Fix getting wrong focus neighbor when the control is in ScrollContainer

Exclude controls inside a `ScrollContainer` that are outside the visible area of ​​
the `ScrollContainer` when looking for focus neighbors.

Author: Rindbee

scene/gui/control.cpp

@@ -32,9 +32,9 @@
 
 #include "container.h"
 #include "core/config/project_settings.h"
-#include "core/math/geometry_2d.h"
 #include "core/os/os.h"
 #include "core/string/translation_server.h"
+#include "scene/gui/scroll_container.h"
 #include "scene/main/canvas_layer.h"
 #include "scene/main/window.h"
 #include "scene/theme/theme_db.h"
@@ -2281,18 +2281,9 @@ Control *Control::_get_focus_neighbor(Side p_side, int p_count) {
 		return c;
 	}
 
-	real_t dist = 1e7;
+	real_t square_of_dist = 1e14;
 	Control *result = nullptr;
 
-	Point2 points[4];
-
-	Transform2D xform = get_global_transform();
-
-	points[0] = xform.xform(Point2());
-	points[1] = xform.xform(Point2(get_size().x, 0));
-	points[2] = xform.xform(get_size());
-	points[3] = xform.xform(Point2(0, get_size().y));
-
 	const Vector2 dir[4] = {
 		Vector2(-1, 0),
 		Vector2(0, -1),
@@ -2302,18 +2293,73 @@ Control *Control::_get_focus_neighbor(Side p_side, int p_count) {
 
 	Vector2 vdir = dir[p_side];
 
-	real_t maxd = -1e7;
+	Rect2 r = get_global_rect();
+	real_t begin_d = vdir.dot(r.get_position());
+	real_t end_d = vdir.dot(r.get_end());
+	real_t maxd = MAX(begin_d, end_d);
 
-	for (int i = 0; i < 4; i++) {
-		real_t d = vdir.dot(points[i]);
-		if (d > maxd) {
-			maxd = d;
-		}
-	}
+	Rect2 clamp = Rect2(-1e7, -1e7, 2e7, 2e7);
+	Rect2 result_rect;
 
 	Node *base = this;
 
 	while (base) {
+		ScrollContainer *sc = Object::cast_to<ScrollContainer>(base);
+
+		if (sc) {
+			Rect2 sc_r = sc->get_global_rect();
+			bool follow_focus = sc->is_following_focus();
+
+			if (result && !follow_focus && !sc_r.intersects(result_rect)) {
+				result = nullptr; // Skip invisible control.
+			}
+
+			if (result == nullptr) {
+				real_t sc_begin_d = vdir.dot(sc_r.get_position());
+				real_t sc_end_d = vdir.dot(sc_r.get_end());
+				real_t sc_maxd = sc_begin_d;
+				real_t sc_mind = sc_end_d;
+				if (sc_begin_d < sc_end_d) {
+					sc_maxd = sc_end_d;
+					sc_mind = sc_begin_d;
+				}
+
+				if (!follow_focus && maxd < sc_mind) {
+					// Reposition to find visible control.
+					maxd = sc_mind;
+					r.set_position(r.get_position() + (sc_mind - maxd) * vdir);
+				}
+
+				if (follow_focus || sc_maxd > maxd) {
+					_window_find_focus_neighbor(vdir, base, r, clamp, maxd, square_of_dist, &result);
+				}
+
+				if (result == nullptr) {
+					// Reposition to search upwards.
+					maxd = sc_maxd;
+					r.set_position(r.get_position() + (sc_maxd - maxd) * vdir);
+				} else {
+					result_rect = result->get_global_rect();
+					if (follow_focus) {
+						real_t r_begin_d = vdir.dot(result_rect.get_position());
+						real_t r_end_d = vdir.dot(result_rect.get_end());
+						real_t r_maxd = r_begin_d;
+						real_t r_mind = r_end_d;
+						if (r_begin_d < r_end_d) {
+							r_maxd = r_end_d;
+							r_mind = r_begin_d;
+						}
+
+						if (r_maxd > sc_maxd) {
+							result_rect.set_position(result_rect.get_position() + (sc_maxd - r_maxd) * vdir);
+						} else if (r_mind < sc_mind) {
+							result_rect.set_position(result_rect.get_position() + (sc_mind - r_mind) * vdir);
+						}
+					}
+				}
+			}
+		}
+
 		Control *c = Object::cast_to<Control>(base);
 		if (c) {
 			if (c->data.RI) {
@@ -2323,11 +2369,15 @@ Control *Control::_get_focus_neighbor(Side p_side, int p_count) {
 		base = base->get_parent();
 	}
 
+	if (result) {
+		return result;
+	}
+
 	if (!base) {
 		return nullptr;
 	}
 
-	_window_find_focus_neighbor(vdir, base, points, maxd, dist, &result);
+	_window_find_focus_neighbor(vdir, base, r, clamp, maxd, square_of_dist, &result);
 
 	return result;
 }
@@ -2336,83 +2386,98 @@ Control *Control::find_valid_focus_neighbor(Side p_side) const {
 	return const_cast<Control *>(this)->_get_focus_neighbor(p_side);
 }
 
-void Control::_window_find_focus_neighbor(const Vector2 &p_dir, Node *p_at, const Point2 *p_points, real_t p_min, real_t &r_closest_dist, Control **r_closest) {
+void Control::_window_find_focus_neighbor(const Vector2 &p_dir, Node *p_at, const Rect2 &p_rect, const Rect2 &p_clamp, real_t p_min, real_t &r_closest_dist_squared, Control **r_closest) {
 	if (Object::cast_to<Viewport>(p_at)) {
-		return; //bye
+		return; // Bye.
 	}
 
 	Control *c = Object::cast_to<Control>(p_at);
+	Container *container = Object::cast_to<Container>(p_at);
+	bool in_container = container ? container->is_ancestor_of(this) : false;
+
+	if (c && c != this && c->get_focus_mode() == FOCUS_ALL && !in_container && p_clamp.intersects(c->get_global_rect())) {
+		Rect2 r_c = c->get_global_rect();
+		r_c = r_c.intersection(p_clamp);
+		real_t begin_d = p_dir.dot(r_c.get_position());
+		real_t end_d = p_dir.dot(r_c.get_end());
+		real_t max = MAX(begin_d, end_d);
+
+		// Use max to allow navigation to overlapping controls (for ScrollContainer case).
+		if (max > (p_min + CMP_EPSILON)) {
+			// Calculate the shortest distance. (No shear transform)
+			// Flip along axis(es) so that C falls in the first quadrant of c (as origin) for easy calculation.
+			// The same transformation would put the direction vector in the positive direction (+x or +y).
+			//       |           -------------
+			//       |           |     |     |
+			//       |           |-----C-----|
+			//   ----|---a       |     |     |
+			//   |   |   |       b------------
+			//  -|---c---|----------------------->
+			//   |   |   |
+			//   ----|----
+			// cC = ca + ab + bC
+			// The shortest distance is the vector ab's length or its positive projection length.
+
+			Vector2 cC_origin = r_c.get_center() - p_rect.get_center();
+			Vector2 cC = cC_origin.abs(); // Converted to fall in the first quadrant of c.
+
+			Vector2 ab = cC - 0.5 * r_c.get_size() - 0.5 * p_rect.get_size();
+
+			real_t min_d_squared = 0.0;
+			if (ab.x > 0.0) {
+				min_d_squared += ab.x * ab.x;
+			}
+			if (ab.y > 0.0) {
+				min_d_squared += ab.y * ab.y;
+			}
 
-	if (c && c != this && c->get_focus_mode() == FOCUS_ALL && c->is_visible_in_tree()) {
-		Point2 points[4];
-
-		Transform2D xform = c->get_global_transform();
-
-		points[0] = xform.xform(Point2());
-		points[1] = xform.xform(Point2(c->get_size().x, 0));
-		points[2] = xform.xform(c->get_size());
-		points[3] = xform.xform(Point2(0, c->get_size().y));
-
-		// Tie-breaking aims to address situations where a potential focus neighbor's bounding rect
-		// is right next to the currently focused control (e.g. in BoxContainer with
-		// separation overridden to 0). This needs specific handling so that the correct
-		// focus neighbor is selected.
-
-		// Calculate centers of the potential neighbor, currently focused, and closest controls.
-		Point2 center = xform.xform(0.5 * c->get_size());
-		// We only have the points, not an actual reference.
-		Point2 p_center = 0.25 * (p_points[0] + p_points[1] + p_points[2] + p_points[3]);
-		Point2 closest_center;
-		bool should_tiebreak = false;
-		if (*r_closest != nullptr) {
-			should_tiebreak = true;
-			Control *closest = *r_closest;
-			Transform2D closest_xform = closest->get_global_transform();
-			closest_center = closest_xform.xform(0.5 * closest->get_size());
-		}
-
-		real_t min = 1e7;
-
-		for (int i = 0; i < 4; i++) {
-			real_t d = p_dir.dot(points[i]);
-			if (d < min) {
-				min = d;
+			if (min_d_squared < r_closest_dist_squared || *r_closest == nullptr) {
+				r_closest_dist_squared = min_d_squared;
+				*r_closest = c;
+			} else if (min_d_squared == r_closest_dist_squared) {
+				// Tie-breaking aims to address situations where a potential focus neighbor's bounding rect
+				// is right next to the currently focused control (e.g. in BoxContainer with
+				// separation overridden to 0). This needs specific handling so that the correct
+				// focus neighbor is selected.
+
+				Point2 p_center = p_rect.get_center();
+				Control *closest = *r_closest;
+				Point2 closest_center = closest->get_global_rect().get_center();
+
+				// Tie-break in favor of the control most aligned with p_dir.
+				if (Math::abs(p_dir.cross(cC_origin)) < Math::abs(p_dir.cross(closest_center - p_center))) {
+					*r_closest = c;
+				}
 			}
 		}
+	}
 
-		if (min > (p_min - CMP_EPSILON)) {
-			for (int i = 0; i < 4; i++) {
-				Vector2 la = p_points[i];
-				Vector2 lb = p_points[(i + 1) % 4];
-
-				for (int j = 0; j < 4; j++) {
-					Vector2 fa = points[j];
-					Vector2 fb = points[(j + 1) % 4];
-
-					Vector2 pa, pb;
-					real_t d = Geometry2D::get_closest_points_between_segments(la, lb, fa, fb, pa, pb);
-					if (d < r_closest_dist) {
-						r_closest_dist = d;
-						*r_closest = c;
-					} else if (should_tiebreak && d == r_closest_dist) {
-						// Tie-break in favor of the control most aligned with p_dir.
-						if (p_dir.dot((center - p_center).normalized()) > p_dir.dot((closest_center - p_center).normalized())) {
-							r_closest_dist = d;
-							*r_closest = c;
-						}
-					}
-				}
+	ScrollContainer *sc = Object::cast_to<ScrollContainer>(c);
+	Rect2 intersection = p_clamp;
+	if (sc) {
+		if (!sc->is_following_focus() || !in_container) {
+			intersection = p_clamp.intersection(sc->get_global_rect());
+			if (!intersection.has_area()) {
+				return;
 			}
 		}
 	}
 
 	for (int i = 0; i < p_at->get_child_count(); i++) {
 		Node *child = p_at->get_child(i);
 		Control *childc = Object::cast_to<Control>(child);
-		if (childc && childc->data.RI) {
-			continue; //subwindow, ignore
+		if (childc) {
+			if (childc->data.RI) {
+				continue; // Subwindow, ignore.
+			}
+			if (!childc->is_visible_in_tree()) {
+				continue; // Skip invisible node trees.
+			}
+			if (Object::cast_to<ScrollContainer>(childc) && childc->is_ancestor_of(this)) {
+				continue; // Already searched in it, skip it.
+			}
 		}
-		_window_find_focus_neighbor(p_dir, p_at->get_child(i), p_points, p_min, r_closest_dist, r_closest);
+		_window_find_focus_neighbor(p_dir, child, p_rect, intersection, p_min, r_closest_dist_squared, r_closest);
 	}
 }
 

scene/gui/control.h

@@ -314,7 +314,7 @@ class Control : public CanvasItem {
 
 	// Focus.
 
-	void _window_find_focus_neighbor(const Vector2 &p_dir, Node *p_at, const Point2 *p_points, real_t p_min, real_t &r_closest_dist, Control **r_closest);
+	void _window_find_focus_neighbor(const Vector2 &p_dir, Node *p_at, const Rect2 &p_rect, const Rect2 &p_clamp, real_t p_min, real_t &r_closest_dist_squared, Control **r_closest);
 	Control *_get_focus_neighbor(Side p_side, int p_count = 0);
 
 	// Theming.