About the only way you could modify a JProgressBar in any meaningful way would be to design your own UI delegate...
This is basically an example based on some work I did a long time ago.
The example updates the progress bar in increments of 25, but the progress bar "attempts" to fill from it's current position to the target value in small increments.
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.LinearGradientPaint;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Point2D;
import java.awt.geom.RoundRectangle2D;
import javax.swing.BoundedRangeModel;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.plaf.basic.BasicProgressBarUI;
public class TestMediaProgressBar {
public static void main(String[] args) {
new TestMediaProgressBar();
}
public TestMediaProgressBar() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private MediaProgressBar pb;
private int value = 0;
private int delta = 25;
public TestPane() {
setBackground(Color.BLACK);
setLayout(new GridBagLayout());
pb = new MediaProgressBar();
add(pb);
Timer timer = new Timer(500, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (value + delta > 100) {
delta *= -1;
value = 100;
} else if (value + delta < 0) {
delta *= -1;
value = 0;
}
value += delta;
pb.setValue(value);
}
});
timer.start();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
public class MediaProgressBar extends JProgressBar {
public MediaProgressBar() {
setUI(new MediaProgressBarUI());
}
@Override
public Dimension getPreferredSize() {
return new Dimension(128, 24);
}
}
public class MediaProgressBarUI extends BasicProgressBarUI {
private Handler handler;
private double renderProgress = 0;
private double targetProgress = 0;
private double progressDelta = 0.04;
private Timer repaintTimer;
private Timer paintTimer;
public MediaProgressBarUI() {
repaintTimer = new Timer(25, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
progressBar.repaint();
}
});
repaintTimer.setRepeats(false);
repaintTimer.setCoalesce(true);
paintTimer = new Timer(40, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (progressDelta < 0) {
if (renderProgress + progressDelta < targetProgress) {
((Timer) e.getSource()).stop();
renderProgress = targetProgress + progressDelta;
}
} else {
if (renderProgress + progressDelta > targetProgress) {
((Timer) e.getSource()).stop();
renderProgress = targetProgress - progressDelta;
}
}
renderProgress += progressDelta;
requestRepaint();
}
});
}
protected void requestRepaint() {
repaintTimer.restart();
}
@Override
protected void installDefaults() {
super.installDefaults();
progressBar.setOpaque(false);
progressBar.setBorder(null);
}
public void setRenderProgress(double value) {
if (value != targetProgress) {
paintTimer.stop();
targetProgress = value;
if (targetProgress < renderProgress && progressDelta > 0) {
progressDelta *= -1;
} else if (targetProgress > renderProgress && progressDelta < 0) {
progressDelta *= -1;
}
System.out.println(progressDelta);
paintTimer.start();
}
}
public double getRenderProgress() {
return renderProgress;
}
@Override
public void paint(Graphics g, JComponent c) {
Graphics2D g2d = (Graphics2D) g.create();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
int iStrokWidth = 3;
g2d.setStroke(new BasicStroke(iStrokWidth, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
g2d.setColor(c.getBackground());
g2d.setBackground(c.getBackground());
int width = c.getWidth();
int height = c.getHeight();
RoundRectangle2D outline = new RoundRectangle2D.Double((iStrokWidth / 2), (iStrokWidth / 2),
width - iStrokWidth, height - iStrokWidth,
height, height);
g2d.draw(outline);
int iInnerHeight = height - (iStrokWidth * 4);
int iInnerWidth = width - (iStrokWidth * 4);
iInnerWidth = (int) Math.round(iInnerWidth * renderProgress);
int x = iStrokWidth * 2;
int y = iStrokWidth * 2;
Point2D start = new Point2D.Double(x, y);
Point2D end = new Point2D.Double(x, y + iInnerHeight);
float[] dist = {0.0f, 0.25f, 1.0f};
Color[] colors = {c.getBackground(), c.getBackground().brighter(), c.getBackground().darker()};
LinearGradientPaint p = new LinearGradientPaint(start, end, dist, colors);
g2d.setPaint(p);
RoundRectangle2D fill = new RoundRectangle2D.Double(iStrokWidth * 2, iStrokWidth * 2,
iInnerWidth, iInnerHeight, iInnerHeight, iInnerHeight);
g2d.fill(fill);
g2d.dispose();
}
@Override
protected void installListeners() {
super.installListeners();
progressBar.addChangeListener(getChangeHandler());
}
protected ChangeListener getChangeHandler() {
return getHandler();
}
protected Handler getHandler() {
if (handler == null) {
handler = new Handler();
}
return handler;
}
protected class Handler implements ChangeListener {
@Override
public void stateChanged(ChangeEvent e) {
BoundedRangeModel model = progressBar.getModel();
int newRange = model.getMaximum() - model.getMinimum();
double dProgress = (double) (model.getValue() / (double) newRange);
if (dProgress < 0) {
dProgress = 0;
} else if (dProgress > 1) {
dProgress = 1;
}
setRenderProgress(dProgress);
}
}
}
}
