feat: cascade negative deltas

example/lib/file_asset_paths.dart

@@ -19,7 +19,11 @@ enum FileAssetPaths {
   ),
   shrinkAndFlexScreen(
     'lib/screens/shrink_and_flex/shrink_and_flex_example_screen.dart',
-  );
+  ),
+  cascadingDeltaScreen(
+    'lib/screens/cascading_delta/cascading_delta_screen.dart',
+  ),
+  ;
 
   const FileAssetPaths(this.path);
   final String path;

example/lib/main.dart

@@ -1,4 +1,5 @@
 import 'package:example/screens/basic/basic_example_screen.dart';
+import 'package:example/screens/cascading_delta/cascading_delta_screen.dart';
 import 'package:example/screens/controller_listen/controller_listen_example_screen.dart';
 import 'package:example/screens/controller_set_sizes/controller_set_sizes_example_screen.dart';
 import 'package:example/screens/divider/custom_divider_example_screen.dart';
@@ -31,6 +32,7 @@ class ExampleApp extends StatelessWidget {
         'shrink': (context) => const ShrinkAndFlexExampleScreen(),
         'future-builder-shrink': (context) =>
             const FutureBuilderShrinkExampleScreen(),
+        'cascading-delta': (context) => const CascadingDeltaScreen(),
       },
     );
   }

example/lib/screens/cascading_delta/cascading_delta_help_dialog.dart

@@ -0,0 +1,71 @@
+import 'package:example/widgets/help_dialog.dart';
+import 'package:flutter/material.dart';
+
+class CascadingDeltaHelpDialog extends StatelessWidget {
+  const CascadingDeltaHelpDialog._({super.key});
+
+  static void show({
+    required BuildContext context,
+  }) {
+    HelpDialog.show(
+      context: context,
+      child: const CascadingDeltaHelpDialog._(
+        key: Key('CascadingDeltaHelpDialog'),
+      ),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return const HelpDialog(
+      title: 'About this example',
+      content: Column(
+        mainAxisSize: MainAxisSize.min,
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Text(
+            'In this example, there are four children, each with a minimum width of 50 pixels.',
+          ),
+          SizedBox(height: 12),
+          Text.rich(TextSpan(children: [
+            TextSpan(text: 'Use the '),
+            TextSpan(
+              text: 'Cascade',
+              style: TextStyle(fontWeight: FontWeight.bold),
+            ),
+            TextSpan(text: ' switch to enable/disable the '),
+            TextSpan(
+              text: 'cascadeNegativeDelta',
+              style: TextStyle(
+                fontFamily: 'Monospace',
+                color: Colors.blueGrey,
+              ),
+            ),
+            TextSpan(text: ' flag in the ResizableContainer.'),
+          ])),
+          SizedBox(height: 12),
+          Text.rich(TextSpan(children: [
+            TextSpan(text: 'With the switch '),
+            TextSpan(
+              text: 'enabled',
+              style: TextStyle(fontWeight: FontWeight.bold),
+            ),
+            TextSpan(
+              text:
+                  ', reducing the size of a child beyond its bound will "cascade" the change to its sibling(s).',
+            ),
+            TextSpan(text: ' With the switch '),
+            TextSpan(
+              text: 'disabled',
+              style: TextStyle(fontWeight: FontWeight.bold),
+            ),
+            TextSpan(
+              text:
+                  ', reducing the size of a child beyond its bound will have no effect (default behavior).',
+            ),
+          ])),
+        ],
+      ),
+    );
+  }
+}

example/lib/screens/cascading_delta/cascading_delta_screen.dart

@@ -0,0 +1,85 @@
+import 'package:example/file_asset_paths.dart';
+import 'package:example/screens/cascading_delta/cascading_delta_help_dialog.dart';
+import 'package:example/widgets/code_view_dialog.dart';
+import 'package:example/widgets/nav_drawer.dart';
+import 'package:example/widgets/size_label.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_resizable_container/flutter_resizable_container.dart';
+
+class CascadingDeltaScreen extends StatefulWidget {
+  const CascadingDeltaScreen({super.key});
+
+  @override
+  State<CascadingDeltaScreen> createState() => _CascadingDeltaScreenState();
+}
+
+class _CascadingDeltaScreenState extends State<CascadingDeltaScreen> {
+  var cascade = false;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text('Basic two-pane example'),
+        actions: [
+          Row(
+            children: [
+              const Text('Cascade'),
+              const SizedBox(width: 8),
+              Switch(
+                value: cascade,
+                onChanged: (cascade) => setState(() => this.cascade = cascade),
+              ),
+            ],
+          ),
+          IconButton(
+            icon: const Icon(Icons.help_center),
+            onPressed: () => CascadingDeltaHelpDialog.show(context: context),
+          ),
+          IconButton(
+            icon: const Icon(Icons.code),
+            onPressed: () => CodeViewDialog.show(
+              context: context,
+              filePath: FileAssetPaths.cascadingDeltaScreen,
+            ),
+          ),
+        ],
+      ),
+      drawer: const NavDrawer(),
+      body: ResizableContainer(
+        direction: Axis.horizontal,
+        cascadeNegativeDelta: cascade,
+        children: [
+          ResizableChild(
+            size: const ResizableSize.expand(min: 50),
+            child: ColoredBox(
+              color: Theme.of(context).colorScheme.primaryContainer,
+              child: const SizeLabel(),
+            ),
+          ),
+          ResizableChild(
+            size: const ResizableSize.expand(min: 50),
+            child: ColoredBox(
+              color: Theme.of(context).colorScheme.secondaryContainer,
+              child: const SizeLabel(),
+            ),
+          ),
+          ResizableChild(
+            size: const ResizableSize.expand(min: 50),
+            child: ColoredBox(
+              color: Theme.of(context).colorScheme.primaryContainer,
+              child: const SizeLabel(),
+            ),
+          ),
+          ResizableChild(
+            size: const ResizableSize.expand(min: 50),
+            child: ColoredBox(
+              color: Theme.of(context).colorScheme.secondaryContainer,
+              child: const SizeLabel(),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}

example/lib/widgets/nav_drawer.dart

@@ -46,6 +46,11 @@ class NavDrawer extends StatelessWidget {
             onTap: () => Navigator.of(context)
                 .pushReplacementNamed('future-builder-shrink'),
           ),
+          ListTile(
+            title: const Text('Cascading Delta Example'),
+            onTap: () =>
+                Navigator.of(context).pushReplacementNamed('cascading-delta'),
+          ),
           const SizedBox(height: 15),
           const NavSectionHeader(title: 'Controller Examples'),
           ListTile(

example/pubspec.lock

@@ -77,10 +77,10 @@ packages:
     dependency: transitive
     description:
       name: ffi
-      sha256: "289279317b4b16eb2bb7e271abccd4bf84ec9bdcbe999e278a94b804f5630418"
+      sha256: "16ed7b077ef01ad6170a3d0c57caa4a112a38d7a2ed5602e0aca9ca6f3d98da6"
       url: "https://pub.dev"
     source: hosted
-    version: "2.1.4"
+    version: "2.1.3"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -320,10 +320,10 @@ packages:
     dependency: transitive
     description:
       name: win32
-      sha256: dc6ecaa00a7c708e5b4d10ee7bec8c270e9276dfcab1783f57e9962d7884305f
+      sha256: daf97c9d80197ed7b619040e86c8ab9a9dad285e7671ee7390f9180cc828a51e
       url: "https://pub.dev"
     source: hosted
-    version: "5.12.0"
+    version: "5.10.1"
 sdks:
-  dart: ">=3.7.0 <4.0.0"
+  dart: ">=3.7.0-0 <4.0.0"
   flutter: ">=3.22.0"

example/pubspec.yaml

@@ -70,6 +70,7 @@ flutter:
     - lib/screens/pixels/pixels_example_screen.dart
     - lib/screens/ratio/ratio_example_screen.dart
     - lib/screens/shrink_and_flex/shrink_and_flex_example_screen.dart
+    - lib/screens/cascading_delta/cascading_delta_screen.dart
 
   # An image asset can refer to one or more resolution-specific "variants", see
   # https://flutter.dev/assets-and-images/#resolution-aware

lib/src/resizable_container.dart

@@ -15,16 +15,15 @@ import 'package:flutter_resizable_container/src/resizable_controller.dart';
 class ResizableContainer extends StatefulWidget {
   /// Creates a new [ResizableContainer] with the given [direction] and list
   /// of [children] Widgets.
-  ///
-  /// The sum of the [children]'s starting ratios must be equal to 1.0.
   const ResizableContainer({
     super.key,
     required this.children,
     required this.direction,
     this.controller,
+    this.cascadeNegativeDelta = false,
   });
 
-  /// A list of resizable [ResizableChild] containing the child [Widget]s and
+  /// A list of [ResizableChild] containing the child [Widget]s and
   /// their sizing configuration.
   final List<ResizableChild> children;
 
@@ -34,6 +33,10 @@ class ResizableContainer extends StatefulWidget {
   /// The direction along which the child widgets will be laid and resized.
   final Axis direction;
 
+  /// When enabled, reducing the size of a child beyond its lower bound will reduce the
+  /// size of its sibling(s). Defaults to `false`.
+  final bool cascadeNegativeDelta;
+
   @override
   State<ResizableContainer> createState() => _ResizableContainerState();
 }
@@ -48,19 +51,25 @@ class _ResizableContainerState extends State<ResizableContainer> {
     super.initState();
 
     manager.initChildren(widget.children);
+    manager.setCascadeNegativeDelta(widget.cascadeNegativeDelta);
   }
 
   @override
   void didUpdateWidget(covariant ResizableContainer oldWidget) {
     final childrenChanged = !listEquals(oldWidget.children, widget.children);
     final directionChanged = oldWidget.direction != widget.direction;
-    final hasChanges = childrenChanged || directionChanged;
+    final cascadeChanged =
+        oldWidget.cascadeNegativeDelta != widget.cascadeNegativeDelta;
+
+    if (childrenChanged) {
+      controller.setChildren(widget.children);
+    }
 
-    if (hasChanges) {
-      if (childrenChanged) {
-        controller.setChildren(widget.children);
-      }
+    if (cascadeChanged) {
+      manager.setCascadeNegativeDelta(widget.cascadeNegativeDelta);
+    }
 
+    if (childrenChanged || directionChanged) {
       manager.setNeedsLayout();
     }