ModalRoute
&& route.settings.name == name;
};
}
// The API for subclasses to override - used by _ModalScope
/// Override this method to build the primary content of this route.
///
/// The arguments have the following meanings:
///
/// * `context`: The context in which the route is being built.
/// * [animation]: The animation for this route's transition. When entering,
/// the animation runs forward from 0.0 to 1.0. When exiting, this animation
/// runs backwards from 1.0 to 0.0.
/// * [secondaryAnimation]: The animation for the route being pushed on top of
/// this route. This animation lets this route coordinate with the entrance
/// and exit transition of routes pushed on top of this route.
///
/// This method is only called when the route is first built, and rarely
/// thereafter. In particular, it is not automatically called again when the
/// route's state changes unless it uses [ModalRoute.of]. For a builder that
/// is called every time the route's state changes, consider
/// [buildTransitions]. For widgets that change their behavior when the
/// route's state changes, consider [ModalRoute.of] to obtain a reference to
/// the route; this will cause the widget to be rebuilt each time the route
/// changes state.
///
/// In general, [buildPage] should be used to build the page contents, and
/// [buildTransitions] for the widgets that change as the page is brought in
/// and out of view. Avoid using [buildTransitions] for content that never
/// changes; building such content once from [buildPage] is more efficient.
Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation);
/// Override this method to wrap the [child] with one or more transition
/// widgets that define how the route arrives on and leaves the screen.
///
/// By default, the child (which contains the widget returned by [buildPage])
/// is not wrapped in any transition widgets.
///
/// The [buildTransitions] method, in contrast to [buildPage], is called each
/// time the [Route]'s state changes (e.g. the value of [canPop]).
///
/// The [buildTransitions] method is typically used to define transitions
/// that animate the new topmost route's comings and goings. When the
/// [Navigator] pushes a route on the top of its stack, the new route's
/// primary [animation] runs from 0.0 to 1.0. When the Navigator pops the
/// topmost route, e.g. because the use pressed the back button, the
/// primary animation runs from 1.0 to 0.0.
///
/// The following example uses the primary animation to drive a
/// [SlideTransition] that translates the top of the new route vertically
/// from the bottom of the screen when it is pushed on the Navigator's
/// stack. When the route is popped the SlideTransition translates the
/// route from the top of the screen back to the bottom.
///
/// ```dart
/// new PageRouteBuilder(
/// pageBuilder: (BuildContext context,
/// Animation<double> animation,
/// Animation<double> secondaryAnimation,
/// Widget child,
/// ) {
/// return new Scaffold(
/// appBar: new AppBar(title: new Text('Hello')),
/// body: new Center(
/// child: new Text('Hello World'),
/// ),
/// );
/// },
/// transitionsBuilder: (
/// BuildContext context,
/// Animation<double> animation,
/// Animation<double> secondaryAnimation,
/// Widget child,
/// ) {
/// return new SlideTransition(
/// position: new Tween<Offset>(
/// begin: const Offset(0.0, 1.0),
/// end: Offset.zero,
/// ).animate(animation),
/// child: child, // child is the value returned by pageBuilder
/// );
/// },
/// );
///```
///
/// We've used [PageRouteBuilder] to demonstrate the [buildTransitions] method
/// here. The body of an override of the [buildTransitions] method would be
/// defined in the same way.
///
/// When the [Navigator] pushes a route on the top of its stack, the
/// [secondaryAnimation] can be used to define how the route that was on
/// the top of the stack leaves the screen. Similarly when the topmost route
/// is popped, the secondaryAnimation can be used to define how the route
/// below it reappears on the screen. When the Navigator pushes a new route
/// on the top of its stack, the old topmost route's secondaryAnimation
/// runs from 0.0 to 1.0. When the Navigator pops the topmost route, the
/// secondaryAnimation for the route below it runs from 1.0 to 0.0.
///
/// The example below adds a transition that's driven by the
/// [secondaryAnimation]. When this route disappears because a new route has
/// been pushed on top of it, it translates in the opposite direction of
/// the new route. Likewise when the route is exposed because the topmost
/// route has been popped off.
///
/// ```dart
/// transitionsBuilder: (
/// BuildContext context,
/// Animation<double> animation,
/// Animation<double> secondaryAnimation,
/// Widget child,
/// ) {
/// return new SlideTransition(
/// position: new AlignmentTween(
/// begin: const Offset(0.0, 1.0),
/// end: Offset.zero,
/// ).animate(animation),
/// child: new SlideTransition(
/// position: new TweenOffset(
/// begin: Offset.zero,
/// end: const Offset(0.0, 1.0),
/// ).animate(secondaryAnimation),
/// child: child,
/// ),
/// );
/// }
/// ```
///
/// In practice the `secondaryAnimation` is used pretty rarely.
///
/// The arguments to this method are as follows:
///
/// * `context`: The context in which the route is being built.
/// * [animation]: When the [Navigator] pushes a route on the top of its stack,
/// the new route's primary [animation] runs from 0.0 to 1.0. When the [Navigator]
/// pops the topmost route this animation runs from 1.0 to 0.0.
/// * [secondaryAnimation]: When the Navigator pushes a new route
/// on the top of its stack, the old topmost route's [secondaryAnimation]
/// runs from 0.0 to 1.0. When the [Navigator] pops the topmost route, the
/// [secondaryAnimation] for the route below it runs from 1.0 to 0.0.
/// * `child`, the page contents, as returned by [buildPage].
///
/// See also:
///
/// * [buildPage], which is used to describe the actual contents of the page,
/// and whose result is passed to the `child` argument of this method.
Widget buildTransitions(
BuildContext context,
Animation<double> animation,
Animation<double> secondaryAnimation,
Widget child,
) {
return child;
}
/// The node this route will use for its root [FocusScope] widget.
final FocusScopeNode focusScopeNode = new FocusScopeNode();
@override
void install(OverlayEntry insertionPoint) {
super.install(insertionPoint);
_animationProxy = new ProxyAnimation(super.animation);
_secondaryAnimationProxy = new ProxyAnimation(super.secondaryAnimation);
}
@override
TickerFuture didPush() {
navigator.focusScopeNode.setFirstFocus(focusScopeNode);
return super.didPush();
}
@override
void dispose() {
focusScopeNode.detach();
super.dispose();
}
// The API for subclasses to override - used by this class
/// Whether you can dismiss this route by tapping the modal barrier.
///
/// The modal barrier is the scrim that is rendered behind each route, which
/// generally prevents the user from interacting with the route below the
/// current route, and normally partially obscures such routes.
///
/// For example, when a dialog is on the screen, the page below the dialog is
/// usually darkened by the modal barrier.
///
/// If [barrierDismissible] is true, then tapping this barrier will cause the
/// current route to be popped (see [Navigator.pop]) with null as the value.
///
/// If [barrierDismissible] is false, then tapping the barrier has no effect.
///
/// If this getter would ever start returning a different color,
/// [changedInternalState] should be invoked so that the change can take
/// effect.
///
/// See also:
///
/// * [barrierColor], which controls the color of the scrim for this route.
/// * [ModalBarrier], the widget that implements this feature.
bool get barrierDismissible;
/// The color to use for the modal barrier. If this is null, the barrier will
/// be transparent.
///
/// The modal barrier is the scrim that is rendered behind each route, which
/// generally prevents the user from interacting with the route below the
/// current route, and normally partially obscures such routes.
///
/// For example, when a dialog is on the screen, the page below the dialog is
/// usually darkened by the modal barrier.
///
/// The color is ignored, and the barrier made invisible, when [offstage] is
/// true.
///
/// While the route is animating into position, the color is animated from
/// transparent to the specified color.
///
/// If this getter would ever start returning a different color,
/// [changedInternalState] should be invoked so that the change can take
/// effect.
///
/// See also:
///
/// * [barrierDismissible], which controls the behavior of the barrier when
/// tapped.
/// * [ModalBarrier], the widget that implements this feature.
Color get barrierColor;
/// The semantic label used for a dismissible barrier.
///
/// If the barrier is dismissible, this label will be read out if
/// accessibility tools (like VoiceOver on iOS) focus on the barrier.
///
/// The modal barrier is the scrim that is rendered behind each route, which
/// generally prevents the user from interacting with the route below the
/// current route, and normally partially obscures such routes.
///
/// For example, when a dialog is on the screen, the page below the dialog is
/// usually darkened by the modal barrier.
///
/// If this getter would ever start returning a different color,
/// [changedInternalState] should be invoked so that the change can take
/// effect.
///
/// See also:
///
/// * [barrierDismissible], which controls the behavior of the barrier when
/// tapped.
/// * [ModalBarrier], the widget that implements this feature.
String get barrierLabel;
/// Whether the route should remain in memory when it is inactive.
///
/// If this is true, then the route is maintained, so that any futures it is
/// holding from the next route will properly resolve when the next route
/// pops. If this is not necessary, this can be set to false to allow the
/// framework to entirely discard the route's widget hierarchy when it is not
/// visible.
///
/// The value of this getter should not change during the lifetime of the
/// object. It is used by [createOverlayEntries], which is called by
/// [install] near the beginning of the route lifecycle.
bool get maintainState;
// The API for _ModalScope and HeroController
/// Whether this route is currently offstage.
///
/// On the first frame of a route's entrance transition, the route is built
/// [Offstage] using an animation progress of 1.0. The route is invisible and
/// non-interactive, but each widget has its final size and position. This
/// mechanism lets the [HeroController] determine the final local of any hero
/// widgets being animated as part of the transition.
///
/// The modal barrier, if any, is not rendered if [offstage] is true (see
/// [barrierColor]).
bool get offstage => _offstage;
bool _offstage = false;
set offstage(bool value) {
if (_offstage == value)
return;
setState(() {
_offstage = value;
});
_animationProxy.parent = _offstage ? kAlwaysCompleteAnimation : super.animation;
_secondaryAnimationProxy.parent = _offstage ? kAlwaysDismissedAnimation : super.secondaryAnimation;
}
/// The build context for the subtree containing the primary content of this route.
BuildContext get subtreeContext => _subtreeKey.currentContext;
@override
Animation<double> get animation => _animationProxy;
ProxyAnimation _animationProxy;
@override
Animation<double> get secondaryAnimation => _secondaryAnimationProxy;
ProxyAnimation _secondaryAnimationProxy;
final List<WillPopCallback> _willPopCallbacks = <WillPopCallback>[];
/// Returns the value of the first callback added with
/// [addScopedWillPopCallback] that returns false. If they all return true,
/// returns the inherited method's result (see [Route.willPop]).
///
/// Typically this method is not overridden because applications usually
/// don't create modal routes directly, they use higher level primitives
/// like [showDialog]. The scoped [WillPopCallback] list makes it possible
/// for ModalRoute descendants to collectively define the value of `willPop`.
///
/// See also:
///
/// * [Form], which provides an `onWillPop` callback that uses this mechanism.
/// * [addScopedWillPopCallback], which adds a callback to the list this
/// method checks.
/// * [removeScopedWillPopCallback], which removes a callback from the list
/// this method checks.
@override
Future<RoutePopDisposition> willPop() async {
final _ModalScopeState<T> scope = _scopeKey.currentState;
assert(scope != null);
for (WillPopCallback callback in new List<WillPopCallback>.from(_willPopCallbacks)) {
if (!await callback())
return RoutePopDisposition.doNotPop;
}
return await super.willPop();
}
/// Enables this route to veto attempts by the user to dismiss it.
///
/// This callback is typically added using a [WillPopScope] widget. That
/// widget finds the enclosing [ModalRoute] and uses this function to register
/// this callback:
///
/// ```dart
/// Widget build(BuildContext context) {
/// return new WillPopScope(
/// onWillPop: askTheUserIfTheyAreSure,
/// child: ...,
/// );
/// }
/// ```
///
/// This callback runs asynchronously and it's possible that it will be called
/// after its route has been disposed. The callback should check [State.mounted]
/// before doing anything.
///
/// A typical application of this callback would be to warn the user about
/// unsaved [Form] data if the user attempts to back out of the form. In that
/// case, use the [Form.onWillPop] property to register the callback.
///
/// To register a callback manually, look up the enclosing [ModalRoute] in a
/// [State.didChangeDependencies] callback:
///
/// ```dart
/// ModalRoute<dynamic> _route;
///
/// @override
/// void didChangeDependencies() {
/// super.didChangeDependencies();
/// _route?.removeScopedWillPopCallback(askTheUserIfTheyAreSure);
/// _route = ModalRoute.of(context);
/// _route?.addScopedWillPopCallback(askTheUserIfTheyAreSure);
/// }
/// ```
///
/// If you register a callback manually, be sure to remove the callback with
/// [removeScopedWillPopCallback] by the time the widget has been disposed. A
/// stateful widget can do this in its dispose method (continuing the previous
/// example):
///
/// ```dart
/// @override
/// void dispose() {
/// _route?.removeScopedWillPopCallback(askTheUserIfTheyAreSure);
/// _route = null;
/// super.dispose();
/// }
/// ```
///
/// See also:
///
/// * [WillPopScope], which manages the registration and unregistration
/// process automatically.
/// * [Form], which provides an `onWillPop` callback that uses this mechanism.
/// * [willPop], which runs the callbacks added with this method.
/// * [removeScopedWillPopCallback], which removes a callback from the list
/// that [willPop] checks.
void addScopedWillPopCallback(WillPopCallback callback) {
assert(_scopeKey.currentState != null, 'Tried to add a willPop callback to a route that is not currently in the tree.');
_willPopCallbacks.add(callback);
}
/// Remove one of the callbacks run by [willPop].
///
/// See also:
///
/// * [Form], which provides an `onWillPop` callback that uses this mechanism.
/// * [addScopedWillPopCallback], which adds callback to the list
/// checked by [willPop].
void removeScopedWillPopCallback(WillPopCallback callback) {
assert(_scopeKey.currentState != null, 'Tried to remove a willPop callback from a route that is not currently in the tree.');
_willPopCallbacks.remove(callback);
}
/// True if one or more [WillPopCallback] callbacks exist.
///
/// This method is used to disable the horizontal swipe pop gesture
/// supported by [MaterialPageRoute] for [TargetPlatform.iOS].
/// If a pop might be vetoed, then the back gesture is disabled.
///
/// The [buildTransitions] method will not be called again if this changes,
/// since it can change during the build as descendants of the route add or
/// remove callbacks.
///
/// See also:
///
/// * [addScopedWillPopCallback], which adds a callback.
/// * [removeScopedWillPopCallback], which removes a callback.
/// * [willHandlePopInternally], which reports on another reason why
/// a pop might be vetoed.
@protected
bool get hasScopedWillPopCallback {
return _willPopCallbacks.isNotEmpty;
}
@override
void didChangePrevious(Route<dynamic> previousRoute) {
super.didChangePrevious(previousRoute);
changedInternalState();
}
@override
void changedInternalState() {
super.changedInternalState();
setState(() { /* internal state already changed */ });
_modalBarrier.markNeedsBuild();
}
@override
void changedExternalState() {
super.changedExternalState();
if (_scopeKey.currentState != null)
_scopeKey.currentState._forceRebuildPage();
}
/// Whether this route can be popped.
///
/// When this changes, the route will rebuild, and any widgets that used
/// [ModalRoute.of] will be notified.
bool get canPop => !isFirst || willHandlePopInternally;
// Internals
final GlobalKey<_ModalScopeState<T>> _scopeKey = new GlobalKey<_ModalScopeState<T>>();
final GlobalKey _subtreeKey = new GlobalKey();
final PageStorageBucket _storageBucket = new PageStorageBucket();
// one of the builders
OverlayEntry _modalBarrier;
Widget _buildModalBarrier(BuildContext context) {
Widget barrier;
if (barrierColor != null && !offstage) { // changedInternalState is called if these update
assert(barrierColor != _kTransparent);
final Animation<Color> color = new ColorTween(
begin: _kTransparent,
end: barrierColor, // changedInternalState is called if this updates
).animate(new CurvedAnimation(
parent: animation,
curve: Curves.ease,
));
barrier = new AnimatedModalBarrier(
color: color,
dismissible: barrierDismissible, // changedInternalState is called if this updates
semanticsLabel: barrierLabel, // changedInternalState is called if this updates
);
} else {
barrier = new ModalBarrier(
dismissible: barrierDismissible, // changedInternalState is called if this updates
semanticsLabel: barrierLabel, // changedInternalState is called if this updates
);
}
return new IgnorePointer(
ignoring: animation.status == AnimationStatus.reverse || // changedInternalState is called when this updates
animation.status == AnimationStatus.dismissed, // dismissed is possible when doing a manual pop gesture
child: barrier,
);
}
// We cache the part of the modal scope that doesn't change from frame to
// frame so that we minimize the amount of building that happens.
Widget _modalScopeCache;
// one of the builders
Widget _buildModalScope(BuildContext context) {
return _modalScopeCache ??= new _ModalScope<T>(
key: _scopeKey,
route: this,
// _ModalScope calls buildTransitions() and buildChild(), defined above
);
}
@override
Iterable<OverlayEntry> createOverlayEntries() sync* {
yield _modalBarrier = new OverlayEntry(builder: _buildModalBarrier);
yield new OverlayEntry(builder: _buildModalScope, maintainState: maintainState);
}
@override
String toString() => '$runtimeType($settings, animation: $_animation)';
}
/// A modal route that overlays a widget over the current route.
abstract class PopupRoute<T> extends ModalRoute<T> {
/// Initializes the [PopupRoute].
PopupRoute({
RouteSettings settings,
}) : super(settings: settings);
@override
bool get opaque => false;
@override
bool get maintainState => true;
}
/// A [Navigator] observer that notifies [RouteAware]s of changes to the
/// state of their [Route].
///
/// [RouteObserver] informs subscribers whenever a route of type `R` is pushed
/// on top of their own route of type `R` or popped from it. This is for example
/// useful to keep track of page transitions, e.g. a `RouteObserver<PageRoute>`
/// will inform subscribed [RouteAware]s whenever the user navigates away from
/// the current page route to another page route.
///
/// To be informed about route changes of any type, consider instantiating a
/// `RouteObserver<Route>`.
///
/// ## Type arguments
///
/// When using more aggressive
/// [lints](http://dart-lang.github.io/linter/lints/), in particular lints such
/// as `always_specify_types`, the Dart analyzer will require that certain types
/// be given with their type arguments. Since the [Route] class and its
/// subclasses have a type argument, this includes the arguments passed to this
/// class. Consider using `dynamic` to specify the entire class of routes rather
/// than only specific subtypes. For example, to watch for all [PageRoute]
/// variants, the `RouteObserver<PageRoute<dynamic>>` type may be used.
///
/// ## Sample code
///
/// To make a [StatefulWidget] aware of its current [Route] state, implement
/// [RouteAware] in its [State] and subscribe it to a [RouteObserver]:
///
/// ```dart
/// // Register the RouteObserver as a navigation observer.
/// final RouteObserver<PageRoute> routeObserver = new RouteObserver<PageRoute>();
/// void main() {
/// runApp(new MaterialApp(
/// home: new Container(),
/// navigatorObservers: [routeObserver],
/// ));
/// }
///
/// class RouteAwareWidget extends StatefulWidget {
/// State<RouteAwareWidget> createState() => new RouteAwareWidgetState();
/// }
///
/// // Implement RouteAware in a widget's state and subscribe it to the RouteObserver.
/// class RouteAwareWidgetState extends State<RouteAwareWidget> with RouteAware {
///
/// @override
/// void didChangeDependencies() {
/// super.didChangeDependencies();
/// routeObserver.subscribe(this, ModalRoute.of(context));
/// }
///
/// @override
/// void dispose() {
/// routeObserver.unsubscribe(this);
/// super.dispose();
/// }
///
/// @override
/// void didPush() {
/// // Route was pushed onto navigator and is now topmost route.
/// }
///
/// @override
/// void didPopNext() {
/// // Covering route was popped off the navigator.
/// }
///
/// @override
/// Widget build(BuildContext context) => new Container();
///
/// }
/// ```
class RouteObserver<R extends Route<dynamic>> extends NavigatorObserver {
final Map<R, Set<RouteAware>> _listeners = <R, Set<RouteAware>>{};
/// Subscribe [routeAware] to be informed about changes to [route].
///
/// Going forward, [routeAware] will be informed about qualifying changes
/// to [route], e.g. when [route] is covered by another route or when [route]
/// is popped off the [Navigator] stack.
void subscribe(RouteAware routeAware, R route) {
assert(routeAware != null);
assert(route != null);
final Set<RouteAware> subscribers = _listeners.putIfAbsent(route, () => new Set<RouteAware>());
if (subscribers.add(routeAware)) {
routeAware.didPush();
}
}
/// Unsubscribe [routeAware].
///
/// [routeAware] is no longer informed about changes to its route. If the given argument was
/// subscribed to multiple types, this will unregister it (once) from each type.
void unsubscribe(RouteAware routeAware) {
assert(routeAware != null);
for (R route in _listeners.keys) {
final Set<RouteAware> subscribers = _listeners[route];
subscribers?.remove(routeAware);
}
}
@override
void didPop(Route<dynamic> route, Route<dynamic> previousRoute) {
if (route is R && previousRoute is R) {
final List<RouteAware> previousSubscribers = _listeners[previousRoute]?.toList();
if (previousSubscribers != null) {
for (RouteAware routeAware in previousSubscribers) {
routeAware.didPopNext();
}
}
final List<RouteAware> subscribers = _listeners[route]?.toList();
if (subscribers != null) {
for (RouteAware routeAware in subscribers) {
routeAware.didPop();
}
}
}
}
@override
void didPush(Route<dynamic> route, Route<dynamic> previousRoute) {
if (route is R && previousRoute is R) {
final Set<RouteAware> previousSubscribers = _listeners[previousRoute];
if (previousSubscribers != null) {
for (RouteAware routeAware in previousSubscribers) {
routeAware.didPushNext();
}
}
}
}
}
/// An interface for objects that are aware of their current [Route].
///
/// This is used with [RouteObserver] to make a widget aware of changes to the
/// [Navigator]'s session history.
abstract class RouteAware {
/// Called when the top route has been popped off, and the current route
/// shows up.
void didPopNext() { }
/// Called when the current route has been pushed.
void didPush() { }
/// Called when the current route has been popped off.
void didPop() { }
/// Called when a new route has been pushed, and the current route is no
/// longer visible.
void didPushNext() { }
}