// Copyright 2014 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. import 'package:flutter/widgets.dart'; import 'divider_theme.dart'; import 'theme.dart'; // Examples can assume: // late BuildContext context; /// A thin horizontal line, with padding on either side. /// /// In the material design language, this represents a divider. Dividers can be /// used in lists, [Drawer]s, and elsewhere to separate content. /// /// To create a divider between [ListTile] items, consider using /// [ListTile.divideTiles], which is optimized for this case. /// /// {@youtube 560 315 https://www.youtube.com/watch?v=_liUC641Nmk} /// /// The box's total height is controlled by [height]. The appropriate /// padding is automatically computed from the height. /// /// {@tool dartpad --template=stateless_widget_scaffold} /// /// This sample shows how to display a Divider between an orange and blue box /// inside a column. The Divider is 20 logical pixels in height and contains a /// vertically centered black line that is 5 logical pixels thick. The black /// line is indented by 20 logical pixels. /// /// ![](https://flutter.github.io/assets-for-api-docs/assets/material/divider.png) /// /// ```dart /// Widget build(BuildContext context) { /// return Center( /// child: Column( /// children: <Widget>[ /// Expanded( /// child: Container( /// color: Colors.amber, /// child: const Center( /// child: Text('Above'), /// ), /// ), /// ), /// const Divider( /// height: 20, /// thickness: 5, /// indent: 20, /// endIndent: 20, /// ), /// // Subheader example from Material spec. /// // https://material.io/components/dividers#types /// Container( /// padding: const EdgeInsets.only(left: 20), /// child: Align( /// alignment: AlignmentDirectional.centerStart, /// child: Text( /// 'Subheader', /// style: Theme.of(context).textTheme.caption, /// textAlign: TextAlign.start, /// ), /// ), /// ), /// Expanded( /// child: Container( /// color: Theme.of(context).colorScheme.primary, /// child: const Center( /// child: Text('Below'), /// ), /// ), /// ), /// ], /// ), /// ); /// } /// ``` /// {@end-tool} /// See also: /// /// * [PopupMenuDivider], which is the equivalent but for popup menus. /// * [ListTile.divideTiles], another approach to dividing widgets in a list. /// * <https://material.io/design/components/dividers.html> class Divider extends StatelessWidget { /// Creates a material design divider. /// /// The [height], [thickness], [indent], and [endIndent] must be null or /// non-negative. const Divider({ Key? key, this.height, this.thickness, this.indent, this.endIndent, this.color, }) : assert(height == null || height >= 0.0), assert(thickness == null || thickness >= 0.0), assert(indent == null || indent >= 0.0), assert(endIndent == null || endIndent >= 0.0), super(key: key); /// The divider's height extent. /// /// The divider itself is always drawn as a horizontal line that is centered /// within the height specified by this value. /// /// If this is null, then the [DividerThemeData.space] is used. If that is /// also null, then this defaults to 16.0. final double? height; /// The thickness of the line drawn within the divider. /// /// A divider with a [thickness] of 0.0 is always drawn as a line with a /// height of exactly one device pixel. /// /// If this is null, then the [DividerThemeData.thickness] is used. If /// that is also null, then this defaults to 0.0. final double? thickness; /// The amount of empty space to the leading edge of the divider. /// /// If this is null, then the [DividerThemeData.indent] is used. If that is /// also null, then this defaults to 0.0. final double? indent; /// The amount of empty space to the trailing edge of the divider. /// /// If this is null, then the [DividerThemeData.endIndent] is used. If that is /// also null, then this defaults to 0.0. final double? endIndent; /// The color to use when painting the line. /// /// If this is null, then the [DividerThemeData.color] is used. If that is /// also null, then [ThemeData.dividerColor] is used. /// /// {@tool snippet} /// /// ```dart /// const Divider( /// color: Colors.deepOrange, /// ) /// ``` /// {@end-tool} final Color? color; /// Computes the [BorderSide] that represents a divider. /// /// If [color] is null, then [DividerThemeData.color] is used. If that is also /// null, then [ThemeData.dividerColor] is used. /// /// If [width] is null, then [DividerThemeData.thickness] is used. If that is /// also null, then this defaults to 0.0 (a hairline border). /// /// If [context] is null, the default color of [BorderSide] is used and the /// default width of 0.0 is used. /// /// {@tool snippet} /// /// This example uses this method to create a box that has a divider above and /// below it. This is sometimes useful with lists, for instance, to separate a /// scrollable section from the rest of the interface. /// /// ```dart /// DecoratedBox( /// decoration: BoxDecoration( /// border: Border( /// top: Divider.createBorderSide(context), /// bottom: Divider.createBorderSide(context), /// ), /// ), /// // child: ... /// ) /// ``` /// {@end-tool} static BorderSide createBorderSide(BuildContext? context, { Color? color, double? width }) { final Color? effectiveColor = color ?? (context != null ? (DividerTheme.of(context).color ?? Theme.of(context).dividerColor) : null); final double effectiveWidth = width ?? (context != null ? DividerTheme.of(context).thickness : null) ?? 0.0; // Prevent assertion since it is possible that context is null and no color // is specified. if (effectiveColor == null) { return BorderSide( width: effectiveWidth, ); } return BorderSide( color: effectiveColor, width: effectiveWidth, ); } @override Widget build(BuildContext context) { final DividerThemeData dividerTheme = DividerTheme.of(context); final double height = this.height ?? dividerTheme.space ?? 16.0; final double thickness = this.thickness ?? dividerTheme.thickness ?? 0.0; final double indent = this.indent ?? dividerTheme.indent ?? 0.0; final double endIndent = this.endIndent ?? dividerTheme.endIndent ?? 0.0; return SizedBox( height: height, child: Center( child: Container( height: thickness, margin: EdgeInsetsDirectional.only(start: indent, end: endIndent), decoration: BoxDecoration( border: Border( bottom: createBorderSide(context, color: color, width: thickness), ), ), ), ), ); } } /// A thin vertical line, with padding on either side. /// /// In the material design language, this represents a divider. Vertical /// dividers can be used in horizontally scrolling lists, such as a /// [ListView] with [ListView.scrollDirection] set to [Axis.horizontal]. /// /// The box's total width is controlled by [width]. The appropriate /// padding is automatically computed from the width. /// /// {@tool dartpad --template=stateless_widget_scaffold} /// /// This sample shows how to display a [VerticalDivider] between an purple and orange box /// inside a [Row]. The [VerticalDivider] is 20 logical pixels in width and contains a /// horizontally centered black line that is 1 logical pixels thick. The grey /// line is indented by 20 logical pixels. /// /// ```dart /// Widget build(BuildContext context) { /// return Container( /// padding: const EdgeInsets.all(10), /// child: Row( /// children: <Widget>[ /// Expanded( /// child: Container( /// decoration: BoxDecoration( /// borderRadius: BorderRadius.circular(10), /// color: Colors.deepPurpleAccent, /// ), /// ), /// ), /// const VerticalDivider( /// color: Colors.grey, /// thickness: 1, /// indent: 20, /// endIndent: 0, /// width: 20, /// ), /// Expanded( /// child: Container( /// decoration: BoxDecoration( /// borderRadius: BorderRadius.circular(10), /// color: Colors.deepOrangeAccent, /// ), /// ), /// ), /// ], /// ), /// ); /// } /// ``` /// {@end-tool} /// See also: /// /// * [ListView.separated], which can be used to generate vertical dividers. /// * <https://material.io/design/components/dividers.html> class VerticalDivider extends StatelessWidget { /// Creates a material design vertical divider. /// /// The [width], [thickness], [indent], and [endIndent] must be null or /// non-negative. const VerticalDivider({ Key? key, this.width, this.thickness, this.indent, this.endIndent, this.color, }) : assert(width == null || width >= 0.0), assert(thickness == null || thickness >= 0.0), assert(indent == null || indent >= 0.0), assert(endIndent == null || endIndent >= 0.0), super(key: key); /// The divider's width. /// /// The divider itself is always drawn as a vertical line that is centered /// within the width specified by this value. /// /// If this is null, then the [DividerThemeData.space] is used. If that is /// also null, then this defaults to 16.0. final double? width; /// The thickness of the line drawn within the divider. /// /// A divider with a [thickness] of 0.0 is always drawn as a line with a /// width of exactly one device pixel. /// /// If this is null, then the [DividerThemeData.thickness] is used which /// defaults to 0.0. final double? thickness; /// The amount of empty space on top of the divider. /// /// If this is null, then the [DividerThemeData.indent] is used. If that is /// also null, then this defaults to 0.0. final double? indent; /// The amount of empty space under the divider. /// /// If this is null, then the [DividerThemeData.endIndent] is used. If that is /// also null, then this defaults to 0.0. final double? endIndent; /// The color to use when painting the line. /// /// If this is null, then the [DividerThemeData.color] is used. If that is /// also null, then [ThemeData.dividerColor] is used. /// /// {@tool snippet} /// /// ```dart /// const Divider( /// color: Colors.deepOrange, /// ) /// ``` /// {@end-tool} final Color? color; @override Widget build(BuildContext context) { final DividerThemeData dividerTheme = DividerTheme.of(context); final double width = this.width ?? dividerTheme.space ?? 16.0; final double thickness = this.thickness ?? dividerTheme.thickness ?? 0.0; final double indent = this.indent ?? dividerTheme.indent ?? 0.0; final double endIndent = this.endIndent ?? dividerTheme.endIndent ?? 0.0; return SizedBox( width: width, child: Center( child: Container( width: thickness, margin: EdgeInsetsDirectional.only(top: indent, bottom: endIndent), decoration: BoxDecoration( border: Border( left: Divider.createBorderSide(context, color: color, width: thickness), ), ), ), ), ); } }