improve Dyn/Topic DraggableScrollableSheet

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

lib/common/widgets/draggable_sheet/dyn.dart

@@ -0,0 +1,91 @@
+part of 'package:PiliPlus/common/widgets/flutter/draggable_scrollable_sheet.dart';
+
+class DynDraggableScrollableSheet extends DraggableScrollableSheet {
+  const DynDraggableScrollableSheet({
+    super.key,
+    super.initialChildSize,
+    super.minChildSize,
+    super.maxChildSize,
+    super.expand,
+    super.snap,
+    super.snapSizes,
+    super.snapAnimationDuration,
+    super.controller,
+    super.shouldCloseOnMinExtent,
+    required super.builder,
+  });
+
+  @override
+  State<DraggableScrollableSheet> createState() =>
+      _DynDraggableScrollableSheetState();
+}
+
+class _DynDraggableScrollableSheetState extends _DraggableScrollableSheetState {
+  @override
+  void initState() {
+    super.initState();
+    _extent = _DraggableSheetExtent(
+      minSize: widget.minChildSize,
+      maxSize: widget.maxChildSize,
+      snap: widget.snap,
+      snapSizes: _impliedSnapSizes(),
+      snapAnimationDuration: widget.snapAnimationDuration,
+      initialSize: widget.initialChildSize,
+      shouldCloseOnMinExtent: widget.shouldCloseOnMinExtent,
+    );
+    _scrollController = _DynDraggableScrollableSheetScrollController(
+      extent: _extent,
+    );
+    widget.controller?._attach(_scrollController);
+  }
+}
+
+class _DynDraggableScrollableSheetScrollController
+    extends _DraggableScrollableSheetScrollController {
+  _DynDraggableScrollableSheetScrollController({
+    required super.extent,
+  });
+
+  @override
+  _DraggableScrollableSheetScrollPosition createScrollPosition(
+    ScrollPhysics physics,
+    ScrollContext context,
+    ScrollPosition? oldPosition,
+  ) {
+    return _DynDraggableScrollableSheetScrollPosition(
+      physics: physics.applyTo(const AlwaysScrollableScrollPhysics()),
+      context: context,
+      oldPosition: oldPosition,
+      getExtent: () => extent,
+    );
+  }
+}
+
+class _DynDraggableScrollableSheetScrollPosition
+    extends _DraggableScrollableSheetScrollPosition {
+  _DynDraggableScrollableSheetScrollPosition({
+    required super.physics,
+    required super.context,
+    super.oldPosition,
+    required super.getExtent,
+  });
+
+  bool _isAtTop = true;
+
+  @override
+  bool get listShouldScroll => !_isAtTop || super.listShouldScroll;
+
+  @override
+  void applyUserOffset(double delta) {
+    if (_isAtTop && pixels > 0) {
+      _isAtTop = false;
+    }
+    super.applyUserOffset(delta);
+  }
+
+  @override
+  Drag drag(DragStartDetails details, VoidCallback dragCancelCallback) {
+    _isAtTop = pixels == 0;
+    return super.drag(details, dragCancelCallback);
+  }
+}

lib/common/widgets/draggable_sheet/topic.dart

@@ -0,0 +1,74 @@
+part of 'package:PiliPlus/common/widgets/flutter/draggable_scrollable_sheet.dart';
+
+class TopicDraggableScrollableSheet extends DraggableScrollableSheet {
+  const TopicDraggableScrollableSheet({
+    super.key,
+    super.initialChildSize,
+    super.minChildSize,
+    super.maxChildSize,
+    super.expand,
+    super.snap,
+    super.snapSizes,
+    super.snapAnimationDuration,
+    super.controller,
+    super.shouldCloseOnMinExtent,
+    required super.builder,
+    this.initialScrollOffset = 0.0,
+  });
+
+  final double initialScrollOffset;
+
+  @override
+  State<DraggableScrollableSheet> createState() =>
+      _TopicDraggableScrollableSheetState();
+}
+
+class _TopicDraggableScrollableSheetState
+    extends _DraggableScrollableSheetState {
+  @override
+  void initState() {
+    super.initState();
+    _extent = _DraggableSheetExtent(
+      minSize: widget.minChildSize,
+      maxSize: widget.maxChildSize,
+      snap: widget.snap,
+      snapSizes: _impliedSnapSizes(),
+      snapAnimationDuration: widget.snapAnimationDuration,
+      initialSize: widget.initialChildSize,
+      shouldCloseOnMinExtent: widget.shouldCloseOnMinExtent,
+    );
+    _scrollController = _TopicDraggableScrollableSheetScrollController(
+      extent: _extent,
+      initialScrollOffset:
+          (widget as TopicDraggableScrollableSheet).initialScrollOffset,
+    );
+    widget.controller?._attach(_scrollController);
+  }
+}
+
+class _TopicDraggableScrollableSheetScrollController
+    extends _DraggableScrollableSheetScrollController {
+  _TopicDraggableScrollableSheetScrollController({
+    required super.extent,
+    double initialScrollOffset = 0.0,
+  }) : _initialScrollOffset = initialScrollOffset;
+
+  @override
+  double get initialScrollOffset => _initialScrollOffset;
+  final double _initialScrollOffset;
+
+  @override
+  _DraggableScrollableSheetScrollPosition createScrollPosition(
+    ScrollPhysics physics,
+    ScrollContext context,
+    ScrollPosition? oldPosition,
+  ) {
+    return _DraggableScrollableSheetScrollPosition(
+      physics: physics.applyTo(const AlwaysScrollableScrollPhysics()),
+      context: context,
+      oldPosition: oldPosition,
+      getExtent: () => extent,
+      initialPixels: _initialScrollOffset,
+    );
+  }
+}