simpler approach to letting overlay screens grab input

stepmania/src/Screen.cpp

@@ -105,6 +105,15 @@ void Screen::MenuBack(	PlayerNumber pn, const InputEventType type )
 		MenuBack(pn); 
 }
 
+/* ScreenManager sends input here first.  Overlay screens can use it to get a first
+ * pass at input.  Return true if the input was handled and should not be passed
+ * to lower screens, or false if not handled.  If true is returned, Input() will
+ * not be called, either.  Normal screens should not overload this function. */
+bool Screen::OverlayInput( const DeviceInput& DeviceI, const InputEventType type, const GameInput &GameI, const MenuInput &MenuI, const StyleInput &StyleI )
+{
+	return false;
+}
+
 void Screen::Input( const DeviceInput& DeviceI, const InputEventType type, const GameInput &GameI, const MenuInput &MenuI, const StyleInput &StyleI )
 {
 	/* Don't send release messages with the default handler. */

stepmania/src/Screen.h

@@ -30,6 +30,7 @@ public:
 	 * exist. */
 	virtual void Init() { }
 	virtual void Update( float fDeltaTime );
+	virtual bool OverlayInput( const DeviceInput& DeviceI, const InputEventType type, const GameInput &GameI, const MenuInput &MenuI, const StyleInput &StyleI );
 	virtual void Input( const DeviceInput& DeviceI, const InputEventType type, const GameInput &GameI, const MenuInput &MenuI, const StyleInput &StyleI );
 	virtual void HandleScreenMessage( const ScreenMessage SM );
 

stepmania/src/ScreenManager.cpp

@@ -247,13 +247,20 @@ void ScreenManager::Input( const DeviceInput& DeviceI, const InputEventType type
 //	LOG->Trace( "ScreenManager::Input( %d-%d, %d-%d, %d-%d, %d-%d )", 
 //		DeviceI.device, DeviceI.button, GameI.controller, GameI.button, MenuI.player, MenuI.button, StyleI.player, StyleI.col );
 
-	// pass input only to topmost state
-	Screen *pInputFocus = NULL;
-	if( !m_ScreenStack.empty() )
-		pInputFocus = m_ScreenStack.back();
+	// First, give overlay screens a shot at the input.  If OverlayInput returns
+	// true, it handled the input, so don't pass it further.  OverlayInput could
+	// probably be merged with Input, but that would require changing all Input
+	// overloads, as well as all MenuLeft, etc. overloads.
+	for( unsigned i = 0; i < m_OverlayScreens.size(); ++i )
+	{
+		Screen *pScreen = m_OverlayScreens[i];
+		if( pScreen->OverlayInput(DeviceI, type, GameI, MenuI, StyleI) )
+			return;
+	}
 
-	if( pInputFocus != NULL )
-		pInputFocus->Input( DeviceI, type, GameI, MenuI, StyleI );
+	// pass input to topmost state
+	if( !m_ScreenStack.empty() )
+		m_ScreenStack.back()->Input( DeviceI, type, GameI, MenuI, StyleI );
 }
 
 /* Just create a new screen; don't do any associated cleanup. */