From 71ff8ba3e070f8b9311f3d12a522576a3cc5fc40 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Mon, 24 Nov 2025 11:22:50 -0700
Subject: [PATCH] refactor horizontal scrolling to use same code/modifiers in
 Editor and PianorollMidiView

---
 gtk2_ardour/editing_context.cc     | 47 ++++++++++++++++++++++++++++++
 gtk2_ardour/editing_context.h      |  5 ++++
 gtk2_ardour/editor.h               |  6 ----
 gtk2_ardour/editor_ops.cc          | 47 ------------------------------
 gtk2_ardour/pianoroll_midi_view.cc | 24 ++++++++++-----
 5 files changed, 69 insertions(+), 60 deletions(-)

diff --git a/gtk2_ardour/editing_context.cc b/gtk2_ardour/editing_context.cc
index 053d17de77..2afa6480c3 100644
--- a/gtk2_ardour/editing_context.cc
+++ b/gtk2_ardour/editing_context.cc
@@ -3918,3 +3918,50 @@ EditingContext::set_minsec_ruler_scale (samplepos_t lower, samplepos_t upper)
 		minsec_ruler_scale = minsec_show_many_hours;
 	}
 }
+
+void
+EditingContext::scroll_left_step ()
+{
+	samplepos_t xdelta = (current_page_samples() / 8);
+
+	if (_leftmost_sample > xdelta) {
+		reset_x_origin (_leftmost_sample - xdelta);
+	} else {
+		reset_x_origin (0);
+	}
+}
+
+
+void
+EditingContext::scroll_right_step ()
+{
+	samplepos_t xdelta = (current_page_samples() / 8);
+
+	if (max_samplepos - xdelta > _leftmost_sample) {
+		reset_x_origin (_leftmost_sample + xdelta);
+	} else {
+		reset_x_origin (max_samplepos - current_page_samples());
+	}
+}
+
+void
+EditingContext::scroll_left_half_page ()
+{
+	samplepos_t xdelta = (current_page_samples() / 2);
+	if (_leftmost_sample > xdelta) {
+		reset_x_origin (_leftmost_sample - xdelta);
+	} else {
+		reset_x_origin (0);
+	}
+}
+
+void
+EditingContext::scroll_right_half_page ()
+{
+	samplepos_t xdelta = (current_page_samples() / 2);
+	if (max_samplepos - xdelta > _leftmost_sample) {
+		reset_x_origin (_leftmost_sample + xdelta);
+	} else {
+		reset_x_origin (max_samplepos - current_page_samples());
+	}
+}
diff --git a/gtk2_ardour/editing_context.h b/gtk2_ardour/editing_context.h
index 2a4fbcbece..4a983dc1ab 100644
--- a/gtk2_ardour/editing_context.h
+++ b/gtk2_ardour/editing_context.h
@@ -123,6 +123,11 @@ class EditingContext : public ARDOUR::SessionHandlePtr, public AxisViewProvider,
 	virtual void stop_canvas_autoscroll () = 0;
 	virtual bool autoscroll_active() const = 0;
 
+	void scroll_left_step ();
+	void scroll_right_step ();
+	void scroll_left_half_page ();
+	void scroll_right_half_page ();
+
 	virtual void redisplay_grid (bool immediate_redraw) = 0;
 	virtual Temporal::timecnt_t get_nudge_distance (Temporal::timepos_t const & pos, Temporal::timecnt_t& next) const = 0;
 
diff --git a/gtk2_ardour/editor.h b/gtk2_ardour/editor.h
index ade2285441..747f18b1b5 100644
--- a/gtk2_ardour/editor.h
+++ b/gtk2_ardour/editor.h
@@ -344,12 +344,6 @@ public:
 	bool scroll_up_one_track (bool skip_child_views = false);
 	bool scroll_down_one_track (bool skip_child_views = false);
 
-	void scroll_left_step ();
-	void scroll_right_step ();
-
-	void scroll_left_half_page ();
-	void scroll_right_half_page ();
-
 	void select_topmost_track ();
 
 	void cleanup_regions ();
diff --git a/gtk2_ardour/editor_ops.cc b/gtk2_ardour/editor_ops.cc
index c23ff0ff69..6f2f8e58b8 100644
--- a/gtk2_ardour/editor_ops.cc
+++ b/gtk2_ardour/editor_ops.cc
@@ -1766,53 +1766,6 @@ Editor::scroll_up_one_track (bool skip_child_views)
 	return false;
 }
 
-void
-Editor::scroll_left_step ()
-{
-	samplepos_t xdelta = (current_page_samples() / 8);
-
-	if (_leftmost_sample > xdelta) {
-		reset_x_origin (_leftmost_sample - xdelta);
-	} else {
-		reset_x_origin (0);
-	}
-}
-
-
-void
-Editor::scroll_right_step ()
-{
-	samplepos_t xdelta = (current_page_samples() / 8);
-
-	if (max_samplepos - xdelta > _leftmost_sample) {
-		reset_x_origin (_leftmost_sample + xdelta);
-	} else {
-		reset_x_origin (max_samplepos - current_page_samples());
-	}
-}
-
-void
-Editor::scroll_left_half_page ()
-{
-	samplepos_t xdelta = (current_page_samples() / 2);
-	if (_leftmost_sample > xdelta) {
-		reset_x_origin (_leftmost_sample - xdelta);
-	} else {
-		reset_x_origin (0);
-	}
-}
-
-void
-Editor::scroll_right_half_page ()
-{
-	samplepos_t xdelta = (current_page_samples() / 2);
-	if (max_samplepos - xdelta > _leftmost_sample) {
-		reset_x_origin (_leftmost_sample + xdelta);
-	} else {
-		reset_x_origin (max_samplepos - current_page_samples());
-	}
-}
-
 /* ZOOM */
 
 void
diff --git a/gtk2_ardour/pianoroll_midi_view.cc b/gtk2_ardour/pianoroll_midi_view.cc
index ad92fd95a7..d7a203b074 100644
--- a/gtk2_ardour/pianoroll_midi_view.cc
+++ b/gtk2_ardour/pianoroll_midi_view.cc
@@ -196,18 +196,28 @@ PianorollMidiView::scroll (GdkEventScroll* ev)
 		return false;
 	}
 
-	if (Keyboard::modifier_state_equals (ev->state, Keyboard::PrimaryModifier)) {
-
-		switch (ev->direction) {
-		case GDK_SCROLL_UP:
+	switch (ev->direction) {
+	case GDK_SCROLL_UP:
+		if (Keyboard::modifier_state_equals (ev->state, Keyboard::ScrollHorizontalModifier)) {
+			_editing_context.scroll_left_step ();
+			return true;
+		}
+		if (Keyboard::modifier_state_equals (ev->state, Keyboard::PrimaryModifier)) {
 			_editing_context.reset_zoom (_editing_context.get_current_zoom() / 2);
 			return true;
-		case GDK_SCROLL_DOWN:
+		}
+	case GDK_SCROLL_DOWN:
+		if (Keyboard::modifier_state_equals (ev->state, Keyboard::ScrollHorizontalModifier)) {
+			_editing_context.scroll_right_step ();
+			return true;
+		}
+		if (Keyboard::modifier_state_equals (ev->state, Keyboard::PrimaryModifier)) {
 			_editing_context.reset_zoom (_editing_context.get_current_zoom() * 2);
 			return true;
-		default:
-			break;
 		}
+		break;
+	default:
+		break;
 	}
 
 	return MidiView::scroll (ev);