[mob][photos] Fix unexpected selections on vertical drag gestures + remove bugs

Now the feature works without any unexpected behaviour

mobile/lib/states/pointer_provider.dart

@@ -15,6 +15,7 @@ class PointerProvider extends StatefulWidget {
 
 class _PointerProviderState extends State<PointerProvider> {
   late Pointer pointer;
+  bool _isFingerOnScreenSinceLongPress = false;
 
   @override
   void dispose() {
@@ -36,15 +37,32 @@ class _PointerProviderState extends State<PointerProvider> {
               pointer.onTapStreamController.add(pointer.pointerPosition);
             },
             onLongPress: () {
+              _isFingerOnScreenSinceLongPress = true;
               pointer.onLongPressStreamController.add(pointer.pointerPosition);
             },
+            onHorizontalDragUpdate: (details) {
+              pointer.moveOffsetStreamController.add(details.localPosition);
+            },
             child: Listener(
               onPointerMove: (event) {
                 pointer.pointerPosition = event.localPosition;
+
+                //onHorizontalDragUpdate is not called when dragging after
+                //long press without lifting finger. This is for handling only
+                //this case.
+                if (_isFingerOnScreenSinceLongPress &&
+                    (event.localDelta.dx.abs() > 0 &&
+                        event.localDelta.dy.abs() > 0)) {
+                  pointer.moveOffsetStreamController.add(event.localPosition);
+                }
               },
               onPointerDown: (event) {
                 pointer.pointerPosition = event.localPosition;
               },
+              onPointerUp: (event) {
+                _isFingerOnScreenSinceLongPress = false;
+                pointer.upOffsetStreamController.add(event.localPosition);
+              },
               child: widget.child,
             ),
           );
@@ -59,7 +77,7 @@ class Pointer extends InheritedWidget {
 
   //This is a List<Offset> instead of just and Offset is so that it can be final
   //and still be mutable. Need to have this as final to keep Pointer immutable
-  //which is a recommended for inherited widgets.
+  //which is recommended for inherited widgets.
   final _pointerPosition =
       List.generate(1, (_) => Offset.zero, growable: false);
 

mobile/lib/ui/viewer/gallery/component/gallery_file_widget.dart

@@ -99,6 +99,7 @@ class _GalleryFileWidgetState extends State<GalleryFileWidget> {
                 .stream
                 .listen((offset) {
               if (bbox.contains(offset)) {
+                _pointerInsideBbox = true;
                 widget.limitSelectionToOne
                     ? _onTapWithSelectionLimit(widget.file)
                     : _onTapNoSelectionLimit(context, widget.file);
@@ -110,6 +111,7 @@ class _GalleryFileWidgetState extends State<GalleryFileWidget> {
                 .stream
                 .listen((offset) {
               if (bbox.contains(offset)) {
+                _pointerInsideBbox = true;
                 widget.limitSelectionToOne
                     ? _onLongPressWithSelectionLimit(context, widget.file)
                     : _onLongPressNoSelectionLimit(context, widget.file);
@@ -254,7 +256,6 @@ class _GalleryFileWidgetState extends State<GalleryFileWidget> {
             GalleryContextState.of(context)!.inSelectionMode;
     if (shouldToggleSelection) {
       _toggleFileSelection(file);
-      _pointerInsideBbox = true;
     } else {
       if (AppLifecycleService.instance.mediaExtensionAction.action ==
           IntentAction.pick) {
@@ -273,7 +274,6 @@ class _GalleryFileWidgetState extends State<GalleryFileWidget> {
         IntentAction.main) {
       HapticFeedback.lightImpact();
       _toggleFileSelection(file);
-      _pointerInsideBbox = true;
     }
   }