SizeObserver crusade: Remove EnterExitTransition

...and friends.

packages/flutter/lib/src/widgets/enter_exit_transition.dart

-// 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 'basic.dart';
-import 'framework.dart';
-
-class SmoothlyResizingOverflowBox extends StatefulComponent {
-  SmoothlyResizingOverflowBox({
-    Key key,
-    this.child,
-    this.size,
-    this.duration,
-    this.curve: Curves.linear
-  }) : super(key: key) {
-    assert(duration != null);
-    assert(curve != null);
-  }
-
-  final Widget child;
-  final Size size;
-  final Duration duration;
-  final Curve curve;
-
-  _SmoothlyResizingOverflowBoxState createState() => new _SmoothlyResizingOverflowBoxState();
-}
-
-class _SmoothlyResizingOverflowBoxState extends State<SmoothlyResizingOverflowBox> {
-  SizeTween _sizeTween;
-  CurveTween _curveTween;
-  Animation<Size> _size;
-  AnimationController _sizeController;
-
-  void initState() {
-    super.initState();
-    _sizeController = new AnimationController(duration: config.duration);
-    _sizeTween = new SizeTween(begin: config.size);
-    _curveTween = new CurveTween(curve: config.curve);
-    _size = _sizeTween.chain(_curveTween).animate(_sizeController)
-      ..addListener(() {
-        setState(() {});
-      });
-  }
-
-  void didUpdateConfig(SmoothlyResizingOverflowBox oldConfig) {
-    bool needsAnimation = false;
-    if (config.size != oldConfig.size) {
-      _sizeTween
-        ..begin = _size.value
-        ..end = config.size;
-      needsAnimation = true;
-    }
-    _sizeController.duration = config.duration;
-    _curveTween.curve = config.curve;
-    if (needsAnimation) {
-      _sizeController
-        ..value = 0.0
-        ..forward();
-    }
-  }
-
-  void dispose() {
-    _sizeController.stop();
-    super.dispose();
-  }
-
-  Widget build(BuildContext context) {
-    return new SizedOverflowBox(
-      size: _size.value,
-      child: config.child
-    );
-  }
-}
-
-class _Entry {
-  _Entry({
-    this.child,
-    this.enterController,
-    this.enterTransition
-  });
-
-  final Widget child;
-  final AnimationController enterController;
-  final Widget enterTransition;
-
-  Size childSize = Size.zero;
-
-  AnimationController exitController;
-  Widget exitTransition;
-
-  Widget get currentTransition => exitTransition ?? enterTransition;
-
-  void dispose() {
-    enterController?.stop();
-    exitController?.stop();
-  }
-}
-
-typedef Widget TransitionBuilderCallback(Animation<double> animation, Widget child);
-
-Widget _identityTransition(Animation<double> animation, Widget child) => child;
-
-class EnterExitTransition extends StatefulComponent {
-  EnterExitTransition({
-    Key key,
-    this.child,
-    this.duration,
-    this.curve: Curves.linear,
-    this.onEnter: _identityTransition,
-    this.onExit: _identityTransition
-  }) : super(key: key) {
-    assert(child != null);
-    assert(duration != null);
-    assert(curve != null);
-    assert(onEnter != null);
-    assert(onExit != null);
-  }
-
-  final Widget child;
-  final Duration duration;
-  final Curve curve;
-  final TransitionBuilderCallback onEnter;
-  final TransitionBuilderCallback onExit;
-
-  _EnterExitTransitionState createState() => new _EnterExitTransitionState();
-}
-
-class _EnterExitTransitionState extends State<EnterExitTransition> {
-  final List<_Entry> _entries = new List<_Entry>();
-
-  void initState() {
-    super.initState();
-    _entries.add(_createEnterTransition());
-  }
-
-  _Entry _createEnterTransition() {
-    AnimationController enterController = new AnimationController(duration: config.duration)..forward();
-    return new _Entry(
-      child: config.child,
-      enterController: enterController,
-      enterTransition: config.onEnter(enterController, new KeyedSubtree(
-        key: new GlobalKey(),
-        child: config.child
-      ))
-    );
-  }
-
-  Future _createExitTransition(_Entry entry) async {
-    AnimationController exitController = new AnimationController(duration: config.duration);
-    entry
-      ..exitController = exitController
-      ..exitTransition = config.onExit(exitController, entry.enterTransition);
-    await exitController.forward();
-    if (!mounted)
-      return;
-    setState(() {
-      _entries.remove(entry);
-    });
-  }
-
-  void didUpdateConfig(EnterExitTransition oldConfig) {
-    if (config.child.key != oldConfig.child.key) {
-      _createExitTransition(_entries.last);
-      _entries.add(_createEnterTransition());
-    }
-  }
-
-  void dispose() {
-    for (_Entry entry in new List<_Entry>.from(_entries))
-      entry.dispose();
-    super.dispose();
-  }
-
-  Widget build(BuildContext context) {
-    return new SmoothlyResizingOverflowBox(
-      size: _entries.last.childSize,
-      duration: config.duration,
-      curve: config.curve,
-      child: new Stack(
-        children: _entries.map((_Entry entry) {
-          return new SizeObserver(
-            key: new ObjectKey(entry),
-            onSizeChanged: (Size newSize) {
-              setState(() {
-                entry.childSize = newSize;
-              });
-            },
-            child: entry.currentTransition
-          );
-        }).toList()
-      )
-    );
-  }
-}

packages/flutter/lib/widgets.dart

@@ -14,7 +14,6 @@ export 'src/widgets/child_view.dart';
 export 'src/widgets/dismissable.dart';
 export 'src/widgets/drag_target.dart';
 export 'src/widgets/editable.dart';
-export 'src/widgets/enter_exit_transition.dart';
 export 'src/widgets/focus.dart';
 export 'src/widgets/framework.dart';
 export 'src/widgets/gesture_detector.dart';