self-updating SongMeterDisplay class

stepmania/src/MeterDisplay.cpp

@@ -1,6 +1,8 @@
 #include "global.h"
 #include "MeterDisplay.h"
 #include "RageUtil.h"
+#include "GameState.h"
+#include "song.h"
 
 
 MeterDisplay::MeterDisplay()
@@ -31,6 +33,18 @@ void MeterDisplay::SetPercent( float fPercent )
 	m_sprTip->SetX( SCALE(fPercent, 0.f, 1.f, -m_fStreamWidth/2, m_fStreamWidth/2) );
 }
 
+void SongMeterDisplay::Update( float fDeltaTime )
+{
+	float fSongStartSeconds = GAMESTATE->m_pCurSong->m_Timing.GetElapsedTimeFromBeat( GAMESTATE->m_pCurSong->m_fFirstBeat );
+	float fSongEndSeconds = GAMESTATE->m_pCurSong->m_Timing.GetElapsedTimeFromBeat( GAMESTATE->m_pCurSong->m_fLastBeat );
+	float fPercentPositionSong = SCALE( GAMESTATE->m_fMusicSeconds, fSongStartSeconds, fSongEndSeconds, 0.0f, 1.0f );
+	CLAMP( fPercentPositionSong, 0, 1 );
+	
+	SetPercent( fPercentPositionSong );
+
+	MeterDisplay::Update( fDeltaTime );
+}
+
 /*
  * (c) 2003-2004 Chris Danford
  * All rights reserved.

stepmania/src/MeterDisplay.h

@@ -21,6 +21,12 @@ private:
 	AutoActor  m_sprTip;
 };
 
+class SongMeterDisplay: public MeterDisplay 
+{
+public:
+	virtual void Update( float fDeltaTime );
+};
+
 #endif
 
 /*

stepmania/src/ScreenGameplay.cpp

@@ -1551,14 +1551,6 @@ void ScreenGameplay::Update( float fDeltaTime )
 	// update lights
 	//
 	UpdateLights();
-	//
-	// update song position meter
-	//
-	float fSongStartSeconds = GAMESTATE->m_pCurSong->m_Timing.GetElapsedTimeFromBeat( GAMESTATE->m_pCurSong->m_fFirstBeat );
-	float fSongEndSeconds = GAMESTATE->m_pCurSong->m_Timing.GetElapsedTimeFromBeat( GAMESTATE->m_pCurSong->m_fLastBeat );
-	float fPercentPositionSong = SCALE( GAMESTATE->m_fMusicSeconds, fSongStartSeconds, fSongEndSeconds, 0.0f, 1.0f );
-	CLAMP( fPercentPositionSong, 0, 1 );
-	m_meterSongPosition.SetPercent( fPercentPositionSong );
 
 	if( NSMAN->useSMserver )
 	{

stepmania/src/ScreenGameplay.h

@@ -134,7 +134,7 @@ protected:
 
 	BitmapText			m_textSurviveTime;	// used in extra stage
 	BitmapText			m_textSongTitle;
-	MeterDisplay		m_meterSongPosition;
+	SongMeterDisplay		m_meterSongPosition;
 
 	Player				m_Player[NUM_PLAYERS];