package com.explodingpixels.widgets.plaf;
import javax.swing.ButtonGroup;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JComboBox;
import javax.swing.JList;
import javax.swing.JMenuItem;
import javax.swing.JPopupMenu;
import javax.swing.MenuElement;
import javax.swing.MenuSelectionManager;
import javax.swing.SwingUtilities;
import javax.swing.plaf.basic.ComboPopup;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Insets;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionAdapter;
import java.awt.event.MouseMotionListener;
/**
* An implementation of {@link ComboPopup} that uses actual {@link JMenuItem}s rather than a
* {@link JList} to display it's contents.
*/
public class EPComboPopup implements ComboPopup {
private final JComboBox fComboBox;
private JPopupMenu fPopupMenu = new JPopupMenu();
private Font fFont;
private ComboBoxVerticalCenterProvider fComboBoxVerticalCenterProvider =
new DefaultVerticalCenterProvider();
private static final int LEFT_SHIFT = 5;
public EPComboPopup(JComboBox comboBox) {
fComboBox = comboBox;
fFont = comboBox.getFont();
}
public void setFont(Font font) {
fFont = font;
}
public void setVerticalComponentCenterProvider(
ComboBoxVerticalCenterProvider comboBoxVerticalCenterProvider) {
if (comboBoxVerticalCenterProvider == null) {
throw new IllegalArgumentException("The given CompnonentCenterProvider cannot be null.");
}
fComboBoxVerticalCenterProvider = comboBoxVerticalCenterProvider;
}
private void togglePopup() {
if (isVisible()) {
hide();
} else {
show();
}
}
private void clearAndFillMenu() {
fPopupMenu.removeAll();
ButtonGroup buttonGroup = new ButtonGroup();
// add the given items to the popup menu.
for (int i = 0; i < fComboBox.getModel().getSize(); i++) {
Object item = fComboBox.getModel().getElementAt(i);
JMenuItem menuItem = new JCheckBoxMenuItem(item.toString());
menuItem.setFont(fFont);
menuItem.addActionListener(createMenuItemListener(item));
buttonGroup.add(menuItem);
fPopupMenu.add(menuItem);
// if the current item is selected, make the menu item reflect that.
if (item.equals(fComboBox.getModel().getSelectedItem())) {
menuItem.setSelected(true);
fPopupMenu.setSelected(menuItem);
}
}
fPopupMenu.pack();
int popupWidth = fComboBox.getWidth() + 5;
int popupHeight = fPopupMenu.getPreferredSize().height;
fPopupMenu.setPreferredSize(new Dimension(popupWidth, popupHeight));
}
private Point placePopupOnScreen() {
// grab the right most location of the button.
int buttonRightX = fComboBox.getWidth();
// figure out how the height of a menu item.
Insets insets = fPopupMenu.getInsets();
// calculate the x and y value at which to place the popup menu.
// by default, this will place the selected menu item in the
// popup item directly over the button.
int x = buttonRightX - fPopupMenu.getPreferredSize().width - LEFT_SHIFT;
int selectedItemIndex = fPopupMenu.getSelectionModel().getSelectedIndex();
int componentCenter = fComboBoxVerticalCenterProvider.provideCenter(fComboBox);
int menuItemHeight = fPopupMenu.getComponent(selectedItemIndex).getPreferredSize().height;
int menuItemCenter = insets.top + (selectedItemIndex * menuItemHeight) + menuItemHeight / 2;
int y = componentCenter - menuItemCenter;
// do a cursory check to make sure we're not placing the popup
// off the bottom of the screen. note that Java on Mac won't
// let the popup show up off screen no matter where you place it.
Dimension size = Toolkit.getDefaultToolkit().getScreenSize();
Point bottomOfMenuOnScreen = new Point(0, y + fPopupMenu.getPreferredSize().height);
SwingUtilities.convertPointToScreen(bottomOfMenuOnScreen, fComboBox);
if (bottomOfMenuOnScreen.y > size.height) {
y = fComboBox.getHeight() - fPopupMenu.getPreferredSize().height;
}
return new Point(x, y);
}
private ActionListener createMenuItemListener(final Object comboBoxItem) {
return new ActionListener() {
public void actionPerformed(ActionEvent e) {
fComboBox.setSelectedItem(comboBoxItem);
}
};
}
private void forceCorrectPopupSelection() {
assert fPopupMenu.isShowing() : "The popup must be showing for this method to work properly.";
// force the correct item to be shown as selected. this is a
// work around for Java bug 4740942, which has been fixed by
// Sun, but not by Apple.
int index = fPopupMenu.getSelectionModel().getSelectedIndex();
MenuElement[] menuPath = new MenuElement[2];
menuPath[0] = fPopupMenu;
menuPath[1] = fPopupMenu.getSubElements()[index];
MenuSelectionManager.defaultManager().setSelectedPath(menuPath);
}
// ComboPopup implementation. /////////////////////////////////////////////////////////////////
public void show() {
clearAndFillMenu();
Point popupLocation = placePopupOnScreen();
fPopupMenu.show(fComboBox, popupLocation.x, popupLocation.y);
forceCorrectPopupSelection();
}
public void hide() {
fPopupMenu.setVisible(false);
}
public boolean isVisible() {
return fPopupMenu.isVisible();
}
/**
* This method is not implemented and would throw an {@link UnsupportedOperationException} if
* {@link javax.swing.plaf.basic.BasicComboBoxUI} didn't call it. Thus, this method should not
* be used, as it always returns null.
*
* @return null.
*/
public JList getList() {
return null;
}
public MouseListener getMouseListener() {
return new MouseAdapter() {
@Override
public void mousePressed(MouseEvent e) {
// TODO add more detailed logic.
togglePopup();
}
@Override
public void mouseReleased(MouseEvent e) {
MenuSelectionManager.defaultManager().processMouseEvent(e);
}
};
}
public MouseMotionListener getMouseMotionListener() {
return new MouseMotionAdapter() {
@Override
public void mouseDragged(MouseEvent e) {
MenuSelectionManager.defaultManager().processMouseEvent(e);
}
};
}
public KeyListener getKeyListener() {
return null;
}
public void uninstallingUI() {
// TODO implement, if necessary.
}
// An interface to allow a third-party to provide the center of a given compoennt. ////////////
public interface ComboBoxVerticalCenterProvider {
int provideCenter(JComboBox comboBox);
}
// A default implementation of ComboBoxVerticalCenterProvider. ////////////////////////////////
private static class DefaultVerticalCenterProvider implements ComboBoxVerticalCenterProvider {
public int provideCenter(JComboBox comboBox) {
return comboBox.getHeight() / 2;
}
}
}