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Extracted an ImplicitlyAnimatedWidgetState from AnimatedWidgetBaseState (#18181)

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Extracted a superclass from AnimatedWidgetBaseState that is called ImplicitlyAnimatedWidgetState. ImplicitlyAnimatedWidgetState implicitly animates, but it does not call setState() automatically. Subclasses must respond to animation changes themselves. This is a useful optimization for Widgets whose render objects listen to animations directly. (#18173)
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matthew-carroll 2018-06-07 14:04:30 -07:00 committed by GitHub
parent 3b9b5acefc
commit 3bc906d372
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1 changed files with 35 additions and 10 deletions
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45
packages/flutter/lib/src/widgets/implicit_animations.dart
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@ -210,7 +210,7 @@ abstract class ImplicitlyAnimatedWidget extends StatefulWidget {
final Duration duration;
@override
AnimatedWidgetBaseState<ImplicitlyAnimatedWidget> createState();
ImplicitlyAnimatedWidgetState<ImplicitlyAnimatedWidget> createState();
@override
void debugFillProperties(DiagnosticPropertiesBuilder properties) {
@ -230,10 +230,17 @@ typedef Tween<T> TweenVisitor<T>(Tween<T> tween, T targetValue, TweenConstructor
/// A base class for widgets with implicit animations.
///
/// Subclasses must implement the [forEachTween] method to help
/// [AnimatedWidgetBaseState] iterate through the subclasses' widget's fields
/// and animate them.
abstract class AnimatedWidgetBaseState<T extends ImplicitlyAnimatedWidget> extends State<T> with SingleTickerProviderStateMixin {
/// [ImplicitlyAnimatedWidgetState] requires that subclasses respond to the
/// animation, themselves. If you would like `setState()` to be called
/// automatically as the animation changes, use [AnimatedWidgetBaseState].
///
/// Subclasses must implement the [forEachTween] method to allow
/// [ImplicitlyAnimatedWidgetState] to iterate through the subclasses' widget's
/// fields and animate them.
abstract class ImplicitlyAnimatedWidgetState<T extends ImplicitlyAnimatedWidget> extends State<T> with SingleTickerProviderStateMixin {
/// The animation controller driving this widget's implicit animations.
@protected
AnimationController get controller => _controller;
AnimationController _controller;
/// The animation driving this widget's implicit animations.
@ -247,7 +254,7 @@ abstract class AnimatedWidgetBaseState<T extends ImplicitlyAnimatedWidget> exten
duration: widget.duration,
debugLabel: '${widget.toStringShort()}',
vsync: this,
)..addListener(_handleAnimationChanged);
);
_updateCurve();
_constructTweens();
}
@ -282,10 +289,6 @@ abstract class AnimatedWidgetBaseState<T extends ImplicitlyAnimatedWidget> exten
super.dispose();
}
void _handleAnimationChanged() {
setState(() { });
}
bool _shouldAnimateTween(Tween<dynamic> tween, dynamic targetValue) {
return targetValue != (tween.end ?? tween.begin);
}
@ -331,6 +334,28 @@ abstract class AnimatedWidgetBaseState<T extends ImplicitlyAnimatedWidget> exten
void forEachTween(TweenVisitor<dynamic> visitor);
}
/// A base class for widgets with implicit animations that need to rebuild their
/// widget tree as the animation runs.
///
/// This class calls [build] each frame that the animation tickets. For a
/// variant that does not rebuild each frame, consider subclassing
/// [ImplicitlyAnimatedWidgetState] directly.
///
/// Subclasses must implement the [forEachTween] method to allow
/// [AnimatedWidgetBaseState] to iterate through the subclasses' widget's fields
/// and animate them.
abstract class AnimatedWidgetBaseState<T extends ImplicitlyAnimatedWidget> extends ImplicitlyAnimatedWidgetState<T> {
@override
void initState() {
super.initState();
controller.addListener(_handleAnimationChanged);
}
void _handleAnimationChanged() {
setState(() { /* The animation ticked. Rebuild with new animation value */ });
}
}
/// A container that gradually changes its values over a period of time.
///
/// The [AnimatedContainer] will automatically animate between the old and