An Image JPanel, A semi-transparent JPanel, and non-opaque components

Question

This is a more intelligent re-asking of the question I posed here: http://forum.java.sun.com/thread.jspa?threadID=579298&tstart=50.
I have a class called ImagePane, which is basically a JPanel with an image background. The code is much like the ImagePanel posted by camickr, discussed in this topic: http://forum.java.sun.com/thread.jspa?forumID=57&threadID=316074 (except mine only draws the image, it does not tile or scale it).
On top of my ImagePane, I can place another component, TransparentContainer. This again extends JPanel, only a color is specified in the constructor, and it is drawn at about 70% opacity. This component is meant to help increase the readability of text components that blend with the background image, without blocking out the background image completely.
This works very well, until I need to add a component, like, say, a non-opaque JRadioButton in a ButtonGroup. When you select a new JRadioButton at runtime, the semi-transparent JPanel fills with a combination of a completely opaque color (the one specifies to the TransparentContainer) and garbage from the non-opaque component being redrawn.
I have noticed that the UI is restored to being non-messed up if you place another application window on top of it and then move it. So apparently, one solution is to redraw the entire UI, or just the part that has the JRadioButton on it, every time the radio button is clicked. However, this seems unnecessarily complicated. It seems to me that I am missing something in my TransparentContainer's paintComponent() method. Does anyone have any ideas?
Here is my TransparentContainer code, if it will help:
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.JPanel;
public final class TransparentContainer extends JPanel
     /* Private Fields: For use only by this class.
      *  These fields hold information needed by more
      *  than one method of this class.
     private boolean fullTransparencyEnabled;
     private Color baseColor;
     private Color outerBorderColor;
     private Color innerBorderColor;
     private int obw;
     private int ibw;
     private int cbw;
     /* -- START OF METHODS -- */
     /* public TransparentContainer(Color color, boolean fullTrans)
      *   Initiallizes the transparent container object
      *   with 'color' as its base color.
     public TransparentContainer(Color color, boolean fullTrans)
          fullTransparencyEnabled = fullTrans;
          baseColor = color;
          Color borders[] = findBorderColors();
          outerBorderColor = borders[0];
          innerBorderColor = borders[1];
          obw = 3;
          ibw = 1;
          cbw = obw + ibw;
     /* private Color[] findBorderColors(Color base)
      *   Calculates the colors for the outer and inner
      *   borders of the object based on the base color.
     private Color[] findBorderColors()
          Color borders[] = new Color[2];
          int colorData[] = new int[9];
          colorData[0] = getBaseColor().getRed();
          colorData[1] = getBaseColor().getGreen();
          colorData[2] = getBaseColor().getBlue();
          colorData[3] = colorData[0] - 50;          // outerBorder red
          colorData[4] = colorData[1] - 45;          // outerBorder green
          colorData[5] = colorData[2] - 35;          // outerBorder blue
          colorData[6] = colorData[0] + 30;          // innerBorder red
          colorData[7] = colorData[1] + 30;          // innerBorder green
          colorData[8] = colorData[2] + 20;          // innerBorder blue
          /* Make sure the new color data is not out of bounds: */
          for (int i = 3; i < colorData.length; i++)
               if (colorData[i] > 255)
                    colorData[i] = 255;
               else if (colorData[i] < 0)
                    colorData[i] = 0;
          borders[0] = new Color(colorData[3], colorData[4], colorData[5]);
          borders[1] = new Color(colorData[6], colorData[7], colorData[8]);
          return borders;
     /* public Color getBaseColor()
      *   Returns the baseColor of this object.
     public Color getBaseColor()
          return baseColor;
     /* public Color getOuterColor()
      *   Returns the outerBorderColor of this object.
     public Color getOuterColor()
          return outerBorderColor;
     /* public Color getInnerColor()
      *   Returns the innerBorderColor of this object.
     public Color getInnerColor()
          return innerBorderColor;
     /* public boolean getFullTransEnabled()
      *   Returns whether or not this object will render
      *   with all of its transparency effects.
     public boolean getFullTransEnabled()
          return fullTransparencyEnabled;
     /* protected void paintComponent(Graphics g)
      *   Paints the component with the borders and colors
      *   that were set up in above methods.
     protected void paintComponent(Graphics g)
          Graphics2D g2d = (Graphics2D) g;
          AlphaComposite alphaComp;
          g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
          g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
          g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION,
                                        RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
          g2d.setColor(getBaseColor());
          /* Draw the main body of the component */
          if (getFullTransEnabled())
               alphaComp = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.6f);
               g2d.setComposite(alphaComp);
          else
               alphaComp = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1.0f);
               g2d.setComposite(alphaComp);
          g2d.fillRect(cbw, cbw, super.getWidth() - 2 * cbw, super.getHeight() - 2 * cbw);
          alphaComp = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.6f);
          g2d.setComposite(alphaComp);
          /* Draw the inner border: */
          g2d.setColor(getInnerColor());
          g2d.fillRect(obw, obw, ibw, super.getHeight() - obw * 2); // left border
          g2d.fillRect(obw, obw, super.getWidth() - obw, ibw); // top border
          g2d.fillRect(super.getWidth() - cbw, obw, ibw, super.getHeight() - obw * 2); // right border
          g2d.fillRect(obw, super.getHeight() - cbw, super.getWidth() - obw * 2, ibw); // bottom border
          /* Draw the outer border: */
          g2d.setColor(getOuterColor());
          g2d.fillRect(0, 0, obw, super.getHeight()); // left border
          g2d.fillRect(0, 0, super.getWidth() + obw, obw); // top border
          g2d.fillRect(super.getWidth() - obw, 0, obw, super.getHeight()); // right border
          g2d.fillRect(0, super.getHeight() - obw, super.getWidth(), obw); // bottom border
          alphaComp = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1.0f);
          g2d.setComposite(alphaComp);
          g2d.dispose();
}

Answer 1

I added the main method to your TransparentContainer class ...
     public static void main(String[] args) {
          JFrame f = new JFrame("test transparent container");
          f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          TransparentContainer tc = new TransparentContainer(Color.RED, true);
          JLabel label = new JLabel("Hello, World!");
          tc.add(label);
          f.getContentPane().add(tc);
          f.setSize(800, 600);
          f.setVisible(true);
     }...using the code you posted the label was not shown. I modified your paintComponent(Graphics g) method and I did this (see the areas in bold):
     /* protected void paintComponent(Graphics g)
      *   Paints the component with the borders and colors
      *   that were set up in above methods.
     protected void paintComponent(Graphics g)
          // Call super so components added to this panel are visible
          super.paintComponent(g);
          Graphics2D g2d = (Graphics2D) g;
          AlphaComposite alphaComp;
          g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
          g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
          g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION,
                                        RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
          g2d.setColor(getBaseColor());
          /* Draw the main body of the component */
          if (getFullTransEnabled())
               alphaComp = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.6f);
               g2d.setComposite(alphaComp);
          else
               alphaComp = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1.0f);
               g2d.setComposite(alphaComp);
          g2d.fillRect(cbw, cbw, super.getWidth() - 2 * cbw, super.getHeight() - 2 * cbw);
          alphaComp = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.6f);
          g2d.setComposite(alphaComp);
          /* Draw the inner border: */
          g2d.setColor(getInnerColor());
          g2d.fillRect(obw, obw, ibw, super.getHeight() - obw * 2); // left border
          g2d.fillRect(obw, obw, super.getWidth() - obw, ibw); // top border
          g2d.fillRect(super.getWidth() - cbw, obw, ibw, super.getHeight() - obw * 2); // right border
          g2d.fillRect(obw, super.getHeight() - cbw, super.getWidth() - obw * 2, ibw); // bottom border
          /* Draw the outer border: */
          g2d.setColor(getOuterColor());
          g2d.fillRect(0, 0, obw, super.getHeight()); // left border
          g2d.fillRect(0, 0, super.getWidth() + obw, obw); // top border
          g2d.fillRect(super.getWidth() - obw, 0, obw, super.getHeight()); // right border
          g2d.fillRect(0, super.getHeight() - obw, super.getWidth(), obw); // bottom border
          alphaComp = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1.0f);
          g2d.setComposite(alphaComp);
          // Do not dispose the graphics
          // g2d.dispose();          
     }...seems to work fine now. Perhaps you should also add methods or additional constructors so the user can easily change the transparency level...and add some javadoc comments to your constructors ...at a first glance I did not know what fullTrans was
public TransparentContainer(Color color, boolean fullTrans)good luck!!