Java JScrollPane更新映像

Question

我正在制作一个具有滚动图像的程序,如果按下按钮,我无法弄清楚如何更新图像(例如:向图像添加绿色椭圆.)它已经绘制了将图像放入JScrollPane并可以滚动,但是当您单击按钮时它不会刷新图像.(代码中的更多细节)这是代码:

public class PegMaster extends JPanel implements ActionListener {

    //Note: not complete code
    public PegBox[] pegbox = new PegBox[9];

    public static Dimension size = new Dimension(520, 500);

    public BufferedImage canvas;
    public Graphics2D g2d;
    public JScrollPane scroller;
    JPanel panel;
    private Canvas window;

    JScrollPane pictureScrollPane;

    public PegMaster() {
        JButton button = new JButton("test");
        button.addActionListener(this);
        add(button);

        canvas = new BufferedImage((int)size.getWidth()-30, 75 * GUESSES, BufferedImage.TYPE_INT_RGB);
        g2d = canvas.createGraphics();
        for(int i = 0;i<=pegbox.length-1;i++) {
           pegbox[i] = new PegBox(i, g2d);
        }
        window = new Canvas(new ImageIcon(toImage(canvas)), 1);
        //Class Canvas is a Scrollable JLabel to draw to (the image)
        pictureScrollPane = new JScrollPane(window);
        pictureScrollPane.setPreferredSize(new Dimension((int)size.getWidth()-10, (int)size.getHeight()-20));
        pictureScrollPane.setViewportBorder(BorderFactory.createLineBorder(Color.black));
        add(pictureScrollPane);

        //adds the scrollpane, but can't update the image in it
    }

    public static void main(String args[]) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createGUI();
                //just adds the scrollpane
            }
        });
    }

    public void paint(Graphics g) {
        super.paint(g);

        for(int i = 0;i<=pegbox.length-1;i++) {
            //pegbox[i] = new PegBox(i);
            pegbox[i].draw(g2d);
        }
        try {
            Thread.sleep(20);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }   
        //tried re-making the scrollpane, didn't work.
        //window = new Canvas(new ImageIcon(toImage(canvas)), 1);
        //pictureScrollPane = new JScrollPane(window);
        //pictureScrollPane.setPreferredSize(new Dimension((int)size.getWidth()-10 (int)size.getHeight()-20));
        //pictureScrollPane.setViewportBorder(BorderFactory.createLineBorder(Color.black));
        //tried imageupdate: pictureScrollPane.imageUpdate(canvas, 0, 0, 0 (int)size.getWidth()-10, (int)size.getHeight()-20);
        //remove(pictureScrollPane);
        //tried this: pictureScrollPane.revalidate();
        repaint();
    }
}

Answer 1

首先,不要使用Canvas它是一个重量级的组件,它只会导致你长期问题,使用JComponent或JPanel

其次,不要覆盖paint,paintComponent改用. paint做了很多工作,包括绘制边框和子组件之类的东西.如果您paintComponent在绘图层次结构中的右侧层使用它,那么它会更好.

第三,永远不要Thread.sleep在Event Dispatching Thread中调用类似的东西.这将导致事件队列暂停并停止响应事件,使您的程序看起来像是停滞不前.

第四,NEVER调用repaint(invalidate,revalidate或可能导致发生一个重画请求的任何方法)的涂料方法内.你最终会最终耗尽你的CPU,你将被迫杀死这个过程.

第五,你没有提供actionPerformed方法,这可能是所有行动(和问题)的所在.我想你需要调用window.repaint()并且可能window.invalidate()(以相反的顺序),但由于你没有提供使用这个代码,这只是猜测......