move color_to_rgba to LuaAPI for consistency

3 files changed, 43 insertions, 0 deletions

diff --git a/libs/ardour/ardour/lua_api.h b/libs/ardour/ardour/lua_api.h
index c5ce0986ce..cbbe750164 100644
--- a/libs/ardour/ardour/lua_api.h
+++ b/libs/ardour/ardour/lua_api.h
@@ -167,6 +167,22 @@ namespace ARDOUR { namespace LuaAPI {
 	int hsla_to_rgba (lua_State *lua);
 
 	/**
+	 * A convenience function to expand RGBA parameters from an integer
+	 *
+	 * convert a Canvas::Color (uint32_t 0xRRGGBBAA) into
+	 * double RGBA values which can be passed as parameters to
+	 * Cairo::Context::set_source_rgba
+	 *
+	 * Example:
+	 * @code
+	 * local r, g, b, a = ARDOUR.LuaAPI.color_to_rgba (0x88aa44ff)
+	 * cairo_ctx:set_source_rgba (ARDOUR.LuaAPI.color_to_rgba (0x11336699)
+	 * @endcode
+	 * @returns 4 parameters: red, green, blue, alpha (in range 0..1)
+	 */
+	int color_to_rgba (lua_State *lua);
+
+	/**
 	 * Creates a filename from a series of elements using the correct separator for filenames.
 	 *
 	 * No attempt is made to force the resulting filename to be an absolute path.
diff --git a/libs/ardour/lua_api.cc b/libs/ardour/lua_api.cc
index 080ba12841..7da81b2965 100644
--- a/libs/ardour/lua_api.cc
+++ b/libs/ardour/lua_api.cc
@@ -503,6 +503,32 @@ ARDOUR::LuaAPI::hsla_to_rgba (lua_State *L)
 }
 
 int
+ARDOUR::LuaAPI::color_to_rgba (lua_State *L)
+{
+	int top = lua_gettop (L);
+	if (top < 1) {
+		return luaL_argerror (L, 1, "invalid number of arguments, color_to_rgba (uint32_t)");
+	}
+	uint32_t color = luabridge::Stack<uint32_t>::get (L, 1);
+	double r, g, b, a;
+
+	/* libardour is no user of libcanvas, otherwise
+	 * we could just call
+	 * ArdourCanvas::color_to_rgba (color, r, g, b, a);
+	 */
+	r = ((color >> 24) & 0xff) / 255.0;
+	g = ((color >> 16) & 0xff) / 255.0;
+	b = ((color >>  8) & 0xff) / 255.0;
+	a = ((color >>  0) & 0xff) / 255.0;
+
+	luabridge::Stack <double>::push (L, r);
+	luabridge::Stack <double>::push (L, g);
+	luabridge::Stack <double>::push (L, b);
+	luabridge::Stack <double>::push (L, a);
+	return 4;
+}
+
+int
 ARDOUR::LuaAPI::build_filename (lua_State *L)
 {
 	std::vector<std::string> elem;
diff --git a/libs/ardour/luabindings.cc b/libs/ardour/luabindings.cc
index 586d3fd99c..51cd397efd 100644
--- a/libs/ardour/luabindings.cc
+++ b/libs/ardour/luabindings.cc
@@ -1930,6 +1930,7 @@ LuaBindings::common (lua_State* L)
 		.addRefFunction ("get_plugin_insert_param", ARDOUR::LuaAPI::get_plugin_insert_param)
 		.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)
 		.addFunction ("usleep", Glib::usleep)
 		.addCFunction ("build_filename", ARDOUR::LuaAPI::build_filename)
 		.addFunction ("new_noteptr", ARDOUR::LuaAPI::new_noteptr)