Я пытаюсь нарисовать некоторые древовидные структуры на подклассе JPanel, который является клиентом (представление ViewPort) JScrollPane.Я могу нарисовать дерево очень хорошо, но даже если оно больше, чем область просмотра, JScrollPane не прокручивается.Идентичный JScrollPane, клиентом которого является JTextArea, работает нормально.
Приведенный ниже код создает кадр с двумя полосами прокрутки рядом - одна работает, а другая - нет.(Я просто рисую текст для простоты.) Я новичок в графическом интерфейсе Swing, поэтому я, несомненно, делаю глупости, но дни поиска и чтения не показали мне моей ошибки.
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JScrollPane;
import java.awt.Graphics;
public class ScrollTest extends javax.swing.JFrame {
public ScrollTest() {
initComponents();
prepComponents();
}
void prepComponents() {
leftScrollPaneContent = new JTextArea();
leftScrollPane.setViewportView(leftScrollPaneContent);
rightScrollPaneContent = new TestPanel();
rightScrollPane.setViewportView(rightScrollPaneContent);
String s = "Test of JTextArea setText()\n\n";
for (int i = 1; i < 30; i++) {
s += "Line " + i + ": This is a test.\n";
}
leftScrollPaneContent.setText(s);
rightScrollPaneContent.repaint();
}
@SuppressWarnings("unchecked")
private void initComponents() {
leftPanel = new javax.swing.JPanel();
jPanelLabel = new javax.swing.JLabel();
leftScrollPane = new javax.swing.JScrollPane();
rightPanel = new javax.swing.JPanel();
subclassLabel = new javax.swing.JLabel();
rightScrollPane = new javax.swing.JScrollPane();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jPanelLabel.setText("JTextArea in a ScrollPane");
leftScrollPane.setHorizontalScrollBarPolicy(javax.swing.ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
leftScrollPane.setVerticalScrollBarPolicy(javax.swing.ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
javax.swing.GroupLayout leftPanelLayout = new javax.swing.GroupLayout(leftPanel);
leftPanel.setLayout(leftPanelLayout);
leftPanelLayout.setHorizontalGroup(
leftPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(leftPanelLayout.createSequentialGroup()
.addContainerGap()
.addComponent(leftScrollPane)
.addContainerGap())
.addGroup(leftPanelLayout.createSequentialGroup()
.addGap(101, 101, 101)
.addComponent(jPanelLabel, javax.swing.GroupLayout.PREFERRED_SIZE, 180, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(114, Short.MAX_VALUE))
);
leftPanelLayout.setVerticalGroup(
leftPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(leftPanelLayout.createSequentialGroup()
.addContainerGap()
.addComponent(jPanelLabel)
.addGap(18, 18, 18)
.addComponent(leftScrollPane, javax.swing.GroupLayout.DEFAULT_SIZE, 332, Short.MAX_VALUE)
.addContainerGap())
);
subclassLabel.setText("JPanel subclass in a ScrollPane");
rightScrollPane.setHorizontalScrollBarPolicy(javax.swing.ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
rightScrollPane.setVerticalScrollBarPolicy(javax.swing.ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
javax.swing.GroupLayout rightPanelLayout = new javax.swing.GroupLayout(rightPanel);
rightPanel.setLayout(rightPanelLayout);
rightPanelLayout.setHorizontalGroup(
rightPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(rightPanelLayout.createSequentialGroup()
.addContainerGap()
.addComponent(rightScrollPane)
.addContainerGap())
.addGroup(rightPanelLayout.createSequentialGroup()
.addGap(66, 66, 66)
.addComponent(subclassLabel, javax.swing.GroupLayout.PREFERRED_SIZE, 200, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(77, Short.MAX_VALUE))
);
rightPanelLayout.setVerticalGroup(
rightPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(rightPanelLayout.createSequentialGroup()
.addComponent(subclassLabel)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(rightScrollPane)
.addContainerGap())
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(leftPanel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addComponent(rightPanel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(14, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(leftPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addGroup(layout.createSequentialGroup()
.addGap(17, 17, 17)
.addComponent(rightPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
.addContainerGap())
);
pack();
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new ScrollTest().setVisible(true);
}
});
}
private javax.swing.JLabel jPanelLabel;
private javax.swing.JPanel leftPanel;
private javax.swing.JScrollPane leftScrollPane;
private javax.swing.JPanel rightPanel;
private javax.swing.JScrollPane rightScrollPane;
private javax.swing.JLabel subclassLabel;
// End of variables declaration
private JTextArea leftScrollPaneContent;
private JPanel rightScrollPaneContent;
public class TestPanel extends JPanel {
public void paint(Graphics g) {
super.paint(g);
g.drawString("Test of JPanel g.drawString()\n", 10, 20);
for (int i = 3; i < 33; i++) {
g.drawString("Line " + (i-2) + ": This is a test.", 10, 20 * i);
}
}
}
}