Add YaruBorderContainer (#333)

* Add YaruBorderContainer

This is sort of a fusion the software app's BorderContainer and the
installer's RoundedContainer.

* Remove default background color

* Use primarily ThemeData.dividerColor

Leave DividerTheme for (Vertical)Divider

* Remove border radius & clip from the inner Material

* Switch back to DividerTheme.color

lib/src/utilities/yaru_border_container.dart

@@ -0,0 +1,100 @@
+import 'package:flutter/material.dart';
+
+import '../constants.dart';
+
+/// A container with a rounded Yaru-style border.
+class YaruBorderContainer extends StatelessWidget {
+  /// Creates a [YaruBorderContainer].
+  const YaruBorderContainer({
+    super.key,
+    this.alignment,
+    this.padding,
+    this.color,
+    this.width,
+    this.height,
+    this.constraints,
+    this.margin,
+    this.transform,
+    this.transformAlignment,
+    this.child,
+    this.clipBehavior = Clip.none,
+    this.border,
+    this.borderRadius,
+  });
+
+  /// See [Container.child].
+  final Widget? child;
+
+  /// See [Container.alignment].
+  final AlignmentGeometry? alignment;
+
+  /// See [Container.padding].
+  final EdgeInsets? padding;
+
+  /// See [Container.color].
+  final Color? color;
+
+  /// See [Container.width].
+  final double? width;
+
+  /// See [Container.height].
+  final double? height;
+
+  /// See [Container.constraints].
+  final BoxConstraints? constraints;
+
+  /// See [Container.margin].
+  final EdgeInsetsGeometry? margin;
+
+  /// See [Container.transform].
+  final Matrix4? transform;
+
+  /// See [Container.transformAlignment].
+  final AlignmentGeometry? transformAlignment;
+
+  /// See [Container.clipBehavior].
+  final Clip clipBehavior;
+
+  /// The border.
+  ///
+  /// The default border is 1px wide and the color is [ThemeData.dividerColor].
+  final BoxBorder? border;
+
+  /// The border radius.
+  ///
+  /// The default border is circular with the radius of `kYaruContainerRadius`.
+  final BorderRadiusGeometry? borderRadius;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final effectiveBorder = border ??
+        Border.all(color: DividerTheme.of(context).color ?? theme.dividerColor);
+    final effectiveBorderRadius =
+        borderRadius ?? BorderRadius.circular(kYaruContainerRadius);
+
+    return Container(
+      alignment: alignment,
+      constraints: constraints,
+      margin: margin,
+      transform: transform,
+      transformAlignment: transformAlignment,
+      clipBehavior: clipBehavior,
+      padding: padding,
+      height: height,
+      width: width,
+      foregroundDecoration: BoxDecoration(
+        border: effectiveBorder,
+        borderRadius: effectiveBorderRadius,
+      ),
+      decoration: BoxDecoration(
+        color: color,
+        borderRadius: effectiveBorderRadius,
+      ),
+      child: Material(
+        color: Colors.transparent,
+        child: child,
+      ),
+    );
+  }
+}

lib/yaru_widgets.dart

@@ -33,6 +33,7 @@ export 'src/pages/yaru_tabbed_page.dart';
 export 'src/pages/yaru_tile.dart';
 // Utilities
 export 'src/utilities/yaru_banner.dart';
+export 'src/utilities/yaru_border_container.dart';
 export 'src/utilities/yaru_carousel.dart';
 export 'src/utilities/yaru_draggable.dart';
 export 'src/utilities/yaru_expandable.dart';

test/utilities/yaru_border_container_test.dart

@@ -0,0 +1,88 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:yaru_icons/yaru_icons.dart';
+import 'package:yaru_widgets/yaru_widgets.dart';
+
+import '../yaru_golden_tester.dart';
+
+void main() {
+  testWidgets(
+    'golden images',
+    (tester) async {
+      final variant = goldenVariant.currentValue!;
+
+      final controller = ScrollController(initialScrollOffset: 72);
+
+      await tester.pumpScaffold(
+        Padding(
+          padding: const EdgeInsets.all(10),
+          child: YaruBorderContainer(
+            color: variant.value!['color'],
+            border: variant.value!['border'],
+            borderRadius: variant.value!['borderRadius'],
+            margin: variant.value!['margin'] ?? EdgeInsets.zero,
+            padding: variant.value!['padding'] ?? EdgeInsets.zero,
+            clipBehavior: variant.value!['clipBehavior'] ?? Clip.none,
+            child: ListView.builder(
+              controller: controller,
+              itemBuilder: (context, index) => ListTile(
+                leading: const Icon(YaruIcons.star_filled),
+                title: Text('Tile $index'),
+                onTap: () {},
+              ),
+            ),
+          ),
+        ),
+        themeMode: variant.themeMode,
+        size: const Size(200, 200),
+      );
+      await tester.pumpAndSettle();
+
+      await tester.down(find.text('Tile 1'));
+      await tester.pumpAndSettle();
+
+      await expectLater(
+        find.byType(YaruBorderContainer),
+        matchesGoldenFile('goldens/yaru_border_container-${variant.label}.png'),
+      );
+    },
+    variant: goldenVariant,
+    tags: 'golden',
+  );
+}
+
+final goldenVariant = ValueVariant({
+  ...goldenThemeVariants('default', <String, dynamic>{}),
+  ...goldenThemeVariants('clip', {
+    'clipBehavior': Clip.antiAlias,
+  }),
+  ...goldenThemeVariants('padding', {
+    'padding': const EdgeInsets.all(10),
+  }),
+  ...goldenThemeVariants('padding-clip', {
+    'padding': const EdgeInsets.all(10),
+    'clipBehavior': Clip.antiAlias,
+  }),
+  ...goldenThemeVariants('margin', {
+    'margin': const EdgeInsets.all(10),
+  }),
+  ...goldenThemeVariants('margin-clip', {
+    'margin': const EdgeInsets.all(10),
+    'clipBehavior': Clip.antiAlias,
+  }),
+  ...goldenThemeVariants('padding-margin', {
+    'padding': const EdgeInsets.all(10),
+    'margin': const EdgeInsets.all(10),
+  }),
+  ...goldenThemeVariants('padding-margin-clip', {
+    'padding': const EdgeInsets.all(10),
+    'margin': const EdgeInsets.all(10),
+    'clipBehavior': Clip.antiAlias,
+  }),
+  ...goldenThemeVariants('custom', {
+    'color': Colors.blue,
+    'border': Border.all(color: Colors.red, width: 2),
+    'borderRadius': BorderRadius.circular(20),
+    'clipBehavior': Clip.antiAlias,
+  }),
+});