在JScrollPane内的JPanel上绘画无法在正确的位置绘画 [英] Painting on a JPanel inside a JScrollPane doesn't paint in the right location

问题描述

所以我在JScrollPane内有一个JPanel. 现在，我试图在面板上画一些东西，但是总是在同一位置. 我可以向各个方向滚动，但不会移动.我在面板上绘制的所有内容都不会滚动.

So I have a JPanel that's inside a JScrollPane. Now I am trying to paint something on the panel, but it's always in same spot. I can scroll in all directions but it's not moving. Whatever I paint on the panel does not get scrolled.

我已经尝试过:

1. 自定义JViewPort
2. 在Opaque = true和Opaque = false之间切换

我还考虑了覆盖面板的paintComponent方法，但这在我的代码中将很难实现.

Also I considered overriding the paintComponent method of the panel but that would be really hard to implement in my code.

public class ScrollPanePaint{

public ScrollPanePaint() {
    JFrame frame = new JFrame();
    final JPanel panel = new JPanel();
    panel.setPreferredSize(new Dimension(1000, 1000));
    //I tried both true and false
    panel.setOpaque(false);
    JScrollPane scrollPane = new JScrollPane(panel);
    frame.add(scrollPane);
    frame.setSize(200, 200);
    frame.setVisible(true);
    //To redraw the drawing constantly because that wat is happening in my code aswell because
    //I am creating an animation by constantly move an image by a little
    new Thread(new Runnable(){
        public void run(){
            Graphics g = panel.getGraphics();
            g.setColor(Color.blue);
            while(true){
                g.fillRect(64, 64, 3 * 64, 3 * 64);
                panel.repaint();
            }
        }
    }).start();
}

public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {

        @Override
        public void run() {
            new ScrollPanePaint();
        }
    });
}

}

我犯的错误很容易解决，但我不知道如何解决.

The mistake I make is probably very easy to fix, but I just can't figure out how.

推荐答案

如何在JPanel上实现paintComponent()?

覆盖getPreferredSize()方法而不是使用setPreferredSize()

final JPanel panel = new JPanel(){
    @Override
    public void paintComponent(Graphics g){
        super.paintComponent(g);
        // your custom painting code here
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(40, 40);
    }
};

一些要点:

1. 覆盖 JComponent#getPreferredSize()而不是使用setPreferredSize()

了解更多信息我应该避免使用Swing中set(Preferred | Maximum | Minimum)Size方法的设置?

使用 Swing Timer 而不是 Java计时器适用于Swing应用程序.

Use Swing Timer instead of Java Timer that is more suitable for Swing application.

了解更多信息如何使用摇摆计时器

使用了解更多信息如何设置外观

如何解决Java中的动画滞后?

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