Using GradientPaint and Swing Components

[John Macek]

Is there is any way to use GradientPaint to have my swing components with a gradiated background? I want to have a Jpanel that shades from one color to another from top to bottom. I am using the JPanel in an extension of the JDialog class. I have tried overriding the paint method in my extension of JDialog and calling Graphics2D's setPaint method to use a GradientPaint. I have also tried calling the JPanel's getGraphics method and using setPaint on that. None of this has made any difference. The runtime class of each Graphics is SunGraphics2D. I have been unable to find source code for this class.
Any help would be greatly appreciated.
Thanks,
John

[Nathan Pruett]

Here's some example code I made for a JPanel that has a GradientPaint background... Hopefully this helps you out...

import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
 
public class GradientPanel extends JPanel {
 
    protected boolean isDark;
 
    public GradientPanel( LayoutManager layout, boolean isDoubleBuffered ) {
        super( layout, isDoubleBuffered );
        setOpaque( true );
        setDark( false );
    }
 
    public GradientPanel( LayoutManager layout ) {
        this( layout, true );
    }
 
    public GradientPanel( boolean isDoubleBuffered ) {
        this( new FlowLayout(), isDoubleBuffered );
    }
 
    public GradientPanel() {
        this( new FlowLayout(), true );
    }
 
    public void setDark( boolean b ) {
        isDark = b;
    }
 
    public void paintComponent( Graphics oldG ) {
        Graphics2D g = (Graphics2D)oldG;
        Point2D startPoint = new Point2D.Float( 0, 0 );
        Point2D endPoint = new Point2D.Float( getWidth(), 0 );
        Color back = Color.white;
        if( isDark ) {
            back = Color.black;
        }
        Paint gradientPaint = new GradientPaint( startPoint, back,
                                                 endPoint, getBackground(),
                                                 false );
        g.setPaint( gradientPaint );
        g.fill( new Rectangle2D.Double( 0, 0, getWidth(), getHeight() ) );
    }
 
    public static void main( String[] arg ) {
        JFrame f = new JFrame( "GradientPanel Test" );
        f.setDefaultCloseOperation( f.EXIT_ON_CLOSE );
        GradientPanel p = new GradientPanel();
        p.setBackground( Color.green );
        p.add( new JButton( "Button" ) );
        p.add( new JTextField( 12 ) );
        p.setBorder( BorderFactory.createTitledBorder( "Gradient Panel" ) );
        f.getContentPane().add( p );
        f.setSize( 300, 300 );
        f.setVisible( true );
    }
}

-Nate

[John Macek]

That's pretty much what I did. Thanks.