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// 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 'dart:ui' as ui show lerpDouble;
import 'package:flutter/foundation.dart';
import 'package:flutter/physics.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter/semantics.dart';
import 'animation.dart';
import 'curves.dart';
import 'listener_helpers.dart';
export 'package:flutter/physics.dart' show Simulation, SpringDescription;
export 'package:flutter/scheduler.dart' show TickerFuture, TickerProvider;
export 'animation.dart' show Animation, AnimationStatus;
export 'curves.dart' show Curve;
// Examples can assume:
// late AnimationController _controller, fadeAnimationController, sizeAnimationController;
// late bool dismissed;
// void setState(VoidCallback fn) { }
/// The direction in which an animation is running.
enum _AnimationDirection {
/// The animation is running from beginning to end.
forward,
/// The animation is running backwards, from end to beginning.
reverse,
}
final SpringDescription _kFlingSpringDescription = SpringDescription.withDampingRatio(
mass: 1.0,
stiffness: 500.0,
);
const Tolerance _kFlingTolerance = Tolerance(
velocity: double.infinity,
distance: 0.01,
);
/// Configures how an [AnimationController] behaves when animations are
/// disabled.
///
/// When [AccessibilityFeatures.disableAnimations] is true, the device is asking
/// Flutter to reduce or disable animations as much as possible. To honor this,
/// we reduce the duration and the corresponding number of frames for
/// animations. This enum is used to allow certain [AnimationController]s to opt
/// out of this behavior.
///
/// For example, the [AnimationController] which controls the physics simulation
/// for a scrollable list will have [AnimationBehavior.preserve], so that when
/// a user attempts to scroll it does not jump to the end/beginning too quickly.
enum AnimationBehavior {
/// The [AnimationController] will reduce its duration when
/// [AccessibilityFeatures.disableAnimations] is true.
normal,
/// The [AnimationController] will preserve its behavior.
///
/// This is the default for repeating animations in order to prevent them from
/// flashing rapidly on the screen if the widget does not take the
/// [AccessibilityFeatures.disableAnimations] flag into account.
preserve,
}
/// A controller for an animation.
///
/// This class lets you perform tasks such as:
///
/// * Play an animation [forward] or in [reverse], or [stop] an animation.
/// * Set the animation to a specific [value].
/// * Define the [upperBound] and [lowerBound] values of an animation.
/// * Create a [fling] animation effect using a physics simulation.
///
/// By default, an [AnimationController] linearly produces values that range
/// from 0.0 to 1.0, during a given duration. The animation controller generates
/// a new value whenever the device running your app is ready to display a new
/// frame (typically, this rate is around 60 values per second).
///
/// ## Ticker providers
///
/// An [AnimationController] needs a [TickerProvider], which is configured using
/// the `vsync` argument on the constructor.
///
/// The [TickerProvider] interface describes a factory for [Ticker] objects. A
/// [Ticker] is an object that knows how to register itself with the
/// [SchedulerBinding] and fires a callback every frame. The
/// [AnimationController] class uses a [Ticker] to step through the animation
/// that it controls.
///
/// If an [AnimationController] is being created from a [State], then the State
/// can use the [TickerProviderStateMixin] and [SingleTickerProviderStateMixin]
/// classes to implement the [TickerProvider] interface. The
/// [TickerProviderStateMixin] class always works for this purpose; the
/// [SingleTickerProviderStateMixin] is slightly more efficient in the case of
/// the class only ever needing one [Ticker] (e.g. if the class creates only a
/// single [AnimationController] during its entire lifetime).
///
/// The widget test framework [WidgetTester] object can be used as a ticker
/// provider in the context of tests. In other contexts, you will have to either
/// pass a [TickerProvider] from a higher level (e.g. indirectly from a [State]
/// that mixes in [TickerProviderStateMixin]), or create a custom
/// [TickerProvider] subclass.
///
/// ## Life cycle
///
/// An [AnimationController] should be [dispose]d when it is no longer needed.
/// This reduces the likelihood of leaks. When used with a [StatefulWidget], it
/// is common for an [AnimationController] to be created in the
/// [State.initState] method and then disposed in the [State.dispose] method.
///
/// ## Using [Future]s with [AnimationController]
///
/// The methods that start animations return a [TickerFuture] object which
/// completes when the animation completes successfully, and never throws an
/// error; if the animation is canceled, the future never completes. This object
/// also has a [TickerFuture.orCancel] property which returns a future that
/// completes when the animation completes successfully, and completes with an
/// error when the animation is aborted.
///
/// This can be used to write code such as the `fadeOutAndUpdateState` method
/// below.
///
/// {@tool snippet}
///
/// Here is a stateful `Foo` widget. Its [State] uses the
/// [SingleTickerProviderStateMixin] to implement the necessary
/// [TickerProvider], creating its controller in the [State.initState] method
/// and disposing of it in the [State.dispose] method. The duration of the
/// controller is configured from a property in the `Foo` widget; as that
/// changes, the [State.didUpdateWidget] method is used to update the
/// controller.
///
/// ```dart
/// class Foo extends StatefulWidget {
/// const Foo({ super.key, required this.duration });
///
/// final Duration duration;
///
/// @override
/// State<Foo> createState() => _FooState();
/// }
///
/// class _FooState extends State<Foo> with SingleTickerProviderStateMixin {
/// late AnimationController _controller;
///
/// @override
/// void initState() {
/// super.initState();
/// _controller = AnimationController(
/// vsync: this, // the SingleTickerProviderStateMixin
/// duration: widget.duration,
/// );
/// }
///
/// @override
/// void didUpdateWidget(Foo oldWidget) {
/// super.didUpdateWidget(oldWidget);
/// _controller.duration = widget.duration;
/// }
///
/// @override
/// void dispose() {
/// _controller.dispose();
/// super.dispose();
/// }
///
/// @override
/// Widget build(BuildContext context) {
/// return Container(); // ...
/// }
/// }
/// ```
/// {@end-tool}
/// {@tool snippet}
///
/// The following method (for a [State] subclass) drives two animation
/// controllers using Dart's asynchronous syntax for awaiting [Future] objects:
///
/// ```dart
/// Future<void> fadeOutAndUpdateState() async {
/// try {
/// await fadeAnimationController.forward().orCancel;
/// await sizeAnimationController.forward().orCancel;
/// setState(() {
/// dismissed = true;
/// });
/// } on TickerCanceled {
/// // the animation got canceled, probably because we were disposed
/// }
/// }
/// ```
/// {@end-tool}
///
/// The assumption in the code above is that the animation controllers are being
/// disposed in the [State] subclass' override of the [State.dispose] method.
/// Since disposing the controller cancels the animation (raising a
/// [TickerCanceled] exception), the code here can skip verifying whether
/// [State.mounted] is still true at each step. (Again, this assumes that the
/// controllers are created in [State.initState] and disposed in
/// [State.dispose], as described in the previous section.)
///
/// See also:
///
/// * [Tween], the base class for converting an [AnimationController] to a
/// range of values of other types.
class AnimationController extends Animation<double>
with AnimationEagerListenerMixin, AnimationLocalListenersMixin, AnimationLocalStatusListenersMixin {
/// Creates an animation controller.
///
/// * `value` is the initial value of the animation. If defaults to the lower
/// bound.
///
/// * [duration] is the length of time this animation should last.
///
/// * [debugLabel] is a string to help identify this animation during
/// debugging (used by [toString]).
///
/// * [lowerBound] is the smallest value this animation can obtain and the
/// value at which this animation is deemed to be dismissed. It cannot be
/// null.
///
/// * [upperBound] is the largest value this animation can obtain and the
/// value at which this animation is deemed to be completed. It cannot be
/// null.
///
/// * `vsync` is the [TickerProvider] for the current context. It can be
/// changed by calling [resync]. It is required and must not be null. See
/// [TickerProvider] for advice on obtaining a ticker provider.
AnimationController({
double? value,
this.duration,
this.reverseDuration,
this.debugLabel,
this.lowerBound = 0.0,
this.upperBound = 1.0,
this.animationBehavior = AnimationBehavior.normal,
required TickerProvider vsync,
}) : assert(upperBound >= lowerBound),
_direction = _AnimationDirection.forward {
_ticker = vsync.createTicker(_tick);
_internalSetValue(value ?? lowerBound);
}
/// Creates an animation controller with no upper or lower bound for its
/// value.
///
/// * [value] is the initial value of the animation.
///
/// * [duration] is the length of time this animation should last.
///
/// * [debugLabel] is a string to help identify this animation during
/// debugging (used by [toString]).
///
/// * `vsync` is the [TickerProvider] for the current context. It can be
/// changed by calling [resync]. It is required and must not be null. See
/// [TickerProvider] for advice on obtaining a ticker provider.
///
/// This constructor is most useful for animations that will be driven using a
/// physics simulation, especially when the physics simulation has no
/// pre-determined bounds.
AnimationController.unbounded({
double value = 0.0,
this.duration,
this.reverseDuration,
this.debugLabel,
required TickerProvider vsync,
this.animationBehavior = AnimationBehavior.preserve,
}) : lowerBound = double.negativeInfinity,
upperBound = double.infinity,
_direction = _AnimationDirection.forward {
_ticker = vsync.createTicker(_tick);
_internalSetValue(value);
}
/// The value at which this animation is deemed to be dismissed.
final double lowerBound;
/// The value at which this animation is deemed to be completed.
final double upperBound;
/// A label that is used in the [toString] output. Intended to aid with
/// identifying animation controller instances in debug output.
final String? debugLabel;
/// The behavior of the controller when [AccessibilityFeatures.disableAnimations]
/// is true.
///
/// Defaults to [AnimationBehavior.normal] for the [AnimationController.new]
/// constructor, and [AnimationBehavior.preserve] for the
/// [AnimationController.unbounded] constructor.
final AnimationBehavior animationBehavior;
/// Returns an [Animation<double>] for this animation controller, so that a
/// pointer to this object can be passed around without allowing users of that
/// pointer to mutate the [AnimationController] state.
Animation<double> get view => this;
/// The length of time this animation should last.
///
/// If [reverseDuration] is specified, then [duration] is only used when going
/// [forward]. Otherwise, it specifies the duration going in both directions.
Duration? duration;
/// The length of time this animation should last when going in [reverse].
///
/// The value of [duration] is used if [reverseDuration] is not specified or
/// set to null.
Duration? reverseDuration;
Ticker? _ticker;
/// Recreates the [Ticker] with the new [TickerProvider].
void resync(TickerProvider vsync) {
final Ticker oldTicker = _ticker!;
_ticker = vsync.createTicker(_tick);
_ticker!.absorbTicker(oldTicker);
}
Simulation? _simulation;
/// The current value of the animation.
///
/// Setting this value notifies all the listeners that the value
/// changed.
///
/// Setting this value also stops the controller if it is currently
/// running; if this happens, it also notifies all the status
/// listeners.
@override
double get value => _value;
late double _value;
/// Stops the animation controller and sets the current value of the
/// animation.
///
/// The new value is clamped to the range set by [lowerBound] and
/// [upperBound].
///
/// Value listeners are notified even if this does not change the value.
/// Status listeners are notified if the animation was previously playing.
///
/// The most recently returned [TickerFuture], if any, is marked as having been
/// canceled, meaning the future never completes and its [TickerFuture.orCancel]
/// derivative future completes with a [TickerCanceled] error.
///
/// See also:
///
/// * [reset], which is equivalent to setting [value] to [lowerBound].
/// * [stop], which aborts the animation without changing its value or status
/// and without dispatching any notifications other than completing or
/// canceling the [TickerFuture].
/// * [forward], [reverse], [animateTo], [animateWith], [fling], and [repeat],
/// which start the animation controller.
set value(double newValue) {
stop();
_internalSetValue(newValue);
notifyListeners();
_checkStatusChanged();
}
/// Sets the controller's value to [lowerBound], stopping the animation (if
/// in progress), and resetting to its beginning point, or dismissed state.
///
/// The most recently returned [TickerFuture], if any, is marked as having been
/// canceled, meaning the future never completes and its [TickerFuture.orCancel]
/// derivative future completes with a [TickerCanceled] error.
///
/// See also:
///
/// * [value], which can be explicitly set to a specific value as desired.
/// * [forward], which starts the animation in the forward direction.
/// * [stop], which aborts the animation without changing its value or status
/// and without dispatching any notifications other than completing or
/// canceling the [TickerFuture].
void reset() {
value = lowerBound;
}
/// The rate of change of [value] per second.
///
/// If [isAnimating] is false, then [value] is not changing and the rate of
/// change is zero.
double get velocity {
if (!isAnimating) {
return 0.0;
}
return _simulation!.dx(lastElapsedDuration!.inMicroseconds.toDouble() / Duration.microsecondsPerSecond);
}
void _internalSetValue(double newValue) {
_value = clampDouble(newValue, lowerBound, upperBound);
if (_value == lowerBound) {
_status = AnimationStatus.dismissed;
} else if (_value == upperBound) {
_status = AnimationStatus.completed;
} else {
_status = (_direction == _AnimationDirection.forward) ?
AnimationStatus.forward :
AnimationStatus.reverse;
}
}
/// The amount of time that has passed between the time the animation started
/// and the most recent tick of the animation.
///
/// If the controller is not animating, the last elapsed duration is null.
Duration? get lastElapsedDuration => _lastElapsedDuration;
Duration? _lastElapsedDuration;
/// Whether this animation is currently animating in either the forward or reverse direction.
///
/// This is separate from whether it is actively ticking. An animation
/// controller's ticker might get muted, in which case the animation
/// controller's callbacks will no longer fire even though time is continuing
/// to pass. See [Ticker.muted] and [TickerMode].
bool get isAnimating => _ticker != null && _ticker!.isActive;
_AnimationDirection _direction;
@override
AnimationStatus get status => _status;
late AnimationStatus _status;
/// Starts running this animation forwards (towards the end).
///
/// Returns a [TickerFuture] that completes when the animation is complete.
///
/// The most recently returned [TickerFuture], if any, is marked as having been
/// canceled, meaning the future never completes and its [TickerFuture.orCancel]
/// derivative future completes with a [TickerCanceled] error.
///
/// During the animation, [status] is reported as [AnimationStatus.forward],
/// which switches to [AnimationStatus.completed] when [upperBound] is
/// reached at the end of the animation.
TickerFuture forward({ double? from }) {
assert(() {
if (duration == null) {
throw FlutterError(
'AnimationController.forward() called with no default duration.\n'
'The "duration" property should be set, either in the constructor or later, before '
'calling the forward() function.',
);
}
return true;
}());
assert(
_ticker != null,
'AnimationController.forward() called after AnimationController.dispose()\n'
'AnimationController methods should not be used after calling dispose.',
);
_direction = _AnimationDirection.forward;
if (from != null) {
value = from;
}
return _animateToInternal(upperBound);
}
/// Starts running this animation in reverse (towards the beginning).
///
/// Returns a [TickerFuture] that completes when the animation is dismissed.
///
/// The most recently returned [TickerFuture], if any, is marked as having been
/// canceled, meaning the future never completes and its [TickerFuture.orCancel]
/// derivative future completes with a [TickerCanceled] error.
///
/// During the animation, [status] is reported as [AnimationStatus.reverse],
/// which switches to [AnimationStatus.dismissed] when [lowerBound] is
/// reached at the end of the animation.
TickerFuture reverse({ double? from }) {
assert(() {
if (duration == null && reverseDuration == null) {
throw FlutterError(
'AnimationController.reverse() called with no default duration or reverseDuration.\n'
'The "duration" or "reverseDuration" property should be set, either in the constructor or later, before '
'calling the reverse() function.',
);
}
return true;
}());
assert(
_ticker != null,
'AnimationController.reverse() called after AnimationController.dispose()\n'
'AnimationController methods should not be used after calling dispose.',
);
_direction = _AnimationDirection.reverse;
if (from != null) {
value = from;
}
return _animateToInternal(lowerBound);
}
/// Drives the animation from its current value to target.
///
/// Returns a [TickerFuture] that completes when the animation is complete.
///
/// The most recently returned [TickerFuture], if any, is marked as having been
/// canceled, meaning the future never completes and its [TickerFuture.orCancel]
/// derivative future completes with a [TickerCanceled] error.
///
/// During the animation, [status] is reported as [AnimationStatus.forward]
/// regardless of whether `target` > [value] or not. At the end of the
/// animation, when `target` is reached, [status] is reported as
/// [AnimationStatus.completed].
///
/// If the `target` argument is the same as the current [value] of the
/// animation, then this won't animate, and the returned [TickerFuture] will
/// be already complete.
TickerFuture animateTo(double target, { Duration? duration, Curve curve = Curves.linear }) {
assert(() {
if (this.duration == null && duration == null) {
throw FlutterError(
'AnimationController.animateTo() called with no explicit duration and no default duration.\n'
'Either the "duration" argument to the animateTo() method should be provided, or the '
'"duration" property should be set, either in the constructor or later, before '
'calling the animateTo() function.',
);
}
return true;
}());
assert(
_ticker != null,
'AnimationController.animateTo() called after AnimationController.dispose()\n'
'AnimationController methods should not be used after calling dispose.',
);
_direction = _AnimationDirection.forward;
return _animateToInternal(target, duration: duration, curve: curve);
}
/// Drives the animation from its current value to target.
///
/// Returns a [TickerFuture] that completes when the animation is complete.
///
/// The most recently returned [TickerFuture], if any, is marked as having been
/// canceled, meaning the future never completes and its [TickerFuture.orCancel]
/// derivative future completes with a [TickerCanceled] error.
///
/// During the animation, [status] is reported as [AnimationStatus.reverse]
/// regardless of whether `target` < [value] or not. At the end of the
/// animation, when `target` is reached, [status] is reported as
/// [AnimationStatus.dismissed].
TickerFuture animateBack(double target, { Duration? duration, Curve curve = Curves.linear }) {
assert(() {
if (this.duration == null && reverseDuration == null && duration == null) {
throw FlutterError(
'AnimationController.animateBack() called with no explicit duration and no default duration or reverseDuration.\n'
'Either the "duration" argument to the animateBack() method should be provided, or the '
'"duration" or "reverseDuration" property should be set, either in the constructor or later, before '
'calling the animateBack() function.',
);
}
return true;
}());
assert(
_ticker != null,
'AnimationController.animateBack() called after AnimationController.dispose()\n'
'AnimationController methods should not be used after calling dispose.',
);
_direction = _AnimationDirection.reverse;
return _animateToInternal(target, duration: duration, curve: curve);
}
TickerFuture _animateToInternal(double target, { Duration? duration, Curve curve = Curves.linear }) {
double scale = 1.0;
if (SemanticsBinding.instance.disableAnimations) {
switch (animationBehavior) {
case AnimationBehavior.normal:
// Since the framework cannot handle zero duration animations, we run it at 5% of the normal
// duration to limit most animations to a single frame.
// Ideally, the framework would be able to handle zero duration animations, however, the common
// pattern of an eternally repeating animation might cause an endless loop if it weren't delayed
// for at least one frame.
scale = 0.05;
case AnimationBehavior.preserve:
break;
}
}
Duration? simulationDuration = duration;
if (simulationDuration == null) {
assert(!(this.duration == null && _direction == _AnimationDirection.forward));
assert(!(this.duration == null && _direction == _AnimationDirection.reverse && reverseDuration == null));
final double range = upperBound - lowerBound;
final double remainingFraction = range.isFinite ? (target - _value).abs() / range : 1.0;
final Duration directionDuration =
(_direction == _AnimationDirection.reverse && reverseDuration != null)
? reverseDuration!
: this.duration!;
simulationDuration = directionDuration * remainingFraction;
} else if (target == value) {
// Already at target, don't animate.
simulationDuration = Duration.zero;
}
stop();
if (simulationDuration == Duration.zero) {
if (value != target) {
_value = clampDouble(target, lowerBound, upperBound);
notifyListeners();
}
_status = (_direction == _AnimationDirection.forward) ?
AnimationStatus.completed :
AnimationStatus.dismissed;
_checkStatusChanged();
return TickerFuture.complete();
}
assert(simulationDuration > Duration.zero);
assert(!isAnimating);
return _startSimulation(_InterpolationSimulation(_value, target, simulationDuration, curve, scale));
}
/// Starts running this animation in the forward direction, and
/// restarts the animation when it completes.
///
/// Defaults to repeating between the [lowerBound] and [upperBound] of the
/// [AnimationController] when no explicit value is set for [min] and [max].
///
/// With [reverse] set to true, instead of always starting over at [min]
/// the starting value will alternate between [min] and [max] values on each
/// repeat. The [status] will be reported as [AnimationStatus.reverse] when
/// the animation runs from [max] to [min].
///
/// Each run of the animation will have a duration of `period`. If `period` is not
/// provided, [duration] will be used instead, which has to be set before [repeat] is
/// called either in the constructor or later by using the [duration] setter.
///
/// Returns a [TickerFuture] that never completes. The [TickerFuture.orCancel] future
/// completes with an error when the animation is stopped (e.g. with [stop]).
///
/// The most recently returned [TickerFuture], if any, is marked as having been
/// canceled, meaning the future never completes and its [TickerFuture.orCancel]
/// derivative future completes with a [TickerCanceled] error.
TickerFuture repeat({ double? min, double? max, bool reverse = false, Duration? period }) {
min ??= lowerBound;
max ??= upperBound;
period ??= duration;
assert(() {
if (period == null) {
throw FlutterError(
'AnimationController.repeat() called without an explicit period and with no default Duration.\n'
'Either the "period" argument to the repeat() method should be provided, or the '
'"duration" property should be set, either in the constructor or later, before '
'calling the repeat() function.',
);
}
return true;
}());
assert(max >= min);
assert(max <= upperBound && min >= lowerBound);
stop();
return _startSimulation(_RepeatingSimulation(_value, min, max, reverse, period!, _directionSetter));
}
void _directionSetter(_AnimationDirection direction) {
_direction = direction;
_status = (_direction == _AnimationDirection.forward) ?
AnimationStatus.forward :
AnimationStatus.reverse;
_checkStatusChanged();
}
/// Drives the animation with a spring (within [lowerBound] and [upperBound])
/// and initial velocity.
///
/// If velocity is positive, the animation will complete, otherwise it will
/// dismiss. The velocity is specified in units per second. If the
/// [SemanticsBinding.disableAnimations] flag is set, the velocity is somewhat
/// arbitrarily multiplied by 200.
///
/// The [springDescription] parameter can be used to specify a custom
/// [SpringType.criticallyDamped] or [SpringType.overDamped] spring with which
/// to drive the animation. By default, a [SpringType.criticallyDamped] spring
/// is used. See [SpringDescription.withDampingRatio] for how to create a
/// suitable [SpringDescription].
///
/// The resulting spring simulation cannot be of type [SpringType.underDamped];
/// such a spring would oscillate rather than fling.
///
/// Returns a [TickerFuture] that completes when the animation is complete.
///
/// The most recently returned [TickerFuture], if any, is marked as having been
/// canceled, meaning the future never completes and its [TickerFuture.orCancel]
/// derivative future completes with a [TickerCanceled] error.
TickerFuture fling({ double velocity = 1.0, SpringDescription? springDescription, AnimationBehavior? animationBehavior }) {
springDescription ??= _kFlingSpringDescription;
_direction = velocity < 0.0 ? _AnimationDirection.reverse : _AnimationDirection.forward;
final double target = velocity < 0.0 ? lowerBound - _kFlingTolerance.distance
: upperBound + _kFlingTolerance.distance;
double scale = 1.0;
final AnimationBehavior behavior = animationBehavior ?? this.animationBehavior;
if (SemanticsBinding.instance.disableAnimations) {
switch (behavior) {
case AnimationBehavior.normal:
scale = 200.0; // This is arbitrary (it was chosen because it worked for the drawer widget).
case AnimationBehavior.preserve:
break;
}
}
final SpringSimulation simulation = SpringSimulation(springDescription, value, target, velocity * scale)
..tolerance = _kFlingTolerance;
assert(
simulation.type != SpringType.underDamped,
'The specified spring simulation is of type SpringType.underDamped.\n'
'An underdamped spring results in oscillation rather than a fling. '
'Consider specifying a different springDescription, or use animateWith() '
'with an explicit SpringSimulation if an underdamped spring is intentional.',
);
stop();
return _startSimulation(simulation);
}
/// Drives the animation according to the given simulation.
///
/// The values from the simulation are clamped to the [lowerBound] and
/// [upperBound]. To avoid this, consider creating the [AnimationController]
/// using the [AnimationController.unbounded] constructor.
///
/// Returns a [TickerFuture] that completes when the animation is complete.
///
/// The most recently returned [TickerFuture], if any, is marked as having been
/// canceled, meaning the future never completes and its [TickerFuture.orCancel]
/// derivative future completes with a [TickerCanceled] error.
///
/// The [status] is always [AnimationStatus.forward] for the entire duration
/// of the simulation.
TickerFuture animateWith(Simulation simulation) {
assert(
_ticker != null,
'AnimationController.animateWith() called after AnimationController.dispose()\n'
'AnimationController methods should not be used after calling dispose.',
);
stop();
_direction = _AnimationDirection.forward;
return _startSimulation(simulation);
}
TickerFuture _startSimulation(Simulation simulation) {
assert(!isAnimating);
_simulation = simulation;
_lastElapsedDuration = Duration.zero;
_value = clampDouble(simulation.x(0.0), lowerBound, upperBound);
final TickerFuture result = _ticker!.start();
_status = (_direction == _AnimationDirection.forward) ?
AnimationStatus.forward :
AnimationStatus.reverse;
_checkStatusChanged();
return result;
}
/// Stops running this animation.
///
/// This does not trigger any notifications. The animation stops in its
/// current state.
///
/// By default, the most recently returned [TickerFuture] is marked as having
/// been canceled, meaning the future never completes and its
/// [TickerFuture.orCancel] derivative future completes with a [TickerCanceled]
/// error. By passing the `canceled` argument with the value false, this is
/// reversed, and the futures complete successfully.
///
/// See also:
///
/// * [reset], which stops the animation and resets it to the [lowerBound],
/// and which does send notifications.
/// * [forward], [reverse], [animateTo], [animateWith], [fling], and [repeat],
/// which restart the animation controller.
void stop({ bool canceled = true }) {
assert(
_ticker != null,
'AnimationController.stop() called after AnimationController.dispose()\n'
'AnimationController methods should not be used after calling dispose.',
);
_simulation = null;
_lastElapsedDuration = null;
_ticker!.stop(canceled: canceled);
}
/// Release the resources used by this object. The object is no longer usable
/// after this method is called.
///
/// The most recently returned [TickerFuture], if any, is marked as having been
/// canceled, meaning the future never completes and its [TickerFuture.orCancel]
/// derivative future completes with a [TickerCanceled] error.
@override
void dispose() {
assert(() {
if (_ticker == null) {
throw FlutterError.fromParts(<DiagnosticsNode>[
ErrorSummary('AnimationController.dispose() called more than once.'),
ErrorDescription('A given $runtimeType cannot be disposed more than once.\n'),
DiagnosticsProperty<AnimationController>(
'The following $runtimeType object was disposed multiple times',
this,
style: DiagnosticsTreeStyle.errorProperty,
),
]);
}
return true;
}());
_ticker!.dispose();
_ticker = null;
clearStatusListeners();
clearListeners();
super.dispose();
}
AnimationStatus _lastReportedStatus = AnimationStatus.dismissed;
void _checkStatusChanged() {
final AnimationStatus newStatus = status;
if (_lastReportedStatus != newStatus) {
_lastReportedStatus = newStatus;
notifyStatusListeners(newStatus);
}
}
void _tick(Duration elapsed) {
_lastElapsedDuration = elapsed;
final double elapsedInSeconds = elapsed.inMicroseconds.toDouble() / Duration.microsecondsPerSecond;
assert(elapsedInSeconds >= 0.0);
_value = clampDouble(_simulation!.x(elapsedInSeconds), lowerBound, upperBound);
if (_simulation!.isDone(elapsedInSeconds)) {
_status = (_direction == _AnimationDirection.forward) ?
AnimationStatus.completed :
AnimationStatus.dismissed;
stop(canceled: false);
}
notifyListeners();
_checkStatusChanged();
}
@override
String toStringDetails() {
final String paused = isAnimating ? '' : '; paused';
final String ticker = _ticker == null ? '; DISPOSED' : (_ticker!.muted ? '; silenced' : '');
String label = '';
assert(() {
if (debugLabel != null) {
label = '; for $debugLabel';
}
return true;
}());
final String more = '${super.toStringDetails()} ${value.toStringAsFixed(3)}';
return '$more$paused$ticker$label';
}
}
class _InterpolationSimulation extends Simulation {
_InterpolationSimulation(this._begin, this._end, Duration duration, this._curve, double scale)
: assert(duration.inMicroseconds > 0),
_durationInSeconds = (duration.inMicroseconds * scale) / Duration.microsecondsPerSecond;
final double _durationInSeconds;
final double _begin;
final double _end;
final Curve _curve;
@override
double x(double timeInSeconds) {
final double t = clampDouble(timeInSeconds / _durationInSeconds, 0.0, 1.0);
if (t == 0.0) {
return _begin;
} else if (t == 1.0) {
return _end;
} else {
return _begin + (_end - _begin) * _curve.transform(t);
}
}
@override
double dx(double timeInSeconds) {
final double epsilon = tolerance.time;
return (x(timeInSeconds + epsilon) - x(timeInSeconds - epsilon)) / (2 * epsilon);
}
@override
bool isDone(double timeInSeconds) => timeInSeconds > _durationInSeconds;
}
typedef _DirectionSetter = void Function(_AnimationDirection direction);
class _RepeatingSimulation extends Simulation {
_RepeatingSimulation(double initialValue, this.min, this.max, this.reverse, Duration period, this.directionSetter)
: _periodInSeconds = period.inMicroseconds / Duration.microsecondsPerSecond,
_initialT = (max == min) ? 0.0 : (initialValue / (max - min)) * (period.inMicroseconds / Duration.microsecondsPerSecond) {
assert(_periodInSeconds > 0.0);
assert(_initialT >= 0.0);
}
final double min;
final double max;
final bool reverse;
final _DirectionSetter directionSetter;
final double _periodInSeconds;
final double _initialT;
@override
double x(double timeInSeconds) {
assert(timeInSeconds >= 0.0);
final double totalTimeInSeconds = timeInSeconds + _initialT;
final double t = (totalTimeInSeconds / _periodInSeconds) % 1.0;
final bool isPlayingReverse = (totalTimeInSeconds ~/ _periodInSeconds).isOdd;
if (reverse && isPlayingReverse) {
directionSetter(_AnimationDirection.reverse);
return ui.lerpDouble(max, min, t)!;
} else {
directionSetter(_AnimationDirection.forward);
return ui.lerpDouble(min, max, t)!;
}
}
@override
double dx(double timeInSeconds) => (max - min) / _periodInSeconds;
@override
bool isDone(double timeInSeconds) => false;
}