Merge pull request #52096 from kleonc/tree-item-drag-drop-drawing

Tree Fix line rendering when drag and dropping TreeItem

scene/gui/tree.cpp

@@ -1717,24 +1717,30 @@ int Tree::draw_item(const Point2i &p_pos, const Point2 &p_draw_ofs, const Size2
 				}
 			}
 
-			if (drop_mode_flags && drop_mode_over == p_item) {
+			if (drop_mode_flags && drop_mode_over) {
 				Rect2 r = cell_rect;
-				bool has_parent = p_item->get_first_child() != nullptr;
 				if (rtl) {
 					r.position.x = get_size().width - r.position.x - r.size.x;
 				}
-
-				if (drop_mode_section == -1 || has_parent || drop_mode_section == 0) {
-					RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x, r.position.y, r.size.x, 1), cache.drop_position_color);
-				}
-
-				if (drop_mode_section == 0) {
-					RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x, r.position.y, 1, r.size.y), cache.drop_position_color);
-					RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x + r.size.x - 1, r.position.y, 1, r.size.y), cache.drop_position_color);
-				}
-
-				if ((drop_mode_section == 1 && !has_parent) || drop_mode_section == 0) {
-					RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x, r.position.y + r.size.y, r.size.x, 1), cache.drop_position_color);
+				if (drop_mode_over == p_item) {
+					if (drop_mode_section == 0 || drop_mode_section == -1) {
+						// Line above.
+						RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x, r.position.y, r.size.x, 1), cache.drop_position_color);
+					}
+					if (drop_mode_section == 0) {
+						// Side lines.
+						RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x, r.position.y, 1, r.size.y), cache.drop_position_color);
+						RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x + r.size.x - 1, r.position.y, 1, r.size.y), cache.drop_position_color);
+					}
+					if (drop_mode_section == 0 || (drop_mode_section == 1 && (!p_item->get_first_child() || p_item->is_collapsed()))) {
+						// Line below.
+						RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x, r.position.y + r.size.y, r.size.x, 1), cache.drop_position_color);
+					}
+				} else if (drop_mode_over == p_item->get_parent()) {
+					if (drop_mode_section == 1 && !p_item->get_prev() /* && !drop_mode_over->is_collapsed() */) { // The drop_mode_over shouldn't ever be collapsed in here, otherwise we would be drawing a child of a collapsed item.
+						// Line above.
+						RenderingServer::get_singleton()->canvas_item_add_rect(ci, Rect2(r.position.x, r.position.y, r.size.x, 1), cache.drop_position_color);
+					}
 				}
 			}