Add example of BouncingBehavior and its subclasses (#180)

Closes #176.

cookbook/lib/tutorial/bouncing_behaviors.dart

@@ -0,0 +1,123 @@
+import 'package:flutter/material.dart';
+import 'package:smooth_sheets/smooth_sheets.dart';
+
+void main() {
+  runApp(const MaterialApp(home: _Home()));
+}
+
+class _Home extends StatelessWidget {
+  const _Home();
+
+  @override
+  Widget build(BuildContext context) {
+    void showModalSheet(Widget sheet) {
+      Navigator.push(context, ModalSheetRoute(builder: (_) => sheet));
+    }
+
+    return Scaffold(
+      body: Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            ListTile(
+              title: const Text('FixedBouncingBehavior'),
+              subtitle: const Text('with ScrollableSheet'),
+              onTap: () => showModalSheet(
+                const _ScrollableSheet(
+                  behavior: FixedBouncingBehavior(
+                    // Allows the sheet position to exceed the content bounds
+                    // by ±10% of the content height.
+                    Extent.proportional(0.1),
+                  ),
+                ),
+              ),
+            ),
+            ListTile(
+              title: const Text('FixedBouncingBehavior'),
+              subtitle: const Text('with DraggableSheet'),
+              onTap: () => showModalSheet(
+                const _DraggableSheet(
+                  behavior: FixedBouncingBehavior(
+                    // Allows the sheet position to exceed the content bounds by ±50 pixels.
+                    Extent.pixels(50),
+                  ),
+                ),
+              ),
+            ),
+            ListTile(
+              title: const Text('DirectionAwareBouncingBehavior'),
+              subtitle: const Text('with ScrollableSheet'),
+              onTap: () => showModalSheet(
+                const _ScrollableSheet(
+                  behavior: DirectionAwareBouncingBehavior(
+                    // Allows the sheet position to exceed the content bounds by 10 pixels
+                    // when dragging the sheet upwards, and by ±30% of the content height
+                    // when dragging it downwards.
+                    upward: Extent.pixels(20),
+                    downward: Extent.proportional(0.3),
+                  ),
+                ),
+              ),
+            ),
+            ListTile(
+              title: const Text('DirectionAwareBouncingBehavior'),
+              subtitle: const Text('with DraggableSheet'),
+              onTap: () => showModalSheet(
+                const _DraggableSheet(
+                  behavior: DirectionAwareBouncingBehavior(
+                    // Allows the sheet to bounce only when dragging it downwards.
+                    upward: Extent.pixels(0),
+                    downward: Extent.proportional(0.1),
+                  ),
+                ),
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class _ScrollableSheet extends StatelessWidget {
+  const _ScrollableSheet({required this.behavior});
+
+  final BouncingBehavior behavior;
+
+  @override
+  Widget build(BuildContext context) {
+    return ScrollableSheet(
+      physics: BouncingSheetPhysics(behavior: behavior),
+      child: Material(
+        color: Colors.white,
+        child: SizedBox(
+          height: 500,
+          child: ListView(
+            children: List.generate(
+              30,
+              (index) => ListTile(title: Text('Item $index')),
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+class _DraggableSheet extends StatelessWidget {
+  const _DraggableSheet({required this.behavior});
+
+  final BouncingBehavior behavior;
+
+  @override
+  Widget build(BuildContext context) {
+    return DraggableSheet(
+      physics: BouncingSheetPhysics(behavior: behavior),
+      child: Container(
+        height: 500,
+        width: double.infinity,
+        color: Colors.white,
+      ),
+    );
+  }
+}

docs/migration-guide-0.8.x.md

@@ -32,3 +32,4 @@ See also:
 
 - [FixedBouncingBehavior](https://pub.dev/documentation/smooth_sheets/latest/smooth_sheets/FixedBouncingBehavior-class.html), which allows the sheet position to exceeds the content bounds by a fixed amount.
 - [DirectionAwareBouncingBehavior](https://pub.dev/documentation/smooth_sheets/latest/smooth_sheets/DirectionAwareBouncingBehavior-class.html), which is similar to `FixedBouncingBehavior`, but different bounceable ranges can be set for each direction.
+- [tutorial/bouncing_behaviors.dart](https://github.com/fujidaiti/smooth_sheets/blob/main/cookbook/lib/tutorial/bouncing_behaviors.dart), an interactive example of `BouncingBehavior` classes.

package/README.md

@@ -220,9 +220,9 @@ See also:
 
 A physics determines how the sheet will behave when over-dragged or under-dragged, or when the user stops dragging. There are 3 predefined physics:
 
-- ClampingSheetPhysics: Prevents the sheet from reaching beyond the draggable bounds
-- BouncingSheetPhysics: Allows the sheet to go beyond the draggable bounds, but then bounce the sheet back to the edge of those bounds
-- SnappingSheetPhysics: Automatically snaps the sheet to a certain extent when the user stops dragging
+- ClampingSheetPhysics: Prevents the sheet from reaching beyond the content bounds.
+- BouncingSheetPhysics: Allows the sheet to go beyond the content bounds, but then bounce the sheet back to the edge of those bounds. Use [BouncingBehavior](https://pub.dev/documentation/smooth_sheets/latest/smooth_sheets/BouncingBehavior-class.html) and its subclasses to tweak the bouncing behavior.
+- SnappingSheetPhysics: Automatically snaps the sheet to a certain extent when the user stops dragging.
 
 These physics can be combined to create more complex behavior (e.g. bouncing behavior + snapping behavior).
 
@@ -231,6 +231,7 @@ These physics can be combined to create more complex behavior (e.g. bouncing beh
 See also:
 
 - [sheet_physics.dart](https://github.com/fujidaiti/smooth_sheets/blob/main/cookbook/lib/tutorial/sheet_physics.dart) for basic usage.
+- [bouncing_behaviors.dart](https://github.com/fujidaiti/smooth_sheets/blob/main/cookbook/lib/tutorial/bouncing_behaviors.dart), which shows how to tweak the bouncing behavior of BouncingSheetPhysics.
 
 <br/>