| // 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:math' as math; |
| |
| import 'package:flutter/widgets.dart'; |
| |
| import 'colors.dart'; |
| import 'debug.dart'; |
| import 'icon_button.dart'; |
| import 'icons.dart'; |
| import 'material_localizations.dart'; |
| import 'theme.dart'; |
| |
| /// A widget representing a rotating expand/collapse button. The icon rotates |
| /// 180 degrees when pressed, then reverts the animation on a second press. |
| /// The underlying icon is [Icons.expand_more]. |
| /// |
| /// The expand icon does not include a semantic label for accessibility. In |
| /// order to be accessible it should be combined with a label using |
| /// [MergeSemantics]. This is done automatically by the [ExpansionPanel] widget. |
| /// |
| /// See [IconButton] for a more general implementation of a pressable button |
| /// with an icon. |
| /// |
| /// See also: |
| /// |
| /// * https://material.io/design/iconography/system-icons.html |
| class ExpandIcon extends StatefulWidget { |
| /// Creates an [ExpandIcon] with the given padding, and a callback that is |
| /// triggered when the icon is pressed. |
| const ExpandIcon({ |
| Key key, |
| this.isExpanded = false, |
| this.size = 24.0, |
| @required this.onPressed, |
| this.padding = const EdgeInsets.all(8.0), |
| this.color, |
| this.disabledColor, |
| this.expandedColor, |
| }) : assert(isExpanded != null), |
| assert(size != null), |
| assert(padding != null), |
| super(key: key); |
| |
| /// Whether the icon is in an expanded state. |
| /// |
| /// Rebuilding the widget with a different [isExpanded] value will trigger |
| /// the animation, but will not trigger the [onPressed] callback. |
| final bool isExpanded; |
| |
| /// The size of the icon. |
| /// |
| /// This property must not be null. It defaults to 24.0. |
| final double size; |
| |
| /// The callback triggered when the icon is pressed and the state changes |
| /// between expanded and collapsed. The value passed to the current state. |
| /// |
| /// If this is set to null, the button will be disabled. |
| final ValueChanged<bool> onPressed; |
| |
| /// The padding around the icon. The entire padded icon will react to input |
| /// gestures. |
| /// |
| /// This property must not be null. It defaults to 8.0 padding on all sides. |
| final EdgeInsetsGeometry padding; |
| |
| |
| /// The color of the icon. |
| /// |
| /// Defaults to [Colors.black54] when the theme's |
| /// [ThemeData.brightness] is [Brightness.light] and to |
| /// [Colors.white60] when it is [Brightness.dark]. This adheres to the |
| /// Material Design specifications for [icons](https://material.io/design/iconography/system-icons.html#color) |
| /// and for [dark theme](https://material.io/design/color/dark-theme.html#ui-application) |
| final Color color; |
| |
| /// The color of the icon when it is disabled, |
| /// i.e. if [onPressed] is null. |
| /// |
| /// Defaults to [Colors.black38] when the theme's |
| /// [ThemeData.brightness] is [Brightness.light] and to |
| /// [Colors.white38] when it is [Brightness.dark]. This adheres to the |
| /// Material Design specifications for [icons](https://material.io/design/iconography/system-icons.html#color) |
| /// and for [dark theme](https://material.io/design/color/dark-theme.html#ui-application) |
| final Color disabledColor; |
| |
| /// The color of the icon when the icon is expanded. |
| /// |
| /// Defaults to [Colors.black54] when the theme's |
| /// [ThemeData.brightness] is [Brightness.light] and to |
| /// [Colors.white] when it is [Brightness.dark]. This adheres to the |
| /// Material Design specifications for [icons](https://material.io/design/iconography/system-icons.html#color) |
| /// and for [dark theme](https://material.io/design/color/dark-theme.html#ui-application) |
| final Color expandedColor; |
| |
| @override |
| _ExpandIconState createState() => _ExpandIconState(); |
| } |
| |
| class _ExpandIconState extends State<ExpandIcon> with SingleTickerProviderStateMixin { |
| AnimationController _controller; |
| Animation<double> _iconTurns; |
| |
| static final Animatable<double> _iconTurnTween = Tween<double>(begin: 0.0, end: 0.5) |
| .chain(CurveTween(curve: Curves.fastOutSlowIn)); |
| |
| @override |
| void initState() { |
| super.initState(); |
| _controller = AnimationController(duration: kThemeAnimationDuration, vsync: this); |
| _iconTurns = _controller.drive(_iconTurnTween); |
| // If the widget is initially expanded, rotate the icon without animating it. |
| if (widget.isExpanded) { |
| _controller.value = math.pi; |
| } |
| } |
| |
| @override |
| void dispose() { |
| _controller.dispose(); |
| super.dispose(); |
| } |
| |
| @override |
| void didUpdateWidget(ExpandIcon oldWidget) { |
| super.didUpdateWidget(oldWidget); |
| if (widget.isExpanded != oldWidget.isExpanded) { |
| if (widget.isExpanded) { |
| _controller.forward(); |
| } else { |
| _controller.reverse(); |
| } |
| } |
| } |
| |
| void _handlePressed() { |
| if (widget.onPressed != null) |
| widget.onPressed(widget.isExpanded); |
| } |
| |
| /// Default icon colors and opacities for when [Theme.brightness] is set to |
| /// [Brightness.light] are based on the |
| /// [Material Design system icon specifications](https://material.io/design/iconography/system-icons.html#color). |
| /// Icon colors and opacities for [Brightness.dark] are based on the |
| /// [Material Design dark theme specifications](https://material.io/design/color/dark-theme.html#ui-application) |
| Color get _iconColor { |
| if (widget.isExpanded && widget.expandedColor != null) { |
| return widget.expandedColor; |
| } |
| |
| if (widget.color != null) { |
| return widget.color; |
| } |
| |
| switch(Theme.of(context).brightness) { |
| case Brightness.light: |
| return Colors.black54; |
| case Brightness.dark: |
| return Colors.white60; |
| } |
| |
| assert(false); |
| return null; |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| assert(debugCheckHasMaterial(context)); |
| assert(debugCheckHasMaterialLocalizations(context)); |
| final MaterialLocalizations localizations = MaterialLocalizations.of(context); |
| final String onTapHint = widget.isExpanded ? localizations.expandedIconTapHint : localizations.collapsedIconTapHint; |
| |
| return Semantics( |
| onTapHint: widget.onPressed == null ? null : onTapHint, |
| child: IconButton( |
| padding: widget.padding, |
| color: _iconColor, |
| disabledColor: widget.disabledColor, |
| onPressed: widget.onPressed == null ? null : _handlePressed, |
| icon: RotationTransition( |
| turns: _iconTurns, |
| child: const Icon(Icons.expand_more), |
| ), |
| ), |
| ); |
| } |
| } |