/// <summary>
/// Replaces the current topmost screen with the one provided, removing the previous one from the internal screens stack. This does not call LoadContent() or UnloadContent() on either screen; use this to store a screen in "standby" for returning to later.
/// </summary>
/// <param name="screen">The new screen to add. It must not already be in the screens stack.</param>
/// <param name="previousScreen">If successful, this will contain the previous topmost screen (or null if there was no screens).</param>
/// <returns>True if the swap was successful.</returns>
public bool SwapScreen(GameScreen screen, out GameScreen previousScreen)
{
previousScreen = null;
//if the new screen is invalid, return false;
if (screen == null || screens.Contains(screen))
return false;
//remove and store old screen
if (screens.Count > 0)
{
previousScreen = screens[screens.Count - 1];
previousScreen.Removed();
screens.RemoveAt(screens.Count - 1);
screensToUpdate.Remove(previousScreen);
}
//push new one
screens.Add(screen);
screen.Added();
return true;
}
/// <summary>
/// Removes a screen from the screen manager. You should normally
/// use GameScreen.ExitScreen instead of calling this directly, so
/// the screen can gradually transition off rather than just being
/// instantly removed.
/// </summary>
public void RemoveScreen(GameScreen screen)
{
if (screen == null || !screens.Contains(screen))
screen.Removed();
// If we have a graphics device, tell the screen to unload content.
if (isInitialized)
screen.UnloadContent();
screens.Remove(screen);
screensToUpdate.Remove(screen);
}