Fix glitchness in DnDVBox placeholders.

git-svn-id: svn://localhost/ardour2/branches/3.0@10640 d708f5d6-7413-0410-9779-e7cbd77b26cf

1 files changed, 21 insertions, 5 deletions

diff --git a/libs/gtkmm2ext/gtkmm2ext/dndvbox.h b/libs/gtkmm2ext/gtkmm2ext/dndvbox.h
index a5b85234c4..2f09779e71 100644
--- a/libs/gtkmm2ext/gtkmm2ext/dndvbox.h
+++ b/libs/gtkmm2ext/gtkmm2ext/dndvbox.h
@@ -218,6 +218,24 @@ public:
 	sigc::signal<void> SelectionChanged;
 
 private:
+
+	/** @return the bottom y position of a child, pretending any placeholder
+	 *  is not there.
+	 */
+	double bottom_of_child_ignoring_placeholder (T* child) const
+	{
+		Gtk::Allocation const a = child->widget().get_allocation ();
+		double bottom = a.get_y() + a.get_height();
+
+		if (_placeholder) {
+			Gtk::Allocation const b = _placeholder->get_allocation ();
+			if (b.get_y() < a.get_y()) {
+				bottom -= (b.get_height () + _internal_vbox.get_spacing ());
+			}
+		}
+
+		return bottom;
+	}
 	
 	/** Look at a y coordinate and find the children below y, and the ones either side.
 	 *  @param y y position.
@@ -242,8 +260,7 @@ private:
 		/* top of current child */
 		double top = 0;
 		/* bottom of current child */
-		Gtk::Allocation const a = (*j)->widget().get_allocation();
-		double bottom = a.get_y() + a.get_height();
+		double bottom = bottom_of_child_ignoring_placeholder (*j);
 
 		while (y >= bottom && j != _children.end()) {
 
@@ -254,8 +271,7 @@ private:
 			++j;
 
 			if (j != _children.end()) {
-				Gtk::Allocation const a = (*j)->widget().get_allocation();
-				bottom = a.get_y() + a.get_height();
+				bottom = bottom_of_child_ignoring_placeholder (*j);
 			}
 		}
 
@@ -270,7 +286,7 @@ private:
 		++j;
 		*after = j != _children.end() ? *j : 0;
 
-		return i + ((y - top) / (*at)->widget().get_allocation().get_height());
+		return i + ((y - top) / (bottom - top));
 	}
 
 	void drag_begin (Glib::RefPtr<Gdk::DragContext> const & context, T* child)