packages/flutter/lib/src/cupertino/button.dart - mirrors/flutter - Git at Google

 // 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 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';

 import 'colors.dart';
 import 'constants.dart';
 import 'theme.dart';

 // Measured against iOS 12 in Xcode.
 const EdgeInsets _kButtonPadding = EdgeInsets.all(16.0);
 const EdgeInsets _kBackgroundButtonPadding = EdgeInsets.symmetric(
   vertical: 14.0,
   horizontal: 64.0,
 );

 /// An iOS-style button.
 ///
 /// Takes in a text or an icon that fades out and in on touch. May optionally have a
 /// background.
 ///
 /// See also:
 ///
 ///  * <https://developer.apple.com/ios/human-interface-guidelines/controls/buttons/>
 class CupertinoButton extends StatefulWidget {
   /// Creates an iOS-style button.
   const CupertinoButton({
     Key key,
     @required this.child,
     this.padding,
     this.color,
     this.disabledColor = CupertinoColors.quaternarySystemFill,
     this.minSize = kMinInteractiveDimensionCupertino,
     this.pressedOpacity = 0.4,
     this.borderRadius = const BorderRadius.all(Radius.circular(8.0)),
     @required this.onPressed,
   }) : assert(pressedOpacity == null || (pressedOpacity >= 0.0 && pressedOpacity <= 1.0)),
        assert(disabledColor != null),
        _filled = false,
        super(key: key);

   /// Creates an iOS-style button with a filled background.
   ///
   /// The background color is derived from the [CupertinoTheme]'s `primaryColor`.
   ///
   /// To specify a custom background color, use the [color] argument of the
   /// default constructor.
   const CupertinoButton.filled({
     Key key,
     @required this.child,
     this.padding,
     this.disabledColor = CupertinoColors.quaternarySystemFill,
     this.minSize = kMinInteractiveDimensionCupertino,
     this.pressedOpacity = 0.4,
     this.borderRadius = const BorderRadius.all(Radius.circular(8.0)),
     @required this.onPressed,
   }) : assert(pressedOpacity == null || (pressedOpacity >= 0.0 && pressedOpacity <= 1.0)),
        assert(disabledColor != null),
        color = null,
        _filled = true,
        super(key: key);

   /// The widget below this widget in the tree.
   ///
   /// Typically a [Text] widget.
   final Widget child;

   /// The amount of space to surround the child inside the bounds of the button.
   ///
   /// Defaults to 16.0 pixels.
   final EdgeInsetsGeometry padding;

   /// The color of the button's background.
   ///
   /// Defaults to null which produces a button with no background or border.
   ///
   /// Defaults to the [CupertinoTheme]'s `primaryColor` when the
   /// [CupertinoButton.filled] constructor is used.
   final Color color;

   /// The color of the button's background when the button is disabled.
   ///
   /// Ignored if the [CupertinoButton] doesn't also have a [color].
   ///
   /// Defaults to [CupertinoColors.quaternarySystemFill] when [color] is
   /// specified. Must not be null.
   final Color disabledColor;

   /// The callback that is called when the button is tapped or otherwise activated.
   ///
   /// If this is set to null, the button will be disabled.
   final VoidCallback onPressed;

   /// Minimum size of the button.
   ///
   /// Defaults to kMinInteractiveDimensionCupertino which the iOS Human
   /// Interface Guidelines recommends as the minimum tappable area.
   final double minSize;

   /// The opacity that the button will fade to when it is pressed.
   /// The button will have an opacity of 1.0 when it is not pressed.
   ///
   /// This defaults to 0.4. If null, opacity will not change on pressed if using
   /// your own custom effects is desired.
   final double pressedOpacity;

   /// The radius of the button's corners when it has a background color.
   ///
   /// Defaults to round corners of 8 logical pixels.
   final BorderRadius borderRadius;

   final bool _filled;

   /// Whether the button is enabled or disabled. Buttons are disabled by default. To
   /// enable a button, set its [onPressed] property to a non-null value.
   bool get enabled => onPressed != null;

   @override
   _CupertinoButtonState createState() => _CupertinoButtonState();

   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
     properties.add(FlagProperty('enabled', value: enabled, ifFalse: 'disabled'));
   }
 }

 class _CupertinoButtonState extends State<CupertinoButton> with SingleTickerProviderStateMixin {
   // Eyeballed values. Feel free to tweak.
   static const Duration kFadeOutDuration = Duration(milliseconds: 10);
   static const Duration kFadeInDuration = Duration(milliseconds: 100);
   final Tween<double> _opacityTween = Tween<double>(begin: 1.0);

   AnimationController _animationController;
   Animation<double> _opacityAnimation;

   @override
   void initState() {
     super.initState();
     _animationController = AnimationController(
       duration: const Duration(milliseconds: 200),
       value: 0.0,
       vsync: this,
     );
     _opacityAnimation = _animationController
       .drive(CurveTween(curve: Curves.decelerate))
       .drive(_opacityTween);
     _setTween();
   }

   @override
   void didUpdateWidget(CupertinoButton old) {
     super.didUpdateWidget(old);
     _setTween();
   }

   void _setTween() {
     _opacityTween.end = widget.pressedOpacity ?? 1.0;
   }

   @override
   void dispose() {
     _animationController.dispose();
     _animationController = null;
     super.dispose();
   }

   bool _buttonHeldDown = false;

   void _handleTapDown(TapDownDetails event) {
     if (!_buttonHeldDown) {
       _buttonHeldDown = true;
       _animate();
     }
   }

   void _handleTapUp(TapUpDetails event) {
     if (_buttonHeldDown) {
       _buttonHeldDown = false;
       _animate();
     }
   }

   void _handleTapCancel() {
     if (_buttonHeldDown) {
       _buttonHeldDown = false;
       _animate();
     }
   }

   void _animate() {
     if (_animationController.isAnimating)
       return;
     final bool wasHeldDown = _buttonHeldDown;
     final TickerFuture ticker = _buttonHeldDown
         ? _animationController.animateTo(1.0, duration: kFadeOutDuration)
         : _animationController.animateTo(0.0, duration: kFadeInDuration);
     ticker.then<void>((void value) {
       if (mounted && wasHeldDown != _buttonHeldDown)
         _animate();
     });
   }

   @override
   Widget build(BuildContext context) {
     final bool enabled = widget.enabled;
     final CupertinoThemeData themeData = CupertinoTheme.of(context);
     final Color primaryColor = themeData.primaryColor;
     final Color backgroundColor = widget.color == null
       ? (widget._filled ? primaryColor : null)
       : CupertinoDynamicColor.resolve(widget.color, context);

     final Color foregroundColor = backgroundColor != null
       ? themeData.primaryContrastingColor
       : enabled
         ? primaryColor
         : CupertinoDynamicColor.resolve(CupertinoColors.placeholderText, context);

     final TextStyle textStyle = themeData.textTheme.textStyle.copyWith(color: foregroundColor);

     return GestureDetector(
       behavior: HitTestBehavior.opaque,
       onTapDown: enabled ? _handleTapDown : null,
       onTapUp: enabled ? _handleTapUp : null,
       onTapCancel: enabled ? _handleTapCancel : null,
       onTap: widget.onPressed,
       child: Semantics(
         button: true,
         child: ConstrainedBox(
           constraints: widget.minSize == null
             ? const BoxConstraints()
             : BoxConstraints(
               minWidth: widget.minSize,
               minHeight: widget.minSize,
             ),
           child: FadeTransition(
             opacity: _opacityAnimation,
             child: DecoratedBox(
               decoration: BoxDecoration(
                 borderRadius: widget.borderRadius,
                 color: backgroundColor != null && !enabled
                   ? CupertinoDynamicColor.resolve(widget.disabledColor, context)
                   : backgroundColor,
               ),
               child: Padding(
                 padding: widget.padding ?? (backgroundColor != null
                   ? _kBackgroundButtonPadding
                   : _kButtonPadding),
                 child: Center(
                   widthFactor: 1.0,
                   heightFactor: 1.0,
                   child: DefaultTextStyle(
                     style: textStyle,
                     child: IconTheme(
                       data: IconThemeData(color: foregroundColor),
                       child: widget.child,
                     ),
                   ),
                 ),
               ),
             ),
           ),
         ),
       ),
     );
   }
 }
	// 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 'package:flutter/foundation.dart';
	import 'package:flutter/widgets.dart';

	import 'colors.dart';
	import 'constants.dart';
	import 'theme.dart';

	// Measured against iOS 12 in Xcode.
	const EdgeInsets _kButtonPadding = EdgeInsets.all(16.0);
	const EdgeInsets _kBackgroundButtonPadding = EdgeInsets.symmetric(
	vertical: 14.0,
	horizontal: 64.0,
	);

	/// An iOS-style button.
	///
	/// Takes in a text or an icon that fades out and in on touch. May optionally have a
	/// background.
	///
	/// See also:
	///
	/// * <https://developer.apple.com/ios/human-interface-guidelines/controls/buttons/>
	class CupertinoButton extends StatefulWidget {
	/// Creates an iOS-style button.
	const CupertinoButton({
	Key key,
	@required this.child,
	this.padding,
	this.color,
	this.disabledColor = CupertinoColors.quaternarySystemFill,
	this.minSize = kMinInteractiveDimensionCupertino,
	this.pressedOpacity = 0.4,
	this.borderRadius = const BorderRadius.all(Radius.circular(8.0)),
	@required this.onPressed,
	}) : assert(pressedOpacity == null \|\| (pressedOpacity >= 0.0 && pressedOpacity <= 1.0)),
	assert(disabledColor != null),
	_filled = false,
	super(key: key);

	/// Creates an iOS-style button with a filled background.
	///
	/// The background color is derived from the [CupertinoTheme]'s `primaryColor`.
	///
	/// To specify a custom background color, use the [color] argument of the
	/// default constructor.
	const CupertinoButton.filled({
	Key key,
	@required this.child,
	this.padding,
	this.disabledColor = CupertinoColors.quaternarySystemFill,
	this.minSize = kMinInteractiveDimensionCupertino,
	this.pressedOpacity = 0.4,
	this.borderRadius = const BorderRadius.all(Radius.circular(8.0)),
	@required this.onPressed,
	}) : assert(pressedOpacity == null \|\| (pressedOpacity >= 0.0 && pressedOpacity <= 1.0)),
	assert(disabledColor != null),
	color = null,
	_filled = true,
	super(key: key);

	/// The widget below this widget in the tree.
	///
	/// Typically a [Text] widget.
	final Widget child;

	/// The amount of space to surround the child inside the bounds of the button.
	///
	/// Defaults to 16.0 pixels.
	final EdgeInsetsGeometry padding;

	/// The color of the button's background.
	///
	/// Defaults to null which produces a button with no background or border.
	///
	/// Defaults to the [CupertinoTheme]'s `primaryColor` when the
	/// [CupertinoButton.filled] constructor is used.
	final Color color;

	/// The color of the button's background when the button is disabled.
	///
	/// Ignored if the [CupertinoButton] doesn't also have a [color].
	///
	/// Defaults to [CupertinoColors.quaternarySystemFill] when [color] is
	/// specified. Must not be null.
	final Color disabledColor;

	/// The callback that is called when the button is tapped or otherwise activated.
	///
	/// If this is set to null, the button will be disabled.
	final VoidCallback onPressed;

	/// Minimum size of the button.
	///
	/// Defaults to kMinInteractiveDimensionCupertino which the iOS Human
	/// Interface Guidelines recommends as the minimum tappable area.
	final double minSize;

	/// The opacity that the button will fade to when it is pressed.
	/// The button will have an opacity of 1.0 when it is not pressed.
	///
	/// This defaults to 0.4. If null, opacity will not change on pressed if using
	/// your own custom effects is desired.
	final double pressedOpacity;

	/// The radius of the button's corners when it has a background color.
	///
	/// Defaults to round corners of 8 logical pixels.
	final BorderRadius borderRadius;

	final bool _filled;

	/// Whether the button is enabled or disabled. Buttons are disabled by default. To
	/// enable a button, set its [onPressed] property to a non-null value.
	bool get enabled => onPressed != null;

	@override
	_CupertinoButtonState createState() => _CupertinoButtonState();

	@override
	void debugFillProperties(DiagnosticPropertiesBuilder properties) {
	super.debugFillProperties(properties);
	properties.add(FlagProperty('enabled', value: enabled, ifFalse: 'disabled'));
	}
	}

	class _CupertinoButtonState extends State<CupertinoButton> with SingleTickerProviderStateMixin {
	// Eyeballed values. Feel free to tweak.
	static const Duration kFadeOutDuration = Duration(milliseconds: 10);
	static const Duration kFadeInDuration = Duration(milliseconds: 100);
	final Tween<double> _opacityTween = Tween<double>(begin: 1.0);

	AnimationController _animationController;
	Animation<double> _opacityAnimation;

	@override
	void initState() {
	super.initState();
	_animationController = AnimationController(
	duration: const Duration(milliseconds: 200),
	value: 0.0,
	vsync: this,
	);
	_opacityAnimation = _animationController
	.drive(CurveTween(curve: Curves.decelerate))
	.drive(_opacityTween);
	_setTween();
	}

	@override
	void didUpdateWidget(CupertinoButton old) {
	super.didUpdateWidget(old);
	_setTween();
	}

	void _setTween() {
	_opacityTween.end = widget.pressedOpacity ?? 1.0;
	}

	@override
	void dispose() {
	_animationController.dispose();
	_animationController = null;
	super.dispose();
	}

	bool _buttonHeldDown = false;

	void _handleTapDown(TapDownDetails event) {
	if (!_buttonHeldDown) {
	_buttonHeldDown = true;
	_animate();
	}
	}

	void _handleTapUp(TapUpDetails event) {
	if (_buttonHeldDown) {
	_buttonHeldDown = false;
	_animate();
	}
	}

	void _handleTapCancel() {
	if (_buttonHeldDown) {
	_buttonHeldDown = false;
	_animate();
	}
	}

	void _animate() {
	if (_animationController.isAnimating)
	return;
	final bool wasHeldDown = _buttonHeldDown;
	final TickerFuture ticker = _buttonHeldDown
	? _animationController.animateTo(1.0, duration: kFadeOutDuration)
	: _animationController.animateTo(0.0, duration: kFadeInDuration);
	ticker.then<void>((void value) {
	if (mounted && wasHeldDown != _buttonHeldDown)
	_animate();
	});
	}

	@override
	Widget build(BuildContext context) {
	final bool enabled = widget.enabled;
	final CupertinoThemeData themeData = CupertinoTheme.of(context);
	final Color primaryColor = themeData.primaryColor;
	final Color backgroundColor = widget.color == null
	? (widget._filled ? primaryColor : null)
	: CupertinoDynamicColor.resolve(widget.color, context);

	final Color foregroundColor = backgroundColor != null
	? themeData.primaryContrastingColor
	: enabled
	? primaryColor
	: CupertinoDynamicColor.resolve(CupertinoColors.placeholderText, context);

	final TextStyle textStyle = themeData.textTheme.textStyle.copyWith(color: foregroundColor);

	return GestureDetector(
	behavior: HitTestBehavior.opaque,
	onTapDown: enabled ? _handleTapDown : null,
	onTapUp: enabled ? _handleTapUp : null,
	onTapCancel: enabled ? _handleTapCancel : null,
	onTap: widget.onPressed,
	child: Semantics(
	button: true,
	child: ConstrainedBox(
	constraints: widget.minSize == null
	? const BoxConstraints()
	: BoxConstraints(
	minWidth: widget.minSize,
	minHeight: widget.minSize,
	),
	child: FadeTransition(
	opacity: _opacityAnimation,
	child: DecoratedBox(
	decoration: BoxDecoration(
	borderRadius: widget.borderRadius,
	color: backgroundColor != null && !enabled
	? CupertinoDynamicColor.resolve(widget.disabledColor, context)
	: backgroundColor,
	),
	child: Padding(
	padding: widget.padding ?? (backgroundColor != null
	? _kBackgroundButtonPadding
	: _kButtonPadding),
	child: Center(
	widthFactor: 1.0,
	heightFactor: 1.0,
	child: DefaultTextStyle(
	style: textStyle,
	child: IconTheme(
	data: IconThemeData(color: foregroundColor),
	child: widget.child,
	),
	),
	),
	),
	),
	),
	),
	),
	);
	}
	}