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74575775bd
This fixes some theoretical bugs whereby we were using hashCode to try
to get unique keys for objects, but really we wanted object identity.
It also lays the groundwork for a new GlobalKey concept.
I tried to keep the impact on the code minimal, which is why the "Key"
constructor is actually a factory that returns a StringKey. The code
has this class hierarchy:
```
KeyBase
|
Key--------------+---------------+
| | |
StringKey ObjectKey UniqueKey
```
...where the constructors are Key and Key.stringify (StringKey),
Key.fromObjectIdentity (ObjectKey), and Key.unique (UniqueKey).
We could instead of factory methods use regular constructors with the
following hierarchy:
```
KeyBase
|
LocalKey---------+---------------+
| | |
Key ObjectIdentityKey UniqueKey
```
...with constructors Key, Key.stringify, ObjectIdentityKey, and
UniqueKey, but I felt that that was maybe a more confusing hierarchy.
I don't have a strong opinion on this.
88 lines
2.3 KiB
Dart
88 lines
2.3 KiB
Dart
// Copyright 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'dart:sky' as sky;
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import 'package:sky/animation/animated_value.dart';
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import 'package:sky/animation/animation_performance.dart';
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import 'package:sky/animation/curves.dart';
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import 'package:sky/widgets/animated_component.dart';
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import 'package:sky/widgets/basic.dart';
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typedef void ValueChanged(value);
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const Duration _kCheckDuration = const Duration(milliseconds: 200);
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abstract class Toggleable extends AnimatedComponent {
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Toggleable({
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Key key,
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this.value,
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this.onChanged
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}) : super(key: key);
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bool value;
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ValueChanged onChanged;
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AnimatedValue<double> _position;
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AnimatedValue<double> get position => _position;
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AnimationPerformance _performance;
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AnimationPerformance get performance => _performance;
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void initState() {
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_position = new AnimatedValue<double>(0.0, end: 1.0);
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_performance = new AnimationPerformance()
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..variable = position
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..duration = _kCheckDuration
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..progress = value ? 1.0 : 0.0;
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watch(performance);
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}
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void syncFields(Toggleable source) {
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onChanged = source.onChanged;
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if (value != source.value) {
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value = source.value;
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// TODO(abarth): Setting the curve on the position means there's a
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// discontinuity when we reverse the timeline.
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if (value) {
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position.curve = curveUp;
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performance.play();
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} else {
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position.curve = curveDown;
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performance.reverse();
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}
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}
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super.syncFields(source);
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}
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void _handleClick(sky.Event e) {
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onChanged(!value);
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}
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// Override these to draw yourself
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void customPaintCallback(sky.Canvas canvas, Size size);
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Size get size;
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EdgeDims get margin => const EdgeDims.symmetric(horizontal: 5.0);
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double get duration => 200.0;
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Curve get curveUp => easeIn;
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Curve get curveDown => easeOut;
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Widget build() {
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return new Listener(
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child: new Container(
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margin: margin,
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width: size.width,
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height: size.height,
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child: new CustomPaint(
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token: position.value,
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callback: customPaintCallback
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)
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),
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onGestureTap: _handleClick
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);
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}
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}
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