| // 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:math' as math; |
| import 'dart:ui' show lerpDouble; |
| |
| import 'package:flutter/foundation.dart'; |
| import 'package:flutter/gestures.dart' show DragStartBehavior; |
| import 'package:flutter/rendering.dart'; |
| import 'package:flutter/widgets.dart'; |
| |
| import 'app_bar.dart'; |
| import 'color_scheme.dart'; |
| import 'colors.dart'; |
| import 'constants.dart'; |
| import 'debug.dart'; |
| import 'ink_well.dart'; |
| import 'material.dart'; |
| import 'material_localizations.dart'; |
| import 'material_state.dart'; |
| import 'tab_bar_theme.dart'; |
| import 'tab_controller.dart'; |
| import 'tab_indicator.dart'; |
| import 'text_theme.dart'; |
| import 'theme.dart'; |
| |
| const double _kTabHeight = 46.0; |
| const double _kTextAndIconTabHeight = 72.0; |
| const double _kStartOffset = 52.0; |
| |
| /// Defines how the bounds of the selected tab indicator are computed. |
| /// |
| /// See also: |
| /// |
| /// * [TabBar], which displays a row of tabs. |
| /// * [TabBarView], which displays a widget for the currently selected tab. |
| /// * [TabBar.indicator], which defines the appearance of the selected tab |
| /// indicator relative to the tab's bounds. |
| enum TabBarIndicatorSize { |
| /// The tab indicator's bounds are as wide as the space occupied by the tab |
| /// in the tab bar: from the right edge of the previous tab to the left edge |
| /// of the next tab. |
| tab, |
| |
| /// The tab's bounds are only as wide as the (centered) tab widget itself. |
| /// |
| /// This value is used to align the tab's label, typically a [Tab] |
| /// widget's text or icon, with the selected tab indicator. |
| label, |
| } |
| |
| /// Defines how tabs are aligned horizontally in a [TabBar]. |
| /// |
| /// See also: |
| /// |
| /// * [TabBar], which displays a row of tabs. |
| /// * [TabBarView], which displays a widget for the currently selected tab. |
| /// * [TabBar.tabAlignment], which defines the horizontal alignment of the |
| /// tabs within the [TabBar]. |
| enum TabAlignment { |
| // TODO(tahatesser): Add a link to the Material Design spec for |
| // horizontal offset when it is available. |
| // It's currently sourced from androidx/compose/material3/TabRow.kt. |
| /// If [TabBar.isScrollable] is true, tabs are aligned to the |
| /// start of the [TabBar]. Otherwise throws an exception. |
| /// |
| /// It is not recommended to set [TabAlignment.start] when |
| /// [ThemeData.useMaterial3] is false. |
| start, |
| |
| /// If [TabBar.isScrollable] is true, tabs are aligned to the |
| /// start of the [TabBar] with an offset of 52.0 pixels. |
| /// Otherwise throws an exception. |
| /// |
| /// It is not recommended to set [TabAlignment.startOffset] when |
| /// [ThemeData.useMaterial3] is false. |
| startOffset, |
| |
| /// If [TabBar.isScrollable] is false, tabs are stretched to fill the |
| /// [TabBar]. Otherwise throws an exception. |
| fill, |
| |
| /// Tabs are aligned to the center of the [TabBar]. |
| center, |
| } |
| |
| /// A Material Design [TabBar] tab. |
| /// |
| /// If both [icon] and [text] are provided, the text is displayed below |
| /// the icon. |
| /// |
| /// See also: |
| /// |
| /// * [TabBar], which displays a row of tabs. |
| /// * [TabBarView], which displays a widget for the currently selected tab. |
| /// * [TabController], which coordinates tab selection between a [TabBar] and a [TabBarView]. |
| /// * <https://material.io/design/components/tabs.html> |
| class Tab extends StatelessWidget implements PreferredSizeWidget { |
| /// Creates a Material Design [TabBar] tab. |
| /// |
| /// At least one of [text], [icon], and [child] must be non-null. The [text] |
| /// and [child] arguments must not be used at the same time. The |
| /// [iconMargin] is only useful when [icon] and either one of [text] or |
| /// [child] is non-null. |
| const Tab({ |
| super.key, |
| this.text, |
| this.icon, |
| this.iconMargin = const EdgeInsets.only(bottom: 10.0), |
| this.height, |
| this.child, |
| }) : assert(text != null || child != null || icon != null), |
| assert(text == null || child == null); |
| |
| /// The text to display as the tab's label. |
| /// |
| /// Must not be used in combination with [child]. |
| final String? text; |
| |
| /// The widget to be used as the tab's label. |
| /// |
| /// Usually a [Text] widget, possibly wrapped in a [Semantics] widget. |
| /// |
| /// Must not be used in combination with [text]. |
| final Widget? child; |
| |
| /// An icon to display as the tab's label. |
| final Widget? icon; |
| |
| /// The margin added around the tab's icon. |
| /// |
| /// Only useful when used in combination with [icon], and either one of |
| /// [text] or [child] is non-null. |
| final EdgeInsetsGeometry iconMargin; |
| |
| /// The height of the [Tab]. |
| /// |
| /// If null, the height will be calculated based on the content of the [Tab]. When `icon` is not |
| /// null along with `child` or `text`, the default height is 72.0 pixels. Without an `icon`, the |
| /// height is 46.0 pixels. |
| final double? height; |
| |
| Widget _buildLabelText() { |
| return child ?? Text(text!, softWrap: false, overflow: TextOverflow.fade); |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| assert(debugCheckHasMaterial(context)); |
| |
| final double calculatedHeight; |
| final Widget label; |
| if (icon == null) { |
| calculatedHeight = _kTabHeight; |
| label = _buildLabelText(); |
| } else if (text == null && child == null) { |
| calculatedHeight = _kTabHeight; |
| label = icon!; |
| } else { |
| calculatedHeight = _kTextAndIconTabHeight; |
| label = Column( |
| mainAxisAlignment: MainAxisAlignment.center, |
| children: <Widget>[ |
| Container( |
| margin: iconMargin, |
| child: icon, |
| ), |
| _buildLabelText(), |
| ], |
| ); |
| } |
| |
| return SizedBox( |
| height: height ?? calculatedHeight, |
| child: Center( |
| widthFactor: 1.0, |
| child: label, |
| ), |
| ); |
| } |
| |
| @override |
| void debugFillProperties(DiagnosticPropertiesBuilder properties) { |
| super.debugFillProperties(properties); |
| properties.add(StringProperty('text', text, defaultValue: null)); |
| properties.add(DiagnosticsProperty<Widget>('icon', icon, defaultValue: null)); |
| } |
| |
| @override |
| Size get preferredSize { |
| if (height != null) { |
| return Size.fromHeight(height!); |
| } else if ((text != null || child != null) && icon != null) { |
| return const Size.fromHeight(_kTextAndIconTabHeight); |
| } else { |
| return const Size.fromHeight(_kTabHeight); |
| } |
| } |
| } |
| |
| class _TabStyle extends AnimatedWidget { |
| const _TabStyle({ |
| required Animation<double> animation, |
| required this.isSelected, |
| required this.isPrimary, |
| required this.labelColor, |
| required this.unselectedLabelColor, |
| required this.labelStyle, |
| required this.unselectedLabelStyle, |
| required this.defaults, |
| required this.child, |
| }) : super(listenable: animation); |
| |
| final TextStyle? labelStyle; |
| final TextStyle? unselectedLabelStyle; |
| final bool isSelected; |
| final bool isPrimary; |
| final Color? labelColor; |
| final Color? unselectedLabelColor; |
| final TabBarTheme defaults; |
| final Widget child; |
| |
| MaterialStateColor _resolveWithLabelColor(BuildContext context) { |
| final ThemeData themeData = Theme.of(context); |
| final TabBarTheme tabBarTheme = TabBarTheme.of(context); |
| final Animation<double> animation = listenable as Animation<double>; |
| |
| // labelStyle.color (and tabBarTheme.labelStyle.color) is not considered |
| // as it'll be a breaking change without a possible migration plan. for |
| // details: https://github.com/flutter/flutter/pull/109541#issuecomment-1294241417 |
| Color selectedColor = labelColor |
| ?? tabBarTheme.labelColor |
| ?? defaults.labelColor!; |
| |
| final Color unselectedColor; |
| |
| if (selectedColor is MaterialStateColor) { |
| unselectedColor = selectedColor.resolve(const <MaterialState>{}); |
| selectedColor = selectedColor.resolve(const <MaterialState>{MaterialState.selected}); |
| } else { |
| // unselectedLabelColor and tabBarTheme.unselectedLabelColor are ignored |
| // when labelColor is a MaterialStateColor. |
| unselectedColor = unselectedLabelColor |
| ?? tabBarTheme.unselectedLabelColor |
| ?? (themeData.useMaterial3 |
| ? defaults.unselectedLabelColor! |
| : selectedColor.withAlpha(0xB2)); // 70% alpha |
| } |
| |
| return MaterialStateColor.resolveWith((Set<MaterialState> states) { |
| if (states.contains(MaterialState.selected)) { |
| return Color.lerp(selectedColor, unselectedColor, animation.value)!; |
| } |
| return Color.lerp(unselectedColor, selectedColor, animation.value)!; |
| }); |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| final TabBarTheme tabBarTheme = TabBarTheme.of(context); |
| final Animation<double> animation = listenable as Animation<double>; |
| |
| final Set<MaterialState> states = isSelected |
| ? const <MaterialState>{MaterialState.selected} |
| : const <MaterialState>{}; |
| |
| // To enable TextStyle.lerp(style1, style2, value), both styles must have |
| // the same value of inherit. Force that to be inherit=true here. |
| final TextStyle defaultStyle = (labelStyle |
| ?? tabBarTheme.labelStyle |
| ?? defaults.labelStyle! |
| ).copyWith(inherit: true); |
| final TextStyle defaultUnselectedStyle = (unselectedLabelStyle |
| ?? tabBarTheme.unselectedLabelStyle |
| ?? labelStyle |
| ?? defaults.unselectedLabelStyle! |
| ).copyWith(inherit: true); |
| final TextStyle textStyle = isSelected |
| ? TextStyle.lerp(defaultStyle, defaultUnselectedStyle, animation.value)! |
| : TextStyle.lerp(defaultUnselectedStyle, defaultStyle, animation.value)!; |
| final Color color = _resolveWithLabelColor(context).resolve(states); |
| |
| return DefaultTextStyle( |
| style: textStyle.copyWith(color: color), |
| child: IconTheme.merge( |
| data: IconThemeData( |
| size: 24.0, |
| color: color, |
| ), |
| child: child, |
| ), |
| ); |
| } |
| } |
| |
| typedef _LayoutCallback = void Function(List<double> xOffsets, TextDirection textDirection, double width); |
| |
| class _TabLabelBarRenderer extends RenderFlex { |
| _TabLabelBarRenderer({ |
| required super.direction, |
| required super.mainAxisSize, |
| required super.mainAxisAlignment, |
| required super.crossAxisAlignment, |
| required TextDirection super.textDirection, |
| required super.verticalDirection, |
| required this.onPerformLayout, |
| }); |
| |
| _LayoutCallback onPerformLayout; |
| |
| @override |
| void performLayout() { |
| super.performLayout(); |
| // xOffsets will contain childCount+1 values, giving the offsets of the |
| // leading edge of the first tab as the first value, of the leading edge of |
| // the each subsequent tab as each subsequent value, and of the trailing |
| // edge of the last tab as the last value. |
| RenderBox? child = firstChild; |
| final List<double> xOffsets = <double>[]; |
| while (child != null) { |
| final FlexParentData childParentData = child.parentData! as FlexParentData; |
| xOffsets.add(childParentData.offset.dx); |
| assert(child.parentData == childParentData); |
| child = childParentData.nextSibling; |
| } |
| assert(textDirection != null); |
| switch (textDirection!) { |
| case TextDirection.rtl: |
| xOffsets.insert(0, size.width); |
| case TextDirection.ltr: |
| xOffsets.add(size.width); |
| } |
| onPerformLayout(xOffsets, textDirection!, size.width); |
| } |
| } |
| |
| // This class and its renderer class only exist to report the widths of the tabs |
| // upon layout. The tab widths are only used at paint time (see _IndicatorPainter) |
| // or in response to input. |
| class _TabLabelBar extends Flex { |
| const _TabLabelBar({ |
| super.children, |
| required this.onPerformLayout, |
| required super.mainAxisSize, |
| }) : super( |
| direction: Axis.horizontal, |
| mainAxisAlignment: MainAxisAlignment.start, |
| crossAxisAlignment: CrossAxisAlignment.center, |
| verticalDirection: VerticalDirection.down, |
| ); |
| |
| final _LayoutCallback onPerformLayout; |
| |
| @override |
| RenderFlex createRenderObject(BuildContext context) { |
| return _TabLabelBarRenderer( |
| direction: direction, |
| mainAxisAlignment: mainAxisAlignment, |
| mainAxisSize: mainAxisSize, |
| crossAxisAlignment: crossAxisAlignment, |
| textDirection: getEffectiveTextDirection(context)!, |
| verticalDirection: verticalDirection, |
| onPerformLayout: onPerformLayout, |
| ); |
| } |
| |
| @override |
| void updateRenderObject(BuildContext context, _TabLabelBarRenderer renderObject) { |
| super.updateRenderObject(context, renderObject); |
| renderObject.onPerformLayout = onPerformLayout; |
| } |
| } |
| |
| double _indexChangeProgress(TabController controller) { |
| final double controllerValue = controller.animation!.value; |
| final double previousIndex = controller.previousIndex.toDouble(); |
| final double currentIndex = controller.index.toDouble(); |
| |
| // The controller's offset is changing because the user is dragging the |
| // TabBarView's PageView to the left or right. |
| if (!controller.indexIsChanging) { |
| return clampDouble((currentIndex - controllerValue).abs(), 0.0, 1.0); |
| } |
| |
| // The TabController animation's value is changing from previousIndex to currentIndex. |
| return (controllerValue - currentIndex).abs() / (currentIndex - previousIndex).abs(); |
| } |
| |
| class _IndicatorPainter extends CustomPainter { |
| _IndicatorPainter({ |
| required this.controller, |
| required this.indicator, |
| required this.indicatorSize, |
| required this.tabKeys, |
| required _IndicatorPainter? old, |
| required this.indicatorPadding, |
| required this.labelPaddings, |
| this.dividerColor, |
| }) : super(repaint: controller.animation) { |
| if (old != null) { |
| saveTabOffsets(old._currentTabOffsets, old._currentTextDirection); |
| } |
| } |
| |
| final TabController controller; |
| final Decoration indicator; |
| final TabBarIndicatorSize? indicatorSize; |
| final EdgeInsetsGeometry indicatorPadding; |
| final List<GlobalKey> tabKeys; |
| final Color? dividerColor; |
| final List<EdgeInsetsGeometry> labelPaddings; |
| |
| // _currentTabOffsets and _currentTextDirection are set each time TabBar |
| // layout is completed. These values can be null when TabBar contains no |
| // tabs, since there are nothing to lay out. |
| List<double>? _currentTabOffsets; |
| TextDirection? _currentTextDirection; |
| |
| Rect? _currentRect; |
| BoxPainter? _painter; |
| bool _needsPaint = false; |
| void markNeedsPaint() { |
| _needsPaint = true; |
| } |
| |
| void dispose() { |
| _painter?.dispose(); |
| } |
| |
| void saveTabOffsets(List<double>? tabOffsets, TextDirection? textDirection) { |
| _currentTabOffsets = tabOffsets; |
| _currentTextDirection = textDirection; |
| } |
| |
| // _currentTabOffsets[index] is the offset of the start edge of the tab at index, and |
| // _currentTabOffsets[_currentTabOffsets.length] is the end edge of the last tab. |
| int get maxTabIndex => _currentTabOffsets!.length - 2; |
| |
| double centerOf(int tabIndex) { |
| assert(_currentTabOffsets != null); |
| assert(_currentTabOffsets!.isNotEmpty); |
| assert(tabIndex >= 0); |
| assert(tabIndex <= maxTabIndex); |
| return (_currentTabOffsets![tabIndex] + _currentTabOffsets![tabIndex + 1]) / 2.0; |
| } |
| |
| Rect indicatorRect(Size tabBarSize, int tabIndex) { |
| assert(_currentTabOffsets != null); |
| assert(_currentTextDirection != null); |
| assert(_currentTabOffsets!.isNotEmpty); |
| assert(tabIndex >= 0); |
| assert(tabIndex <= maxTabIndex); |
| double tabLeft, tabRight; |
| switch (_currentTextDirection!) { |
| case TextDirection.rtl: |
| tabLeft = _currentTabOffsets![tabIndex + 1]; |
| tabRight = _currentTabOffsets![tabIndex]; |
| case TextDirection.ltr: |
| tabLeft = _currentTabOffsets![tabIndex]; |
| tabRight = _currentTabOffsets![tabIndex + 1]; |
| } |
| |
| if (indicatorSize == TabBarIndicatorSize.label) { |
| final double tabWidth = tabKeys[tabIndex].currentContext!.size!.width; |
| final EdgeInsetsGeometry labelPadding = labelPaddings[tabIndex]; |
| final EdgeInsets insets = labelPadding.resolve(_currentTextDirection); |
| final double delta = ((tabRight - tabLeft) - (tabWidth + insets.horizontal)) / 2.0; |
| tabLeft += delta + insets.left; |
| tabRight = tabLeft + tabWidth; |
| } |
| |
| final EdgeInsets insets = indicatorPadding.resolve(_currentTextDirection); |
| final Rect rect = Rect.fromLTWH(tabLeft, 0.0, tabRight - tabLeft, tabBarSize.height); |
| |
| if (!(rect.size >= insets.collapsedSize)) { |
| throw FlutterError( |
| 'indicatorPadding insets should be less than Tab Size\n' |
| 'Rect Size : ${rect.size}, Insets: $insets', |
| ); |
| } |
| return insets.deflateRect(rect); |
| } |
| |
| @override |
| void paint(Canvas canvas, Size size) { |
| _needsPaint = false; |
| _painter ??= indicator.createBoxPainter(markNeedsPaint); |
| |
| final double index = controller.index.toDouble(); |
| final double value = controller.animation!.value; |
| final bool ltr = index > value; |
| final int from = (ltr ? value.floor() : value.ceil()).clamp(0, maxTabIndex); // ignore_clamp_double_lint |
| final int to = (ltr ? from + 1 : from - 1).clamp(0, maxTabIndex); // ignore_clamp_double_lint |
| final Rect fromRect = indicatorRect(size, from); |
| final Rect toRect = indicatorRect(size, to); |
| _currentRect = Rect.lerp(fromRect, toRect, (value - from).abs()); |
| assert(_currentRect != null); |
| |
| final ImageConfiguration configuration = ImageConfiguration( |
| size: _currentRect!.size, |
| textDirection: _currentTextDirection, |
| ); |
| if (dividerColor != null) { |
| final Paint dividerPaint = Paint()..color = dividerColor!..strokeWidth = 1; |
| canvas.drawLine(Offset(0, size.height), Offset(size.width, size.height), dividerPaint); |
| } |
| _painter!.paint(canvas, _currentRect!.topLeft, configuration); |
| } |
| |
| @override |
| bool shouldRepaint(_IndicatorPainter old) { |
| return _needsPaint |
| || controller != old.controller |
| || indicator != old.indicator |
| || tabKeys.length != old.tabKeys.length |
| || (!listEquals(_currentTabOffsets, old._currentTabOffsets)) |
| || _currentTextDirection != old._currentTextDirection; |
| } |
| } |
| |
| class _ChangeAnimation extends Animation<double> with AnimationWithParentMixin<double> { |
| _ChangeAnimation(this.controller); |
| |
| final TabController controller; |
| |
| @override |
| Animation<double> get parent => controller.animation!; |
| |
| @override |
| void removeStatusListener(AnimationStatusListener listener) { |
| if (controller.animation != null) { |
| super.removeStatusListener(listener); |
| } |
| } |
| |
| @override |
| void removeListener(VoidCallback listener) { |
| if (controller.animation != null) { |
| super.removeListener(listener); |
| } |
| } |
| |
| @override |
| double get value => _indexChangeProgress(controller); |
| } |
| |
| class _DragAnimation extends Animation<double> with AnimationWithParentMixin<double> { |
| _DragAnimation(this.controller, this.index); |
| |
| final TabController controller; |
| final int index; |
| |
| @override |
| Animation<double> get parent => controller.animation!; |
| |
| @override |
| void removeStatusListener(AnimationStatusListener listener) { |
| if (controller.animation != null) { |
| super.removeStatusListener(listener); |
| } |
| } |
| |
| @override |
| void removeListener(VoidCallback listener) { |
| if (controller.animation != null) { |
| super.removeListener(listener); |
| } |
| } |
| |
| @override |
| double get value { |
| assert(!controller.indexIsChanging); |
| final double controllerMaxValue = (controller.length - 1).toDouble(); |
| final double controllerValue = clampDouble(controller.animation!.value, 0.0, controllerMaxValue); |
| return clampDouble((controllerValue - index.toDouble()).abs(), 0.0, 1.0); |
| } |
| } |
| |
| // This class, and TabBarScrollController, only exist to handle the case |
| // where a scrollable TabBar has a non-zero initialIndex. In that case we can |
| // only compute the scroll position's initial scroll offset (the "correct" |
| // pixels value) after the TabBar viewport width and scroll limits are known. |
| class _TabBarScrollPosition extends ScrollPositionWithSingleContext { |
| _TabBarScrollPosition({ |
| required super.physics, |
| required super.context, |
| required super.oldPosition, |
| required this.tabBar, |
| }) : super( |
| initialPixels: null, |
| ); |
| |
| final _TabBarState tabBar; |
| |
| bool _viewportDimensionWasNonZero = false; |
| |
| // The scroll position should be adjusted at least once. |
| bool _needsPixelsCorrection = true; |
| |
| @override |
| bool applyContentDimensions(double minScrollExtent, double maxScrollExtent) { |
| bool result = true; |
| if (!_viewportDimensionWasNonZero) { |
| _viewportDimensionWasNonZero = viewportDimension != 0.0; |
| } |
| // If the viewport never had a non-zero dimension, we just want to jump |
| // to the initial scroll position to avoid strange scrolling effects in |
| // release mode: the viewport temporarily may have a dimension of zero |
| // before the actual dimension is calculated. In that scenario, setting |
| // the actual dimension would cause a strange scroll effect without this |
| // guard because the super call below would start a ballistic scroll activity. |
| if (!_viewportDimensionWasNonZero || _needsPixelsCorrection) { |
| _needsPixelsCorrection = false; |
| correctPixels(tabBar._initialScrollOffset(viewportDimension, minScrollExtent, maxScrollExtent)); |
| result = false; |
| } |
| return super.applyContentDimensions(minScrollExtent, maxScrollExtent) && result; |
| } |
| |
| void markNeedsPixelsCorrection() { |
| _needsPixelsCorrection = true; |
| } |
| } |
| |
| // This class, and TabBarScrollPosition, only exist to handle the case |
| // where a scrollable TabBar has a non-zero initialIndex. |
| class _TabBarScrollController extends ScrollController { |
| _TabBarScrollController(this.tabBar); |
| |
| final _TabBarState tabBar; |
| |
| @override |
| ScrollPosition createScrollPosition(ScrollPhysics physics, ScrollContext context, ScrollPosition? oldPosition) { |
| return _TabBarScrollPosition( |
| physics: physics, |
| context: context, |
| oldPosition: oldPosition, |
| tabBar: tabBar, |
| ); |
| } |
| } |
| |
| /// A Material Design primary tab bar. |
| /// |
| /// Primary tabs are placed at the top of the content pane under a top app bar. |
| /// They display the main content destinations. |
| /// |
| /// Typically created as the [AppBar.bottom] part of an [AppBar] and in |
| /// conjunction with a [TabBarView]. |
| /// |
| /// {@youtube 560 315 https://www.youtube.com/watch?v=POtoEH-5l40} |
| /// |
| /// If a [TabController] is not provided, then a [DefaultTabController] ancestor |
| /// must be provided instead. The tab controller's [TabController.length] must |
| /// equal the length of the [tabs] list and the length of the |
| /// [TabBarView.children] list. |
| /// |
| /// Requires one of its ancestors to be a [Material] widget. |
| /// |
| /// Uses values from [TabBarTheme] if it is set in the current context. |
| /// |
| /// {@tool dartpad} |
| /// This sample shows the implementation of [TabBar] and [TabBarView] using a [DefaultTabController]. |
| /// Each [Tab] corresponds to a child of the [TabBarView] in the order they are written. |
| /// |
| /// ** See code in examples/api/lib/material/tabs/tab_bar.0.dart ** |
| /// {@end-tool} |
| /// |
| /// {@tool dartpad} |
| /// [TabBar] can also be implemented by using a [TabController] which provides more options |
| /// to control the behavior of the [TabBar] and [TabBarView]. This can be used instead of |
| /// a [DefaultTabController], demonstrated below. |
| /// |
| /// ** See code in examples/api/lib/material/tabs/tab_bar.1.dart ** |
| /// {@end-tool} |
| /// |
| /// {@tool dartpad} |
| /// This sample showcases nested Material 3 [TabBar]s. It consists of a primary |
| /// [TabBar] with nested a secondary [TabBar]. The primary [TabBar] uses a |
| /// [DefaultTabController] while the secondary [TabBar] uses a [TabController]. |
| /// |
| /// ** See code in examples/api/lib/material/tabs/tab_bar.2.dart ** |
| /// {@end-tool} |
| /// |
| /// See also: |
| /// |
| /// * [TabBar.secondary], for a secondary tab bar. |
| /// * [TabBarView], which displays page views that correspond to each tab. |
| /// * [TabController], which coordinates tab selection between a [TabBar] and a [TabBarView]. |
| /// * https://m3.material.io/components/tab-bar/overview, the Material 3 |
| /// tab bar specification. |
| class TabBar extends StatefulWidget implements PreferredSizeWidget { |
| /// Creates a Material Design primary tab bar. |
| /// |
| /// The [tabs] argument must not be null and its length must match the [controller]'s |
| /// [TabController.length]. |
| /// |
| /// If a [TabController] is not provided, then there must be a |
| /// [DefaultTabController] ancestor. |
| /// |
| /// The [indicatorWeight] parameter defaults to 2, and must not be null. |
| /// |
| /// The [indicatorPadding] parameter defaults to [EdgeInsets.zero], and must not be null. |
| /// |
| /// If [indicator] is not null or provided from [TabBarTheme], |
| /// then [indicatorWeight] and [indicatorColor] are ignored. |
| const TabBar({ |
| super.key, |
| required this.tabs, |
| this.controller, |
| this.isScrollable = false, |
| this.padding, |
| this.indicatorColor, |
| this.automaticIndicatorColorAdjustment = true, |
| this.indicatorWeight = 2.0, |
| this.indicatorPadding = EdgeInsets.zero, |
| this.indicator, |
| this.indicatorSize, |
| this.dividerColor, |
| this.labelColor, |
| this.labelStyle, |
| this.labelPadding, |
| this.unselectedLabelColor, |
| this.unselectedLabelStyle, |
| this.dragStartBehavior = DragStartBehavior.start, |
| this.overlayColor, |
| this.mouseCursor, |
| this.enableFeedback, |
| this.onTap, |
| this.physics, |
| this.splashFactory, |
| this.splashBorderRadius, |
| this.tabAlignment, |
| }) : _isPrimary = true, |
| assert(indicator != null || (indicatorWeight > 0.0)); |
| |
| /// Creates a Material Design secondary tab bar. |
| /// |
| /// Secondary tabs are used within a content area to further separate related |
| /// content and establish hierarchy. |
| /// |
| /// {@tool dartpad} |
| /// This sample showcases nested Material 3 [TabBar]s. It consists of a primary |
| /// [TabBar] with nested a secondary [TabBar]. The primary [TabBar] uses a |
| /// [DefaultTabController] while the secondary [TabBar] uses a [TabController]. |
| /// |
| /// ** See code in examples/api/lib/material/tabs/tab_bar.2.dart ** |
| /// {@end-tool} |
| /// |
| /// See also: |
| /// |
| /// * [TabBar], for a primary tab bar. |
| /// * [TabBarView], which displays page views that correspond to each tab. |
| /// * [TabController], which coordinates tab selection between a [TabBar] and a [TabBarView]. |
| /// * https://m3.material.io/components/tab-bar/overview, the Material 3 |
| /// tab bar specification. |
| const TabBar.secondary({ |
| super.key, |
| required this.tabs, |
| this.controller, |
| this.isScrollable = false, |
| this.padding, |
| this.indicatorColor, |
| this.automaticIndicatorColorAdjustment = true, |
| this.indicatorWeight = 2.0, |
| this.indicatorPadding = EdgeInsets.zero, |
| this.indicator, |
| this.indicatorSize, |
| this.dividerColor, |
| this.labelColor, |
| this.labelStyle, |
| this.labelPadding, |
| this.unselectedLabelColor, |
| this.unselectedLabelStyle, |
| this.dragStartBehavior = DragStartBehavior.start, |
| this.overlayColor, |
| this.mouseCursor, |
| this.enableFeedback, |
| this.onTap, |
| this.physics, |
| this.splashFactory, |
| this.splashBorderRadius, |
| this.tabAlignment, |
| }) : _isPrimary = false, |
| assert(indicator != null || (indicatorWeight > 0.0)); |
| |
| /// Typically a list of two or more [Tab] widgets. |
| /// |
| /// The length of this list must match the [controller]'s [TabController.length] |
| /// and the length of the [TabBarView.children] list. |
| final List<Widget> tabs; |
| |
| /// This widget's selection and animation state. |
| /// |
| /// If [TabController] is not provided, then the value of [DefaultTabController.of] |
| /// will be used. |
| final TabController? controller; |
| |
| /// Whether this tab bar can be scrolled horizontally. |
| /// |
| /// If [isScrollable] is true, then each tab is as wide as needed for its label |
| /// and the entire [TabBar] is scrollable. Otherwise each tab gets an equal |
| /// share of the available space. |
| final bool isScrollable; |
| |
| /// The amount of space by which to inset the tab bar. |
| /// |
| /// When [isScrollable] is false, this will yield the same result as if [TabBar] was wrapped |
| /// in a [Padding] widget. When [isScrollable] is true, the scrollable itself is inset, |
| /// allowing the padding to scroll with the tab bar, rather than enclosing it. |
| final EdgeInsetsGeometry? padding; |
| |
| /// The color of the line that appears below the selected tab. |
| /// |
| /// If this parameter is null, then the value of the Theme's indicatorColor |
| /// property is used. |
| /// |
| /// If [indicator] is specified or provided from [TabBarTheme], |
| /// this property is ignored. |
| final Color? indicatorColor; |
| |
| /// The thickness of the line that appears below the selected tab. |
| /// |
| /// The value of this parameter must be greater than zero. |
| /// |
| /// If [ThemeData.useMaterial3] is true and [TabBar] is used to create a |
| /// primary tab bar, the default value is 3.0. If the provided value is less |
| /// than 3.0, the default value is used. |
| /// |
| /// If [ThemeData.useMaterial3] is true and [TabBar.secondary] is used to |
| /// create a secondary tab bar, the default value is 2.0. |
| /// |
| /// If [ThemeData.useMaterial3] is false, the default value is 2.0. |
| /// |
| /// If [indicator] is specified or provided from [TabBarTheme], |
| /// this property is ignored. |
| final double indicatorWeight; |
| |
| /// The padding for the indicator. |
| /// |
| /// The default value of this property is [EdgeInsets.zero]. |
| /// |
| /// For [isScrollable] tab bars, specifying [kTabLabelPadding] will align |
| /// the indicator with the tab's text for [Tab] widgets and all but the |
| /// shortest [Tab.text] values. |
| final EdgeInsetsGeometry indicatorPadding; |
| |
| /// Defines the appearance of the selected tab indicator. |
| /// |
| /// If [indicator] is specified or provided from [TabBarTheme], |
| /// the [indicatorColor] and [indicatorWeight] properties are ignored. |
| /// |
| /// The default, underline-style, selected tab indicator can be defined with |
| /// [UnderlineTabIndicator]. |
| /// |
| /// The indicator's size is based on the tab's bounds. If [indicatorSize] |
| /// is [TabBarIndicatorSize.tab] the tab's bounds are as wide as the space |
| /// occupied by the tab in the tab bar. If [indicatorSize] is |
| /// [TabBarIndicatorSize.label], then the tab's bounds are only as wide as |
| /// the tab widget itself. |
| /// |
| /// See also: |
| /// |
| /// * [splashBorderRadius], which defines the clipping radius of the splash |
| /// and is generally used with [BoxDecoration.borderRadius]. |
| final Decoration? indicator; |
| |
| /// Whether this tab bar should automatically adjust the [indicatorColor]. |
| /// |
| /// The default value of this property is true. |
| /// |
| /// If [automaticIndicatorColorAdjustment] is true, |
| /// then the [indicatorColor] will be automatically adjusted to [Colors.white] |
| /// when the [indicatorColor] is same as [Material.color] of the [Material] |
| /// parent widget. |
| final bool automaticIndicatorColorAdjustment; |
| |
| /// Defines how the selected tab indicator's size is computed. |
| /// |
| /// The size of the selected tab indicator is defined relative to the |
| /// tab's overall bounds if [indicatorSize] is [TabBarIndicatorSize.tab] |
| /// (the default) or relative to the bounds of the tab's widget if |
| /// [indicatorSize] is [TabBarIndicatorSize.label]. |
| /// |
| /// The selected tab's location appearance can be refined further with |
| /// the [indicatorColor], [indicatorWeight], [indicatorPadding], and |
| /// [indicator] properties. |
| final TabBarIndicatorSize? indicatorSize; |
| |
| /// The color of the divider. |
| /// |
| /// If null and [ThemeData.useMaterial3] is true, [TabBarTheme.dividerColor] |
| /// color is used. If that is null and [ThemeData.useMaterial3] is true, |
| /// [ColorScheme.surfaceVariant] will be used, otherwise divider will not be drawn. |
| final Color? dividerColor; |
| |
| /// The color of selected tab labels. |
| /// |
| /// If null, then [TabBarTheme.labelColor] is used. If that is also null and |
| /// [ThemeData.useMaterial3] is true, [ColorScheme.primary] will be used, |
| /// otherwise the color of the [ThemeData.primaryTextTheme]'s |
| /// [TextTheme.bodyLarge] text color is used. |
| /// |
| /// If [labelColor] (or, if null, [TabBarTheme.labelColor]) is a |
| /// [MaterialStateColor], then the effective tab color will depend on the |
| /// [MaterialState.selected] state, i.e. if the [Tab] is selected or not, |
| /// ignoring [unselectedLabelColor] even if it's non-null. |
| /// |
| /// The color specified in the [labelStyle] and the [TabBarTheme.labelStyle] |
| /// do not affect the effective [labelColor]. |
| /// |
| /// See also: |
| /// |
| /// * [unselectedLabelColor], for color of unselected tab labels. |
| final Color? labelColor; |
| |
| /// The color of unselected tab labels. |
| /// |
| /// If [labelColor] (or, if null, [TabBarTheme.labelColor]) is a |
| /// [MaterialStateColor], then the unselected tabs are rendered with |
| /// that [MaterialStateColor]'s resolved color for unselected state, even if |
| /// [unselectedLabelColor] is non-null. |
| /// |
| /// If null, then [TabBarTheme.unselectedLabelColor] is used. If that is also |
| /// null and [ThemeData.useMaterial3] is true, [ColorScheme.onSurfaceVariant] |
| /// will be used, otherwise unselected tab labels are rendered with |
| /// [labelColor] at 70% opacity. |
| /// |
| /// The color specified in the [unselectedLabelStyle] and the |
| /// [TabBarTheme.unselectedLabelStyle] are ignored in [unselectedLabelColor]'s |
| /// precedence calculation. |
| /// |
| /// See also: |
| /// |
| /// * [labelColor], for color of selected tab labels. |
| final Color? unselectedLabelColor; |
| |
| /// The text style of the selected tab labels. |
| /// |
| /// This does not influence color of the tab labels even if [TextStyle.color] |
| /// is non-null. Refer [labelColor] to color selected tab labels instead. |
| /// |
| /// If [unselectedLabelStyle] is null, then this text style will be used for |
| /// both selected and unselected label styles. |
| /// |
| /// If this property is null and [ThemeData.useMaterial3] is true, [TextTheme.titleSmall] |
| /// will be used, otherwise the text style of the [ThemeData.primaryTextTheme]'s |
| /// [TextTheme.bodyLarge] definition is used. |
| final TextStyle? labelStyle; |
| |
| /// The text style of the unselected tab labels. |
| /// |
| /// This does not influence color of the tab labels even if [TextStyle.color] |
| /// is non-null. Refer [unselectedLabelColor] to color unselected tab labels |
| /// instead. |
| /// |
| /// If this property is null and [ThemeData.useMaterial3] is true, |
| /// [TextTheme.titleSmall] will be used, otherwise then the [labelStyle] value |
| /// is used. If [labelStyle] is null, the text style of the |
| /// [ThemeData.primaryTextTheme]'s [TextTheme.bodyLarge] definition is used. |
| final TextStyle? unselectedLabelStyle; |
| |
| /// The padding added to each of the tab labels. |
| /// |
| /// If there are few tabs with both icon and text and few |
| /// tabs with only icon or text, this padding is vertically |
| /// adjusted to provide uniform padding to all tabs. |
| /// |
| /// If this property is null, then kTabLabelPadding is used. |
| final EdgeInsetsGeometry? labelPadding; |
| |
| /// Defines the ink response focus, hover, and splash colors. |
| /// |
| /// If non-null, it is resolved against one of [MaterialState.focused], |
| /// [MaterialState.hovered], and [MaterialState.pressed]. |
| /// |
| /// [MaterialState.pressed] triggers a ripple (an ink splash), per |
| /// the current Material Design spec. |
| /// |
| /// If the overlay color is null or resolves to null, then the default values |
| /// for [InkResponse.focusColor], [InkResponse.hoverColor], [InkResponse.splashColor], |
| /// and [InkResponse.highlightColor] will be used instead. |
| final MaterialStateProperty<Color?>? overlayColor; |
| |
| /// {@macro flutter.widgets.scrollable.dragStartBehavior} |
| final DragStartBehavior dragStartBehavior; |
| |
| /// {@template flutter.material.tabs.mouseCursor} |
| /// The cursor for a mouse pointer when it enters or is hovering over the |
| /// individual tab widgets. |
| /// |
| /// If [mouseCursor] is a [MaterialStateProperty<MouseCursor>], |
| /// [MaterialStateProperty.resolve] is used for the following [MaterialState]s: |
| /// |
| /// * [MaterialState.selected]. |
| /// {@endtemplate} |
| /// |
| /// If null, then the value of [TabBarTheme.mouseCursor] is used. If |
| /// that is also null, then [MaterialStateMouseCursor.clickable] is used. |
| /// |
| /// See also: |
| /// |
| /// * [MaterialStateMouseCursor], which can be used to create a [MouseCursor] |
| /// that is also a [MaterialStateProperty<MouseCursor>]. |
| final MouseCursor? mouseCursor; |
| |
| /// Whether detected gestures should provide acoustic and/or haptic feedback. |
| /// |
| /// For example, on Android a tap will produce a clicking sound and a long-press |
| /// will produce a short vibration, when feedback is enabled. |
| /// |
| /// Defaults to true. |
| final bool? enableFeedback; |
| |
| /// An optional callback that's called when the [TabBar] is tapped. |
| /// |
| /// The callback is applied to the index of the tab where the tap occurred. |
| /// |
| /// This callback has no effect on the default handling of taps. It's for |
| /// applications that want to do a little extra work when a tab is tapped, |
| /// even if the tap doesn't change the TabController's index. TabBar [onTap] |
| /// callbacks should not make changes to the TabController since that would |
| /// interfere with the default tap handler. |
| final ValueChanged<int>? onTap; |
| |
| /// How the [TabBar]'s scroll view should respond to user input. |
| /// |
| /// For example, determines how the scroll view continues to animate after the |
| /// user stops dragging the scroll view. |
| /// |
| /// Defaults to matching platform conventions. |
| final ScrollPhysics? physics; |
| |
| /// Creates the tab bar's [InkWell] splash factory, which defines |
| /// the appearance of "ink" splashes that occur in response to taps. |
| /// |
| /// Use [NoSplash.splashFactory] to defeat ink splash rendering. For example |
| /// to defeat both the splash and the hover/pressed overlay, but not the |
| /// keyboard focused overlay: |
| /// |
| /// ```dart |
| /// TabBar( |
| /// splashFactory: NoSplash.splashFactory, |
| /// overlayColor: MaterialStateProperty.resolveWith<Color?>( |
| /// (Set<MaterialState> states) { |
| /// return states.contains(MaterialState.focused) ? null : Colors.transparent; |
| /// }, |
| /// ), |
| /// tabs: const <Widget>[ |
| /// // ... |
| /// ], |
| /// ) |
| /// ``` |
| final InteractiveInkFeatureFactory? splashFactory; |
| |
| /// Defines the clipping radius of splashes that extend outside the bounds of the tab. |
| /// |
| /// This can be useful to match the [BoxDecoration.borderRadius] provided as [indicator]. |
| /// |
| /// ```dart |
| /// TabBar( |
| /// indicator: BoxDecoration( |
| /// borderRadius: BorderRadius.circular(40), |
| /// ), |
| /// splashBorderRadius: BorderRadius.circular(40), |
| /// tabs: const <Widget>[ |
| /// // ... |
| /// ], |
| /// ) |
| /// ``` |
| /// |
| /// If this property is null, it is interpreted as [BorderRadius.zero]. |
| final BorderRadius? splashBorderRadius; |
| |
| /// Specifies the horizontal alignment of the tabs within a [TabBar]. |
| /// |
| /// If [TabBar.isScrollable] is false, only [TabAlignment.fill] and |
| /// [TabAlignment.center] are supported. Otherwise an exception is thrown. |
| /// |
| /// If [TabBar.isScrollable] is true, only [TabAlignment.start], [TabAlignment.startOffset], |
| /// and [TabAlignment.center] are supported. Otherwise an exception is thrown. |
| /// |
| /// If this is null, then the value of [TabBarTheme.tabAlignment] is used. |
| /// |
| /// If [TabBarTheme.tabAlignment] is null and [ThemeData.useMaterial3] is true, |
| /// then [TabAlignment.startOffset] is used if [isScrollable] is true, |
| /// otherwise [TabAlignment.fill] is used. |
| /// |
| /// If [TabBarTheme.tabAlignment] is null and [ThemeData.useMaterial3] is false, |
| /// then [TabAlignment.center] is used if [isScrollable] is true, |
| /// otherwise [TabAlignment.fill] is used. |
| final TabAlignment? tabAlignment; |
| |
| /// A size whose height depends on if the tabs have both icons and text. |
| /// |
| /// [AppBar] uses this size to compute its own preferred size. |
| @override |
| Size get preferredSize { |
| double maxHeight = _kTabHeight; |
| for (final Widget item in tabs) { |
| if (item is PreferredSizeWidget) { |
| final double itemHeight = item.preferredSize.height; |
| maxHeight = math.max(itemHeight, maxHeight); |
| } |
| } |
| return Size.fromHeight(maxHeight + indicatorWeight); |
| } |
| |
| /// Returns whether the [TabBar] contains a tab with both text and icon. |
| /// |
| /// [TabBar] uses this to give uniform padding to all tabs in cases where |
| /// there are some tabs with both text and icon and some which contain only |
| /// text or icon. |
| bool get tabHasTextAndIcon { |
| for (final Widget item in tabs) { |
| if (item is PreferredSizeWidget) { |
| if (item.preferredSize.height == _kTextAndIconTabHeight) { |
| return true; |
| } |
| } |
| } |
| return false; |
| } |
| |
| /// Whether this tab bar is a primary tab bar. |
| /// |
| /// Otherwise, it is a secondary tab bar. |
| final bool _isPrimary; |
| |
| @override |
| State<TabBar> createState() => _TabBarState(); |
| } |
| |
| class _TabBarState extends State<TabBar> { |
| ScrollController? _scrollController; |
| TabController? _controller; |
| _IndicatorPainter? _indicatorPainter; |
| int? _currentIndex; |
| late double _tabStripWidth; |
| late List<GlobalKey> _tabKeys; |
| late List<EdgeInsetsGeometry> _labelPaddings; |
| bool _debugHasScheduledValidTabsCountCheck = false; |
| |
| @override |
| void initState() { |
| super.initState(); |
| // If indicatorSize is TabIndicatorSize.label, _tabKeys[i] is used to find |
| // the width of tab widget i. See _IndicatorPainter.indicatorRect(). |
| _tabKeys = widget.tabs.map((Widget tab) => GlobalKey()).toList(); |
| _labelPaddings = List<EdgeInsetsGeometry>.filled(widget.tabs.length, EdgeInsets.zero, growable: true); |
| } |
| |
| TabBarTheme get _defaults { |
| if (Theme.of(context).useMaterial3) { |
| return widget._isPrimary |
| ? _TabsPrimaryDefaultsM3(context, widget.isScrollable) |
| : _TabsSecondaryDefaultsM3(context, widget.isScrollable); |
| } else { |
| return _TabsDefaultsM2(context, widget.isScrollable); |
| } |
| } |
| |
| Decoration _getIndicator(TabBarIndicatorSize indicatorSize) { |
| final ThemeData theme = Theme.of(context); |
| final TabBarTheme tabBarTheme = TabBarTheme.of(context); |
| |
| if (widget.indicator != null) { |
| return widget.indicator!; |
| } |
| if (tabBarTheme.indicator != null) { |
| return tabBarTheme.indicator!; |
| } |
| |
| Color color = widget.indicatorColor |
| ?? (theme.useMaterial3 |
| ? tabBarTheme.indicatorColor ?? _defaults.indicatorColor! |
| : Theme.of(context).indicatorColor); |
| // ThemeData tries to avoid this by having indicatorColor avoid being the |
| // primaryColor. However, it's possible that the tab bar is on a |
| // Material that isn't the primaryColor. In that case, if the indicator |
| // color ends up matching the material's color, then this overrides it. |
| // When that happens, automatic transitions of the theme will likely look |
| // ugly as the indicator color suddenly snaps to white at one end, but it's |
| // not clear how to avoid that any further. |
| // |
| // The material's color might be null (if it's a transparency). In that case |
| // there's no good way for us to find out what the color is so we don't. |
| // |
| // TODO(xu-baolin): Remove automatic adjustment to white color indicator |
| // with a better long-term solution. |
| // https://github.com/flutter/flutter/pull/68171#pullrequestreview-517753917 |
| if (widget.automaticIndicatorColorAdjustment && |
| color.value == Material.maybeOf(context)?.color?.value) { |
| color = Colors.white; |
| } |
| |
| final bool primaryWithLabelIndicator = widget._isPrimary && indicatorSize == TabBarIndicatorSize.label; |
| final double effectiveIndicatorWeight = theme.useMaterial3 && primaryWithLabelIndicator |
| ? math.max(widget.indicatorWeight, _TabsPrimaryDefaultsM3.indicatorWeight) |
| : widget.indicatorWeight; |
| // Only Material 3 primary TabBar with label indicatorSize should be rounded. |
| final BorderRadius? effectiveBorderRadius = theme.useMaterial3 && primaryWithLabelIndicator |
| ? BorderRadius.only( |
| topLeft: Radius.circular(effectiveIndicatorWeight), |
| topRight: Radius.circular(effectiveIndicatorWeight), |
| ) |
| : null; |
| return UnderlineTabIndicator( |
| borderRadius: effectiveBorderRadius, |
| borderSide: BorderSide( |
| // TODO(tahatesser): Make sure this value matches Material 3 Tabs spec |
| // when `preferredSize`and `indicatorWeight` are updated to support Material 3 |
| // https://m3.material.io/components/tabs/specs#149a189f-9039-4195-99da-15c205d20e30, |
| // https://github.com/flutter/flutter/issues/116136 |
| width: effectiveIndicatorWeight, |
| color: color, |
| ), |
| ); |
| } |
| |
| // If the TabBar is rebuilt with a new tab controller, the caller should |
| // dispose the old one. In that case the old controller's animation will be |
| // null and should not be accessed. |
| bool get _controllerIsValid => _controller?.animation != null; |
| |
| void _updateTabController() { |
| final TabController? newController = widget.controller ?? DefaultTabController.maybeOf(context); |
| assert(() { |
| if (newController == null) { |
| throw FlutterError( |
| 'No TabController for ${widget.runtimeType}.\n' |
| 'When creating a ${widget.runtimeType}, you must either provide an explicit ' |
| 'TabController using the "controller" property, or you must ensure that there ' |
| 'is a DefaultTabController above the ${widget.runtimeType}.\n' |
| 'In this case, there was neither an explicit controller nor a default controller.', |
| ); |
| } |
| return true; |
| }()); |
| |
| if (newController == _controller) { |
| return; |
| } |
| |
| if (_controllerIsValid) { |
| _controller!.animation!.removeListener(_handleTabControllerAnimationTick); |
| _controller!.removeListener(_handleTabControllerTick); |
| } |
| _controller = newController; |
| if (_controller != null) { |
| _controller!.animation!.addListener(_handleTabControllerAnimationTick); |
| _controller!.addListener(_handleTabControllerTick); |
| _currentIndex = _controller!.index; |
| } |
| } |
| |
| void _initIndicatorPainter() { |
| final ThemeData theme = Theme.of(context); |
| final TabBarTheme tabBarTheme = TabBarTheme.of(context); |
| final TabBarIndicatorSize indicatorSize = widget.indicatorSize |
| ?? tabBarTheme.indicatorSize |
| ?? _defaults.indicatorSize!; |
| |
| _indicatorPainter = !_controllerIsValid ? null : _IndicatorPainter( |
| controller: _controller!, |
| indicator: _getIndicator(indicatorSize), |
| indicatorSize: widget.indicatorSize ?? tabBarTheme.indicatorSize ?? _defaults.indicatorSize!, |
| indicatorPadding: widget.indicatorPadding, |
| tabKeys: _tabKeys, |
| old: _indicatorPainter, |
| dividerColor: theme.useMaterial3 ? widget.dividerColor ?? tabBarTheme.dividerColor ?? _defaults.dividerColor : null, |
| labelPaddings: _labelPaddings, |
| ); |
| } |
| |
| @override |
| void didChangeDependencies() { |
| super.didChangeDependencies(); |
| assert(debugCheckHasMaterial(context)); |
| _updateTabController(); |
| _initIndicatorPainter(); |
| } |
| |
| @override |
| void didUpdateWidget(TabBar oldWidget) { |
| super.didUpdateWidget(oldWidget); |
| if (widget.controller != oldWidget.controller) { |
| _updateTabController(); |
| _initIndicatorPainter(); |
| // Adjust scroll position. |
| if (_scrollController != null && _scrollController!.hasClients) { |
| final ScrollPosition position = _scrollController!.position; |
| if (position is _TabBarScrollPosition) { |
| position.markNeedsPixelsCorrection(); |
| } |
| } |
| } else if (widget.indicatorColor != oldWidget.indicatorColor || |
| widget.indicatorWeight != oldWidget.indicatorWeight || |
| widget.indicatorSize != oldWidget.indicatorSize || |
| widget.indicatorPadding != oldWidget.indicatorPadding || |
| widget.indicator != oldWidget.indicator) { |
| _initIndicatorPainter(); |
| } |
| |
| if (widget.tabs.length > _tabKeys.length) { |
| final int delta = widget.tabs.length - _tabKeys.length; |
| _tabKeys.addAll(List<GlobalKey>.generate(delta, (int n) => GlobalKey())); |
| _labelPaddings.addAll(List<EdgeInsetsGeometry>.filled(delta, EdgeInsets.zero)); |
| } else if (widget.tabs.length < _tabKeys.length) { |
| _tabKeys.removeRange(widget.tabs.length, _tabKeys.length); |
| _labelPaddings.removeRange(widget.tabs.length, _tabKeys.length); |
| } |
| } |
| |
| @override |
| void dispose() { |
| _indicatorPainter!.dispose(); |
| if (_controllerIsValid) { |
| _controller!.animation!.removeListener(_handleTabControllerAnimationTick); |
| _controller!.removeListener(_handleTabControllerTick); |
| } |
| _controller = null; |
| // We don't own the _controller Animation, so it's not disposed here. |
| super.dispose(); |
| } |
| |
| int get maxTabIndex => _indicatorPainter!.maxTabIndex; |
| |
| double _tabScrollOffset(int index, double viewportWidth, double minExtent, double maxExtent) { |
| if (!widget.isScrollable) { |
| return 0.0; |
| } |
| double tabCenter = _indicatorPainter!.centerOf(index); |
| double paddingStart; |
| switch (Directionality.of(context)) { |
| case TextDirection.rtl: |
| paddingStart = widget.padding?.resolve(TextDirection.rtl).right ?? 0; |
| tabCenter = _tabStripWidth - tabCenter; |
| case TextDirection.ltr: |
| paddingStart = widget.padding?.resolve(TextDirection.ltr).left ?? 0; |
| } |
| |
| return clampDouble(tabCenter + paddingStart - viewportWidth / 2.0, minExtent, maxExtent); |
| } |
| |
| double _tabCenteredScrollOffset(int index) { |
| final ScrollPosition position = _scrollController!.position; |
| return _tabScrollOffset(index, position.viewportDimension, position.minScrollExtent, position.maxScrollExtent); |
| } |
| |
| double _initialScrollOffset(double viewportWidth, double minExtent, double maxExtent) { |
| return _tabScrollOffset(_currentIndex!, viewportWidth, minExtent, maxExtent); |
| } |
| |
| void _scrollToCurrentIndex() { |
| final double offset = _tabCenteredScrollOffset(_currentIndex!); |
| _scrollController!.animateTo(offset, duration: kTabScrollDuration, curve: Curves.ease); |
| } |
| |
| void _scrollToControllerValue() { |
| final double? leadingPosition = _currentIndex! > 0 ? _tabCenteredScrollOffset(_currentIndex! - 1) : null; |
| final double middlePosition = _tabCenteredScrollOffset(_currentIndex!); |
| final double? trailingPosition = _currentIndex! < maxTabIndex ? _tabCenteredScrollOffset(_currentIndex! + 1) : null; |
| |
| final double index = _controller!.index.toDouble(); |
| final double value = _controller!.animation!.value; |
| final double offset; |
| if (value == index - 1.0) { |
| offset = leadingPosition ?? middlePosition; |
| } else if (value == index + 1.0) { |
| offset = trailingPosition ?? middlePosition; |
| } else if (value == index) { |
| offset = middlePosition; |
| } else if (value < index) { |
| offset = leadingPosition == null ? middlePosition : lerpDouble(middlePosition, leadingPosition, index - value)!; |
| } else { |
| offset = trailingPosition == null ? middlePosition : lerpDouble(middlePosition, trailingPosition, value - index)!; |
| } |
| |
| _scrollController!.jumpTo(offset); |
| } |
| |
| void _handleTabControllerAnimationTick() { |
| assert(mounted); |
| if (!_controller!.indexIsChanging && widget.isScrollable) { |
| // Sync the TabBar's scroll position with the TabBarView's PageView. |
| _currentIndex = _controller!.index; |
| _scrollToControllerValue(); |
| } |
| } |
| |
| void _handleTabControllerTick() { |
| if (_controller!.index != _currentIndex) { |
| _currentIndex = _controller!.index; |
| if (widget.isScrollable) { |
| _scrollToCurrentIndex(); |
| } |
| } |
| setState(() { |
| // Rebuild the tabs after a (potentially animated) index change |
| // has completed. |
| }); |
| } |
| |
| // Called each time layout completes. |
| void _saveTabOffsets(List<double> tabOffsets, TextDirection textDirection, double width) { |
| _tabStripWidth = width; |
| _indicatorPainter?.saveTabOffsets(tabOffsets, textDirection); |
| } |
| |
| void _handleTap(int index) { |
| assert(index >= 0 && index < widget.tabs.length); |
| _controller!.animateTo(index); |
| widget.onTap?.call(index); |
| } |
| |
| Widget _buildStyledTab(Widget child, bool isSelected, Animation<double> animation, TabBarTheme defaults) { |
| return _TabStyle( |
| animation: animation, |
| isSelected: isSelected, |
| isPrimary: widget._isPrimary, |
| labelColor: widget.labelColor, |
| unselectedLabelColor: widget.unselectedLabelColor, |
| labelStyle: widget.labelStyle, |
| unselectedLabelStyle: widget.unselectedLabelStyle, |
| defaults: defaults, |
| child: child, |
| ); |
| } |
| |
| bool _debugScheduleCheckHasValidTabsCount() { |
| if (_debugHasScheduledValidTabsCountCheck) { |
| return true; |
| } |
| WidgetsBinding.instance.addPostFrameCallback((Duration duration) { |
| _debugHasScheduledValidTabsCountCheck = false; |
| if (!mounted) { |
| return; |
| } |
| assert(() { |
| if (_controller!.length != widget.tabs.length) { |
| throw FlutterError( |
| "Controller's length property (${_controller!.length}) does not match the " |
| "number of tabs (${widget.tabs.length}) present in TabBar's tabs property.", |
| ); |
| } |
| return true; |
| }()); |
| }); |
| _debugHasScheduledValidTabsCountCheck = true; |
| return true; |
| } |
| |
| bool _debugTabAlignmentIsValid(TabAlignment tabAlignment) { |
| assert(() { |
| if (widget.isScrollable && tabAlignment == TabAlignment.fill) { |
| throw FlutterError( |
| '$tabAlignment is only valid for non-scrollable tab bars.', |
| ); |
| } |
| if (!widget.isScrollable |
| && (tabAlignment == TabAlignment.start |
| || tabAlignment == TabAlignment.startOffset)) { |
| throw FlutterError( |
| '$tabAlignment is only valid for scrollable tab bars.', |
| ); |
| } |
| return true; |
| }()); |
| return true; |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| assert(debugCheckHasMaterialLocalizations(context)); |
| assert(_debugScheduleCheckHasValidTabsCount()); |
| final TabBarTheme tabBarTheme = TabBarTheme.of(context); |
| final TabAlignment effectiveTabAlignment = widget.tabAlignment ?? tabBarTheme.tabAlignment ?? _defaults.tabAlignment!; |
| assert(_debugTabAlignmentIsValid(effectiveTabAlignment)); |
| |
| final MaterialLocalizations localizations = MaterialLocalizations.of(context); |
| if (_controller!.length == 0) { |
| return Container( |
| height: _kTabHeight + widget.indicatorWeight, |
| ); |
| } |
| |
| |
| final List<Widget> wrappedTabs = List<Widget>.generate(widget.tabs.length, (int index) { |
| const double verticalAdjustment = (_kTextAndIconTabHeight - _kTabHeight)/2.0; |
| EdgeInsetsGeometry? adjustedPadding; |
| |
| if (widget.tabs[index] is PreferredSizeWidget) { |
| final PreferredSizeWidget tab = widget.tabs[index] as PreferredSizeWidget; |
| if (widget.tabHasTextAndIcon && tab.preferredSize.height == _kTabHeight) { |
| if (widget.labelPadding != null || tabBarTheme.labelPadding != null) { |
| adjustedPadding = (widget.labelPadding ?? tabBarTheme.labelPadding!).add(const EdgeInsets.symmetric(vertical: verticalAdjustment)); |
| } |
| else { |
| adjustedPadding = const EdgeInsets.symmetric(vertical: verticalAdjustment, horizontal: 16.0); |
| } |
| } |
| } |
| |
| _labelPaddings[index] = adjustedPadding ?? widget.labelPadding ?? tabBarTheme.labelPadding ?? kTabLabelPadding; |
| |
| return Center( |
| heightFactor: 1.0, |
| child: Padding( |
| padding: _labelPaddings[index], |
| child: KeyedSubtree( |
| key: _tabKeys[index], |
| child: widget.tabs[index], |
| ), |
| ), |
| ); |
| }); |
| |
| // If the controller was provided by DefaultTabController and we're part |
| // of a Hero (typically the AppBar), then we will not be able to find the |
| // controller during a Hero transition. See https://github.com/flutter/flutter/issues/213. |
| if (_controller != null) { |
| final int previousIndex = _controller!.previousIndex; |
| |
| if (_controller!.indexIsChanging) { |
| // The user tapped on a tab, the tab controller's animation is running. |
| assert(_currentIndex != previousIndex); |
| final Animation<double> animation = _ChangeAnimation(_controller!); |
| wrappedTabs[_currentIndex!] = _buildStyledTab(wrappedTabs[_currentIndex!], true, animation, _defaults); |
| wrappedTabs[previousIndex] = _buildStyledTab(wrappedTabs[previousIndex], false, animation, _defaults); |
| } else { |
| // The user is dragging the TabBarView's PageView left or right. |
| final int tabIndex = _currentIndex!; |
| final Animation<double> centerAnimation = _DragAnimation(_controller!, tabIndex); |
| wrappedTabs[tabIndex] = _buildStyledTab(wrappedTabs[tabIndex], true, centerAnimation, _defaults); |
| if (_currentIndex! > 0) { |
| final int tabIndex = _currentIndex! - 1; |
| final Animation<double> previousAnimation = ReverseAnimation(_DragAnimation(_controller!, tabIndex)); |
| wrappedTabs[tabIndex] = _buildStyledTab(wrappedTabs[tabIndex], false, previousAnimation, _defaults); |
| } |
| if (_currentIndex! < widget.tabs.length - 1) { |
| final int tabIndex = _currentIndex! + 1; |
| final Animation<double> nextAnimation = ReverseAnimation(_DragAnimation(_controller!, tabIndex)); |
| wrappedTabs[tabIndex] = _buildStyledTab(wrappedTabs[tabIndex], false, nextAnimation, _defaults); |
| } |
| } |
| } |
| |
| // Add the tap handler to each tab. If the tab bar is not scrollable, |
| // then give all of the tabs equal flexibility so that they each occupy |
| // the same share of the tab bar's overall width. |
| final int tabCount = widget.tabs.length; |
| for (int index = 0; index < tabCount; index += 1) { |
| final Set<MaterialState> selectedState = <MaterialState>{ |
| if (index == _currentIndex) MaterialState.selected, |
| }; |
| |
| final MouseCursor effectiveMouseCursor = MaterialStateProperty.resolveAs<MouseCursor?>(widget.mouseCursor, selectedState) |
| ?? tabBarTheme.mouseCursor?.resolve(selectedState) |
| ?? MaterialStateMouseCursor.clickable.resolve(selectedState); |
| |
| final MaterialStateProperty<Color?> defaultOverlay = MaterialStateProperty.resolveWith<Color?>( |
| (Set<MaterialState> states) { |
| final Set<MaterialState> effectiveStates = selectedState..addAll(states); |
| return _defaults.overlayColor?.resolve(effectiveStates); |
| }, |
| ); |
| wrappedTabs[index] = InkWell( |
| mouseCursor: effectiveMouseCursor, |
| onTap: () { _handleTap(index); }, |
| enableFeedback: widget.enableFeedback ?? true, |
| overlayColor: widget.overlayColor ?? tabBarTheme.overlayColor ?? defaultOverlay, |
| splashFactory: widget.splashFactory ?? tabBarTheme.splashFactory ?? _defaults.splashFactory, |
| borderRadius: widget.splashBorderRadius, |
| child: Padding( |
| padding: EdgeInsets.only(bottom: widget.indicatorWeight), |
| child: Stack( |
| children: <Widget>[ |
| wrappedTabs[index], |
| Semantics( |
| selected: index == _currentIndex, |
| label: localizations.tabLabel(tabIndex: index + 1, tabCount: tabCount), |
| ), |
| ], |
| ), |
| ), |
| ); |
| if (!widget.isScrollable && effectiveTabAlignment == TabAlignment.fill) { |
| wrappedTabs[index] = Expanded(child: wrappedTabs[index]); |
| } |
| } |
| |
| Widget tabBar = CustomPaint( |
| painter: _indicatorPainter, |
| child: _TabStyle( |
| animation: kAlwaysDismissedAnimation, |
| isSelected: false, |
| isPrimary: widget._isPrimary, |
| labelColor: widget.labelColor, |
| unselectedLabelColor: widget.unselectedLabelColor, |
| labelStyle: widget.labelStyle, |
| unselectedLabelStyle: widget.unselectedLabelStyle, |
| defaults: _defaults, |
| child: _TabLabelBar( |
| onPerformLayout: _saveTabOffsets, |
| mainAxisSize: effectiveTabAlignment == TabAlignment.fill ? MainAxisSize.max : MainAxisSize.min, |
| children: wrappedTabs, |
| ), |
| ), |
| ); |
| |
| if (widget.isScrollable) { |
| final EdgeInsetsGeometry? effectivePadding = effectiveTabAlignment == TabAlignment.startOffset |
| ? const EdgeInsetsDirectional.only(start: _kStartOffset).add(widget.padding ?? EdgeInsets.zero) |
| : widget.padding; |
| _scrollController ??= _TabBarScrollController(this); |
| tabBar = ScrollConfiguration( |
| // The scrolling tabs should not show an overscroll indicator. |
| behavior: ScrollConfiguration.of(context).copyWith(overscroll: false), |
| child: SingleChildScrollView( |
| dragStartBehavior: widget.dragStartBehavior, |
| scrollDirection: Axis.horizontal, |
| controller: _scrollController, |
| padding: effectivePadding, |
| physics: widget.physics, |
| child: tabBar, |
| ), |
| ); |
| } else if (widget.padding != null) { |
| tabBar = Padding( |
| padding: widget.padding!, |
| child: tabBar, |
| ); |
| } |
| |
| return tabBar; |
| } |
| } |
| |
| /// A page view that displays the widget which corresponds to the currently |
| /// selected tab. |
| /// |
| /// This widget is typically used in conjunction with a [TabBar]. |
| /// |
| /// {@youtube 560 315 https://www.youtube.com/watch?v=POtoEH-5l40} |
| /// |
| /// If a [TabController] is not provided, then there must be a [DefaultTabController] |
| /// ancestor. |
| /// |
| /// The tab controller's [TabController.length] must equal the length of the |
| /// [children] list and the length of the [TabBar.tabs] list. |
| /// |
| /// To see a sample implementation, visit the [TabController] documentation. |
| class TabBarView extends StatefulWidget { |
| /// Creates a page view with one child per tab. |
| /// |
| /// The length of [children] must be the same as the [controller]'s length. |
| const TabBarView({ |
| super.key, |
| required this.children, |
| this.controller, |
| this.physics, |
| this.dragStartBehavior = DragStartBehavior.start, |
| this.viewportFraction = 1.0, |
| this.clipBehavior = Clip.hardEdge, |
| }); |
| |
| /// This widget's selection and animation state. |
| /// |
| /// If [TabController] is not provided, then the value of [DefaultTabController.of] |
| /// will be used. |
| final TabController? controller; |
| |
| /// One widget per tab. |
| /// |
| /// Its length must match the length of the [TabBar.tabs] |
| /// list, as well as the [controller]'s [TabController.length]. |
| final List<Widget> children; |
| |
| /// How the page view should respond to user input. |
| /// |
| /// For example, determines how the page view continues to animate after the |
| /// user stops dragging the page view. |
| /// |
| /// The physics are modified to snap to page boundaries using |
| /// [PageScrollPhysics] prior to being used. |
| /// |
| /// Defaults to matching platform conventions. |
| final ScrollPhysics? physics; |
| |
| /// {@macro flutter.widgets.scrollable.dragStartBehavior} |
| final DragStartBehavior dragStartBehavior; |
| |
| /// {@macro flutter.widgets.pageview.viewportFraction} |
| final double viewportFraction; |
| |
| /// {@macro flutter.material.Material.clipBehavior} |
| /// |
| /// Defaults to [Clip.hardEdge]. |
| final Clip clipBehavior; |
| |
| @override |
| State<TabBarView> createState() => _TabBarViewState(); |
| } |
| |
| class _TabBarViewState extends State<TabBarView> { |
| TabController? _controller; |
| late PageController _pageController; |
| late List<Widget> _childrenWithKey; |
| int? _currentIndex; |
| int _warpUnderwayCount = 0; |
| int _scrollUnderwayCount = 0; |
| bool _debugHasScheduledValidChildrenCountCheck = false; |
| |
| // If the TabBarView is rebuilt with a new tab controller, the caller should |
| // dispose the old one. In that case the old controller's animation will be |
| // null and should not be accessed. |
| bool get _controllerIsValid => _controller?.animation != null; |
| |
| void _updateTabController() { |
| final TabController? newController = widget.controller ?? DefaultTabController.maybeOf(context); |
| assert(() { |
| if (newController == null) { |
| throw FlutterError( |
| 'No TabController for ${widget.runtimeType}.\n' |
| 'When creating a ${widget.runtimeType}, you must either provide an explicit ' |
| 'TabController using the "controller" property, or you must ensure that there ' |
| 'is a DefaultTabController above the ${widget.runtimeType}.\n' |
| 'In this case, there was neither an explicit controller nor a default controller.', |
| ); |
| } |
| return true; |
| }()); |
| |
| if (newController == _controller) { |
| return; |
| } |
| |
| if (_controllerIsValid) { |
| _controller!.animation!.removeListener(_handleTabControllerAnimationTick); |
| } |
| _controller = newController; |
| if (_controller != null) { |
| _controller!.animation!.addListener(_handleTabControllerAnimationTick); |
| } |
| } |
| |
| void _jumpToPage(int page) { |
| _warpUnderwayCount += 1; |
| _pageController.jumpToPage(page); |
| _warpUnderwayCount -= 1; |
| } |
| |
| Future<void> _animateToPage( |
| int page, { |
| required Duration duration, |
| required Curve curve, |
| }) async { |
| _warpUnderwayCount += 1; |
| await _pageController.animateToPage(page, duration: duration, curve: curve); |
| _warpUnderwayCount -= 1; |
| } |
| |
| @override |
| void initState() { |
| super.initState(); |
| _updateChildren(); |
| } |
| |
| @override |
| void didChangeDependencies() { |
| super.didChangeDependencies(); |
| _updateTabController(); |
| _currentIndex = _controller!.index; |
| _pageController = PageController( |
| initialPage: _currentIndex!, |
| viewportFraction: widget.viewportFraction, |
| ); |
| } |
| |
| @override |
| void didUpdateWidget(TabBarView oldWidget) { |
| super.didUpdateWidget(oldWidget); |
| if (widget.controller != oldWidget.controller) { |
| _updateTabController(); |
| _currentIndex = _controller!.index; |
| _jumpToPage(_currentIndex!); |
| } |
| // While a warp is under way, we stop updating the tab page contents. |
| // This is tracked in https://github.com/flutter/flutter/issues/31269. |
| if (widget.children != oldWidget.children && _warpUnderwayCount == 0) { |
| _updateChildren(); |
| } |
| } |
| |
| @override |
| void dispose() { |
| if (_controllerIsValid) { |
| _controller!.animation!.removeListener(_handleTabControllerAnimationTick); |
| } |
| _controller = null; |
| // We don't own the _controller Animation, so it's not disposed here. |
| super.dispose(); |
| } |
| |
| void _updateChildren() { |
| _childrenWithKey = KeyedSubtree.ensureUniqueKeysForList(widget.children); |
| } |
| |
| void _handleTabControllerAnimationTick() { |
| if (_scrollUnderwayCount > 0 || !_controller!.indexIsChanging) { |
| return; |
| } // This widget is driving the controller's animation. |
| |
| if (_controller!.index != _currentIndex) { |
| _currentIndex = _controller!.index; |
| _warpToCurrentIndex(); |
| } |
| } |
| |
| void _warpToCurrentIndex() { |
| if (!mounted || _pageController.page == _currentIndex!.toDouble()) { |
| return; |
| } |
| |
| final bool adjacentDestination = (_currentIndex! - _controller!.previousIndex).abs() == 1; |
| if (adjacentDestination) { |
| _warpToAdjacentTab(_controller!.animationDuration); |
| } else { |
| _warpToNonAdjacentTab(_controller!.animationDuration); |
| } |
| } |
| |
| Future<void> _warpToAdjacentTab(Duration duration) async { |
| if (duration == Duration.zero) { |
| _jumpToPage(_currentIndex!); |
| } else { |
| await _animateToPage(_currentIndex!, duration: duration, curve: Curves.ease); |
| } |
| if (mounted) { |
| setState(() { _updateChildren(); }); |
| } |
| return Future<void>.value(); |
| } |
| |
| Future<void> _warpToNonAdjacentTab(Duration duration) async { |
| final int previousIndex = _controller!.previousIndex; |
| assert((_currentIndex! - previousIndex).abs() > 1); |
| |
| // initialPage defines which page is shown when starting the animation. |
| // This page is adjacent to the destination page. |
| final int initialPage = _currentIndex! > previousIndex |
| ? _currentIndex! - 1 |
| : _currentIndex! + 1; |
| |
| setState(() { |
| // Needed for `RenderSliverMultiBoxAdaptor.move` and kept alive children. |
| // For motivation, see https://github.com/flutter/flutter/pull/29188 and |
| // https://github.com/flutter/flutter/issues/27010#issuecomment-486475152. |
| _childrenWithKey = List<Widget>.of(_childrenWithKey, growable: false); |
| final Widget temp = _childrenWithKey[initialPage]; |
| _childrenWithKey[initialPage] = _childrenWithKey[previousIndex]; |
| _childrenWithKey[previousIndex] = temp; |
| }); |
| |
| // Make a first jump to the adjacent page. |
| _jumpToPage(initialPage); |
| |
| // Jump or animate to the destination page. |
| if (duration == Duration.zero) { |
| _jumpToPage(_currentIndex!); |
| } else { |
| await _animateToPage(_currentIndex!, duration: duration, curve: Curves.ease); |
| } |
| |
| if (mounted) { |
| setState(() { _updateChildren(); }); |
| } |
| } |
| |
| void _syncControllerOffset() { |
| _controller!.offset = clampDouble(_pageController.page! - _controller!.index, -1.0, 1.0); |
| } |
| |
| // Called when the PageView scrolls |
| bool _handleScrollNotification(ScrollNotification notification) { |
| if (_warpUnderwayCount > 0 || _scrollUnderwayCount > 0) { |
| return false; |
| } |
| |
| if (notification.depth != 0) { |
| return false; |
| } |
| |
| _scrollUnderwayCount += 1; |
| if (notification is ScrollUpdateNotification && !_controller!.indexIsChanging) { |
| final bool pageChanged = (_pageController.page! - _controller!.index).abs() > 1.0; |
| if (pageChanged) { |
| _controller!.index = _pageController.page!.round(); |
| _currentIndex =_controller!.index; |
| } |
| _syncControllerOffset(); |
| } else if (notification is ScrollEndNotification) { |
| _controller!.index = _pageController.page!.round(); |
| _currentIndex = _controller!.index; |
| if (!_controller!.indexIsChanging) { |
| _syncControllerOffset(); |
| } |
| } |
| _scrollUnderwayCount -= 1; |
| |
| return false; |
| } |
| |
| bool _debugScheduleCheckHasValidChildrenCount() { |
| if (_debugHasScheduledValidChildrenCountCheck) { |
| return true; |
| } |
| WidgetsBinding.instance.addPostFrameCallback((Duration duration) { |
| _debugHasScheduledValidChildrenCountCheck = false; |
| if (!mounted) { |
| return; |
| } |
| assert(() { |
| if (_controller!.length != widget.children.length) { |
| throw FlutterError( |
| "Controller's length property (${_controller!.length}) does not match the " |
| "number of children (${widget.children.length}) present in TabBarView's children property.", |
| ); |
| } |
| return true; |
| }()); |
| }); |
| _debugHasScheduledValidChildrenCountCheck = true; |
| return true; |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| assert(_debugScheduleCheckHasValidChildrenCount()); |
| |
| return NotificationListener<ScrollNotification>( |
| onNotification: _handleScrollNotification, |
| child: PageView( |
| dragStartBehavior: widget.dragStartBehavior, |
| clipBehavior: widget.clipBehavior, |
| controller: _pageController, |
| physics: widget.physics == null |
| ? const PageScrollPhysics().applyTo(const ClampingScrollPhysics()) |
| : const PageScrollPhysics().applyTo(widget.physics), |
| children: _childrenWithKey, |
| ), |
| ); |
| } |
| } |
| |
| /// Displays a single circle with the specified size, border style, border color |
| /// and background colors. |
| /// |
| /// Used by [TabPageSelector] to indicate the selected page. |
| class TabPageSelectorIndicator extends StatelessWidget { |
| /// Creates an indicator used by [TabPageSelector]. |
| /// |
| /// The [backgroundColor], [borderColor], and [size] parameters must not be null. |
| const TabPageSelectorIndicator({ |
| super.key, |
| required this.backgroundColor, |
| required this.borderColor, |
| required this.size, |
| this.borderStyle = BorderStyle.solid, |
| }); |
| |
| /// The indicator circle's background color. |
| final Color backgroundColor; |
| |
| /// The indicator circle's border color. |
| final Color borderColor; |
| |
| /// The indicator circle's diameter. |
| final double size; |
| |
| /// The indicator circle's border style. |
| /// |
| /// Defaults to [BorderStyle.solid] if value is not specified. |
| final BorderStyle borderStyle; |
| |
| @override |
| Widget build(BuildContext context) { |
| return Container( |
| width: size, |
| height: size, |
| margin: const EdgeInsets.all(4.0), |
| decoration: BoxDecoration( |
| color: backgroundColor, |
| border: Border.all(color: borderColor, style: borderStyle), |
| shape: BoxShape.circle, |
| ), |
| ); |
| } |
| } |
| |
| /// Uses [TabPageSelectorIndicator] to display a row of small circular |
| /// indicators, one per tab. |
| /// |
| /// {@youtube 560 315 https://www.youtube.com/watch?v=Q628ue9Cq7U} |
| /// |
| /// The selected tab's indicator is highlighted. Often used in conjunction with |
| /// a [TabBarView]. |
| /// |
| /// If a [TabController] is not provided, then there must be a |
| /// [DefaultTabController] ancestor. |
| class TabPageSelector extends StatelessWidget { |
| /// Creates a compact widget that indicates which tab has been selected. |
| const TabPageSelector({ |
| super.key, |
| this.controller, |
| this.indicatorSize = 12.0, |
| this.color, |
| this.selectedColor, |
| this.borderStyle, |
| }) : assert(indicatorSize > 0.0); |
| |
| /// This widget's selection and animation state. |
| /// |
| /// If [TabController] is not provided, then the value of |
| /// [DefaultTabController.of] will be used. |
| final TabController? controller; |
| |
| /// The indicator circle's diameter (the default value is 12.0). |
| final double indicatorSize; |
| |
| /// The indicator circle's fill color for unselected pages. |
| /// |
| /// If this parameter is null, then the indicator is filled with [Colors.transparent]. |
| final Color? color; |
| |
| /// The indicator circle's fill color for selected pages and border color |
| /// for all indicator circles. |
| /// |
| /// If this parameter is null, then the indicator is filled with the theme's |
| /// [ColorScheme.secondary]. |
| final Color? selectedColor; |
| |
| /// The indicator circle's border style. |
| /// |
| /// Defaults to [BorderStyle.solid] if value is not specified. |
| final BorderStyle? borderStyle; |
| |
| Widget _buildTabIndicator( |
| int tabIndex, |
| TabController tabController, |
| ColorTween selectedColorTween, |
| ColorTween previousColorTween, |
| ) { |
| final Color background; |
| if (tabController.indexIsChanging) { |
| // The selection's animation is animating from previousValue to value. |
| final double t = 1.0 - _indexChangeProgress(tabController); |
| if (tabController.index == tabIndex) { |
| background = selectedColorTween.lerp(t)!; |
| } else if (tabController.previousIndex == tabIndex) { |
| background = previousColorTween.lerp(t)!; |
| } else { |
| background = selectedColorTween.begin!; |
| } |
| } else { |
| // The selection's offset reflects how far the TabBarView has / been dragged |
| // to the previous page (-1.0 to 0.0) or the next page (0.0 to 1.0). |
| final double offset = tabController.offset; |
| if (tabController.index == tabIndex) { |
| background = selectedColorTween.lerp(1.0 - offset.abs())!; |
| } else if (tabController.index == tabIndex - 1 && offset > 0.0) { |
| background = selectedColorTween.lerp(offset)!; |
| } else if (tabController.index == tabIndex + 1 && offset < 0.0) { |
| background = selectedColorTween.lerp(-offset)!; |
| } else { |
| background = selectedColorTween.begin!; |
| } |
| } |
| return TabPageSelectorIndicator( |
| backgroundColor: background, |
| borderColor: selectedColorTween.end!, |
| size: indicatorSize, |
| borderStyle: borderStyle ?? BorderStyle.solid, |
| ); |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| final Color fixColor = color ?? Colors.transparent; |
| final Color fixSelectedColor = selectedColor ?? Theme.of(context).colorScheme.secondary; |
| final ColorTween selectedColorTween = ColorTween(begin: fixColor, end: fixSelectedColor); |
| final ColorTween previousColorTween = ColorTween(begin: fixSelectedColor, end: fixColor); |
| final TabController? tabController = controller ?? DefaultTabController.maybeOf(context); |
| final MaterialLocalizations localizations = MaterialLocalizations.of(context); |
| assert(() { |
| if (tabController == null) { |
| throw FlutterError( |
| 'No TabController for $runtimeType.\n' |
| 'When creating a $runtimeType, you must either provide an explicit TabController ' |
| 'using the "controller" property, or you must ensure that there is a ' |
| 'DefaultTabController above the $runtimeType.\n' |
| 'In this case, there was neither an explicit controller nor a default controller.', |
| ); |
| } |
| return true; |
| }()); |
| final Animation<double> animation = CurvedAnimation( |
| parent: tabController!.animation!, |
| curve: Curves.fastOutSlowIn, |
| ); |
| return AnimatedBuilder( |
| animation: animation, |
| builder: (BuildContext context, Widget? child) { |
| return Semantics( |
| label: localizations.tabLabel(tabIndex: tabController.index + 1, tabCount: tabController.length), |
| child: Row( |
| mainAxisSize: MainAxisSize.min, |
| children: List<Widget>.generate(tabController.length, (int tabIndex) { |
| return _buildTabIndicator(tabIndex, tabController, selectedColorTween, previousColorTween); |
| }).toList(), |
| ), |
| ); |
| }, |
| ); |
| } |
| } |
| |
| // Hand coded defaults based on Material Design 2. |
| class _TabsDefaultsM2 extends TabBarTheme { |
| const _TabsDefaultsM2(this.context, this.isScrollable) |
| : super(indicatorSize: TabBarIndicatorSize.tab); |
| |
| final BuildContext context; |
| final bool isScrollable; |
| |
| @override |
| Color? get indicatorColor => Theme.of(context).indicatorColor; |
| |
| @override |
| Color? get labelColor => Theme.of(context).primaryTextTheme.bodyLarge!.color!; |
| |
| @override |
| TextStyle? get labelStyle => Theme.of(context).primaryTextTheme.bodyLarge; |
| |
| @override |
| TextStyle? get unselectedLabelStyle => Theme.of(context).primaryTextTheme.bodyLarge; |
| |
| @override |
| InteractiveInkFeatureFactory? get splashFactory => Theme.of(context).splashFactory; |
| |
| @override |
| TabAlignment? get tabAlignment => isScrollable ? TabAlignment.start : TabAlignment.fill; |
| } |
| |
| // BEGIN GENERATED TOKEN PROPERTIES - Tabs |
| |
| // Do not edit by hand. The code between the "BEGIN GENERATED" and |
| // "END GENERATED" comments are generated from data in the Material |
| // Design token database by the script: |
| // dev/tools/gen_defaults/bin/gen_defaults.dart. |
| |
| // Token database version: v0_162 |
| |
| class _TabsPrimaryDefaultsM3 extends TabBarTheme { |
| _TabsPrimaryDefaultsM3(this.context, this.isScrollable) |
| : super(indicatorSize: TabBarIndicatorSize.label); |
| |
| final BuildContext context; |
| late final ColorScheme _colors = Theme.of(context).colorScheme; |
| late final TextTheme _textTheme = Theme.of(context).textTheme; |
| final bool isScrollable; |
| |
| @override |
| Color? get dividerColor => _colors.surfaceVariant; |
| |
| @override |
| Color? get indicatorColor => _colors.primary; |
| |
| @override |
| Color? get labelColor => _colors.primary; |
| |
| @override |
| TextStyle? get labelStyle => _textTheme.titleSmall; |
| |
| @override |
| Color? get unselectedLabelColor => _colors.onSurfaceVariant; |
| |
| @override |
| TextStyle? get unselectedLabelStyle => _textTheme.titleSmall; |
| |
| @override |
| MaterialStateProperty<Color?> get overlayColor { |
| return MaterialStateProperty.resolveWith((Set<MaterialState> states) { |
| if (states.contains(MaterialState.selected)) { |
| if (states.contains(MaterialState.pressed)) { |
| return _colors.primary.withOpacity(0.12); |
| } |
| if (states.contains(MaterialState.hovered)) { |
| return _colors.primary.withOpacity(0.08); |
| } |
| if (states.contains(MaterialState.focused)) { |
| return _colors.primary.withOpacity(0.12); |
| } |
| return null; |
| } |
| if (states.contains(MaterialState.pressed)) { |
| return _colors.primary.withOpacity(0.12); |
| } |
| if (states.contains(MaterialState.hovered)) { |
| return _colors.onSurface.withOpacity(0.08); |
| } |
| if (states.contains(MaterialState.focused)) { |
| return _colors.onSurface.withOpacity(0.12); |
| } |
| return null; |
| }); |
| } |
| |
| @override |
| InteractiveInkFeatureFactory? get splashFactory => Theme.of(context).splashFactory; |
| |
| @override |
| TabAlignment? get tabAlignment => isScrollable ? TabAlignment.start : TabAlignment.fill; |
| |
| static double indicatorWeight = 3.0; |
| } |
| |
| class _TabsSecondaryDefaultsM3 extends TabBarTheme { |
| _TabsSecondaryDefaultsM3(this.context, this.isScrollable) |
| : super(indicatorSize: TabBarIndicatorSize.tab); |
| |
| final BuildContext context; |
| late final ColorScheme _colors = Theme.of(context).colorScheme; |
| late final TextTheme _textTheme = Theme.of(context).textTheme; |
| final bool isScrollable; |
| |
| @override |
| Color? get dividerColor => _colors.surfaceVariant; |
| |
| @override |
| Color? get indicatorColor => _colors.primary; |
| |
| @override |
| Color? get labelColor => _colors.onSurface; |
| |
| @override |
| TextStyle? get labelStyle => _textTheme.titleSmall; |
| |
| @override |
| Color? get unselectedLabelColor => _colors.onSurfaceVariant; |
| |
| @override |
| TextStyle? get unselectedLabelStyle => _textTheme.titleSmall; |
| |
| @override |
| MaterialStateProperty<Color?> get overlayColor { |
| return MaterialStateProperty.resolveWith((Set<MaterialState> states) { |
| if (states.contains(MaterialState.selected)) { |
| if (states.contains(MaterialState.pressed)) { |
| return _colors.onSurface.withOpacity(0.12); |
| } |
| if (states.contains(MaterialState.hovered)) { |
| return _colors.onSurface.withOpacity(0.08); |
| } |
| if (states.contains(MaterialState.focused)) { |
| return _colors.onSurface.withOpacity(0.12); |
| } |
| return null; |
| } |
| if (states.contains(MaterialState.pressed)) { |
| return _colors.onSurface.withOpacity(0.12); |
| } |
| if (states.contains(MaterialState.hovered)) { |
| return _colors.onSurface.withOpacity(0.08); |
| } |
| if (states.contains(MaterialState.focused)) { |
| return _colors.onSurface.withOpacity(0.12); |
| } |
| return null; |
| }); |
| } |
| |
| @override |
| InteractiveInkFeatureFactory? get splashFactory => Theme.of(context).splashFactory; |
| |
| @override |
| TabAlignment? get tabAlignment => isScrollable ? TabAlignment.start : TabAlignment.fill; |
| } |
| |
| // END GENERATED TOKEN PROPERTIES - Tabs |