我的游戏（JFrame）上的背景图片

Question

I recently started developing a Java mini-game and I'm stuck at managing to put a background image on my frame. I searched on StackOverflow for this and I found a couple of threads with good suggestions but I simply couldn't implement them on my already done Frame (the things is I found ways to make a new frame and add a background image on the newly created frame with a class, but I already created my frame and I just can't make that code work on my project).

Here is what I found: http://java-demos.blogspot.ro/2012/09/setting-background-image-in-jframe.html

I tried everything but couldn't make it work. The best I could do was putting this line: **frame**.setContentPane(new JLabel(new ImageIcon("C:\\\\Users\\\\Computer\\\\Downloads\\\\colorful design.png")));

This line succesfully set my background image but I couldn't control the square with my keys anymore and I had some errors.

This is my relevant code on which I need help to apply a background image to my Frame (with frame, canvas or panel, any option is welcomed).

    public class Game implements Runnable{ 

   final int WIDTH = 640;
   final int HEIGHT = 480;

   JFrame frame;
   Canvas canvas;
   BufferStrategy bufferStrategy;

   public Game(){

      frame = new JFrame("Basic Game");




      JPanel panel = (JPanel) frame.getContentPane();
      panel.setPreferredSize(new Dimension(WIDTH, HEIGHT));
      panel.setLayout(null);



      canvas = new Canvas();
      canvas.setBounds(0, 0, WIDTH, HEIGHT);
      canvas.setIgnoreRepaint(true);

      panel.add(canvas);
      canvas.addKeyListener(new KeyControl()); //adds the controller 





      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      frame.pack();
      frame.setResizable(false); //non resizable window
      frame.setVisible(true);



      canvas.createBufferStrategy(2);
      bufferStrategy = canvas.getBufferStrategy();

      canvas.requestFocus();

   }

Answer 1

Do not mix AWT components (Canvas) with SWING components (JFrame). It doesn't work. Do something like this.

public class Game extends JFrame {

   public Game() {

       initUI();
   }  

   private void initUI() {

       JLabel background = new JLabel("image.png");
       setContentPane(background);

       pack();
       repaint();

       setResizable(false);
       setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       setLocationRelativeTo(null);
   }

   public static void main(String[] args) {
       EventQueue.invokeLater(new Runnable() {
           @Override
           public void run() {
               Game g = new Game();
               g.setVisible(true);
               running = true;
           }
       });

   }

Answer 2

Remember, java.awt.Canvas (and all AWT components) do not support transparency.

Generally speaking, you shouldn't be mixing BufferStrategy with Swing, as they use different painting process which can cause issues.

Instead of trying to paint the background via a different component, simply paint the background directly to your BufferStrategy and then paint the remaining game state in top of it...