Jbutton在Jbutton背景图片上吗？

Question

可以说我创建了一个带有jbutton的2d瓦片地图，然后在地图顶部创建了单位，当单位（也是jbutton）位于瓦片上方时，有一种方法可以显示地图背景，因为现在单元的背景只是被涂成红色，是否可以通过jbuttons而不是jbuttons来做到这一点？

Answer 1

If the Topmost JButton being Translucent can solve your purpose, here is one example code, how you can do that. Simply change the AlphaComposite values ie 0.7f , used in my case, to whatever deemed fit for your instance of the code :

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.FlowLayout;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.net.URL;

import javax.swing.*;

public class TransparentButton
{       
    private CustomButton button;
    private ImageIcon backgroundImage;

    private void displayGUI()
    {
        JFrame frame = new JFrame("Transparent Button");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel contentPane = new JPanel();
        contentPane.setOpaque(true);
        contentPane.setBackground(Color.BLUE);

        try
        {
            backgroundImage = new ImageIcon(
                    new URL("http://gagandeepbali.uk.to/" + 
                            "gaganisonline/images/404error.jpg"));
        }
        catch(IOException ioe)
        {
            ioe.printStackTrace();
        }

        JButton baseButton = new JButton(backgroundImage);
        baseButton.setOpaque(true);
        baseButton.setLayout(new FlowLayout(FlowLayout.LEFT, 5, 5));

        button = new CustomButton("Transparent Button");
        baseButton.add(button);

        contentPane.add(baseButton);
        frame.setContentPane(contentPane);
        frame.setSize(300, 300);
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new TransparentButton().displayGUI();
            }
        });
    }
}

class CustomButton extends JButton
{
    private BufferedImage buttonImage = null;

    public CustomButton(String title)
    {
        super(title);
        setOpaque(false);
    }

    @Override
    public void paint(Graphics g)
    {
        if (buttonImage == null ||
                buttonImage.getWidth() != getWidth() ||
                    buttonImage.getHeight() != getHeight())
        {
            buttonImage = (BufferedImage) createImage(
                                getWidth(), getHeight());                               
        }   

        Graphics gButton = buttonImage.getGraphics();
        gButton.setClip(g.getClip());
        super.paint(gButton);
        /*
         * Make the graphics object sent to 
         * this paint() method translucent.
         */     
        Graphics2D g2 = (Graphics2D) g;
        AlphaComposite newComposite = 
            AlphaComposite.getInstance(
                AlphaComposite.SRC_OVER, 0.7f);
        g2.setComposite(newComposite);      
        /*
         * Copy the JButton's image to the destination
         * graphics, translucently.      
         */         
        g2.drawImage(buttonImage, 0, 0, null);          
    }
}

Here is the output of the same :

Answer 2

Possible, yes, advisable, ah, probably not.

I believe you're going to need to change the layout of the title button to something you can control (this is going to depend upon your visual requirements).

I, personally, would probably go for a panel with a label inside it, using mouse listeners to monitor for mouse actions & probably input/action maps for keyboard interaction.

Jbuttons are just jcomponent, so they get all the functionality that jcomponents have