Consider children Control nodes for mouse-enter/exit notifications

`NOTIFICATION_MOUSE_ENTER` and `NOTIFICATION_MOUSE_EXIT` now includes the areas of children control nodes. In order to check if a Control node itself was entered/exited, the newly introduced `NOTIFICATION_MOUSE_ENTER_SELF` and `NOTIFICATION_MOUSE_EXIT_SELF` can be used. Co-authored-by: Markus Sauermann <[email protected]>
kitbdev · Nov 1, 2023 · 1eda4ce · 1eda4ce
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Showing 5 changed files with 90 additions and 16 deletions.
diff --git a/doc/classes/Control.xml b/doc/classes/Control.xml
@@ -1104,13 +1104,13 @@
 		</signal>
 		<signal name="mouse_entered">
 			<description>
-				Emitted when the mouse cursor enters the control's visible area, that is not occluded behind other Controls or Windows, provided its [member mouse_filter] lets the event reach it and regardless if it's currently focused or not.
+				Emitted when the mouse cursor enters the control's (or any child control's) visible area, that is not occluded behind other Controls or Windows, provided its [member mouse_filter] lets the event reach it and regardless if it's currently focused or not.
 				[b]Note:[/b] [member CanvasItem.z_index] doesn't affect, which Control receives the signal.
 			</description>
 		</signal>
 		<signal name="mouse_exited">
 			<description>
-				Emitted when the mouse cursor leaves the control's visible area, that is not occluded behind other Controls or Windows, provided its [member mouse_filter] lets the event reach it and regardless if it's currently focused or not.
+				Emitted when the mouse cursor leaves the control's (and all child control's) visible area, that is not occluded behind other Controls or Windows, provided its [member mouse_filter] lets the event reach it and regardless if it's currently focused or not.
 				[b]Note:[/b] [member CanvasItem.z_index] doesn't affect, which Control receives the signal.
 				[b]Note:[/b] If you want to check whether the mouse truly left the area, ignoring any top nodes, you can use code like this:
 				[codeblock]
@@ -1150,12 +1150,24 @@
 			Sent when the node changes size. Use [member size] to get the new size.
 		</constant>
 		<constant name="NOTIFICATION_MOUSE_ENTER" value="41">
-			Sent when the mouse cursor enters the control's visible area, that is not occluded behind other Controls or Windows, provided its [member mouse_filter] lets the event reach it and regardless if it's currently focused or not.
+			Sent when the mouse cursor enters the control's (or any child control's) visible area, that is not occluded behind other Controls or Windows, provided its [member mouse_filter] lets the event reach it and regardless if it's currently focused or not.
 			[b]Note:[/b] [member CanvasItem.z_index] doesn't affect, which Control receives the notification.
+			See also [constant NOTIFICATION_MOUSE_ENTER_SELF].
 		</constant>
 		<constant name="NOTIFICATION_MOUSE_EXIT" value="42">
+			Sent when the mouse cursor leaves the control's (and all child control's) visible area, that is not occluded behind other Controls or Windows, provided its [member mouse_filter] lets the event reach it and regardless if it's currently focused or not.
+			[b]Note:[/b] [member CanvasItem.z_index] doesn't affect, which Control receives the notification.
+			See also [constant NOTIFICATION_MOUSE_EXIT_SELF].
+		</constant>
+		<constant name="NOTIFICATION_MOUSE_ENTER_SELF" value="60">
+			Sent when the mouse cursor enters the control's visible area, that is not occluded behind other Controls or Windows, provided its [member mouse_filter] lets the event reach it and regardless if it's currently focused or not.
+			[b]Note:[/b] [member CanvasItem.z_index] doesn't affect, which Control receives the notification.
+			See also [constant NOTIFICATION_MOUSE_ENTER].
+		</constant>
+		<constant name="NOTIFICATION_MOUSE_EXIT_SELF" value="61">
 			Sent when the mouse cursor leaves the control's visible area, that is not occluded behind other Controls or Windows, provided its [member mouse_filter] lets the event reach it and regardless if it's currently focused or not.
 			[b]Note:[/b] [member CanvasItem.z_index] doesn't affect, which Control receives the notification.
+			See also [constant NOTIFICATION_MOUSE_EXIT].
 		</constant>
 		<constant name="NOTIFICATION_FOCUS_ENTER" value="43">
 			Sent when the node grabs focus.

diff --git a/scene/gui/control.cpp b/scene/gui/control.cpp
@@ -3568,6 +3568,8 @@ void Control::_bind_methods() {
 	BIND_CONSTANT(NOTIFICATION_RESIZED);
 	BIND_CONSTANT(NOTIFICATION_MOUSE_ENTER);
 	BIND_CONSTANT(NOTIFICATION_MOUSE_EXIT);
+	BIND_CONSTANT(NOTIFICATION_MOUSE_ENTER_SELF);
+	BIND_CONSTANT(NOTIFICATION_MOUSE_EXIT_SELF);
 	BIND_CONSTANT(NOTIFICATION_FOCUS_ENTER);
 	BIND_CONSTANT(NOTIFICATION_FOCUS_EXIT);
 	BIND_CONSTANT(NOTIFICATION_THEME_CHANGED);

diff --git a/scene/gui/control.h b/scene/gui/control.h
@@ -368,6 +368,8 @@ class Control : public CanvasItem {
 		NOTIFICATION_SCROLL_BEGIN = 47,
 		NOTIFICATION_SCROLL_END = 48,
 		NOTIFICATION_LAYOUT_DIRECTION_CHANGED = 49,
+		NOTIFICATION_MOUSE_ENTER_SELF = 60,
+		NOTIFICATION_MOUSE_EXIT_SELF = 61,
 	};
 
 	// Editor plugin interoperability.

diff --git a/scene/main/viewport.cpp b/scene/main/viewport.cpp
@@ -2408,9 +2408,7 @@ void Viewport::_gui_hide_control(Control *p_control) {
 	if (gui.key_focus == p_control) {
 		gui_release_focus();
 	}
-	if (gui.mouse_over == p_control) {
-		_drop_mouse_over();
-	}
+	_reevaluate_mouse_over();
 	if (gui.drag_mouse_over == p_control) {
 		gui.drag_mouse_over = nullptr;
 	}
@@ -2431,8 +2429,9 @@ void Viewport::_gui_remove_control(Control *p_control) {
 	if (gui.key_focus == p_control) {
 		gui.key_focus = nullptr;
 	}
-	if (gui.mouse_over == p_control) {
-		_drop_mouse_over();
+	if (gui.mouse_over == p_control || gui.mouse_over_hierarchy.find(p_control) >= 0) {
+		_drop_mouse_over(p_control->get_parent_control());
+		callable_mp(this, &Viewport::_reevaluate_mouse_over).call_deferred();
 	}
 	if (gui.drag_mouse_over == p_control) {
 		gui.drag_mouse_over = nullptr;
@@ -2987,6 +2986,14 @@ bool Viewport::_sub_windows_forward_input(const Ref<InputEvent> &p_event) {
 	return true;
 }
 
+void Viewport::_reevaluate_mouse_over() {
+	if (!gui.mouse_in_viewport) {
+		return;
+	}
+	// Send mouse entered exited notifications for current viewport.
+	_update_mouse_over(gui.last_mouse_pos);
+}
+
 void Viewport::_update_mouse_over() {
 	// Update gui.mouse_over and gui.subwindow_over in all Viewports.
 	// Send necessary mouse_enter/mouse_exit signals and the MOUSE_ENTER/MOUSE_EXIT notifications for every Viewport in the SceneTree.
@@ -3070,15 +3077,55 @@ void Viewport::_update_mouse_over(Vector2 p_pos) {
 	Control *over = gui_find_control(p_pos);
 	bool notify_embedded_viewports = false;
 	if (over != gui.mouse_over) {
-		if (gui.mouse_over) {
-			_drop_mouse_over();
+		// Find the common ancestor of `gui.mouse_over` and `over`.
+		Control *common_ancestor = nullptr;
+		LocalVector<Control *> over_ancestors;
+
+		if (over) {
+			// Get all ancestors that the mouse is currently over and need an enter signal.
+			Control *ancestor = over;
+			while (ancestor) {
+				int found = gui.mouse_over_hierarchy.find(ancestor);
+				if (found >= 0) {
+					common_ancestor = gui.mouse_over_hierarchy[found];
+					break;
+				}
+				if (ancestor->get_mouse_filter() != Control::MOUSE_FILTER_IGNORE) {
+					over_ancestors.push_back(ancestor);
+				}
+				if (ancestor->is_set_as_top_level() || ancestor->get_mouse_filter() == Control::MOUSE_FILTER_STOP) {
+					// Top level Control nodes and MOUSE_FILTER_STOP break the propagation chain.
+					break;
+				}
+				// Consider only direct Control parents. (Could be changed to include non-Control CanvasItems.)
+				ancestor = ancestor->get_parent_control();
+			}
+		}
+
+		if (gui.mouse_over || !gui.mouse_over_hierarchy.is_empty()) {
+			// Send Mouse Exit Self and Mouse Exit notifications.
+			_drop_mouse_over(common_ancestor);
 		} else {
 			_drop_physics_mouseover();
 		}
 
-		gui.mouse_over = over;
 		if (over) {
-			over->notification(Control::NOTIFICATION_MOUSE_ENTER);
+			gui.mouse_over = over;
+			gui.mouse_over_hierarchy.reserve(gui.mouse_over_hierarchy.size() + over_ancestors.size());
+
+			// Send Mouse Enter notifications to parents first.
+			for (int i = over_ancestors.size() - 1; i >= 0; i--) {
+				over_ancestors[i]->notification(Control::NOTIFICATION_MOUSE_ENTER);
+				gui.mouse_over_hierarchy.push_back(over_ancestors[i]);
+			}
+
+			// Send Mouse Enter Self notification.
+			if (!over_ancestors.is_empty()) {
+				over_ancestors[0]->notification(Control::NOTIFICATION_MOUSE_ENTER_SELF);
+			} else if (gui.mouse_over->get_mouse_filter() != Control::MOUSE_FILTER_IGNORE) {
+				gui.mouse_over->notification(Control::NOTIFICATION_MOUSE_ENTER_SELF);
+			}
+
 			notify_embedded_viewports = true;
 		}
 	}
@@ -3119,7 +3166,7 @@ void Viewport::_mouse_leave_viewport() {
 	notification(NOTIFICATION_VP_MOUSE_EXIT);
 }
 
-void Viewport::_drop_mouse_over() {
+void Viewport::_drop_mouse_over(Control *p_until_control) {
 	_gui_cancel_tooltip();
 	SubViewportContainer *c = Object::cast_to<SubViewportContainer>(gui.mouse_over);
 	if (c) {
@@ -3131,10 +3178,19 @@ void Viewport::_drop_mouse_over() {
 			v->_mouse_leave_viewport();
 		}
 	}
-	if (gui.mouse_over->is_inside_tree()) {
-		gui.mouse_over->notification(Control::NOTIFICATION_MOUSE_EXIT);
+	if (gui.mouse_over && gui.mouse_over->is_inside_tree()) {
+		gui.mouse_over->notification(Control::NOTIFICATION_MOUSE_EXIT_SELF);
 	}
 	gui.mouse_over = nullptr;
+
+	// Send Mouse Exit notifications to children first. Don't send to p_until_control or above.
+	int notification_until = p_until_control ? gui.mouse_over_hierarchy.find(p_until_control) + 1 : 0;
+	for (int i = gui.mouse_over_hierarchy.size() - 1; i >= notification_until; i--) {
+		if (gui.mouse_over_hierarchy[i]->is_inside_tree()) {
+			gui.mouse_over_hierarchy[i]->notification(Control::NOTIFICATION_MOUSE_EXIT);
+		}
+	}
+	gui.mouse_over_hierarchy.resize(notification_until);
 }
 
 void Viewport::push_input(const Ref<InputEvent> &p_event, bool p_local_coords) {

diff --git a/scene/main/viewport.h b/scene/main/viewport.h
@@ -361,6 +361,7 @@ class Viewport : public Node {
 		BitField<MouseButtonMask> mouse_focus_mask;
 		Control *key_focus = nullptr;
 		Control *mouse_over = nullptr;
+		LocalVector<Control *> mouse_over_hierarchy;
 		Window *subwindow_over = nullptr; // mouse_over and subwindow_over are mutually exclusive. At all times at least one of them is nullptr.
 		Window *windowmanager_window_over = nullptr; // Only used in root Viewport.
 		Control *drag_mouse_over = nullptr;
@@ -455,7 +456,7 @@ class Viewport : public Node {
 	void _canvas_layer_add(CanvasLayer *p_canvas_layer);
 	void _canvas_layer_remove(CanvasLayer *p_canvas_layer);
 
-	void _drop_mouse_over();
+	void _drop_mouse_over(Control *p_until_control = nullptr);
 	void _drop_mouse_focus();
 	void _drop_physics_mouseover(bool p_paused_only = false);
 
@@ -475,6 +476,7 @@ class Viewport : public Node {
 	void _update_mouse_over();
 	virtual void _update_mouse_over(Vector2 p_pos);
 	virtual void _mouse_leave_viewport();
+	void _reevaluate_mouse_over();
 
 	virtual bool _can_consume_input_events() const { return true; }
 	uint64_t event_count = 0;