Add Lua binding to query plugin-presets and scalepoints

libs/ardour/ardour/lua_api.h

@@ -175,6 +175,13 @@ namespace ARDOUR { namespace LuaAPI {
 	 */
 	int plugin_automation (lua_State *lua);
 
+	/*
+	 * A convenience function to get a scale-points from a ParamaterDescriptor
+	 * @param p a ParameterDescriptor
+	 * @returns Lua Table with "name" -> value pairs
+	 */
+	int desc_scale_points (lua_State* p);
+
 	/**
 	 * A convenience function for colorspace HSL to RGB conversion.
 	 * All ranges are 0..1

libs/ardour/lua_api.cc

@@ -338,6 +338,28 @@ ARDOUR::LuaAPI::plugin_automation (lua_State *L)
 	return 3;
 }
 
+int
+ARDOUR::LuaAPI::desc_scale_points (lua_State *L)
+{
+	typedef ParameterDescriptor T;
+
+	int top = lua_gettop (L);
+	if (top < 1) {
+		return luaL_argerror (L, 1, "invalid number of arguments, :plugin_scale_points (ParameterDescriptor)");
+	}
+
+	T* const pd = luabridge::Userdata::get<T> (L, 1, false);
+	luabridge::LuaRef tbl (luabridge::newTable (L));
+
+	if (pd && pd->scale_points) {
+		for (ARDOUR::ScalePoints::const_iterator i = pd->scale_points->begin(); i != pd->scale_points->end(); ++i) {
+			tbl[i->first] = i->second;
+		}
+	}
+	luabridge::push (L, tbl);
+	return 1;
+}
+
 int
 ARDOUR::LuaAPI::sample_to_timecode (lua_State *L)
 {

libs/ardour/luabindings.cc

@@ -1571,6 +1571,7 @@ LuaBindings::common (lua_State* L)
 		.addFunction ("preset_by_label", &Plugin::preset_by_label)
 		.addFunction ("preset_by_uri", &Plugin::preset_by_uri)
 		.addFunction ("load_preset", &Plugin::load_preset)
+		.addFunction ("last_preset", &Plugin::last_preset)
 		.addFunction ("parameter_is_input", &Plugin::parameter_is_input)
 		.addFunction ("parameter_is_output", &Plugin::parameter_is_output)
 		.addFunction ("parameter_is_control", &Plugin::parameter_is_control)
@@ -2627,6 +2628,7 @@ LuaBindings::common (lua_State* L)
 		.addFunction ("reset_processor_to_default", ARDOUR::LuaAPI::reset_processor_to_default)
 		.addRefFunction ("get_processor_param", ARDOUR::LuaAPI::get_processor_param)
 		.addRefFunction ("get_plugin_insert_param", ARDOUR::LuaAPI::get_plugin_insert_param)
+		.addCFunction ("desc_scale_points", ARDOUR::LuaAPI::desc_scale_points)
 		.addCFunction ("plugin_automation", ARDOUR::LuaAPI::plugin_automation)
 		.addCFunction ("hsla_to_rgba", ARDOUR::LuaAPI::hsla_to_rgba)
 		.addCFunction ("color_to_rgba", ARDOUR::LuaAPI::color_to_rgba)

share/scripts/s_pluginutils.lua

@@ -7,7 +7,7 @@ function factory () return function ()
 	for p in ARDOUR.LuaAPI.list_plugins():iter() do
 		print (p.name, p.unique_id, p.type)
 		local psets = p:get_presets()
-		if not empty:empty() then
+		if not psets:empty() then
 			for pset in psets:iter() do
 				print (" - ", pset.label)
 			end
@@ -25,19 +25,36 @@ function factory () return function ()
 		end
 	end
 
-
 	-------------------------------------------------------------------------------
 	-- load a plugin preset
-	route = Session:get_remote_nth_route(2)
+	local route = Session:get_remote_nth_route(2)
 	assert (route)
 	-- to 4th plugin (from top), ardour starts counting at zero
-	plugin = route:nth_plugin(3):to_insert():plugin(0)
+	local plugin = route:nth_plugin(3):to_insert():plugin(0)
 	assert (not plugin:isnil())
-	ps = plugin:preset_by_label("cutbass") -- get preset by name
-	assert (ps)
-	print (ps.uri)
-	plugin:load_preset (ps)
+	local ps = plugin:preset_by_label("cutbass") -- get preset by name
+	if ps and ps.valid then
+		print (ps.uri)
+		plugin:load_preset (ps)
+	end
 
+	-- query preset
+	local lp = plugin:last_preset ()
+	print ("valid?", lp.valid, "Preset ID:", lp.uri, "Preset Name:", lp.label, "User Preset (not factory):", lp.user)
+
+	-- list preset of given plugin
+	if not psets:empty() then
+		for pset in psets:iter() do
+			print (" - ", pset.label, pset.uri)
+		end
+	end
+
+	-- print scale-points of a given plugin-parameter
+	local _, pd = plugin:get_parameter_descriptor (3, ARDOUR.ParameterDescriptor())
+	local sp = ARDOUR.LuaAPI.desc_scale_points (pd[2]);
+	for k, v in pairs(sp) do
+		print (k, v)
+	end
 
 	-------------------------------------------------------------------------------
 	-- add a LuaProcessor (here "Scope") to all tracks