Add automatic keyboard dismissing behavior on dragging/scrolling

package/lib/smooth_sheets.dart

@@ -2,6 +2,7 @@ export 'src/draggable/draggable_sheet.dart';
 export 'src/draggable/sheet_draggable.dart';
 export 'src/foundation/animation.dart';
 export 'src/foundation/framework.dart';
+export 'src/foundation/keyboard_dismissible.dart';
 export 'src/foundation/modal_sheet.dart';
 export 'src/foundation/notification.dart';
 export 'src/foundation/sheet_activity.dart';

package/lib/src/draggable/draggable_sheet.dart

@@ -6,6 +6,7 @@ class DraggableSheet extends SingleChildSheet {
   const DraggableSheet({
     super.key,
     this.hitTestBehavior = HitTestBehavior.translucent,
+    super.keyboardDismissBehavior,
     super.resizeToAvoidBottomInset,
     super.initialExtent,
     super.minExtent,

package/lib/src/foundation/keyboard_dismissible.dart

@@ -0,0 +1,149 @@
+import 'package:flutter/widgets.dart';
+import 'package:smooth_sheets/src/draggable/draggable_sheet.dart';
+import 'package:smooth_sheets/src/foundation/notification.dart';
+
+/// A widget that dismisses the on-screen keyboard when the user
+/// drags the sheet below this widget.
+///
+/// It is rarely used directly since the sheets internally have this widget
+/// and expose a slot for a [SheetKeyboardDismissBehavior], which is directly
+/// passed to this widget.
+///
+/// See also:
+/// - [DraggableSheet.keyboardDismissBehavior], which is the slot for
+///   a custom [SheetKeyboardDismissBehavior].
+class SheetKeyboardDismissible extends StatelessWidget {
+  /// Creates a widget that dismisses the on-screen keyboard when the user
+  /// drags the sheet below this widget.
+  const SheetKeyboardDismissible({
+    super.key,
+    required this.dismissBehavior,
+    required this.child,
+  });
+
+  /// Determines when the on-screen keyboard should be dismissed.
+  final SheetKeyboardDismissBehavior dismissBehavior;
+
+  /// The widget below this widget in the tree.
+  final Widget child;
+
+  @override
+  Widget build(BuildContext context) {
+    Widget result = NotificationListener<SheetDragUpdateNotification>(
+      onNotification: (notification) {
+        if (primaryFocus?.hasFocus == true &&
+            dismissBehavior.shouldDismissKeyboard(notification.delta)) {
+          primaryFocus!.unfocus();
+        }
+        return false;
+      },
+      child: child,
+    );
+
+    if (dismissBehavior.isContentScrollAware) {
+      result = NotificationListener<ScrollUpdateNotification>(
+        onNotification: (notification) {
+          final dragDelta = notification.dragDetails?.delta.dy;
+          if (notification.depth == 0 &&
+              dragDelta != null &&
+              primaryFocus?.hasFocus == true &&
+              dismissBehavior.shouldDismissKeyboard(-1 * dragDelta)) {
+            primaryFocus!.unfocus();
+          }
+          return false;
+        },
+        child: result,
+      );
+    }
+
+    return result;
+  }
+}
+
+/// Determines when the on-screen keyboard should be dismissed.
+abstract class SheetKeyboardDismissBehavior {
+  /// Creates an object that determines when the on-screen keyboard
+  /// should be dismissed.
+  const SheetKeyboardDismissBehavior({
+    this.isContentScrollAware = false,
+  });
+
+  /// {@macro drag_sheet_keyboard_dismiss_behavior.ctor}
+  const factory SheetKeyboardDismissBehavior.onDrag(
+      {bool isContentScrollAware}) = DragSheetKeyboardDismissBehavior;
+
+  /// {@macro drag_down_sheet_keyboard_dismiss_behavior.ctor}
+  const factory SheetKeyboardDismissBehavior.onDragDown(
+      {bool isContentScrollAware}) = DragDownSheetKeyboardDismissBehavior;
+
+  /// {@macro drag_up_sheet_keyboard_dismiss_behavior.ctor}
+  const factory SheetKeyboardDismissBehavior.onDragUp(
+      {bool isContentScrollAware}) = DragUpSheetKeyboardDismissBehavior;
+
+  /// Whether the sheet should be aware of the content scrolling.
+  ///
+  /// If this is `true`, [shouldDismissKeyboard] will also be called whenever
+  /// the user scrolls a scrollable content within the sheet.
+  final bool isContentScrollAware;
+
+  /// Whether the on-screen keyboard should be dismissed.
+  ///
+  /// This method is called whenever the sheet is dragged by the user.
+  /// Returns `true` if the on-screen keyboard should be dismissed.
+  bool shouldDismissKeyboard(double userDragDelta);
+}
+
+/// A [SheetKeyboardDismissBehavior] that always dismisses the on-screen
+/// keyboard when the sheet is dragged.
+class DragSheetKeyboardDismissBehavior extends SheetKeyboardDismissBehavior {
+  /// {@template drag_sheet_keyboard_dismiss_behavior.ctor}
+  /// Creates a [SheetKeyboardDismissBehavior] that always dismisses the
+  /// on-screen keyboard when the sheet is dragged.
+  ///
+  /// If [isContentScrollAware] is `true`, the keyboard will also be dismissed
+  /// when the user scrolls a scrollable content within the sheet.
+  /// {@endtemplate}
+  const DragSheetKeyboardDismissBehavior({super.isContentScrollAware});
+
+  @override
+  bool shouldDismissKeyboard(double userDragDelta) {
+    return userDragDelta.abs() > 0;
+  }
+}
+
+/// A [SheetKeyboardDismissBehavior] that dismisses the on-screen keyboard
+/// only when the sheet is dragged down.
+class DragDownSheetKeyboardDismissBehavior
+    extends SheetKeyboardDismissBehavior {
+  /// {@template drag_down_sheet_keyboard_dismiss_behavior.ctor}
+  /// Creates a [SheetKeyboardDismissBehavior] that dismisses the on-screen
+  /// keyboard only when the sheet is dragged down.
+  ///
+  /// If [isContentScrollAware] is `true`, the keyboard will also be dismissed
+  /// when the user scrolls up a scrollable content within the sheet.
+  /// {@endtemplate}
+  const DragDownSheetKeyboardDismissBehavior({super.isContentScrollAware});
+
+  @override
+  bool shouldDismissKeyboard(double userDragDelta) {
+    return userDragDelta < 0;
+  }
+}
+
+/// A [SheetKeyboardDismissBehavior] that dismisses the on-screen keyboard
+/// only when the sheet is dragged up.
+class DragUpSheetKeyboardDismissBehavior extends SheetKeyboardDismissBehavior {
+  /// {@template drag_up_sheet_keyboard_dismiss_behavior.ctor}
+  /// Creates a [SheetKeyboardDismissBehavior] that dismisses the on-screen
+  /// keyboard only when the sheet is dragged up.
+  ///
+  /// If [isContentScrollAware] is `true`, the keyboard will also be dismissed
+  /// when the user scrolls down a scrollable content within the sheet.
+  /// {@endtemplate}
+  const DragUpSheetKeyboardDismissBehavior({super.isContentScrollAware});
+
+  @override
+  bool shouldDismissKeyboard(double userDragDelta) {
+    return userDragDelta > 0;
+  }
+}

package/lib/src/foundation/single_child_sheet.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/widgets.dart';
 import 'package:smooth_sheets/src/foundation/framework.dart';
+import 'package:smooth_sheets/src/foundation/keyboard_dismissible.dart';
 import 'package:smooth_sheets/src/foundation/sheet_controller.dart';
 import 'package:smooth_sheets/src/foundation/sheet_extent.dart';
 import 'package:smooth_sheets/src/foundation/sheet_physics.dart';
@@ -34,6 +35,7 @@ abstract class SingleChildSheetExtentFactory extends SheetExtentFactory {
 abstract class SingleChildSheet extends StatefulWidget {
   const SingleChildSheet({
     super.key,
+    this.keyboardDismissBehavior,
     this.resizeToAvoidBottomInset = true,
     this.initialExtent = const Extent.proportional(1),
     this.minExtent = const Extent.proportional(1),
@@ -45,6 +47,7 @@ abstract class SingleChildSheet extends StatefulWidget {
     required this.child,
   });
 
+  final SheetKeyboardDismissBehavior? keyboardDismissBehavior;
   final bool resizeToAvoidBottomInset;
   final Extent initialExtent;
   final Extent minExtent;
@@ -83,12 +86,21 @@ abstract class SingleChildSheetState<T extends SingleChildSheet>
 
   @override
   Widget build(BuildContext context) {
-    return SheetContainer(
+    Widget result = SheetContainer(
       factory: factory,
       controller: widget.controller,
       resizeToAvoidBottomInset: widget.resizeToAvoidBottomInset,
       child: buildContent(context),
     );
+
+    if (widget.keyboardDismissBehavior != null) {
+      result = SheetKeyboardDismissible(
+        dismissBehavior: widget.keyboardDismissBehavior!,
+        child: result,
+      );
+    }
+
+    return result;
   }
 
   /// Builds the content of the sheet.

package/lib/src/navigation/navigation_sheet.dart

@@ -3,6 +3,7 @@ import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:smooth_sheets/src/foundation/framework.dart';
+import 'package:smooth_sheets/src/foundation/keyboard_dismissible.dart';
 import 'package:smooth_sheets/src/foundation/sheet_activity.dart';
 import 'package:smooth_sheets/src/foundation/sheet_controller.dart';
 import 'package:smooth_sheets/src/foundation/sheet_extent.dart';
@@ -15,6 +16,7 @@ class NavigationSheet extends StatefulWidget with TransitionAwareWidgetMixin {
   const NavigationSheet({
     super.key,
     required this.transitionObserver,
+    this.keyboardDismissBehavior,
     this.resizeToAvoidBottomInset = true,
     this.controller,
     required this.child,
@@ -23,6 +25,7 @@ class NavigationSheet extends StatefulWidget with TransitionAwareWidgetMixin {
   @override
   final NavigationSheetTransitionObserver transitionObserver;
 
+  final SheetKeyboardDismissBehavior? keyboardDismissBehavior;
   final bool resizeToAvoidBottomInset;
   final SheetController? controller;
   final Widget child;
@@ -93,7 +96,7 @@ class NavigationSheetState extends State<NavigationSheet>
 
   @override
   Widget build(BuildContext context) {
-    return SheetContainer(
+    Widget result = SheetContainer(
       resizeToAvoidBottomInset: widget.resizeToAvoidBottomInset,
       factory: const _NavigationSheetExtentFactory(),
       controller: widget.controller,
@@ -102,6 +105,15 @@ class NavigationSheetState extends State<NavigationSheet>
       },
       child: widget.child,
     );
+
+    if (widget.keyboardDismissBehavior != null) {
+      result = SheetKeyboardDismissible(
+        dismissBehavior: widget.keyboardDismissBehavior!,
+        child: result,
+      );
+    }
+
+    return result;
   }
 }
 

package/lib/src/scrollable/scrollable_sheet.dart

@@ -9,6 +9,7 @@ import 'package:smooth_sheets/src/scrollable/scrollable_sheet_extent.dart';
 class ScrollableSheet extends SingleChildSheet {
   const ScrollableSheet({
     super.key,
+    super.keyboardDismissBehavior,
     super.resizeToAvoidBottomInset,
     super.initialExtent,
     super.minExtent,