我有一些文本组件(特别是 JEditorPane
),并且需要作为对特定事件的响应以使文本组件中的某些行可见 - 即,如果需要,滚动到它。如何使用 Swing 做到这一点?
我找到了 setCaretPosition
但它并不总是很好。如果插入符号已经位于为其新设置的位置,则不会使其再次可见。
最佳答案
来自教程 How to Use Editor Panes and Text Panes和 How to Use Scroll Panes你可以获得JViewPort那就是确定可见的矩形
例子:
import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
public class IsRectVisible {
private static void createAndShowUI() {
JFrame frame = new JFrame("IsRectVisible");
frame.getContentPane().add(new IsRectVisibleGui());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowUI();
}
});
}
private IsRectVisible() {
}
}
class IsRectVisibleGui extends JPanel {
public static final Rectangle RECT = new Rectangle(450, 400, 100, 100);
public static final Dimension INNER_PANEL_SIZE = new Dimension(600, 800);
private static final Dimension SCROLLPANE_SIZE = new Dimension(250, 300);
private static final String NOT_VISIBLE = "Not Visible";
private static final String VISIBLE = "Visible";
private static final long serialVersionUID = 1L;
private InnerPanel innerPanel = new InnerPanel();
private JViewport viewport = new JViewport();
private JLabel statusLabel = new JLabel(NOT_VISIBLE);
IsRectVisibleGui() {
JScrollPane scrollpane = new JScrollPane();
scrollpane.setViewport(viewport);
viewport.add(innerPanel);
scrollpane.setPreferredSize(SCROLLPANE_SIZE);
viewport.addChangeListener(new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
Rectangle viewRect = viewport.getViewRect();
if (viewRect.intersects(RECT)) {
statusLabel.setText(VISIBLE);
} else {
statusLabel.setText(NOT_VISIBLE);
}
}
});
setLayout(new BorderLayout());
add(scrollpane, BorderLayout.CENTER);
add(statusLabel, BorderLayout.SOUTH);
}
class InnerPanel extends JPanel {
private static final long serialVersionUID = 1L;
InnerPanel() {
setPreferredSize(INNER_PANEL_SIZE);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.red);
g2.setStroke(new BasicStroke(4));
g2.draw(RECT);
}
}
}
关于java - Swing - 确保文本组件中的可见行,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/6261778/