Once again, I found some code that seems to be doing something that I would like to try, but I get a Static Error when I try to run the code (apparently, I may be the only one).
By the way, the code comes from the book, "Swing Hacks" By Joshua Marinacci, Chris Adamson. Credit where credit is due.
Here is the run-time error message:
Static Error: No constructor in TransparentBackground matches this invocation
Arguments: ()
Candidate signatures: TransparentBackground(JFrame)
And here is the code I am compiling and running in DrJava:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
public class TransparentBackground extends JComponent
implements ComponentListener, WindowFocusListener, Runnable {
// constants ---------------------------------------------------------------
// instance ----------------------------------------------------------------
private JFrame _frame;
private BufferedImage _background;
private long _lastUpdate = 0;
private boolean _refreshRequested = true;
private Robot _robot;
private Rectangle _screenRect;
private ConvolveOp _blurOp;
// constructor -------------------------------------------------------------
public TransparentBackground(JFrame frame) {
_frame = frame;
try {
_robot = new Robot();
} catch (AWTException e) {
e.printStackTrace();
return;
}
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
_screenRect = new Rectangle(dim.width, dim.height);
float[] my_kernel = {
0.10f, 0.10f, 0.10f,
0.10f, 0.20f, 0.10f,
0.10f, 0.10f, 0.10f};
_blurOp = new ConvolveOp(new Kernel(3, 3, my_kernel));
updateBackground();
_frame.addComponentListener(this);
_frame.addWindowFocusListener(this);
new Thread(this).start();
}
// protected ---------------------------------------------------------------
protected void updateBackground() {
_background = _robot.createScreenCapture(_screenRect);
}
protected void refresh() {
if (_frame.isVisible() && this.isVisible()) {
repaint();
_refreshRequested = true;
_lastUpdate = System.currentTimeMillis();
}
}
// JComponent --------------------------------------------------------------
protected void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
Point pos = this.getLocationOnScreen();
BufferedImage buf = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
buf.getGraphics().drawImage(_background, -pos.x, -pos.y, null);
Image img = _blurOp.filter(buf, null);
g2.drawImage(img, 0, 0, null);
g2.setColor(new Color(255, 255, 255, 192));
g2.fillRect(0, 0, getWidth(), getHeight());
}
// ComponentListener -------------------------------------------------------
public void componentHidden(ComponentEvent e) {
}
public void componentMoved(ComponentEvent e) {
repaint();
}
public void componentResized(ComponentEvent e) {
repaint();
}
public void componentShown(ComponentEvent e) {
repaint();
}
// WindowFocusListener -----------------------------------------------------
public void windowGainedFocus(WindowEvent e) {
refresh();
}
public void windowLostFocus(WindowEvent e) {
refresh();
}
// Runnable ----------------------------------------------------------------
public void run() {
try {
while (true) {
Thread.sleep(100);
long now = System.currentTimeMillis();
if (_refreshRequested && ((now - _lastUpdate) > 1000)) {
if (_frame.isVisible()) {
Point location = _frame.getLocation();
_frame.setLocation(-_frame.getWidth(), -_frame.getHeight());
updateBackground();
_frame.setLocation(location);
refresh();
}
_lastUpdate = now;
_refreshRequested = false;
}
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
JFrame frame = new JFrame("Transparent Window");
TransparentBackground bg = new TransparentBackground(frame);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(bg);
frame.pack();
frame.setSize(200, 200);
frame.setLocation(500, 500);
frame.setVisible(true);
}
}