From 6e28c43ceff7b0a5ca0d41c803a95d465755e1b2 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Sun, 28 Jan 2024 14:51:15 +0100
Subject: [PATCH] Don't show plugin preset UI for plugins without controls

Notably Ardour's General MIDI Synth has no presets, but
users try.

This also prevents presets of plugins with internal state,
but no user visible controls. But those usually have a plugin
provided presets.
---
 libs/ardour/ardour/plugin_insert.h |  1 +
 libs/ardour/plugin_insert.cc       | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/libs/ardour/ardour/plugin_insert.h b/libs/ardour/ardour/plugin_insert.h
index 883f3ca364..57d11d00c3 100644
--- a/libs/ardour/ardour/plugin_insert.h
+++ b/libs/ardour/ardour/plugin_insert.h
@@ -192,6 +192,7 @@ public:
 	bool has_no_audio_inputs() const;
 
 	bool is_instrument () const;
+	bool has_automatables () const;
 
 	bool has_output_presets (
 			ChanCount in = ChanCount (DataType::MIDI, 1),
diff --git a/libs/ardour/plugin_insert.cc b/libs/ardour/plugin_insert.cc
index ed14a145d1..e794a58dc4 100644
--- a/libs/ardour/plugin_insert.cc
+++ b/libs/ardour/plugin_insert.cc
@@ -462,13 +462,43 @@ PluginInsert::is_instrument() const
 	return (pip->is_instrument ());
 }
 
+bool
+PluginInsert::has_automatables () const
+{
+	for (size_t i = 0; i < plugin(0)->parameter_count (); ++i) {
+		if (!plugin(0)->parameter_is_control (i)) {
+			continue;
+		}
+		if (!plugin(0)->parameter_is_input (i)) {
+			continue;
+		}
+		std::shared_ptr<AutomationControl const> ac = automation_control (Evoral::Parameter (PluginAutomation, 0, i));
+		if (!ac) {
+			continue;
+		}
+		if (ac->flags () & Controllable::HiddenControl) {
+			continue;
+		}
+		if (ac->flags () & Controllable::NotAutomatable) {
+			continue;
+		}
+		return true;
+		break;
+	}
+	return false;
+}
+
 PlugInsertBase::UIElements
 PluginInsert::ui_elements () const
 {
 	if (owner () == (ARDOUR::SessionObject*)(_session.the_auditioner().get())) {
 		return NoGUIToolbar;
 	}
+
 	UIElements rv = AllUIElements;
+	if (!has_automatables ()) {
+		rv = static_cast<PlugInsertBase::UIElements> (static_cast <std::uint8_t>(rv) & ~static_cast<std::uint8_t> (PlugInsertBase::PluginPreset));
+	}
 	if (!is_instrument()) {
 		rv = static_cast<PlugInsertBase::UIElements> (static_cast <std::uint8_t>(rv) & ~static_cast<std::uint8_t> (PlugInsertBase::MIDIKeyboard));
 	}