NiftyBasicGame.java

package de.lessvoid.nifty.slick2d;

import de.lessvoid.nifty.Nifty;
import org.newdawn.slick.GameContainer;
import org.newdawn.slick.Graphics;
import org.newdawn.slick.SlickException;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

/**
 * This "game" implements all the features of a Slick BasicGame with the sole purpose of displaying a NiftyGUI on top of
 * it.
 *
 * @author Martin Karing <nitram@illarion.org>
 */
public abstract class NiftyBasicGame extends NiftyOverlayBasicGame {
  /**
   * The screen that is called when preparing the GUI.
   */
  @Nullable
  private final String startScreen;

  /**
   * Create a new game that displays the Nifty GUI and set the title that is shown.
   *
   * @param gameTitle the title of the game
   */
  protected NiftyBasicGame(@Nonnull final String gameTitle) {
    this(gameTitle, "start");
  }

  /**
   * Create a new game that displays the Nifty GUI and set the title and the start screen for this game.
   *
   * @param gameTitle        the title of the game
   * @param niftyStartScreen the name of the screen that should be called first
   */
  protected NiftyBasicGame(@Nonnull final String gameTitle, @Nullable final String niftyStartScreen) {
    super(gameTitle);
    startScreen = niftyStartScreen;
  }

  /**
   * When initializing the game its only needed to prepare the GUI for display.
   */
  @Override
  protected void initGameAndGUI(@Nonnull final GameContainer container) {
    initNifty(container);
    if (startScreen != null) {
      Nifty nifty = getNifty();
      if (nifty == null) {
        throw new IllegalStateException("Nifty is not initialized, but it should be.");
      }
      nifty.gotoScreen(startScreen);
    }
  }

  /**
   * Rendering the GUI only requires that the display is cleared before rendering the screen.
   */
  @Override
  protected void renderGame(@Nonnull final GameContainer container, @Nonnull final Graphics g) {
    g.clear();
  }

  /**
   * Updating the game is not needed in this implementation as only the GUI is displayed.
   */
  @Override
  protected void updateGame(@Nonnull final GameContainer container, final int delta) throws SlickException {
    // nothing to do
  }
}