feat: dyn reaction

Signed-off-by: dom <githubaccount56556@proton.me>

lib/common/widgets/sliver/sliver_to_box_adapter.dart

@@ -0,0 +1,85 @@
+import 'package:flutter/rendering.dart' show RenderSliverToBoxAdapter;
+import 'package:flutter/widgets.dart';
+
+class SliverToBoxWithOffsetAdapter extends SliverToBoxAdapter {
+  const SliverToBoxWithOffsetAdapter({
+    super.key,
+    required this.offset,
+    required this.onVisibilityChanged,
+    super.child,
+  });
+
+  final double offset;
+  final ValueChanged<bool> onVisibilityChanged;
+
+  @override
+  RenderSliverToBoxWithOffsetAdapter createRenderObject(BuildContext context) =>
+      RenderSliverToBoxWithOffsetAdapter(
+        offset: offset,
+        onVisibilityChanged: onVisibilityChanged,
+      );
+}
+
+class RenderSliverToBoxWithOffsetAdapter extends RenderSliverToBoxAdapter {
+  RenderSliverToBoxWithOffsetAdapter({
+    required this.offset,
+    required this.onVisibilityChanged,
+    super.child,
+  });
+
+  bool? _visible;
+  final double offset;
+  final ValueChanged<bool> onVisibilityChanged;
+
+  @override
+  void performLayout() {
+    final visible = constraints.scrollOffset > offset;
+    if (_visible != visible) {
+      _visible = visible;
+      WidgetsBinding.instance.addPostFrameCallback(
+        (_) => onVisibilityChanged(visible),
+      );
+    }
+    super.performLayout();
+  }
+}
+
+class SliverToBoxWithVisibilityAdapter extends SliverToBoxAdapter {
+  const SliverToBoxWithVisibilityAdapter({
+    super.key,
+    required this.onVisibilityChanged,
+    super.child,
+  });
+
+  final ValueChanged<bool> onVisibilityChanged;
+
+  @override
+  RenderSliverToBoxWithVisibilityAdapter createRenderObject(
+    BuildContext context,
+  ) => RenderSliverToBoxWithVisibilityAdapter(
+    onVisibilityChanged: onVisibilityChanged,
+  );
+}
+
+class RenderSliverToBoxWithVisibilityAdapter extends RenderSliverToBoxAdapter {
+  RenderSliverToBoxWithVisibilityAdapter({
+    required this.onVisibilityChanged,
+    super.child,
+  });
+
+  final ValueChanged<bool> onVisibilityChanged;
+
+  bool? _visible;
+
+  @override
+  void performLayout() {
+    super.performLayout();
+    final visible = geometry!.visible;
+    if (_visible != visible) {
+      _visible = visible;
+      WidgetsBinding.instance.addPostFrameCallback(
+        (_) => onVisibilityChanged(visible),
+      );
+    }
+  }
+}