If a screen is already prepared, don't reload it in PrepareScreen.

Prepare backgrounds, too.
Disallow calling SetNewScreen from a screen ctor/Init; it complicates things.
When loading a new screen (through LoadDelayedScreen), load the
screen with PrepareScreen, to reduce code paths.

stepmania/src/ScreenManager.cpp

@@ -296,19 +296,45 @@ void ScreenManager::PrepareScreen( const CString &sScreenName )
 {
 	m_bZeroNextUpdate = true;
 
-	// Delete previously prepared versions of the screen.
+	// If the screen is already prepared, stop.
 	for( int i = (int)m_vPreparedScreens.size()-1; i>=0; i-- )
 	{
 		Screen *&pScreen = m_vPreparedScreens[i];
 		if( pScreen->m_sName == sScreenName )
+			return;
+	}
+
+	Screen* pNewScreen = MakeNewScreen(sScreenName);
+	m_vPreparedScreens.push_back( pNewScreen );
+
+	/* Don't delete previously prepared versions of the screen's background,
+	 * and only prepare it if it's different than the current background
+	 * and not already loaded. */
+	CString sNewBGA;
+	if( pNewScreen->UsesBackground() )
+		sNewBGA = THEME->GetPathB(sScreenName,"background");
+
+	if( !sNewBGA.empty() && sNewBGA != m_pSharedBGA->GetName() )
 	{
-			SAFE_DELETE( pScreen );
+		Actor *pNewBGA = NULL;
-			m_vPreparedScreens.erase( m_vPreparedScreens.begin()+i );
+		FOREACH( Actor*, m_vPreparedBackgrounds, a )
+		{
+			if( (*a)->m_sName == sNewBGA )
+			{
+				pNewBGA = *a;
 				break;
 			}
 		}
 
-	m_vPreparedScreens.push_back( MakeNewScreen(sScreenName) );
+		// Create the new background before deleting the previous so that we keep
+		// any common textures loaded.
+		if( pNewBGA == NULL )
+		{
+			pNewBGA = ActorUtil::MakeActor( sNewBGA );
+			pNewBGA->SetName( sNewBGA );
+			m_vPreparedBackgrounds.push_back( pNewBGA );
+		}
+	}
 }
 
 void ScreenManager::DeletePreparedScreens()
@@ -318,6 +344,9 @@ void ScreenManager::DeletePreparedScreens()
 	FOREACH( Screen*, m_vPreparedScreens, s )
 		SAFE_DELETE( *s );
 	m_vPreparedScreens.clear();
+	FOREACH( Actor*, m_vPreparedBackgrounds, a )
+		SAFE_DELETE( *a );
+	m_vPreparedBackgrounds.clear();
 
 	TEXTUREMAN->DeleteCachedTextures();
 }
@@ -370,14 +399,15 @@ void ScreenManager::LoadDelayedScreen()
 		EmptyDeleteQueue();
 	}
 
-retry:
 	CString sScreenName = m_sDelayedScreen;
 	m_sDelayedScreen = "";
 
 
+	// Load the screen, if it's not already prepared.
+	PrepareScreen( sScreenName );
+
 	//
-	// Search prepped screens to see if we already have this screen available.
+	// Find the prepped screen.
-	// If not prepped, then make it.
 	//
 	Screen* pNewScreen = NULL;
 	FOREACH( Screen*, m_vPreparedScreens, s )
@@ -389,32 +419,43 @@ retry:
 			break;
 		}
 	}
-	if( pNewScreen == NULL )
+	ASSERT( pNewScreen != NULL );
-		pNewScreen = MakeNewScreen(sScreenName);
 
 	if( m_sDelayedScreen != "" )
 	{
-		// While constructing this Screen, it's constructor called
+		// While constructing this Screen, its constructor called
 		// SetNewScreen again!  That SetNewScreen Command should
 		// override this older one.
-		SAFE_DELETE( pNewScreen );
+
-		goto retry;
+		// This is no longer allowed.  Instead, figure out which screen
+		// you really wanted in the first place with Lua, and don't waste
+		// time constructing an extra screen.
+
+		FAIL_M( ssprintf("%s, %s", sScreenName.c_str(), m_sDelayedScreen.c_str()) );
 	}
 	
-	// Load shared background
+	// Find the prepared shared background (if any), and activate it.
 	CString sNewBGA;
 	if( pNewScreen->UsesBackground() )
 		sNewBGA = THEME->GetPathB(sScreenName,"background");
 	if( sNewBGA != m_pSharedBGA->GetName() )
 	{
-		// Create the new background before deleting the previous so that we keep
+		Actor *pNewBGA = NULL;
-		// any common textures loaded.
-		Actor *pNewBGA;
 		if( sNewBGA.empty() )
 			pNewBGA = new Actor;
 		else
-			pNewBGA = ActorUtil::MakeActor( sNewBGA );
+		{
-		pNewBGA->SetName( sNewBGA );
+			FOREACH( Actor*, m_vPreparedBackgrounds, a )
+			{
+				if( (*a)->m_sName == sNewBGA )
+				{
+					pNewBGA = *a;
+					m_vPreparedBackgrounds.erase( a );
+					break;
+				}
+			}
+		}
+		ASSERT( pNewBGA != NULL );
 
 		SAFE_DELETE( m_pSharedBGA );
 		m_pSharedBGA = pNewBGA;

stepmania/src/ScreenManager.h

@@ -81,6 +81,7 @@ private:
 	CString				m_sDelayedScreen;
 	CString				m_sSystemMessage;
 	vector<Screen*>		m_vPreparedScreens;
+	vector<Actor*>		m_vPreparedBackgrounds;
 	vector<Screen*>		m_vScreensToDelete;
 	
 	// Set this to true anywhere we create of delete objects.  These