From 47e635b689f9f2343c8a103d547560a28971908b Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Fri, 28 Feb 2025 11:57:16 -0700
Subject: [PATCH] initial work on displaying non-selected-channel notes in
 pianoroll

---
 gtk2_ardour/midi_view.cc | 49 ++++++++++++++++++++++++++++++++++++----
 gtk2_ardour/midi_view.h  |  7 ++++++
 gtk2_ardour/pianoroll.cc |  1 +
 3 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/gtk2_ardour/midi_view.cc b/gtk2_ardour/midi_view.cc
index d4fa1be699..1f441f7551 100644
--- a/gtk2_ardour/midi_view.cc
+++ b/gtk2_ardour/midi_view.cc
@@ -126,6 +126,7 @@ MidiView::MidiView (std::shared_ptr<MidiTrack> mt,
 	, _show_source (false)
 	, selection_drag (nullptr)
 	, draw_drag (nullptr)
+	, _visible_channel (-1)
 	, _optimization_iterator (_events.end())
 	, _list_editor (nullptr)
 	, _no_sound_notes (false)
@@ -161,6 +162,7 @@ MidiView::MidiView (MidiView const & other)
 	, _show_source (false)
 	, selection_drag (nullptr)
 	, draw_drag (nullptr)
+	, _visible_channel (-1)
 	, _optimization_iterator (_events.end())
 	, _list_editor (0)
 	, _no_sound_notes (false)
@@ -1281,6 +1283,26 @@ MidiView::view_changed()
 	size_end_rect ();
 }
 
+void
+MidiView::visible_channel_changed ()
+{
+	if (!display_is_enabled()) {
+		return;
+	}
+
+	if (!_model) {
+		return;
+	}
+
+	for (auto & [note, gui] : _events) {
+
+		if (gui->item()->visible()) {
+			color_note (gui, note->channel());
+			gui->set_ignore_events (note->channel() != _visible_channel);
+		}
+	}
+}
+
 void
 MidiView::display_patch_changes ()
 {
@@ -1767,11 +1789,22 @@ MidiView::update_sustained (Note* ev)
 		ev->set_outline_all ();
 	}
 
-	// Update color in case velocity has changed
-	const uint32_t base_col = ev->base_color();
-	ev->set_fill_color (base_col);
-	ev->set_outline_color (ev->calculate_outline(base_col, ev->selected()));
 
+	color_note (ev, note->channel());
+}
+
+void
+MidiView::color_note (NoteBase* ev, int channel)
+{
+	// Update color in case velocity has changed
+	uint32_t base_color = ev->base_color();
+
+	if (channel != _visible_channel) {
+		base_color = Gtkmm2ext::change_alpha (base_color, 0.2);
+	}
+
+	ev->set_fill_color (base_color);
+	ev->set_outline_color (ev->calculate_outline (base_color, ev->selected()));
 }
 
 void
@@ -5218,6 +5251,13 @@ MidiView::set_visibility_note_range (MidiViewBackground::VisibleNoteRange nvr, b
 	_midi_context.set_note_visibility_range_style (nvr);
 }
 
+void
+MidiView::set_visible_channel (int chn)
+{
+	_visible_channel = chn;
+	visible_channel_changed ();
+}
+
 void
 StartBoundaryRect::render  (ArdourCanvas::Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 {
@@ -5313,3 +5353,4 @@ EndBoundaryRect::compute_bounding_box() const
 	const double radius = 10. * scale;
 	_bounding_box = _bounding_box.expand (0., 0., 0., radius + _outline_width);
 }
+
diff --git a/gtk2_ardour/midi_view.h b/gtk2_ardour/midi_view.h
index e4b1af436d..29e6364008 100644
--- a/gtk2_ardour/midi_view.h
+++ b/gtk2_ardour/midi_view.h
@@ -381,6 +381,9 @@ class MidiView : public virtual sigc::trackable, public LineMerger
 
 	virtual bool midi_canvas_group_event(GdkEvent* ev);
 
+	int visible_channel() const { return _visible_channel; }
+	void set_visible_channel (int);
+
   protected:
 	void init (std::shared_ptr<ARDOUR::MidiTrack>);
 	virtual void region_resized (const PBD::PropertyChange&);
@@ -540,6 +543,7 @@ class MidiView : public virtual sigc::trackable, public LineMerger
 	bool                                 _show_source;
 	Drag*                                 selection_drag;
 	Drag*                                 draw_drag;
+	int                                  _visible_channel;
 
 	/** Currently selected NoteBase objects */
 	Selection _selection;
@@ -687,6 +691,9 @@ class MidiView : public virtual sigc::trackable, public LineMerger
 	bool end_boundary_event (GdkEvent*);
 
 	virtual void add_control_points_to_selection (Temporal::timepos_t const &, Temporal::timepos_t const &, double y0, double y1) {}
+
+	void color_note (NoteBase*, int channel);
+	void visible_channel_changed ();
 };
 
 
diff --git a/gtk2_ardour/pianoroll.cc b/gtk2_ardour/pianoroll.cc
index c5a4d095d8..4548d53521 100644
--- a/gtk2_ardour/pianoroll.cc
+++ b/gtk2_ardour/pianoroll.cc
@@ -440,6 +440,7 @@ Pianoroll::set_visible_channel (int n)
 	rebuild_parameter_button_map ();
 
 	if (view) {
+		view->set_visible_channel (n);
 		view->swap_automation_channel (n);
 	}
 }