当用户输入无效时,我希望能够绘制一个图标。我找到了 Oracle 的一个示例,并根据我的需求进行了修改。图标的绘制是正确的,但是当我更改值以使其正确时,图标并没有完全消失:在 JPanel 上绘制的部分仍然显示出来。
以下是我的代码:
import java.awt.AlphaComposite;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.text.NumberFormat;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayer;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.plaf.LayerUI;
public class FieldValidator extends JPanel {
private static final int ICON_SIZE = 12;
private static final Icon ICON = createResizedIcon((ImageIcon) UIManager.getIcon("OptionPane.errorIcon"));
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createUI();
}
});
}
public static void createUI() {
final JFrame f = new JFrame ("FieldValidator");
final JComponent content = createContent();
f.add (content);
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLocationRelativeTo (null);
f.setVisible (true);
}
private static JComponent createContent() {
final LayerUI<JPanel> panelUI = new ValidationLayerUI();
// Number field.
final JLabel numberLabel = new JLabel("Number:");
final NumberFormat numberFormat = NumberFormat.getInstance();
final JFormattedTextField numberField = new JFormattedTextField(numberFormat) {
/**
* {@inheritDoc}
*/
@Override
public void replaceSelection(String content) {
super.replaceSelection(content);
getParent().repaint();
}
};
numberField.setColumns(16);
numberField.setFocusLostBehavior(JFormattedTextField.PERSIST);
numberField.setValue(42);
final int i = (ICON_SIZE / 2) + (ICON_SIZE % 2);
final JPanel numberPanel = new JPanel();
numberPanel.add(numberLabel);
final JPanel panel = new JPanel(new GridBagLayout());
final GridBagConstraints constr = new GridBagConstraints();
constr.insets = new Insets(i, i, i, i);
constr.weightx = 1;
constr.weighty = 1;
constr.fill = GridBagConstraints.BOTH;
panel.add(numberField, constr);
numberPanel.add(new JLayer<JPanel>(panel, panelUI));
return numberPanel;
}
//Icon resized to 12x12
private static Icon createResizedIcon(ImageIcon anIcon) {
final BufferedImage result = new BufferedImage(ICON_SIZE, ICON_SIZE, BufferedImage.TYPE_INT_ARGB);
final Graphics2D g = result.createGraphics();
g.setComposite(AlphaComposite.Src);
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BICUBIC);
g.drawImage(anIcon.getImage(), 0, 0, ICON_SIZE, ICON_SIZE, null);
g.dispose();
return new ImageIcon(result);
}
static class ValidationLayerUI extends LayerUI<JPanel> {
@Override
public void paint (Graphics g, JComponent c) {
super.paint (g, c);
final JLayer jlayer = (JLayer) c;
final JPanel panel = (JPanel) jlayer.getView();
final JFormattedTextField ftf = (JFormattedTextField) panel.getComponent(0);
if (!ftf.isEditValid()) {
ICON.paintIcon(panel, g, 0, panel.getHeight() - ICON.getIconHeight());
}
}
}
}
这里是屏幕截图: 初始状态都正确。
当我绘制无效的图标时,仍然一切正常。
但是当值变为正确时,只有文本字段会被重新绘制。
如何强制JPanel重新绘制?
附:我已经找到了使用JLayeredPane的方法,可以正常工作,但我想知道我的代码哪里出了问题?
JTextComponent#replaceSelection(...)
不会被调用。 - aterai