// 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 'dart:ui' show lerpDouble; import 'package:flutter/foundation.dart'; import 'package:flutter/widgets.dart'; import 'material_state.dart'; import 'theme.dart'; /// Defines default property values for descendant [Scrollbar] widgets. /// /// Descendant widgets obtain the current [ScrollbarThemeData] object with /// `ScrollbarTheme.of(context)`. Instances of [ScrollbarThemeData] can be customized /// with [ScrollbarThemeData.copyWith]. /// /// Typically the [ScrollbarThemeData] of a [ScrollbarTheme] is specified as part of the overall /// [Theme] with [ThemeData.scrollbarTheme]. /// /// All [ScrollbarThemeData] properties are `null` by default. When null, the [Scrollbar] /// computes its own default values, typically based on the overall theme's /// [ThemeData.colorScheme]. /// /// See also: /// /// * [ThemeData], which describes the overall theme information for the /// application. @immutable class ScrollbarThemeData with Diagnosticable { /// Creates a theme that can be used for [ThemeData.scrollbarTheme]. const ScrollbarThemeData({ this.thickness, this.showTrackOnHover, this.isAlwaysShown, this.radius, this.thumbColor, this.trackColor, this.trackBorderColor, this.crossAxisMargin, this.mainAxisMargin, this.minThumbLength, this.interactive, }); /// Overrides the default value of [Scrollbar.thickness] in all /// descendant [Scrollbar] widgets. /// /// Resolves in the following states: /// * [MaterialState.hovered] on web and desktop platforms. final MaterialStateProperty<double?>? thickness; /// Overrides the default value of [Scrollbar.showTrackOnHover] in all /// descendant [Scrollbar] widgets. final bool? showTrackOnHover; /// Overrides the default value of [Scrollbar.isAlwaysShown] in all /// descendant [Scrollbar] widgets. final bool? isAlwaysShown; /// Overrides the default value of [Scrollbar.interactive] in all /// descendant [Scrollbar] widgets. final bool? interactive; /// Overrides the default value of [Scrollbar.radius] in all /// descendant widgets. final Radius? radius; /// Overrides the default [Color] of the [Scrollbar] thumb in all descendant /// [Scrollbar] widgets. /// /// Resolves in the following states: /// * [MaterialState.dragged]. /// * [MaterialState.hovered] on web and desktop platforms. final MaterialStateProperty<Color?>? thumbColor; /// Overrides the default [Color] of the [Scrollbar] track when /// [showTrackOnHover] is true in all descendant [Scrollbar] widgets. /// /// Resolves in the following states: /// * [MaterialState.hovered] on web and desktop platforms. final MaterialStateProperty<Color?>? trackColor; /// Overrides the default [Color] of the [Scrollbar] track border when /// [showTrackOnHover] is true in all descendant [Scrollbar] widgets. /// /// Resolves in the following states: /// * [MaterialState.hovered] on web and desktop platforms. final MaterialStateProperty<Color?>? trackBorderColor; /// Overrides the default value of the [ScrollbarPainter.crossAxisMargin] /// property in all descendant [Scrollbar] widgets. /// /// See also: /// /// * [ScrollbarPainter.crossAxisMargin], which sets the distance from the /// scrollbar's side to the nearest edge in logical pixels. final double? crossAxisMargin; /// Overrides the default value of the [ScrollbarPainter.mainAxisMargin] /// property in all descendant [Scrollbar] widgets. /// /// See also: /// /// * [ScrollbarPainter.mainAxisMargin], which sets the distance from the /// scrollbar's start and end to the edge of the viewport in logical pixels. final double? mainAxisMargin; /// Overrides the default value of the [ScrollbarPainter.minLength] /// property in all descendant [Scrollbar] widgets. /// /// See also: /// /// * [ScrollbarPainter.minLength], which sets the preferred smallest size /// the scrollbar can shrink to when the total scrollable extent is large, /// the current visible viewport is small, and the viewport is not /// overscrolled. final double? minThumbLength; /// Creates a copy of this object with the given fields replaced with the /// new values. ScrollbarThemeData copyWith({ MaterialStateProperty<double?>? thickness, bool? showTrackOnHover, bool? isAlwaysShown, bool? interactive, Radius? radius, MaterialStateProperty<Color?>? thumbColor, MaterialStateProperty<Color?>? trackColor, MaterialStateProperty<Color?>? trackBorderColor, double? crossAxisMargin, double? mainAxisMargin, double? minThumbLength, }) { return ScrollbarThemeData( thickness: thickness ?? this.thickness, showTrackOnHover: showTrackOnHover ?? this.showTrackOnHover, isAlwaysShown: isAlwaysShown ?? this.isAlwaysShown, interactive: interactive ?? this.interactive, radius: radius ?? this.radius, thumbColor: thumbColor ?? this.thumbColor, trackColor: trackColor ?? this.trackColor, trackBorderColor: trackBorderColor ?? this.trackBorderColor, crossAxisMargin: crossAxisMargin ?? this.crossAxisMargin, mainAxisMargin: mainAxisMargin ?? this.mainAxisMargin, minThumbLength: minThumbLength ?? this.minThumbLength, ); } /// Linearly interpolate between two Scrollbar themes. /// /// The argument `t` must not be null. /// /// {@macro dart.ui.shadow.lerp} static ScrollbarThemeData lerp(ScrollbarThemeData? a, ScrollbarThemeData? b, double t) { assert(t != null); return ScrollbarThemeData( thickness: _lerpProperties<double?>(a?.thickness, b?.thickness, t, lerpDouble), showTrackOnHover: t < 0.5 ? a?.showTrackOnHover : b?.showTrackOnHover, isAlwaysShown: t < 0.5 ? a?.isAlwaysShown : b?.isAlwaysShown, interactive: t < 0.5 ? a?.interactive : b?.interactive, radius: Radius.lerp(a?.radius, b?.radius, t), thumbColor: _lerpProperties<Color?>(a?.thumbColor, b?.thumbColor, t, Color.lerp), trackColor: _lerpProperties<Color?>(a?.trackColor, b?.trackColor, t, Color.lerp), trackBorderColor: _lerpProperties<Color?>(a?.trackBorderColor, b?.trackBorderColor, t, Color.lerp), crossAxisMargin: lerpDouble(a?.crossAxisMargin, b?.crossAxisMargin, t), mainAxisMargin: lerpDouble(a?.mainAxisMargin, b?.mainAxisMargin, t), minThumbLength: lerpDouble(a?.minThumbLength, b?.minThumbLength, t), ); } @override int get hashCode { return hashValues( thickness, showTrackOnHover, isAlwaysShown, interactive, radius, thumbColor, trackColor, trackBorderColor, crossAxisMargin, mainAxisMargin, minThumbLength, ); } @override bool operator ==(Object other) { if (identical(this, other)) return true; if (other.runtimeType != runtimeType) return false; return other is ScrollbarThemeData && other.thickness == thickness && other.showTrackOnHover == showTrackOnHover && other.isAlwaysShown == isAlwaysShown && other.interactive == interactive && other.radius == radius && other.thumbColor == thumbColor && other.trackColor == trackColor && other.trackBorderColor == trackBorderColor && other.crossAxisMargin == crossAxisMargin && other.mainAxisMargin == mainAxisMargin && other.minThumbLength == minThumbLength; } @override void debugFillProperties(DiagnosticPropertiesBuilder properties) { super.debugFillProperties(properties); properties.add(DiagnosticsProperty<MaterialStateProperty<double?>>('thickness', thickness, defaultValue: null)); properties.add(DiagnosticsProperty<bool>('showTrackOnHover', showTrackOnHover, defaultValue: null)); properties.add(DiagnosticsProperty<bool>('isAlwaysShown', isAlwaysShown, defaultValue: null)); properties.add(DiagnosticsProperty<bool>('interactive', interactive, defaultValue: null)); properties.add(DiagnosticsProperty<Radius>('radius', radius, defaultValue: null)); properties.add(DiagnosticsProperty<MaterialStateProperty<Color?>>('thumbColor', thumbColor, defaultValue: null)); properties.add(DiagnosticsProperty<MaterialStateProperty<Color?>>('trackColor', trackColor, defaultValue: null)); properties.add(DiagnosticsProperty<MaterialStateProperty<Color?>>('trackBorderColor', trackBorderColor, defaultValue: null)); properties.add(DiagnosticsProperty<double>('crossAxisMargin', crossAxisMargin, defaultValue: null)); properties.add(DiagnosticsProperty<double>('mainAxisMargin', mainAxisMargin, defaultValue: null)); properties.add(DiagnosticsProperty<double>('minThumbLength', minThumbLength, defaultValue: null)); } static MaterialStateProperty<T>? _lerpProperties<T>( MaterialStateProperty<T>? a, MaterialStateProperty<T>? b, double t, T Function(T?, T?, double) lerpFunction, ) { // Avoid creating a _LerpProperties object for a common case. if (a == null && b == null) return null; return _LerpProperties<T>(a, b, t, lerpFunction); } } class _LerpProperties<T> implements MaterialStateProperty<T> { const _LerpProperties(this.a, this.b, this.t, this.lerpFunction); final MaterialStateProperty<T>? a; final MaterialStateProperty<T>? b; final double t; final T Function(T?, T?, double) lerpFunction; @override T resolve(Set<MaterialState> states) { final T? resolvedA = a?.resolve(states); final T? resolvedB = b?.resolve(states); return lerpFunction(resolvedA, resolvedB, t); } } /// Applies a scrollbar theme to descendant [Scrollbar] widgets. /// /// Descendant widgets obtain the current theme's [ScrollbarThemeData] using /// [ScrollbarTheme.of]. When a widget uses [ScrollbarTheme.of], it is /// automatically rebuilt if the theme later changes. /// /// A scrollbar theme can be specified as part of the overall Material theme /// using [ThemeData.scrollbarTheme]. /// /// See also: /// /// * [ScrollbarThemeData], which describes the configuration of a /// scrollbar theme. class ScrollbarTheme extends InheritedWidget { /// Constructs a scrollbar theme that configures all descendant [Scrollbar] /// widgets. const ScrollbarTheme({ Key? key, required this.data, required Widget child, }) : super(key: key, child: child); /// The properties used for all descendant [Scrollbar] widgets. final ScrollbarThemeData data; /// Returns the configuration [data] from the closest [ScrollbarTheme] /// ancestor. If there is no ancestor, it returns [ThemeData.scrollbarTheme]. /// /// Typical usage is as follows: /// /// ```dart /// ScrollbarThemeData theme = ScrollbarTheme.of(context); /// ``` static ScrollbarThemeData of(BuildContext context) { final ScrollbarTheme? scrollbarTheme = context.dependOnInheritedWidgetOfExactType<ScrollbarTheme>(); return scrollbarTheme?.data ?? Theme.of(context).scrollbarTheme; } @override bool updateShouldNotify(ScrollbarTheme oldWidget) => data != oldWidget.data; }