https://openjdk.java.net/ 
/*
 * Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package javax.swing.plaf.synth;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.plaf.*;
import javax.swing.event.*;
import javax.swing.plaf.basic.*;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeEvent;


Provides the Synth L&F UI delegate for JComboBox. 
Author:Scott Violet
Since:1.7
/**
 * Provides the Synth L&F UI delegate for
 * {@link javax.swing.JComboBox}.
 *
 * @author Scott Violet
 * @since 1.7
 */
public class SynthComboBoxUI extends BasicComboBoxUI implements
                              PropertyChangeListener, SynthUI {
    private SynthStyle style;
    private boolean useListColors;

    
Used to adjust the location and size of the popup. Very useful for
situations such as we find in Nimbus where part of the border is used
to paint the focus. In such cases, the border is empty space, and not
part of the "visual" border, and in these cases, you'd like the popup
to be adjusted such that it looks as if it were next to the visual border.
You may want to use negative insets to get the right look.

/**
     * Used to adjust the location and size of the popup. Very useful for
     * situations such as we find in Nimbus where part of the border is used
     * to paint the focus. In such cases, the border is empty space, and not
     * part of the "visual" border, and in these cases, you'd like the popup
     * to be adjusted such that it looks as if it were next to the visual border.
     * You may want to use negative insets to get the right look.
     */
    Insets popupInsets;

    
This flag may be set via UIDefaults. By default, it is false, to
preserve backwards compatibility. If true, then the combo will
"act as a button" when it is not editable.

/**
     * This flag may be set via UIDefaults. By default, it is false, to
     * preserve backwards compatibility. If true, then the combo will
     * "act as a button" when it is not editable.
     */
    private boolean buttonWhenNotEditable;

    
A flag to indicate that the combo box and combo box button should
remain in the PRESSED state while the combo popup is visible.

/**
     * A flag to indicate that the combo box and combo box button should
     * remain in the PRESSED state while the combo popup is visible.
     */
    private boolean pressedWhenPopupVisible;

    
When buttonWhenNotEditable is true, this field is used to help make
the combo box appear and function as a button when the combo box is
not editable. In such a state, you can click anywhere on the button
to get it to open the popup. Also, anywhere you hover over the combo
will cause the entire combo to go into "rollover" state, and anywhere
you press will go into "pressed" state. This also keeps in sync the
state of the combo and the arrowButton.

/**
     * When buttonWhenNotEditable is true, this field is used to help make
     * the combo box appear and function as a button when the combo box is
     * not editable. In such a state, you can click anywhere on the button
     * to get it to open the popup. Also, anywhere you hover over the combo
     * will cause the entire combo to go into "rollover" state, and anywhere
     * you press will go into "pressed" state. This also keeps in sync the
     * state of the combo and the arrowButton.
     */
    private ButtonHandler buttonHandler;

    
Handler for repainting combo when editor component gains/looses focus

/**
     * Handler for repainting combo when editor component gains/looses focus
     */
    private EditorFocusHandler editorFocusHandler;

    
If true, then the cell renderer will be forced to be non-opaque when
used for rendering the selected item in the combo box (not in the list),
and forced to opaque after rendering the selected value.

/**
     * If true, then the cell renderer will be forced to be non-opaque when
     * used for rendering the selected item in the combo box (not in the list),
     * and forced to opaque after rendering the selected value.
     */
    private boolean forceOpaque = false;

    
Creates a new UI object for the given component.

Params:
  • c – component to create UI object for
Returns:the UI object
/**
     * Creates a new UI object for the given component.
     *
     * @param c component to create UI object for
     * @return the UI object
     */
    public static ComponentUI createUI(JComponent c) {
        return new SynthComboBoxUI();
    }

    
{@inheritDoc}
Overridden to ensure that ButtonHandler is created prior to any of
the other installXXX methods, since several of them reference
buttonHandler.

/**
     * {@inheritDoc}
     *
     * Overridden to ensure that ButtonHandler is created prior to any of
     * the other installXXX methods, since several of them reference
     * buttonHandler.
     */
    @Override
    public void installUI(JComponent c) {
        buttonHandler = new ButtonHandler();
        super.installUI(c);
    }

    @Override
    protected void installDefaults() {
        updateStyle(comboBox);
    }

    private void updateStyle(JComboBox<?> comboBox) {
        SynthStyle oldStyle = style;
        SynthContext context = getContext(comboBox, ENABLED);

        style = SynthLookAndFeel.updateStyle(context, this);
        if (style != oldStyle) {
            padding = (Insets) style.get(context, "ComboBox.padding");
            popupInsets = (Insets)style.get(context, "ComboBox.popupInsets");
            useListColors = style.getBoolean(context,
                    "ComboBox.rendererUseListColors", true);
            buttonWhenNotEditable = style.getBoolean(context,
                    "ComboBox.buttonWhenNotEditable", false);
            pressedWhenPopupVisible = style.getBoolean(context,
                    "ComboBox.pressedWhenPopupVisible", false);
            squareButton = style.getBoolean(context,
                    "ComboBox.squareButton", true);

            if (oldStyle != null) {
                uninstallKeyboardActions();
                installKeyboardActions();
            }
            forceOpaque = style.getBoolean(context,
                    "ComboBox.forceOpaque", false);
        }

        if(listBox != null) {
            SynthLookAndFeel.updateStyles(listBox);
        }
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected void installListeners() {
        comboBox.addPropertyChangeListener(this);
        comboBox.addMouseListener(buttonHandler);
        editorFocusHandler = new EditorFocusHandler(comboBox);
        super.installListeners();
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    public void uninstallUI(JComponent c) {
        if (popup instanceof SynthComboPopup) {
            ((SynthComboPopup)popup).removePopupMenuListener(buttonHandler);
        }
        super.uninstallUI(c);
        buttonHandler = null;
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected void uninstallDefaults() {
        SynthContext context = getContext(comboBox, ENABLED);

        style.uninstallDefaults(context);
        style = null;
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected void uninstallListeners() {
        editorFocusHandler.unregister();
        comboBox.removePropertyChangeListener(this);
        comboBox.removeMouseListener(buttonHandler);
        buttonHandler.pressed = false;
        buttonHandler.over = false;
        super.uninstallListeners();
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    public SynthContext getContext(JComponent c) {
        return getContext(c, getComponentState(c));
    }

    private SynthContext getContext(JComponent c, int state) {
        return SynthContext.getContext(c, style, state);
    }

    private int getComponentState(JComponent c) {
        // currently we have a broken situation where if a developer
        // takes the border from a JComboBox and sets it on a JTextField
        // then the codepath will eventually lead back to this method
        // but pass in a JTextField instead of JComboBox! In case this
        // happens, we just return the normal synth state for the component
        // instead of doing anything special
        if (!(c instanceof JComboBox)) return SynthLookAndFeel.getComponentState(c);

        JComboBox<?> box = (JComboBox)c;
        if (shouldActLikeButton()) {
            int state = ENABLED;
            if ((!c.isEnabled())) {
                state = DISABLED;
            }
            if (buttonHandler.isPressed()) {
                state |= PRESSED;
            }
            if (buttonHandler.isRollover()) {
                state |= MOUSE_OVER;
            }
            if (box.isFocusOwner()) {
                state |= FOCUSED;
            }
            return state;
        } else {
            // for editable combos the editor component has the focus not the
            // combo box its self, so we should make the combo paint focused
            // when its editor has focus
            int basicState = SynthLookAndFeel.getComponentState(c);
            if (box.isEditable() &&
                     box.getEditor().getEditorComponent().isFocusOwner()) {
                basicState |= FOCUSED;
            }
            return basicState;
        }
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected ComboPopup createPopup() {
        SynthComboPopup p = new SynthComboPopup(comboBox);
        p.addPopupMenuListener(buttonHandler);
        return p;
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected ListCellRenderer<Object> createRenderer() {
        return new SynthComboBoxRenderer();
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected ComboBoxEditor createEditor() {
        return new SynthComboBoxEditor();
    }

    //
    // end UI Initialization
    //======================

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    public void propertyChange(PropertyChangeEvent e) {
        if (SynthLookAndFeel.shouldUpdateStyle(e)) {
            updateStyle(comboBox);
        }
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected JButton createArrowButton() {
        SynthArrowButton button = new SynthArrowButton(SwingConstants.SOUTH);
        button.setName("ComboBox.arrowButton");
        button.setModel(buttonHandler);
        return button;
    }

    //=================================
    // begin ComponentUI Implementation

    
Notifies this UI delegate to repaint the specified component. This method paints the component background, then calls the paint(SynthContext, Graphics) method. 
In general, this method does not need to be overridden by subclasses. All Look and Feel rendering code should reside in the paint method. 
Params:
  • g – the Graphics object used for painting
  • c – the component being painted
See Also:
/**
     * Notifies this UI delegate to repaint the specified component.
     * This method paints the component background, then calls
     * the {@link #paint(SynthContext,Graphics)} method.
     *
     * <p>In general, this method does not need to be overridden by subclasses.
     * All Look and Feel rendering code should reside in the {@code paint} method.
     *
     * @param g the {@code Graphics} object used for painting
     * @param c the component being painted
     * @see #paint(SynthContext,Graphics)
     */
    @Override
    public void update(Graphics g, JComponent c) {
        SynthContext context = getContext(c);

        SynthLookAndFeel.update(context, g);
        context.getPainter().paintComboBoxBackground(context, g, 0, 0,
                                                  c.getWidth(), c.getHeight());
        paint(context, g);
    }

    
Paints the specified component according to the Look and Feel.

This method is not used by Synth Look and Feel. Painting is handled by the paint(SynthContext, Graphics) method. 
Params:
  • g – the Graphics object used for painting
  • c – the component being painted
See Also:
/**
     * Paints the specified component according to the Look and Feel.
     * <p>This method is not used by Synth Look and Feel.
     * Painting is handled by the {@link #paint(SynthContext,Graphics)} method.
     *
     * @param g the {@code Graphics} object used for painting
     * @param c the component being painted
     * @see #paint(SynthContext,Graphics)
     */
    @Override
    public void paint(Graphics g, JComponent c) {
        SynthContext context = getContext(c);

        paint(context, g);
    }

    
Paints the specified component.

Params:
  • context – context for the component being painted
  • g – the Graphics object used for painting
See Also:
/**
     * Paints the specified component.
     *
     * @param context context for the component being painted
     * @param g the {@code Graphics} object used for painting
     * @see #update(Graphics,JComponent)
     */
    protected void paint(SynthContext context, Graphics g) {
        hasFocus = comboBox.hasFocus();
        if ( !comboBox.isEditable() ) {
            Rectangle r = rectangleForCurrentValue();
            paintCurrentValue(g,r,hasFocus);
        }
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    public void paintBorder(SynthContext context, Graphics g, int x,
                            int y, int w, int h) {
        context.getPainter().paintComboBoxBorder(context, g, x, y, w, h);
    }

    
Paints the currently selected item.

/**
     * Paints the currently selected item.
     */
    @Override
    public void paintCurrentValue(Graphics g,Rectangle bounds,boolean hasFocus) {
        ListCellRenderer<Object> renderer = comboBox.getRenderer();
        Component c;

        c = renderer.getListCellRendererComponent(
                listBox, comboBox.getSelectedItem(), -1, false, false );

        // Fix for 4238829: should lay out the JPanel.
        boolean shouldValidate = false;
        if (c instanceof JPanel)  {
            shouldValidate = true;
        }

        if (c instanceof UIResource) {
            c.setName("ComboBox.renderer");
        }

        boolean force = forceOpaque && c instanceof JComponent;
        if (force) {
            ((JComponent)c).setOpaque(false);
        }

        int x = bounds.x, y = bounds.y, w = bounds.width, h = bounds.height;
        if (padding != null) {
            x = bounds.x + padding.left;
            y = bounds.y + padding.top;
            w = bounds.width - (padding.left + padding.right);
            h = bounds.height - (padding.top + padding.bottom);
        }

        currentValuePane.paintComponent(g, c, comboBox, x, y, w, h, shouldValidate);

        if (force) {
            ((JComponent)c).setOpaque(true);
        }
    }

    
Returns:true if this combo box should act as one big button. Typically
only happens when buttonWhenNotEditable is true, and comboBox.isEditable
is false.
/**
     * @return true if this combo box should act as one big button. Typically
     * only happens when buttonWhenNotEditable is true, and comboBox.isEditable
     * is false.
     */
    private boolean shouldActLikeButton() {
        return buttonWhenNotEditable && !comboBox.isEditable();
    }

    
Returns the default size of an empty display area of the combo box using
the current renderer and font.
This method was overridden to use SynthComboBoxRenderer instead of
DefaultListCellRenderer as the default renderer when calculating the
size of the combo box. This is used in the case of the combo not having
any data.

See Also:
Returns:the size of an empty display area
/**
     * Returns the default size of an empty display area of the combo box using
     * the current renderer and font.
     *
     * This method was overridden to use SynthComboBoxRenderer instead of
     * DefaultListCellRenderer as the default renderer when calculating the
     * size of the combo box. This is used in the case of the combo not having
     * any data.
     *
     * @return the size of an empty display area
     * @see #getDisplaySize
     */
    @Override
    protected Dimension getDefaultSize() {
        SynthComboBoxRenderer r = new SynthComboBoxRenderer();
        Dimension d = getSizeForComponent(r.getListCellRendererComponent(listBox, " ", -1, false, false));
        return new Dimension(d.width, d.height);
    }

    
From BasicComboBoxRenderer v 1.18.
Be aware that SynthFileChooserUIImpl relies on the fact that the default
renderer installed on a Synth combo box is a JLabel. If this is changed,
then an assert will fail in SynthFileChooserUIImpl

/**
     * From BasicComboBoxRenderer v 1.18.
     *
     * Be aware that SynthFileChooserUIImpl relies on the fact that the default
     * renderer installed on a Synth combo box is a JLabel. If this is changed,
     * then an assert will fail in SynthFileChooserUIImpl
     */
    @SuppressWarnings("serial") // Superclass is not serializable across versions
    private class SynthComboBoxRenderer extends JLabel implements ListCellRenderer<Object>, UIResource {
        public SynthComboBoxRenderer() {
            super();
            setText(" ");
        }

        @Override
        public String getName() {
            // SynthComboBoxRenderer should have installed Name while constructor is working.
            // The setName invocation in the SynthComboBoxRenderer() constructor doesn't work
            // because of the opaque property is installed in the constructor based on the
            // component name (see GTKStyle.isOpaque())
            String name = super.getName();

            return name == null ? "ComboBox.renderer" : name;
        }

        @Override
        public Component getListCellRendererComponent(JList<?> list, Object value,
                         int index, boolean isSelected, boolean cellHasFocus) {
            setName("ComboBox.listRenderer");
            SynthLookAndFeel.resetSelectedUI();
            if (isSelected) {
                setBackground(list.getSelectionBackground());
                setForeground(list.getSelectionForeground());
                if (!useListColors) {
                    SynthLookAndFeel.setSelectedUI(
                         (SynthLabelUI)SynthLookAndFeel.getUIOfType(getUI(),
                         SynthLabelUI.class), isSelected, cellHasFocus,
                         list.isEnabled(), false);
                }
            } else {
                setBackground(list.getBackground());
                setForeground(list.getForeground());
            }

            setFont(list.getFont());

            if (value instanceof Icon) {
                setIcon((Icon)value);
                setText("");
            } else {
                String text = (value == null) ? " " : value.toString();

                if ("".equals(text)) {
                    text = " ";
                }
                setText(text);
            }

            // The renderer component should inherit the enabled and
            // orientation state of its parent combobox.  This is
            // especially needed for GTK comboboxes, where the
            // ListCellRenderer's state determines the visual state
            // of the combobox.
            if (comboBox != null){
                setEnabled(comboBox.isEnabled());
                setComponentOrientation(comboBox.getComponentOrientation());
            }

            return this;
        }

        @Override
        public void paint(Graphics g) {
            super.paint(g);
            SynthLookAndFeel.resetSelectedUI();
        }
    }


    private static class SynthComboBoxEditor
            extends BasicComboBoxEditor.UIResource {

        @Override public JTextField createEditorComponent() {
            JTextField f = new JTextField("", 9);
            f.setName("ComboBox.textField");
            return f;
        }
    }


    
Handles all the logic for treating the combo as a button when it is
not editable, and when shouldActLikeButton() is true. This class is a
special ButtonModel, and installed on the arrowButton when appropriate.
It also is installed as a mouse listener and mouse motion listener on
the combo box. In this way, the state between the button and combo
are in sync. Whenever one is "over" both are. Whenever one is pressed,
both are.

/**
     * Handles all the logic for treating the combo as a button when it is
     * not editable, and when shouldActLikeButton() is true. This class is a
     * special ButtonModel, and installed on the arrowButton when appropriate.
     * It also is installed as a mouse listener and mouse motion listener on
     * the combo box. In this way, the state between the button and combo
     * are in sync. Whenever one is "over" both are. Whenever one is pressed,
     * both are.
     */
    @SuppressWarnings("serial") // Superclass is not serializable across versions
    private final class ButtonHandler extends DefaultButtonModel
            implements MouseListener, PopupMenuListener {
        
Indicates that the mouse is over the combo or the arrow button.
This field only has meaning if buttonWhenNotEnabled is true.

/**
         * Indicates that the mouse is over the combo or the arrow button.
         * This field only has meaning if buttonWhenNotEnabled is true.
         */
        private boolean over;
        
Indicates that the combo or arrow button has been pressed. This
field only has meaning if buttonWhenNotEnabled is true.

/**
         * Indicates that the combo or arrow button has been pressed. This
         * field only has meaning if buttonWhenNotEnabled is true.
         */
        private boolean pressed;

        //------------------------------------------------------------------
        // State Methods
        //------------------------------------------------------------------

        
Updates the internal "pressed" state. If shouldActLikeButton()
is true, and if this method call will change the internal state,
then the combo and button will be repainted.


Note that this method is called either when a press event
occurs on the combo box, or on the arrow button.


/**
         * <p>Updates the internal "pressed" state. If shouldActLikeButton()
         * is true, and if this method call will change the internal state,
         * then the combo and button will be repainted.</p>
         *
         * <p>Note that this method is called either when a press event
         * occurs on the combo box, or on the arrow button.</p>
         */
        private void updatePressed(boolean p) {
            this.pressed = p && isEnabled();
            if (shouldActLikeButton()) {
                comboBox.repaint();
            }
        }

        
Updates the internal "over" state. If shouldActLikeButton()
is true, and if this method call will change the internal state,
then the combo and button will be repainted.


Note that this method is called either when a mouseover/mouseoff event
occurs on the combo box, or on the arrow button.


/**
         * <p>Updates the internal "over" state. If shouldActLikeButton()
         * is true, and if this method call will change the internal state,
         * then the combo and button will be repainted.</p>
         *
         * <p>Note that this method is called either when a mouseover/mouseoff event
         * occurs on the combo box, or on the arrow button.</p>
         */
        private void updateOver(boolean o) {
            boolean old = isRollover();
            this.over = o && isEnabled();
            boolean newo = isRollover();
            if (shouldActLikeButton() && old != newo) {
                comboBox.repaint();
            }
        }

        //------------------------------------------------------------------
        // DefaultButtonModel Methods
        //------------------------------------------------------------------

        
@inheritDoc
Ensures that isPressed() will return true if the combo is pressed,
or the arrowButton is pressed, or if the combo popup is
visible. This is the case because a combo box looks pressed when
the popup is visible, and so should the arrow button.
/**
         * @inheritDoc
         *
         * Ensures that isPressed() will return true if the combo is pressed,
         * or the arrowButton is pressed, <em>or</em> if the combo popup is
         * visible. This is the case because a combo box looks pressed when
         * the popup is visible, and so should the arrow button.
         */
        @Override
        public boolean isPressed() {
            boolean b = shouldActLikeButton() ? pressed : super.isPressed();
            return b || (pressedWhenPopupVisible && comboBox.isPopupVisible());
        }

        
@inheritDoc
Ensures that the armed state is in sync with the pressed state
if shouldActLikeButton is true. Without this method, the arrow
button will not look pressed when the popup is open, regardless
of the result of isPressed() alone.
/**
         * @inheritDoc
         *
         * Ensures that the armed state is in sync with the pressed state
         * if shouldActLikeButton is true. Without this method, the arrow
         * button will not look pressed when the popup is open, regardless
         * of the result of isPressed() alone.
         */
        @Override
        public boolean isArmed() {
            boolean b = shouldActLikeButton() ||
                        (pressedWhenPopupVisible && comboBox.isPopupVisible());
            return b ? isPressed() : super.isArmed();
        }

        
@inheritDoc
Ensures that isRollover() will return true if the combo is
rolled over, or the arrowButton is rolled over.
/**
         * @inheritDoc
         *
         * Ensures that isRollover() will return true if the combo is
         * rolled over, or the arrowButton is rolled over.
         */
        @Override
        public boolean isRollover() {
            return shouldActLikeButton() ? over : super.isRollover();
        }

        
@inheritDoc
Forwards pressed states to the internal "pressed" field
/**
         * @inheritDoc
         *
         * Forwards pressed states to the internal "pressed" field
         */
        @Override
        public void setPressed(boolean b) {
            super.setPressed(b);
            updatePressed(b);
        }

        
@inheritDoc
Forwards rollover states to the internal "over" field
/**
         * @inheritDoc
         *
         * Forwards rollover states to the internal "over" field
         */
        @Override
        public void setRollover(boolean b) {
            super.setRollover(b);
            updateOver(b);
        }

        //------------------------------------------------------------------
        // MouseListener/MouseMotionListener Methods
        //------------------------------------------------------------------

        @Override
        public void mouseEntered(MouseEvent mouseEvent) {
            updateOver(true);
        }

        @Override
        public void mouseExited(MouseEvent mouseEvent) {
            updateOver(false);
        }

        @Override
        public void mousePressed(MouseEvent mouseEvent) {
            updatePressed(true);
        }

        @Override
        public void mouseReleased(MouseEvent mouseEvent) {
            updatePressed(false);
        }

        @Override
        public void mouseClicked(MouseEvent e) {}

        //------------------------------------------------------------------
        // PopupMenuListener Methods
        //------------------------------------------------------------------

        
@inheritDoc
Ensures that the combo box is repainted when the popup is closed.
This avoids a bug where clicking off the combo wasn't causing a repaint,
and thus the combo box still looked pressed even when it was not.
This bug was only noticed when acting as a button, but may be generally
present. If so, remove the if() block
/**
         * @inheritDoc
         *
         * Ensures that the combo box is repainted when the popup is closed.
         * This avoids a bug where clicking off the combo wasn't causing a repaint,
         * and thus the combo box still looked pressed even when it was not.
         *
         * This bug was only noticed when acting as a button, but may be generally
         * present. If so, remove the if() block
         */
        @Override
        public void popupMenuCanceled(PopupMenuEvent e) {
            if (shouldActLikeButton() || pressedWhenPopupVisible) {
                comboBox.repaint();
            }
        }

        @Override
        public void popupMenuWillBecomeVisible(PopupMenuEvent e) {}
        @Override
        public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {}
    }

    
Handler for repainting combo when editor component gains/looses focus

/**
     * Handler for repainting combo when editor component gains/looses focus
     */
    private static class EditorFocusHandler implements FocusListener,
            PropertyChangeListener {
        private JComboBox<?> comboBox;
        private ComboBoxEditor editor = null;
        private Component editorComponent = null;

        private EditorFocusHandler(JComboBox<?> comboBox) {
            this.comboBox = comboBox;
            editor = comboBox.getEditor();
            if (editor != null){
                editorComponent = editor.getEditorComponent();
                if (editorComponent != null){
                    editorComponent.addFocusListener(this);
                }
            }
            comboBox.addPropertyChangeListener("editor",this);
        }

        public void unregister(){
            comboBox.removePropertyChangeListener(this);
            if (editorComponent!=null){
                editorComponent.removeFocusListener(this);
            }
        }

        
Invoked when a component gains the keyboard focus. 
/** Invoked when a component gains the keyboard focus. */
        public void focusGained(FocusEvent e) {
            // repaint whole combo on focus gain
            comboBox.repaint();
        }

        
Invoked when a component loses the keyboard focus. 
/** Invoked when a component loses the keyboard focus. */
        public void focusLost(FocusEvent e) {
            // repaint whole combo on focus loss
            comboBox.repaint();
        }

        
Called when the combos editor changes

Params:
  • evt – A PropertyChangeEvent object describing the event source and
           the property that has changed.
/**
         * Called when the combos editor changes
         *
         * @param evt A PropertyChangeEvent object describing the event source and
         *            the property that has changed.
         */
        public void propertyChange(PropertyChangeEvent evt) {
            ComboBoxEditor newEditor = comboBox.getEditor();
            if (editor != newEditor){
                if (editorComponent!=null){
                    editorComponent.removeFocusListener(this);
                }
                editor = newEditor;
                if (editor != null){
                    editorComponent = editor.getEditorComponent();
                    if (editorComponent != null){
                        editorComponent.addFocusListener(this);
                    }
                }
            }
        }
    }
}