more work on patch change redisplay.

- fixes just-introduced undo crash.

gtk2_ardour/midi_region_view.cc

@@ -1302,7 +1302,9 @@ MidiRegionView::display_patch_changes_on_channel (uint8_t channel, bool active_c
 		if ((p = find_canvas_patch_change (*i)) != 0) {
 			framecnt_t region_frames = source_beats_to_region_frames ((*i)->time());
 			const double x = trackview.editor().sample_to_pixel (region_frames);
+			const string patch_name = instrument_info().get_patch_name ((*i)->bank(), (*i)->program(), channel);
 			p->canvas_item()->set_position (ArdourCanvas::Duple (x, 1.0));
+			p->flag()->set_text (patch_name);
 		} else {
 			const string patch_name = instrument_info().get_patch_name ((*i)->bank(), (*i)->program(), channel);
 			add_canvas_patch_change (*i, patch_name, active_channel);
@@ -1984,8 +1986,6 @@ MidiRegionView::change_patch_change (PatchChange& pc, const MIDI::Name::PatchPri
 	string name = _("alter patch change");
 	trackview.editor().begin_reversible_command (name);
 
-	remove_canvas_patch_change (&pc);
-
 	MidiModel::PatchChangeDiffCommand* c = _model->new_patch_change_diff_command (name);
 
 	if (pc.patch()->program() != new_patch.program()) {
@@ -2000,6 +2000,7 @@ MidiRegionView::change_patch_change (PatchChange& pc, const MIDI::Name::PatchPri
 	_model->apply_command (*trackview.session(), c);
 	trackview.editor().commit_reversible_command ();
 
+	remove_canvas_patch_change (&pc);
 	display_patch_changes ();
 }
 
@@ -2010,13 +2011,6 @@ MidiRegionView::change_patch_change (MidiModel::PatchChangePtr old_change, const
 	trackview.editor().begin_reversible_command (name);
 	MidiModel::PatchChangeDiffCommand* c = _model->new_patch_change_diff_command (name);
 
-	for (PatchChanges::iterator x = _patch_changes.begin(); x != _patch_changes.end(); ++x) {
-		if ((*x)->patch() == old_change) {
-			_patch_changes.erase (x);
-			break;
-		}
-	}	
-
 	if (old_change->time() != new_change.time()) {
 		c->change_time (old_change, new_change.time());
 	}
@@ -2036,6 +2030,13 @@ MidiRegionView::change_patch_change (MidiModel::PatchChangePtr old_change, const
 	_model->apply_command (*trackview.session(), c);
 	trackview.editor().commit_reversible_command ();
 
+	for (PatchChanges::iterator x = _patch_changes.begin(); x != _patch_changes.end(); ++x) {
+		if ((*x)->patch() == old_change) {
+			_patch_changes.erase (x);
+			break;
+		}
+	}
+
 	display_patch_changes ();
 }
 
@@ -2083,13 +2084,12 @@ MidiRegionView::delete_patch_change (PatchChange* pc)
 {
 	trackview.editor().begin_reversible_command (_("delete patch change"));
 
-	remove_canvas_patch_change (pc);
-
 	MidiModel::PatchChangeDiffCommand* c = _model->new_patch_change_diff_command (_("delete patch change"));
 	c->remove (pc->patch ());
 	_model->apply_command (*trackview.session(), c);
 	trackview.editor().commit_reversible_command ();
 
+	remove_canvas_patch_change (pc);
 	display_patch_changes ();
 }
 

gtk2_ardour/patch_change.h

@@ -59,6 +59,7 @@ public:
 	ARDOUR::MidiModel::PatchChangePtr patch()       const { return _patch; }
 	ArdourCanvas::Item*               canvas_item() const { return _flag; }
 	ArdourCanvas::Item&               item()        const { return *_flag; }
+	ArdourCanvas::Flag*               flag()        const { return _flag; }
 
 private:
 	bool event_handler (GdkEvent *);

libs/canvas/flag.cc

@@ -74,6 +74,8 @@ Flag::set_text (string const & text)
 {
 	if (text.empty ()) {
 		_text->set (" ");
+	} else if (text == _text->text()) {
+		return;
 	} else {
 		_text->set (text);
 	}