彩色jcombobox彩色項目和焦點

Question

我想用彩色項目（請參閱下面的代碼）作出彩色下拉列表。在組合框失去焦點後，顏色被應用。

這是正確的行爲？

當組合框具有焦點時，我怎樣才能獲得前景和/或背景顏色？

感謝

import java.awt.*; 
import java.awt.event.*; 
import java.util.*; 
import javax.swing.*; 
import javax.swing.border.*; 
public class DropDown { 
    enum Colors { 
     red(Color.red), orange(Color.orange), green(Color.green), yellow(Color.yellow), blue(Color.blue); 
     Colors(Color color) { 
      this.color = color; 
     } 
     static String[] listModel() { 
      java.util.List<Colors> values = Arrays.asList(values()); 
      String s = values.toString().replaceAll(" ", ""); 
      return s.substring(1, s.length() - 1).split(","); 
     } 
     final Color color; 
    } 
    static class ColoredCellRenderer implements ListCellRenderer { 
     protected DefaultListCellRenderer defaultRenderer = new DefaultListCellRenderer(); 
     private final static Dimension preferredSize = new Dimension(0, 20); 
     public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, 
       boolean cellHasFocus) { 
      JLabel renderer = (JLabel) defaultRenderer.getListCellRendererComponent(list, value, index, isSelected, 
        cellHasFocus); 
      if (index != -1) if (value instanceof String) renderer.setForeground(Colors.valueOf((String) value).color); 
      else 
       System.out.println("not a string"); 
      else 
       System.out.println("in getListCellRendererComponent, index=-1"); 
      renderer.setPreferredSize(preferredSize); 
      return renderer; 
     } 
    } 
    private static JComboBox addLabeledComboBox(Container c, String label, String[] model) { 
     JPanel panel = new JPanel(); 
     panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS)); 
     Border border = BorderFactory.createLineBorder(Color.green, 1); 
     panel.setBorder(border); 
     JLabel l = new JLabel(label); 
     panel.add(l); 
     final JComboBox comboBox = new JComboBox(model); 
     comboBox.setName(label); 
     l.setLabelFor(comboBox); 
     comboBox.setRenderer(new ColoredCellRenderer()); 
     panel.add(comboBox); 
     c.add(panel); 
     return comboBox; 
    } 
    private static void addContent(Container c) { 
     c.setLayout(new BoxLayout(c, BoxLayout.Y_AXIS)); 
     ActionListener actionListener = new ActionListener() { 
      @Override public void actionPerformed(ActionEvent e) { 
       if (e.getSource() instanceof JComboBox) { 
        final JComboBox comboBox = (JComboBox) e.getSource(); 
        Object selected = comboBox.getSelectedItem(); 
        String string = (String) selected; 
        Color color = Colors.valueOf(string).color; 
        int i = comboBox.getSelectedIndex(); 
        if (i != -1) { 
         System.out.println("comboBox " + comboBox.getName() + " " + color); 
         comboBox.setForeground(color); 
         System.out.println(comboBox.hasFocus()); 
         // comboBox.repaint(); 
        } else 
         System.out.println("in actionListener selected=" + selected); 
       } else 
        System.out.println("in actionListener selected is not a comboBox"); 
      } 
     }; 
     c.add(new JButton("button")); 
     for (int i = 0; i < 2; i++) { 
      JPanel panel = new JPanel(); 
      Border border = BorderFactory.createLineBorder(Color.red, 1); 
      panel.setBorder(border); 
      panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS)); 
      panel.add(new JLabel("label " +(i+1))); 
      JComboBox comboBox = addLabeledComboBox(panel, "" + (i + 1), Colors.listModel()); 
      comboBox.addActionListener(actionListener); 
      comboBox.setSelectedIndex(0); // select something 
      c.add(panel); 
     } 
    } 
    private static void createAndShowGUI() { 
     JFrame frame = new JFrame("Colored JComboBox"); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     addContent(frame.getContentPane()); 
     frame.pack(); 
     frame.setVisible(true); 
    } 
    public static void main(String[] args) { 
     javax.swing.SwingUtilities.invokeLater(new Runnable() { 
      @SuppressWarnings("synthetic-access") public void run() { 
       createAndShowGUI(); 
      } 
     }); 
    } 
} 

Answer 1

這裏是另一種方法：

//JList#setSelectionForeground(...) version 
static class ColoredCellRenderer implements ListCellRenderer { 
    protected DefaultListCellRenderer defaultRenderer = new DefaultListCellRenderer(); 
    private final Color selectionBackground = new Color(240,200,200); 
    public Component getListCellRendererComponent(
     JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) { 
    Color fgc = Colors.valueOf((String)value).color; 
    if(index<0) { 
     //comboBox.setForeground(fgc); //Windows, CDE/Motif Look & Feel 
     list.setSelectionForeground(fgc); 
     list.setSelectionBackground(selectionBackground); 
    } 
    JLabel renderer = (JLabel) defaultRenderer.getListCellRendererComponent(
     list, value, index, isSelected, cellHasFocus); 
    if (index != -1) { 
     renderer.setForeground(fgc); 
    } 
    return renderer; 
    } 
} 

//html version 
static class ComboHtmlRenderer extends DefaultListCellRenderer { 
    private final Color selectionBackground = new Color(240,200,200); 
    @Override public Component getListCellRendererComponent(
     JList list, Object value, int index, boolean isSelected, boolean hasFocus) { 
    Color fgc = Colors.valueOf((String)value).color; 
    if(index<0) { 
     list.setSelectionBackground(selectionBackground); 
    } 
    JLabel l = (JLabel)super.getListCellRendererComponent(
       list, value, index, isSelected, hasFocus); 
    l.setText("<html><font color="+hex(fgc)+">"+value); 
    l.setBackground(isSelected?selectionBackground:list.getBackground()); 
    return l; 
    } 
    private static String hex(Color c) { 
    return String.format("#%06x", c.getRGB()&0xffffff); 
    } 
} 

Answer 2

請拆分編輯器和渲染器，並加入到DefaultListCellRenderer這兩種方法

• cellHasFocus

• isSelected

示例

import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 
import javax.swing.border.LineBorder; 
import javax.swing.event.EventListenerList; 

class ColorComboBoxEditor1 implements ComboBoxEditor { 

    final protected JLabel editor; 
    //final protected JButton editor; 
    private EventListenerList listenerList = new EventListenerList(); 

    ColorComboBoxEditor1(Color initialColor) { 
     editor = new JLabel(""); 
     /*editor = new JButton(""); 
     editor.setBackground(initialColor); 
     ActionListener actionListener = new ActionListener() { 

      @Override 
      public void actionPerformed(ActionEvent e) { 
       Color currentBackground = editor.getBackground(); 
       Color color = JColorChooser.showDialog(editor, "Color Chooser", currentBackground); 
       if ((color != null) && (currentBackground != color)) { 
        //editor.setBackground(color); 
        editor.setForeground(color); 
        fireActionEvent(color); 
       } 
      } 
     }; 
     editor.addActionListener(actionListener);*/ 
    } 

    @Override 
    public void addActionListener(ActionListener l) { 
     listenerList.add(ActionListener.class, l); 
    } 

    @Override 
    public Component getEditorComponent() { 
     return editor; 
    } 

    @Override 
    public Object getItem() { 
     return editor.getBackground(); 
    } 

    @Override 
    public void removeActionListener(ActionListener l) { 
     listenerList.remove(ActionListener.class, l); 
    } 

    @Override 
    public void selectAll() { 
    } 

    @Override 
    public void setItem(Object newValue) { 
     if (newValue instanceof Color) { 
      Color color = (Color) newValue; 
      //editor.setBackground(color); 
      editor.setForeground(color); 
      editor.setText(String.valueOf(newValue)); 
     } else { 
      try { 
       Color color = Color.decode(newValue.toString()); 
       //editor.setBackground(color); 
       editor.setForeground(color); 
       editor.setText(String.valueOf(newValue)); 
      } catch (NumberFormatException e) { 
      } 
     } 
    } 

    protected void fireActionEvent(Color color) { 
     Object listeners[] = listenerList.getListenerList(); 
     for (int i = listeners.length - 2; i >= 0; i -= 2) { 
      if (listeners[i] == ActionListener.class) { 
       ActionEvent actionEvent = new ActionEvent(editor, ActionEvent.ACTION_PERFORMED, color.toString()); 
       ((ActionListener) listeners[i + 1]).actionPerformed(actionEvent); 
      } 
     } 
    } 
} 

class ColorCellRenderer1 implements ListCellRenderer { 

    private DefaultListCellRenderer defaultRenderer = new DefaultListCellRenderer(); 
    // Width doesn't matter as the combo box will size 
    private final static Dimension preferredSize = new Dimension(0, 20); 

    @Override 
    public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) { 
     JLabel renderer = (JLabel) defaultRenderer.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus); 
     if (value instanceof Color) { 
      //renderer.setBackground((Color) value); 
      renderer.setBackground(Color.white); 
      renderer.setForeground((Color) value); 
     } 
     if (cellHasFocus || isSelected) { 
      renderer.setBorder(new LineBorder(Color.DARK_GRAY)); 
     } else { 
      renderer.setBorder(null); 
     } 
     renderer.setPreferredSize(preferredSize); 
     return renderer; 
    } 
} 

class ColorComboBoxEditorRendererDemo1 { 

    public ColorComboBoxEditorRendererDemo1() { 
     Color colors[] = {Color.BLACK, Color.BLUE, Color.GREEN, Color.RED, Color.WHITE, Color.YELLOW}; 
     JFrame frame = new JFrame("Color JComboBox"); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     final JComboBox comboBox = new JComboBox(colors); 
     comboBox.setEditable(true); 
     comboBox.setRenderer(new ColorCellRenderer1()); 
     Color color = (Color) comboBox.getSelectedItem(); 
     ComboBoxEditor editor = new ColorComboBoxEditor1(color); 
     comboBox.setEditor(editor); 
     frame.add(comboBox, BorderLayout.NORTH); 
     final JLabel label = new JLabel(); 
     label.setOpaque(true); 
     label.setBackground((Color) comboBox.getSelectedItem()); 
     frame.add(label, BorderLayout.CENTER); 
     ActionListener actionListener = new ActionListener() { 

      @Override 
      public void actionPerformed(ActionEvent actionEvent) { 
       Color selectedColor = (Color) comboBox.getSelectedItem(); 
       label.setBackground(selectedColor); 
      } 
     }; 
     comboBox.addActionListener(actionListener); 
     frame.setSize(300, 200); 
     frame.setVisible(true); 
    } 

    public static void main(String args[]) { 
     SwingUtilities.invokeLater(new Runnable() { 

      @Override 
      public void run() { 
       ColorComboBoxEditorRendererDemo1 cCBERD1 = new ColorComboBoxEditorRendererDemo1(); 
      } 
     }); 
    } 
} 

Answer 3

示例中的前景文本顏色似乎正常工作。對於給定的Look &感覺，某些其他顏色由組件的UI委託管理，如下所示。請注意，代表可以選擇以在各種狀態下保留對比度的方式應用顏色，例如選中，啓用等。您可以在文章UIManager Defaults中瞭解更多信息。

public static void main(String[] args) { 
    UIManager.put("ComboBox.background", new ColorUIResource(Color.lightGray)); 
    UIManager.put("ComboBox.selectionBackground", new ColorUIResource(Color.magenta)); 
    UIManager.put("ComboBox.selectionForeground", new ColorUIResource(Color.yellow)); 
    javax.swing.SwingUtilities.invokeLater(new Runnable() { 

     @SuppressWarnings("synthetic-access") 
     public void run() { 
      createAndShowGUI(); 
     } 
    }); 
}