From 8eb17211b5d8adab6057ff335c2050b156f91edd Mon Sep 17 00:00:00 2001
From: Carl Hetherington <carl@carlh.net>
Date: Fri, 12 Jun 2009 19:05:16 +0000
Subject: [PATCH] Hopefully fix assertion failures in gnomecanvas when dragging
 track heights.

git-svn-id: svn://localhost/ardour2/branches/3.0@5175 d708f5d6-7413-0410-9779-e7cbd77b26cf
---
 gtk2_ardour/editor.h             |  2 ++
 gtk2_ardour/editor_canvas.cc     | 21 +++++++++++++++++++--
 gtk2_ardour/editor_drag.cc       | 10 +++++-----
 gtk2_ardour/editor_mouse.cc      |  2 +-
 gtk2_ardour/editor_route_list.cc |  2 +-
 5 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/gtk2_ardour/editor.h b/gtk2_ardour/editor.h
index 4d212d581c..caf9b24738 100644
--- a/gtk2_ardour/editor.h
+++ b/gtk2_ardour/editor.h
@@ -2219,6 +2219,8 @@ public:
 	EditorSummary* _summary;
 	void region_view_added (RegionView *);
 
+	void update_canvas_now ();
+
 	friend class Drag;
 	friend class RegionDrag;
 	friend class RegionMoveDrag;
diff --git a/gtk2_ardour/editor_canvas.cc b/gtk2_ardour/editor_canvas.cc
index 573b3af16a..6698c5ee9b 100644
--- a/gtk2_ardour/editor_canvas.cc
+++ b/gtk2_ardour/editor_canvas.cc
@@ -819,7 +819,7 @@ Editor::scroll_canvas_vertically ()
 	}
 	last_trackview_group_vertical_offset = get_trackview_group_vertical_offset ();
 	/* required to keep the controls_layout in lock step with the canvas group */
-	track_canvas->update_now ();
+	update_canvas_now ();
 }
 
 void
@@ -889,8 +889,25 @@ void
 Editor::flush_canvas ()
 {
 	if (is_mapped()) {
-		track_canvas->update_now ();
+		update_canvas_now ();
 		// gdk_window_process_updates (GTK_LAYOUT(track_canvas->gobj())->bin_window, true);
 	}
 }
 
+void
+Editor::update_canvas_now ()
+{
+	/* GnomeCanvas has a bug whereby if its idle handler is not scheduled between
+	   two calls to update_now, an assert will trip.  This wrapper works around
+	   that problem by only calling update_now if the assert will not trip.
+
+	   I think the GC bug is due to the fact that its code will reset need_update
+	   and need_redraw to FALSE without checking to see if an idle handler is scheduled.
+	   If one is scheduled, GC should probably remove it.
+	*/
+	
+	GnomeCanvas* c = track_canvas->gobj ();
+	if (c->need_update || c->need_redraw) {
+		track_canvas->update_now ();
+	}
+}
diff --git a/gtk2_ardour/editor_drag.cc b/gtk2_ardour/editor_drag.cc
index 57e554b0bd..54bc8e276d 100644
--- a/gtk2_ardour/editor_drag.cc
+++ b/gtk2_ardour/editor_drag.cc
@@ -798,7 +798,7 @@ RegionMoveDrag::finished (GdkEvent* event, bool movement_occurred)
 
 	drag_delta = _primary->region()->position() - _last_frame_position;
 
-	_editor->track_canvas->update_now ();
+	_editor->update_canvas_now ();
 
 	/* make a list of where each region ended up */
 	final = find_time_axis_views ();
@@ -1066,7 +1066,7 @@ RegionMotionDrag::copy_regions (GdkEvent* event)
 	   ..only if the mouse is in rapid motion at the time of the grab. 
 	   something to do with regionview creation raking so long?
 	*/
-	_editor->track_canvas->update_now();
+	_editor->update_canvas_now();
 }
 
 bool
@@ -1255,7 +1255,7 @@ RegionMotionDrag::find_time_axis_views ()
 void
 RegionInsertDrag::finished (GdkEvent* event, bool movement_occurred)
 {
-	_editor->track_canvas->update_now ();
+	_editor->update_canvas_now ();
 
 	map<RegionView*, RouteTimeAxisView*> final = find_time_axis_views ();
 	
@@ -1893,7 +1893,7 @@ CursorDrag::motion (GdkEvent* event, bool)
 	_editor->show_verbose_time_cursor (_cursor->current_frame, 10);
 
 #ifdef GTKOSX
-	_editor->track_canvas->update_now ();
+	_editor->update_canvas_now ();
 #endif
 	_editor->UpdateAllTransportClocks (_cursor->current_frame);
 
@@ -2355,7 +2355,7 @@ MarkerDrag::motion (GdkEvent* event, bool)
 	_editor->show_verbose_time_cursor (newframe, 10);
 
 #ifdef GTKOSX
-	_editor->track_canvas->update_now ();
+	_editor->update_canvas_now ();
 #endif
 	_editor->edit_point_clock.set (copy_location->start());
 }
diff --git a/gtk2_ardour/editor_mouse.cc b/gtk2_ardour/editor_mouse.cc
index d29f462bd6..2eb06d4e7a 100644
--- a/gtk2_ardour/editor_mouse.cc
+++ b/gtk2_ardour/editor_mouse.cc
@@ -2550,7 +2550,7 @@ Editor::start_region_grab (ArdourCanvas::Item* item, GdkEvent* event, RegionView
 	begin_reversible_command (_("move region(s)"));
 
 	/* sync the canvas to what we think is its current state */
-	track_canvas->update_now();
+	update_canvas_now();
 }
 
 void
diff --git a/gtk2_ardour/editor_route_list.cc b/gtk2_ardour/editor_route_list.cc
index 340f678228..17d692d8d7 100644
--- a/gtk2_ardour/editor_route_list.cc
+++ b/gtk2_ardour/editor_route_list.cc
@@ -158,7 +158,7 @@ Editor::handle_gui_changes (const string & what, void *src)
 		/* Optional :make tracks change height while it happens, instead 
 		   of on first-idle
 		*/
-		//track_canvas->update_now ();
+		//update_canvas_now ();
 		redisplay_route_list ();
 	}