自由控制下拉框出现的位置的JCombobox

package Custom;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.util.Vector;

import javax.swing.BorderFactory;
import javax.swing.ComboBoxModel;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JDialog;
import javax.swing.JList;
import javax.swing.event.PopupMenuEvent;
import javax.swing.event.PopupMenuListener;
import javax.swing.plaf.basic.BasicComboBoxRenderer;
import javax.swing.plaf.basic.BasicComboPopup;
import javax.swing.plaf.basic.ComboPopup;
import javax.swing.plaf.metal.MetalComboBoxUI;

public class ControlableComboBox extends JComboBox {

    protected int popupWidth;
    
    protected boolean orientation;
    
    private ControlableComboBoxUI controlableComboBoxUI;

    public ControlableComboBox(ComboBoxModel aModel) {
        super(aModel);
        this.controlableComboBoxUI = new ControlableComboBoxUI();
        setUI(this.controlableComboBoxUI);
        popupWidth = 0;
    }

    public ControlableComboBox(Object[] items) {
        super(items);
        this.controlableComboBoxUI = new ControlableComboBoxUI();
        setUI(this.controlableComboBoxUI);
        popupWidth = 0;
    }

    public ControlableComboBox(Vector items) {
        super(items);
        this.controlableComboBoxUI = new ControlableComboBoxUI();
        setUI(this.controlableComboBoxUI);
        popupWidth = 0;
    }
    
    public void setPopupWidth(int width) {
        popupWidth = width;
    }
    
    public Dimension getPopupSize() {
        Dimension size = getSize();
        if (popupWidth < 1) {
            popupWidth = size.width;
        }
        return new Dimension(popupWidth, size.height);
    }
    
    public boolean isOrientation() {
        return orientation;
    }

    public void setOrientation(boolean orientation) {
        this.orientation = orientation;
    }

    private Color buttonBackgroundColor;

    public Color getButtonBackground() {
        return buttonBackgroundColor;
    }

    public void setButtonBackground(Color backgroundColor) {
        this.buttonBackgroundColor = backgroundColor;
        this.controlableComboBoxUI.setButtonBackground(backgroundColor);
    }
    
    public class ControlableComboBoxUI extends MetalComboBoxUI {
        
        public void setButtonBackground(Color color){
            if (buttonBackgroundColor!=null){
                Dimension dimension = this.getDisplaySize();
                BufferedImage brighterImage1 = new BufferedImage(dimension.height, dimension.height, BufferedImage.TYPE_INT_RGB);
                Graphics2D graphics = brighterImage1.createGraphics();
                graphics.setColor(buttonBackgroundColor);
                graphics.fillRect(0, 0, dimension.height, dimension.height);
                graphics.drawImage(brighterImage1, 0, 0, null);
    
                arrowButton.setIcon(new ImageIcon(brighterImage1));
    
                BufferedImage brighterImage2 = new BufferedImage(dimension.height, dimension.height, BufferedImage.TYPE_INT_RGB);
                Graphics2D graphics1 = brighterImage2.createGraphics();
                graphics1.setColor(buttonBackgroundColor.darker());
                graphics1.fillRect(0, 0, dimension.height, dimension.height);
                graphics1.drawImage(brighterImage2, 0, 0, null);

                arrowButton.setPressedIcon(new ImageIcon(brighterImage2));
            }
        }

        protected JButton createArrowButton(){
            arrowButton = super.createArrowButton();
            arrowButton.setMargin(new Insets(0, 0, 0, 0));
            arrowButton.setBorderPainted(false);
            return arrowButton;
        }
        public void paintCurrentValue(Graphics g, Rectangle bounds, boolean hasFocus) {
                bounds.x -= 2;
                bounds.width += 3;
                if (arrowButton != null) {
                    Insets buttonInsets = arrowButton.getInsets();
                    bounds.y -= buttonInsets.top;
                    bounds.height += (buttonInsets.top + buttonInsets.bottom);
                }else {
                    bounds.x += 2;
                    bounds.width -= 4;
                }
                if (bounds.width==0){
                    bounds.width = 1;
                }
                if (bounds.height==0){
                    bounds.height = 1;
                }
                super.paintCurrentValue(g, bounds, hasFocus);
        }

        protected ComboPopup createPopup() {
            BasicComboPopup basicComboPopup = new BasicComboPopup(comboBox) {
                public void show() {
                    Dimension popupSize = ((ControlableComboBox) comboBox).getPopupSize();
                    popupSize.setSize(popupSize.width, getPopupHeightForRowCount(comboBox.getMaximumRowCount()));
                    Rectangle popupBounds = computePopupBounds(0, comboBox.getBounds().height, popupSize.width, popupSize.height);

                    scroller.setPreferredSize(popupBounds.getSize());
                    
//                    scroller.setMaximumSize(popupBounds.getSize());
//                    scroller.setMinimumSize(popupBounds.getSize());
//                    list.invalidate();
//                    int selectedIndex = comboBox.getSelectedIndex();
//                    if (selectedIndex == -1) {
//                        list.clearSelection();
//                    } else {
//                        list.setSelectedIndex(selectedIndex);
//                    }
//                    list.ensureIndexIsVisible(list.getSelectedIndex());
//                    setLightWeightPopupEnabled(comboBox.isLightWeightPopupEnabled());

                    int x = 0;
                    if (comboBox instanceof ControlableComboBox){
                        ControlableComboBox box = (ControlableComboBox) comboBox;
                        if (box.orientation){
//                            x += 1;
                        }else{
                            x = popupSize.width-comboBox.getWidth();
                        }
                    }
                    
                    int y = popupBounds.y;
                    if (y<0){
                        y-=2;
                    }
    
                    show(comboBox, popupBounds.x-x-1, y);
                }
            };
            basicComboPopup.getAccessibleContext().setAccessibleParent(comboBox);
            return basicComboPopup;
        }
        
    }
    

    public static void main(String[] args){
        JDialog dialog = new JDialog();
        
        ControlableComboBox comboBox = new ControlableComboBox(new String[]{"fewfwe", "43r43r43"});
        comboBox.setBorder(BorderFactory.createEmptyBorder());
        comboBox.setPopupWidth(200);
        comboBox.setPreferredSize(new Dimension(21, 23));
        comboBox.setOpaque(false);
        
//        comboBox.setButtonBackground(Color.RED);
        
        BasicComboBoxRenderer defaultListCellRenderer = new BasicComboBoxRenderer(){
            public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
                list.setOpaque(false);
                return super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
            }};
        comboBox.setRenderer(defaultListCellRenderer);
        
        comboBox.addPopupMenuListener(new PopupMenuListener(){
            public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
                JComboBox comboBox = (JComboBox) e.getSource();
                if (comboBox.getSelectedIndex()==1){
                    System.out.println(comboBox.getSelectedItem().toString());
                }
            }
            public void popupMenuCanceled(PopupMenuEvent e) {}
            public void popupMenuWillBecomeVisible(PopupMenuEvent e) {}
        });
        
        dialog.add(comboBox);
        dialog.setSize(50, 50);
        dialog.setLocation(150, 150);
        dialog.setVisible(true);
        dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
    }

}