調用dispatchKeyEvent來執行形狀翻譯

Question

我正在開發一個使用JavaFX的簡單Pong克隆，並且我在移動槳時遇到了困難。我想爲此使用KeyEventDispatcher，並在我的AnimationTimer循環中檢查按鍵。

我Main類：

public class Main extends Application { 

    private Player m_pUser; 

    @Override 
    public void start(Stage primaryStage) throws Exception{ 

     Group root = new Group(); 
     Scene scene = new Scene(root, 500, 300); 
     ObservableList list = root.getChildren(); 

     KeyPressedChecker kpc = new KeyPressedChecker(); 

     m_pUser = new Player(kpc); 

     list.add(m_pUser.getPaddleDrawable()); 

     GamePlayLoop gameLoop = new GamePlayLoop(m_pUser); 
     gameLoop.start(); 

     primaryStage.setScene(scene); 
     primaryStage.show(); 
    } 

    public static void main(String[] args) { 
     launch(args); 
    } 
} 

我GamePlayLoop類：

public class GamePlayLoop extends AnimationTimer { 

    Player m_pUser; 

    public GamePlayLoop(Player p) { 
     m_pUser = p; 
    } 

    public void handle(long now) { 
     m_pUser.update(); 
    } 
} 

我KeyPressedChecker類：

public class KeyPressedChecker implements KeyEventDispatcher { 

    private static boolean downPressed = false; 

    @Override 
    public boolean dispatchKeyEvent(KeyEvent ke) { 
     synchronized (KeyPressedChecker.class) { 
      switch (ke.getID()) { 

       case KeyEvent.KEY_PRESSED: 
        if (ke.getKeyCode() == KeyEvent.VK_DOWN) 
         downPressed = true; 
       break; 
       case KeyEvent.KEY_RELEASED: 
        if (ke.getKeyCode() == KeyEvent.VK_DOWN) 
         downPressed = false; 
        break; 
      } 

      return false; 
     } 
    } 

    public static boolean isDownPressed() { 
     synchronized (KeyPressedChecker.class) { 
      return downPressed; 
     } 
    } 
} 

我Player類：

public class Player { 

    private Paddle m_paddle; 
    private KeyPressedChecker m_kpc; 

    public Player(KeyPressedChecker kpc) { 
     m_paddle = new Paddle(); 
    } 

    public Rectangle getPaddleDrawable() { 
     return m_paddle.getDrawable(); 
    } 

    public void update() { 
     if (m_kpc.isDownPressed()) 
      m_paddle.moveDown(); 
     m_paddle.update(); 
    } 
} 

最後我Paddle類：

public class Paddle { 

    private Rectangle m_rect; 
    private double m_nPosY; 

    public Paddle() { 
     m_rect = new Rectangle(10, 60); 
    } 

    public void moveDown() { 
     m_nPosY += 5; 
    } 

    public Rectangle getDrawable() { 
     return m_rect; 
    } 

    public void update() { 
     m_rect.setTranslateY(m_nPosY); 
    } 
} 

我的問題是，槳不在現場翻譯。實際上，dispatchKeyEvent根本不被調用。爲什麼是這樣？

Answer 1

KeyEventDispatcher是AWT的一部分，AWT是一個完全獨立於JavaFX的工具包。 （即使它是JavaFX的一部分，你只是實例化你的實現類，但不要對它做任何事情......）。

在JavaFX中執行此操作的方法是在場景中爲KeyEvent.KEY_PRESSED事件註冊事件處理程序。

因此，使用當前的設計（約），你會做

public class KeyPressedChecker implements EventHandler<KeyEvent> { 

    private boolean downPressed = false; 

    @Override 
    public void handle(KeyEvent ke) { 
     if (ke.getEventType() == KeyEvent.KEY_PRESSED) { 
      downPressed = true ; 
     } else if (ke.getEventType() == KeyEvent.KEY_RELEASED) { 
      downPressed = false ; 
     } 
    } 

    public boolean isDownPressed() { 
     return downPressed; 
    } 

} 

在你Player類（我改名領域，以配合適當的naming conventions）

public class Player { 

    private Paddle paddle; 
    private KeyPressedChecker kpc; 

    public Player(KeyPressedChecker kpc) { 
     this.paddle = new Paddle(); 
     this.kpc = kpc ; 
    } 

    public Rectangle getPaddleDrawable() { 
     return paddle.getDrawable(); 
    } 

    public void update() { 
     if (kpc.isDownPressed()) 
      paddle.moveDown(); 
     paddle.update(); 
    } 
} 

，然後一切都與

相連

public class Main extends Application { 

    private Player pUser; 

    @Override 
    public void start(Stage primaryStage) throws Exception{ 

     Group root = new Group(); 
     Scene scene = new Scene(root, 500, 300); 
     ObservableList list = root.getChildren(); 

     KeyPressedChecker kpc = new KeyPressedChecker(); 

     scene.addEventHandler(KeyEvent.ANY, kpc); 

     pUser = new Player(kpc); 

     list.add(pUser.getPaddleDrawable()); 

     GamePlayLoop gameLoop = new GamePlayLoop(pUser); 
     gameLoop.start(); 

     primaryStage.setScene(scene); 
     primaryStage.show(); 
    } 

    public static void main(String[] args) { 
     launch(args); 
    } 
}