GradientPanel.java

/*
 * Copyright 2008 Sun Microsystems, Inc.  All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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 */

package com.itemanalysis.jmetrik.swing;

import java.awt.*;
import javax.swing.*;
import javax.swing.border.CompoundBorder;
import javax.swing.border.EmptyBorder;

/**
 * Simple panel subclass which renders a 2-color vertical linear gradient
 * as the background.
 * @author Aim
 */
public class GradientPanel extends JPanel {
    private final Color[] colors = new Color[2];
    private Image image;
    protected float hsb[];

    public GradientPanel(String title) {
        super();
        Color titleColor = UIManager.getColor("nimbusBase");
        hsb = Color.RGBtoHSB(titleColor.getRed(), titleColor.getGreen(), titleColor.getBlue(), null);
        colors[0] = Color.getHSBColor(hsb[0] - .013f, .15f, .85f);
        colors[1] = Color.getHSBColor(hsb[0] - .005f, .24f, .80f);
        setOpaque(false);  // unfortunately required to disable automatic bg painting
        setBackground(colors[0]); // in case colors are derived from background

        setLayout(new BorderLayout());
        setBorder(new CompoundBorder(new ChiselBorder(), new EmptyBorder(6,8,6,0)));

        Font labelFont = UIManager.getFont("Label.font");

        JLabel titleLabel = new JLabel(title);
        titleLabel.setFont(labelFont.deriveFont(Font.BOLD, labelFont.getSize()+4f));
        titleLabel.setOpaque(false);
        titleLabel.setHorizontalAlignment(JLabel.LEADING);
        add(titleLabel, BorderLayout.CENTER);

        
    }

    public void setGradientColor1(Color color) {
        changeGradientColor(0, color);
    }

    public void setGradientColor2(Color color) {
        changeGradientColor(1, color);
    }

    protected void changeGradientColor(int colorIndex, Color newColor) {
        Color oldColor = colors[colorIndex];
        colors[colorIndex] = newColor;
        if (!oldColor.equals(newColor)) {
            image = null;
            firePropertyChange("gradientColor"+colorIndex, oldColor, newColor);
        }
    }

    protected Image getGradientImage() {
        Dimension size = getSize();
        if (image == null ||
                image.getWidth(null) != size.width ||
                image.getHeight(null) != size.height) {

            image = SwingSetUtils.createGradientImage(size.width, size.height,
                    colors[0], colors[1]);

        }
        return image;
    }
   
    @Override
    protected void paintComponent(Graphics g) {
        Image gradientImage = getGradientImage();
        g.drawImage(gradientImage, 0, 0, null);
        super.paintComponent(g);
    }

}