// 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 'package:flutter/foundation.dart'; import 'package:flutter/widgets.dart'; import 'button.dart'; import 'button_theme.dart'; import 'colors.dart'; import 'theme.dart'; import 'theme_data.dart'; /// A material design "flat button". /// /// A flat button is a text label displayed on a (zero elevation) [Material] /// widget that reacts to touches by filling with color. /// /// Use flat buttons on toolbars, in dialogs, or inline with other content but /// offset from that content with padding so that the button's presence is /// obvious. Flat buttons intentionally do not have visible borders and must /// therefore rely on their position relative to other content for context. In /// dialogs and cards, they should be grouped together in one of the bottom /// corners. Avoid using flat buttons where they would blend in with other /// content, for example in the middle of lists. /// /// Material design flat buttons have an all-caps label, some internal padding, /// and some defined dimensions. To have a part of your application be /// interactive, with ink splashes, without also committing to these stylistic /// choices, consider using [InkWell] instead. /// /// If the [onPressed] callback is null, then the button will be disabled, /// will not react to touch, and will be colored as specified by /// the [disabledColor] property instead of the [color] property. If you are /// trying to change the button's [color] and it is not having any effect, check /// that you are passing a non-null [onPressed] handler. /// /// Flat buttons have a minimum size of 88.0 by 36.0 which can be overidden /// with [ButtonTheme]. /// /// See also: /// /// * [RaisedButton], a filled button whose material elevates when pressed. /// * [DropdownButton], which offers the user a choice of a number of options. /// * [SimpleDialogOption], which is used in [SimpleDialog]s. /// * [IconButton], to create buttons that just contain icons. /// * [InkWell], which implements the ink splash part of a flat button. /// * [RawMaterialButton], the widget this widget is based on. /// * <https://material.google.com/components/buttons.html> class FlatButton extends StatelessWidget { /// Create a simple text button. const FlatButton({ Key key, @required this.onPressed, this.onHighlightChanged, this.textTheme, this.textColor, this.disabledTextColor, this.color, this.disabledColor, this.highlightColor, this.splashColor, this.colorBrightness, this.padding, this.shape, this.materialTapTargetSize, @required this.child, }) : super(key: key); /// Create a text button from a pair of widgets that serve as the button's /// [icon] and [label]. /// /// The icon and label are arranged in a row and padded by 12 logical pixels /// at the start, and 16 at the end, with an 8 pixel gap in between. /// /// The [icon] and [label] arguments must not be null. FlatButton.icon({ Key key, @required this.onPressed, this.onHighlightChanged, this.textTheme, this.textColor, this.disabledTextColor, this.color, this.disabledColor, this.highlightColor, this.splashColor, this.colorBrightness, this.shape, this.materialTapTargetSize, @required Widget icon, @required Widget label, }) : assert(icon != null), assert(label != null), padding = const EdgeInsetsDirectional.only(start: 12.0, end: 16.0), child = new Row( mainAxisSize: MainAxisSize.min, children: <Widget>[ icon, const SizedBox(width: 8.0), label, ], ), super(key: key); /// Called when the button is tapped or otherwise activated. /// /// If this is set to null, the button will be disabled, see [enabled]. final VoidCallback onPressed; /// Called by the underlying [InkWell] widget's [InkWell.onHighlightChanged] /// callback. final ValueChanged<bool> onHighlightChanged; /// Defines the button's base colors, and the defaults for the button's minimum /// size, internal padding, and shape. /// /// Defaults to `ButtonTheme.of(context).textTheme`. final ButtonTextTheme textTheme; /// The color to use for this button's text. /// /// The button's [Material.textStyle] will be the current theme's button /// text style, [ThemeData.textTheme.button], configured with this color. /// /// The default text color depends on the button theme's text theme, /// [ButtonThemeData.textTheme]. /// /// See also: /// * [disabledTextColor], the text color to use when the button has been /// disabled. final Color textColor; /// The color to use for this button's text when the button is disabled. /// /// The button's [Material.textStyle] will be the current theme's button /// text style, [ThemeData.textTheme.button], configured with this color. /// /// The default value is the theme's disabled color, /// [ThemeData.disabledColor]. /// /// See also: /// * [textColor] - The color to use for this button's text when the button is [enabled]. final Color disabledTextColor; /// The button's fill color, displayed by its [Material], while it /// is in its default (unpressed, enabled) state. /// /// Typically not specified for [FlatButton]s. /// /// The default is null. final Color color; /// The fill color of the button when the button is disabled. /// /// Typically not specified for [FlatButton]s. /// /// The default is null. final Color disabledColor; /// The splash color of the button's [InkWell]. /// /// The ink splash indicates that the button has been touched. It /// appears on top of the button's child and spreads in an expanding /// circle beginning where the touch occurred. /// /// If [textTheme] is [ButtonTextTheme.primary], the default splash color is /// is based on the theme's primary color [ThemeData.primaryColor], /// otherwise it's the current theme's splash color, [ThemeData.splashColor]. /// /// The appearance of the splash can be configured with the theme's splash /// factory, [ThemeData.splashFactory]. final Color splashColor; /// The highlight color of the button's [InkWell]. /// /// The highlight indicates that the button is actively being pressed. It /// appears on top of the button's child and quickly spreads to fill /// the button, and then fades out. /// /// If [textTheme] is [ButtonTextTheme.primary], the default highlight color is /// transparent (in other words the highlight doesn't appear). Otherwise it's /// the current theme's highlight color, [ThemeData.highlightColor]. final Color highlightColor; /// The theme brightness to use for this button. /// /// Defaults to the theme's brightness, [ThemeData.brightness]. final Brightness colorBrightness; /// Configures the minimum size of the tap target. /// /// Defaults to [ThemeData.materialTapTargetSize]. /// /// See also: /// /// * [MaterialTapTargetSize], for a description of how this affects tap targets. final MaterialTapTargetSize materialTapTargetSize; /// The widget below this widget in the tree. /// /// Typically a [Text] widget in all caps. final Widget child; /// 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; /// The internal padding for the button's [child]. /// /// Defaults to the value from the current [ButtonTheme], /// [ButtonThemeData.padding]. final EdgeInsetsGeometry padding; /// The shape of the button's [Material]. /// /// The button's highlight and splash are clipped to this shape. If the /// button has an elevation, then its drop shadow is defined by this /// shape as well. final ShapeBorder shape; Brightness _getBrightness(ThemeData theme) { return colorBrightness ?? theme.brightness; } ButtonTextTheme _getTextTheme(ButtonThemeData buttonTheme) { return textTheme ?? buttonTheme.textTheme; } Color _getTextColor(ThemeData theme, ButtonThemeData buttonTheme, Color fillColor) { final Color color = enabled ? textColor : disabledTextColor; if (color != null) return color; final bool themeIsDark = _getBrightness(theme) == Brightness.dark; final bool fillIsDark = fillColor == null ? themeIsDark : ThemeData.estimateBrightnessForColor(fillColor) == Brightness.dark; switch (_getTextTheme(buttonTheme)) { case ButtonTextTheme.normal: return enabled ? (themeIsDark ? Colors.white : Colors.black87) : theme.disabledColor; case ButtonTextTheme.accent: return enabled ? theme.accentColor : theme.disabledColor; case ButtonTextTheme.primary: return enabled ? (fillIsDark ? Colors.white : theme.primaryColor) : (themeIsDark ? Colors.white30 : Colors.black38); } return null; } Color _getSplashColor(ThemeData theme, ButtonThemeData buttonTheme) { if (splashColor != null) return splashColor; switch (_getTextTheme(buttonTheme)) { case ButtonTextTheme.normal: case ButtonTextTheme.accent: return theme.splashColor; case ButtonTextTheme.primary: return _getBrightness(theme) == Brightness.dark ? Colors.white12 : theme.primaryColor.withOpacity(0.12); } return Colors.transparent; } Color _getHighlightColor(ThemeData theme, ButtonThemeData buttonTheme) { if (highlightColor != null) return highlightColor; switch (_getTextTheme(buttonTheme)) { case ButtonTextTheme.normal: case ButtonTextTheme.accent: return theme.highlightColor; case ButtonTextTheme.primary: return Colors.transparent; } return Colors.transparent; } @override Widget build(BuildContext context) { final ThemeData theme = Theme.of(context); final ButtonThemeData buttonTheme = ButtonTheme.of(context); final Color fillColor = enabled ? color : disabledColor; final Color textColor = _getTextColor(theme, buttonTheme, fillColor); return new RawMaterialButton( onPressed: onPressed, onHighlightChanged: onHighlightChanged, fillColor: fillColor, textStyle: theme.textTheme.button.copyWith(color: textColor), highlightColor: _getHighlightColor(theme, buttonTheme), splashColor: _getSplashColor(theme, buttonTheme), elevation: 0.0, highlightElevation: 0.0, materialTapTargetSize: materialTapTargetSize ?? theme.materialTapTargetSize, padding: padding ?? buttonTheme.padding, constraints: buttonTheme.constraints, shape: shape ?? buttonTheme.shape, child: child, ); } @override void debugFillProperties(DiagnosticPropertiesBuilder properties) { super.debugFillProperties(properties); properties.add(new ObjectFlagProperty<VoidCallback>('onPressed', onPressed, ifNull: 'disabled')); properties.add(new DiagnosticsProperty<ButtonTextTheme>('textTheme', textTheme, defaultValue: null)); properties.add(new DiagnosticsProperty<Color>('textColor', textColor, defaultValue: null)); properties.add(new DiagnosticsProperty<Color>('disabledTextColor', disabledTextColor, defaultValue: null)); properties.add(new DiagnosticsProperty<Color>('color', color, defaultValue: null)); properties.add(new DiagnosticsProperty<Color>('disabledColor', disabledColor, defaultValue: null)); properties.add(new DiagnosticsProperty<Color>('highlightColor', highlightColor, defaultValue: null)); properties.add(new DiagnosticsProperty<Color>('splashColor', splashColor, defaultValue: null)); properties.add(new DiagnosticsProperty<Brightness>('colorBrightness', colorBrightness, defaultValue: null)); properties.add(new DiagnosticsProperty<EdgeInsetsGeometry>('padding', padding, defaultValue: null)); properties.add(new DiagnosticsProperty<ShapeBorder>('shape', shape, defaultValue: null)); properties.add(new DiagnosticsProperty<MaterialTapTargetSize>('materialTapTargetSize', materialTapTargetSize, defaultValue: null)); } }