packages/flutter/lib/src/material/divider.dart - external/github.com/flutter/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'package:flutter/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}
 /// 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)
 ///
 /// ** See code in examples/api/lib/material/divider/divider.0.dart **
 /// {@end-tool}
 ///
 /// See also:
 ///
 ///  * [PopupMenuDivider], which is the equivalent but for popup menus.
 ///  * [ListTile.divideTiles], another approach to dividing widgets in a list.
 ///  * [VerticalDivider], which is the vertical analog of this widget.
 ///  * <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}
 /// This sample shows how to display a [VerticalDivider] between a 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.
 ///
 /// ** See code in examples/api/lib/material/divider/vertical_divider.0.dart **
 /// {@end-tool}
 ///
 /// See also:
 ///
 ///  * [ListView.separated], which can be used to generate vertical dividers.
 ///  * [Divider], which is the horizontal analog of this widget.
 ///  * <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),
             ),
           ),
         ),
       ),
     );
   }
 }
	// 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}
	/// 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)
	///
	/// See code in examples/api/lib/material/divider/divider.0.dart
	/// {@end-tool}
	///
	/// See also:
	///
	/// * [PopupMenuDivider], which is the equivalent but for popup menus.
	/// * [ListTile.divideTiles], another approach to dividing widgets in a list.
	/// * [VerticalDivider], which is the vertical analog of this widget.
	/// * <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}
	/// This sample shows how to display a [VerticalDivider] between a 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.
	///
	/// See code in examples/api/lib/material/divider/vertical_divider.0.dart
	/// {@end-tool}
	///
	/// See also:
	///
	/// * [ListView.separated], which can be used to generate vertical dividers.
	/// * [Divider], which is the horizontal analog of this widget.
	/// * <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),
	),
	),
	),
	),
	);
	}
	}