back-port carl's workaround for a gnomecanvas bug that causes a crash during certain resize operations and others

git-svn-id: svn://localhost/ardour2/branches/2.0-ongoing@7051 d708f5d6-7413-0410-9779-e7cbd77b26cf

3 files changed, 20 insertions, 9 deletions

diff --git a/gtk2_ardour/editor_canvas.cc b/gtk2_ardour/editor_canvas.cc
index 878967fb6b..a029c6582d 100644
--- a/gtk2_ardour/editor_canvas.cc
+++ b/gtk2_ardour/editor_canvas.cc
@@ -873,7 +873,7 @@ 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 ();
+        flush_canvas ();
 }
 
 void
@@ -948,8 +948,20 @@ void
 Editor::flush_canvas ()
 {
 	if (is_mapped()) {
-		track_canvas->update_now ();
-		// gdk_window_process_updates (GTK_LAYOUT(track_canvas->gobj())->bin_window, true);
+
+                /* 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_mouse.cc b/gtk2_ardour/editor_mouse.cc
index a2ba0476a0..15f8b235e2 100644
--- a/gtk2_ardour/editor_mouse.cc
+++ b/gtk2_ardour/editor_mouse.cc
@@ -2320,7 +2320,7 @@ Editor::cursor_drag_motion_callback (ArdourCanvas::Item* item, GdkEvent* event)
 	show_verbose_time_cursor (cursor->current_frame, 10);
 
 #ifdef GTKOSX
-	track_canvas->update_now ();
+        flush_canvas ();
 #endif
 	UpdateAllTransportClocks (cursor->current_frame);
 
@@ -2634,7 +2634,7 @@ Editor::marker_drag_motion_callback (ArdourCanvas::Item* item, GdkEvent* event)
 	show_verbose_time_cursor (newframe, 10);
 
 #ifdef GTKOSX
-	track_canvas->update_now ();
+        flush_canvas ();
 #endif
 }
 
@@ -3273,7 +3273,7 @@ Editor::start_region_grab (ArdourCanvas::Item* item, GdkEvent* event)
 	_region_motion_group->raise_to_top ();
 
 	/* sync the canvas to what we think is its current state */
-	track_canvas->update_now();
+        flush_canvas ();
 }
 
 void
@@ -3399,7 +3399,7 @@ Editor::possibly_copy_regions_during_grab (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?
 		 */
-		track_canvas->update_now();
+                flush_canvas ();
 	}
 }
 
@@ -4018,7 +4018,7 @@ Editor::region_drag_finished_callback (ArdourCanvas::Item* item, GdkEvent* event
 
 	drag_delta = clicked_regionview->region()->position() - drag_info.last_frame_position;
 
-	track_canvas->update_now ();
+        flush_canvas ();
 
 	for (list<RegionView*>::const_iterator i = selection->regions.by_layer().begin(); i != selection->regions.by_layer().end(); ) {
 			
diff --git a/gtk2_ardour/editor_route_list.cc b/gtk2_ardour/editor_route_list.cc
index 583b6ec8e7..d73c8176ea 100644
--- a/gtk2_ardour/editor_route_list.cc
+++ b/gtk2_ardour/editor_route_list.cc
@@ -114,7 +114,6 @@ 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 ();
 		redisplay_route_list ();
 	}