我在大学有一个任务,画一个椭圆,让它在屏幕上一步一步地移动,只按一次按钮。下面是我的代码:
public class Window extends JPanel {
private static Ellipse2D.Double Ellipse;
private JFrame frame;
public Window() {
super();
int width = 20;
int height = 30;
Ellipse = new Ellipse2D.Double(width, height, 100, 50);
}
public Dimension getPreferredSize()
{
return (new Dimension(frame.getWidth(), frame.getHeight()));
}
@Override
public void paintComponent(Graphics g) {
super.paintComponents(g);
Graphics2D brush = (Graphics2D) g;
int width = getWidth();
int height = getHeight();
g.clearRect(0, 0, width, height);
brush.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
brush.draw(Ellipse);
}
public class MoveCircle implements KeyListener, ActionListener {
@Override
public void keyPressed(KeyEvent e) {
System.out.println("Working on top!");
double newX = 0; double newY = 0;
if (e.getKeyCode() == Event.ENTER) {
for (int i = 0; i < 26; i ++)
{
System.out.println("Working on bottom!");
newX = Ellipse.x + 10;
Ellipse.x = newX;
newY = Ellipse.y + 10;
Ellipse.y = newY;
repaint();
}
}
}
@Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
@Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
}
}
private void createAndDisplayGUI(Window window)
{
frame = new JFrame();
Container container = frame.getContentPane();
container.add(window);
window.addKeyListener(new MoveCircle());
frame.setSize(400, 400);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setVisible(true);
window.requestFocusInWindow();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
Window window = new Window();
window.createAndDisplayGUI(window);
}
});
}
}
虽然我每次都循环调用函数repaint(),但椭圆只是从原始点移动到上次迭代中定义的点,而不是在每次迭代中绘制椭圆的位置。是否有可能使用摆动计时器,使其在每次迭代中重新绘制椭圆?我将非常高兴得到帮助在这方面
你有两个问题:第一个是你的循环正在UI线程上运行。第二是你对重新粉刷的工作方式的误解。repaint所做的就是向UI线程添加一个请求来进行修复。它本身不会进行重漆。因此,如果您在UI线程上运行操作,多次调用它将不会产生任何影响。正如您所建议的,您可以使用Swing Timer修复此问题,正如我在
下面放置的那样。ActionListener al = new ActionListener() {
int iterations = 0;
public void actionPerformed(ActionEvent ae) {
if (iterations == 25) {
timer.stop();
}
interations++;
System.out.println("Working on bottom!");
newX = Ellipse.x + 10;
Ellipse.x = newX;
newY = Ellipse.y + 10;
Ellipse.y = newY;
repaint();
}
};
final timer = new javax.swing.Timer(delay, al);
timer.start();