Changing a color chooser button's background color in Java

问题

I have a Java button that opens a JColorChooser dialog. I would like for the color of the button to change according to the color selected in the dialog. I have tried calling the setBackgroundColor() method of the button, but in my case it has no effect (the button is on a JToolBar in Winsows 7). Also, this question suggests that changing a button's background is not platform independent.

Maybe the answer to this problem is not to use a button in the first place. So, my question is: is there a method of showing a "color picker" control in Java that reflects the picked color? Kind of like how MS Paint would show the picked color on the "fill with color" button.

回答1:

You have several options:

• Change the background of a related component, as shown in @mKorbel's answer.

• Make the button opaque, as suggested by @Robin here.

• Modify the background of a panel containing the button, as shown here.

• Implement the Icon interface and apply an instance to (or near) your button, as shown here.

回答2:

not sure from context, do you meaning this way (code example) or to setBackground for JColorChooser or its JComponents in the JColorChooser

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ComboBoxEditor;
import javax.swing.DefaultListCellRenderer;
import javax.swing.JButton;
import javax.swing.JColorChooser;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.ListCellRenderer;
import javax.swing.border.LineBorder;
import javax.swing.event.EventListenerList;

class ColorComboBoxEditor implements ComboBoxEditor {

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

    ColorComboBoxEditor(Color initialColor) {
        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);
                    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);
        } else {
            try {
                Color color = Color.decode(newValue.toString());
                editor.setBackground(color);
            } 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 ColorCellRenderer implements ListCellRenderer {

    private DefaultListCellRenderer defaultRenderer = new DefaultListCellRenderer();
    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);
        }
        if (cellHasFocus || isSelected) {
            renderer.setBorder(new LineBorder(Color.DARK_GRAY));
        } else {
            renderer.setBorder(null);
        }
        renderer.setPreferredSize(preferredSize);
        return renderer;
    }
}

class ColorComboBoxEditorRendererDemo {

    public ColorComboBoxEditorRendererDemo() {
        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 ColorCellRenderer());
        Color color = (Color) comboBox.getSelectedItem();
        ComboBoxEditor editor = new ColorComboBoxEditor(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[]) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                ColorComboBoxEditorRendererDemo colorComboBoxEditorRendererDemo = new ColorComboBoxEditorRendererDemo();
            }
        });
    } 
}

回答3:

From here, a colour selection button class:

• shows current selected color
• opens a JColorChooser dialog when pressed
• fires events when a color is selected

来源：https://stackoverflow.com/questions/10723115/changing-a-color-chooser-buttons-background-color-in-java