Java KeyListener口吃 [英] Java KeyListener stutters
问题描述
我在java中制作一个非常简单的乒乓球游戏,我正在使用KeyListener进行此操作。我想要它,所以当用户按下键盘上的右或左键时,乒乓块朝那个方向移动。这是一个足够简单的任务,但我发现当用户按住键时,块移动一次,停止一小段时间,然后继续移动直到用户释放键。我注意到当你试图在计算机上按住一个字母键时会发生这种情况。如果我试着按住'a'键,计算机就会这样做:
I'm making a very simple pong game in java and I'm doing this using KeyListener. I want it so when the user presses the right or left keys on the keypad, the pong block goes in that direction. This is a simple enough task, but what I'm finding out is that when the user holds down the key, the block moves once, stops for a short time, then continues moving until the user releases the key. I notice this happens when you try to hold down a letter key on a computer. If I try to hold down the 'a' key, the computer will do:
a [pause] aaaaaaaaaaaaaaaaa
a [pause] aaaaaaaaaaaaaaaa
有没有办法禁用这个口吃,因为它阻碍了我的小游戏的流畅游戏。快速修复将非常感激。
Is there someway to disable this stutter, because it is getting in the way of smooth gameplay for my little game. A quick fix would be deeply appreciated.
推荐答案
我最初有一个关于Key Bindings的答案,但是经过一些测试后,我发现他们仍然有同样的口吃问题。
I originally had an answer about Key Bindings, but after a little testing I found that they still had the same stutter problem.
不要依赖操作系统的重复率。对于每个平台,它可以是不同的,用户也可以自定义它。
Don't rely on the repeat rate of the OS. It can be different for every platform and a user may also customize it.
而是使用Timer来安排事件。你在keyPressed上启动了Timer并在keyReleased上停止了Timer。
Instead use a Timer to schedule the event. You start the Timer on a keyPressed and stop the Timer on keyReleased.
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.util.Map;
import java.util.HashMap;
import javax.imageio.ImageIO;
import javax.swing.*;
public class KeyboardAnimation implements ActionListener
{
private final static String PRESSED = "pressed ";
private final static String RELEASED = "released ";
private final static Point RELEASED_POINT = new Point(0, 0);
private JComponent component;
private Timer timer;
private Map<String, Point> pressedKeys = new HashMap<String, Point>();
public KeyboardAnimation(JComponent component, int delay)
{
this.component = component;
timer = new Timer(delay, this);
timer.setInitialDelay( 0 );
}
public void addAction(String keyStroke, int deltaX, int deltaY)
{
// InputMap inputMap = component.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
InputMap inputMap = component.getInputMap();
ActionMap actionMap = component.getActionMap();
String pressedKey = PRESSED + keyStroke;
KeyStroke pressedKeyStroke = KeyStroke.getKeyStroke( pressedKey );
Action pressedAction = new AnimationAction(keyStroke, new Point(deltaX, deltaY));
inputMap.put(pressedKeyStroke, pressedKey);
actionMap.put(pressedKey, pressedAction);
String releasedKey = RELEASED + keyStroke;
KeyStroke releasedKeyStroke = KeyStroke.getKeyStroke( releasedKey );
Action releasedAction = new AnimationAction(keyStroke, RELEASED_POINT);
inputMap.put(releasedKeyStroke, releasedKey);
actionMap.put(releasedKey, releasedAction);
}
private void handleKeyEvent(String keyStroke, Point moveDelta)
{
// Keep track of which keys are pressed
if (RELEASED_POINT == moveDelta)
pressedKeys.remove( keyStroke );
else
pressedKeys.put(keyStroke, moveDelta);
// Start the Timer when the first key is pressed
if (pressedKeys.size() == 1)
{
timer.start();
}
// Stop the Timer when all keys have been released
if (pressedKeys.size() == 0)
{
timer.stop();
}
}
// Invoked when the Timer fires
public void actionPerformed(ActionEvent e)
{
moveComponent();
}
// Move the component to its new location
private void moveComponent()
{
int componentWidth = component.getSize().width;
int componentHeight = component.getSize().height;
Dimension parentSize = component.getParent().getSize();
int parentWidth = parentSize.width;
int parentHeight = parentSize.height;
// Calculate new move
int deltaX = 0;
int deltaY = 0;
for (Point delta : pressedKeys.values())
{
deltaX += delta.x;
deltaY += delta.y;
}
// Determine next X position
int nextX = Math.max(component.getLocation().x + deltaX, 0);
if ( nextX + componentWidth > parentWidth)
{
nextX = parentWidth - componentWidth;
}
// Determine next Y position
int nextY = Math.max(component.getLocation().y + deltaY, 0);
if ( nextY + componentHeight > parentHeight)
{
nextY = parentHeight - componentHeight;
}
// Move the component
component.setLocation(nextX, nextY);
}
private class AnimationAction extends AbstractAction implements ActionListener
{
private Point moveDelta;
public AnimationAction(String keyStroke, Point moveDelta)
{
super(PRESSED + keyStroke);
putValue(ACTION_COMMAND_KEY, keyStroke);
this.moveDelta = moveDelta;
}
public void actionPerformed(ActionEvent e)
{
handleKeyEvent((String)getValue(ACTION_COMMAND_KEY), moveDelta);
}
}
public static void main(String[] args)
{
JPanel contentPane = new JPanel();
contentPane.setLayout( null );
Icon dukeIcon = null;
try
{
dukeIcon = new ImageIcon( "dukewavered.gif" );
// dukeIcon = new ImageIcon( ImageIO.read( new URL("http://duke.kenai.com/iconSized/duke4.gif") ) );
}
catch(Exception e)
{
System.out.println(e);
}
JLabel duke = new JLabel( dukeIcon );
duke.setSize( duke.getPreferredSize() );
duke.setLocation(100, 100);
contentPane.add( duke );
KeyboardAnimation navigation = new KeyboardAnimation(duke, 24);
navigation.addAction("LEFT", -3, 0);
navigation.addAction("RIGHT", 3, 0);
navigation.addAction("UP", 0, -3);
navigation.addAction("DOWN", 0, 3);
navigation.addAction("A", -5, 0);
navigation.addAction("S", 5, 0);
navigation.addAction("Z", 0, -5);
navigation.addAction("X", 0, 5);
navigation.addAction("V", 5, 5);
JFrame frame = new JFrame();
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
// frame.getContentPane().add(new JTextField(), BorderLayout.SOUTH);
frame.getContentPane().add(contentPane);
frame.setSize(600, 600);
frame.setLocationRelativeTo( null );
frame.setVisible(true);
}
}
此代码在Windows上进行了测试事件的顺序是keyPressed,keyPressed,keyPressed ... keyReleased。
This code was tested on Windows where the order of events is keyPressed, keyPressed, keyPressed... keyReleased.
但是,我认为在Mac(或Unix)上事件的顺序是keyPressed,keyReleased, keyPressed,keyReleased ...所以我不确定这段代码是否比你当前的代码更好。
However, I think on a Mac (or Unix) the order of events is keyPressed, keyReleased, keyPressed, keyReleased... So I'm not sure if this code would works any better than your current code.
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