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I have a JComboBox that displays multiple text colors per line. I can't render it using HTML because the combo will contain large values (causing text wrapping). Instead, I created a custom renderer which extends JPanel (then I'm adding different JLabels to that panel which have different foreground/background colors).

In order to display the colors correctly, for each label I have to change setOpaque to true. This overrides the selected item's background color at the top as well:

enter image description here

Is there any way to prevent this behavior? Changing the JPanel's color doesn't change top's background color, but apparently its children JLabels do?

Renderer:

import java.awt.Color;
import java.awt.Component;

import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JList;
import javax.swing.JComboBox;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.ListCellRenderer;

public class CustomComboBoxRenderer extends JPanel implements ListCellRenderer {

    private JLabel[] labels = { new JLabel(), new JLabel(), new JLabel() };

    public CustomComboBoxRenderer() {
        setLayout(new BoxLayout(this, BoxLayout.X_AXIS));

        for (JLabel label : labels) {
            label.setOpaque(true);
            label.setVerticalAlignment(JLabel.CENTER);
            add(label);
        }
    }

    public Component getListCellRendererComponent(JList list, Object value, int index,
                    boolean isSelected, boolean cellHasFocus) {

        if(value != null) {
            String valueString = value.toString();

            if(valueString.contains("<red>")) {
                int redStart = valueString.indexOf("<red>");
                valueString = valueString.replace("<red>", "");
                int redEnd = valueString.indexOf("</red>");
                valueString = valueString.replace("</red>", "");

                if(redStart > 0) {
                    labels[0].setText(valueString.substring(0, redStart));
                }

                labels[1].setText(valueString.substring(redStart, redEnd));

                if(redEnd < valueString.length()) {
                    labels[2].setText(valueString.substring(redEnd, valueString.length()));
                }
            } else {
                labels[0].setText(valueString);
                labels[1].setText("");
                labels[2].setText("");
            }
        }

        if (isSelected) {
            labels[0].setBackground(list.getSelectionBackground());
            labels[1].setBackground(list.getSelectionBackground());
            labels[2].setBackground(list.getSelectionBackground());

            labels[0].setForeground(list.getSelectionForeground());
            labels[1].setForeground(Color.RED);
            labels[2].setForeground(list.getSelectionForeground());
        } else {
            labels[0].setBackground(list.getBackground());
            labels[1].setBackground(list.getBackground());
            labels[2].setBackground(list.getBackground());

            labels[0].setForeground(list.getForeground());
            labels[1].setForeground(Color.RED);
            labels[2].setForeground(list.getForeground());
        }

        setBackground(list.getBackground());
        return this;
    }
}

To set part of the text to red, a simple tag is used:

String comboString = "TEST (<red>Red Text</red>) TEST";
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1 回答 1

3

Normally in situations like this, I set the opaque state only when item is selected

setOpaque(isSelected);
于 2016-01-05T00:18:24.497 回答