Add love.joystick.setBackgroundEvents(bool) and hasBackgroundEvents.

Resolves #2270.

src/modules/joystick/JoystickModule.h

@@ -70,6 +70,16 @@ public:
 	 **/
 	virtual int getJoystickCount() const = 0;
 
+	/**
+	 * Sets whether joystick input events are produced while the app doesn't have focus.
+	 **/
+	virtual void setBackgroundEvents(bool enable) = 0;
+
+	/**
+	 * Gets whether joystick input events are produced while the app doesn't have focus.
+	 **/
+	virtual bool hasBackgroundEvents() const = 0;
+
 	/**
 	 * Sets the virtual Gamepad mapping for a joystick input value for all
 	 * joystick devices with the specified joystick product GUID.

src/modules/joystick/sdl/JoystickModule.cpp

@@ -95,6 +95,16 @@ int JoystickModule::getJoystickCount() const
 	return (int) activeSticks.size();
 }
 
+void JoystickModule::setBackgroundEvents(bool enable)
+{
+	SDL_SetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS, enable ? "1" : "0");
+}
+
+bool JoystickModule::hasBackgroundEvents() const
+{
+	return SDL_GetHintBoolean(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS, false);
+}
+
 love::joystick::Joystick *JoystickModule::getJoystickFromID(int instanceid)
 {
 	for (auto stick : activeSticks)

src/modules/joystick/sdl/JoystickModule.h

@@ -52,6 +52,9 @@ public:
 	int getIndex(const love::joystick::Joystick *joystick) override;
 	int getJoystickCount() const override;
 
+	void setBackgroundEvents(bool enable) override;
+	bool hasBackgroundEvents() const override;
+
 	bool setGamepadMapping(const std::string &guid, Joystick::GamepadInput gpinput, Joystick::JoystickInput joyinput) override;
 	void loadGamepadMappings(const std::string &mappings) override;
 

src/modules/joystick/wrap_JoystickModule.cpp

@@ -65,6 +65,18 @@ int w_getJoystickCount(lua_State *L)
 	return 1;
 }
 
+int w_setBackgroundEvents(lua_State *L)
+{
+	instance()->setBackgroundEvents(luax_checkboolean(L, 1));
+	return 0;
+}
+
+int w_hasBackgroundEvents(lua_State *L)
+{
+	luax_pushboolean(L, instance()->hasBackgroundEvents());
+	return 1;
+}
+
 int w_setGamepadMapping(lua_State *L)
 {
 	// Only accept a GUID string. We don't accept a Joystick object because
@@ -176,6 +188,8 @@ static const luaL_Reg functions[] =
 {
 	{ "getJoysticks", w_getJoysticks },
 	{ "getJoystickCount", w_getJoystickCount },
+	{ "setBackgroundEvents", w_setBackgroundEvents },
+	{ "hasBackgroundEvents", w_hasBackgroundEvents },
 	{ "setGamepadMapping", w_setGamepadMapping },
 	{ "loadGamepadMappings", w_loadGamepadMappings },
 	{ "saveGamepadMappings", w_saveGamepadMappings },