我试图在JScrollPane上绘制一个红色正方形。我下面的代码可以很好地完成此工作,但是有时当我过快滚动视口时,红色正方形会上下跳动。
因为JScrollPane本身是固定的,所以这让我感到很奇怪,因此我认为Swing不会尝试在其中绘制的组件周围移动。我猜测实际发生的是红色正方形与视口相关联,视口显示确实在移动的图形。
无论如何,如何防止红色方块跳来跳去并成功在列表上绘制红色方块?也许我完全采用了错误的方法。
package components;
import java.awt.*;
import java.util.Vector;
import javax.swing.*;
import javax.swing.event.*;
@SuppressWarnings("serial")
public class DialogWithScrollPane extends JFrame {
public DialogWithScrollPane() {
super();
setResizable(false);
Container pane = getContentPane();
Vector<Object> listOfStuff = new Vector<Object>();
for (int i = 0; i < 100; i++) {
listOfStuff.add(Integer.toString(i));
}
final JScrollPane scrollPane = new JScrollPane() {
public void paint(Graphics g) {
System.out.println("JScrollPane.paint() called.");
super.paint(g);
g.setColor(Color.red);
g.fillRect(20, 50, 100, 200);
}
};
JList list = new JList(listOfStuff) {
public void paint(Graphics g) {
System.out.println("JList.paint() called.");
super.paint(g);
// Well, I could do this...
//
// scrollPane.repaint();
//
// ...and it would solve the problem, but it would also result in an
// infinite recursion since JScrollPane.paint() would call this
// function again.
}
};
// Repaint the JScrollPane any time the viewport is moved or an item in the
// list is selected.
scrollPane.getViewport().addChangeListener(new ChangeListener() {
public void stateChanged(ChangeEvent e) {
scrollPane.repaint();
}
});
list.addListSelectionListener(new ListSelectionListener() {
public void valueChanged(ListSelectionEvent e) {
scrollPane.repaint();
}
});
scrollPane.setViewportView(list);
pane.add(scrollPane);
setMinimumSize(new Dimension(300, 300));
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocation(500, 250);
setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
new DialogWithScrollPane();
}
});
}
}
JScrollPane应该画在 JViewport的后面,而JViewport应该画在列表的后面。我猜想这仅是有效的,因为您覆盖了paint而不是paintComponent,并且一直在JScrollPane上调用repaint,以便它在绘制其组件之后再次进行自我绘制。
也许您想使用JLayeredPane并让它保持JScrollPane并在其上绘画。
编辑:或者就像我现在看到的那样建议的玻璃窗格,但是如果您这样做,并且将玻璃窗格设置为可见,恐怕您将失去与基础滚动窗格进行交互的能力。
编辑2
例如
import java.awt.*;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.util.Vector;
import javax.swing.*;
@SuppressWarnings("serial")
public class DialogWithScrollPane2 extends JFrame {
public DialogWithScrollPane2() {
super();
//setResizable(false);
final JPanel pane = (JPanel) getContentPane();
Vector<Object> listOfStuff = new Vector<Object>();
for (int i = 0; i < 100; i++) {
listOfStuff.add(Integer.toString(i));
}
final JScrollPane scrollPane = new JScrollPane();
JList list = new JList(listOfStuff);
scrollPane.setViewportView(list);
final JPanel blueRectPanel = new JPanel() {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.blue);
g.fillRect(20, 50, 100, 200);
}
};
blueRectPanel.setOpaque(false);
final JLayeredPane layeredPane = new JLayeredPane();
layeredPane.add(scrollPane, JLayeredPane.DEFAULT_LAYER);
layeredPane.add(blueRectPanel, JLayeredPane.PALETTE_LAYER);
layeredPane.addComponentListener(new ComponentAdapter() {
private void resizeLayers() {
final JViewport viewport = scrollPane.getViewport();
scrollPane.setBounds(layeredPane.getBounds());
blueRectPanel.setBounds(viewport.getBounds());
SwingUtilities.invokeLater(new Runnable() {
public void run() {
blueRectPanel.setBounds(viewport.getBounds());
}
});
}
@Override
public void componentShown(ComponentEvent e) {
resizeLayers();
}
@Override
public void componentResized(ComponentEvent e) {
resizeLayers();
}
});
pane.add(layeredPane);
setPreferredSize(new Dimension(300, 300));
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
setLocation(500, 250);
setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
new DialogWithScrollPane2();
}
});
}
}
本文收集自互联网,转载请注明来源。
如有侵权,请联系 [email protected] 删除。
我来说两句