问题
I want to do a print screen behind a JFrame who i call source. But the JFrame(source) itself not and print it in another JFrame, who i call destiny... like the picture in the link: https://drive.google.com/file/d/0B4iWj2t4ATQ5ZllwVEE0M1BxUnc/view?usp=sharing
I tried to use setVisible(false) and after setVisible(true) but i don't want it closes and open again. How I do it?
Here is my actual code:
package tests;
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
public class Offscreen {
private static BufferedImage img;
public static void main(String[] main) throws AWTException {
// starts all frames
JFrame source = new JFrame();
source.setSize(500, 500);
source.setLocation(700, 0);
source.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
source.setVisible(true);
JFrame destiny = new JFrame() {
public void paint(Graphics g) {
if (img != null)
// draw print screen
g.drawImage(img, 0, 0, null);
}
};
destiny.setSize(500, 500);;
destiny.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
destiny.setVisible(true);
// print screen
Robot r = new Robot();
// hide source
source.setVisible(false);
long l = System.currentTimeMillis();
while (System.currentTimeMillis() - l < 200) { // take the time to hide
}
// take the picture
img = r.createScreenCapture(source.getBounds());
// show the source again
source.setVisible(true);
// print on destiny
destiny.repaint();
}
}
回答1:
"Assuming" you only want to capture the area behind the active frame (and as you say, without the frame), then something like..
import java.awt.AWTException;
import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.awt.image.BufferedImage;
import java.lang.reflect.InvocationTargetException;
import java.util.concurrent.ExecutionException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class PrintScreen01 {
public static void main(String[] args) {
new PrintScreen01();
}
private Timer timer;
public PrintScreen01() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
} catch (InstantiationException ex) {
} catch (IllegalAccessException ex) {
} catch (UnsupportedLookAndFeelException ex) {
}
final PrintPane printPane = new PrintPane();
final JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(printPane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.addComponentListener(new ComponentAdapter() {
@Override
public void componentMoved(ComponentEvent e) {
timer.restart();
}
@Override
public void componentResized(ComponentEvent e) {
timer.restart();
}
});
timer = new Timer(250, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (frame.isVisible()) {
takeSnapShot(frame, printPane);
}
}
});
timer.setRepeats(false);
frame.setVisible(true);
// takeSnapShot(frame, printPane);
}
});
}
public void takeSnapShot(JFrame frame, PrintPane pane) {
Rectangle bounds = new Rectangle(pane.getLocationOnScreen(), pane.getSize());
frame.setVisible(false);
new SnapShotWorker(frame, pane, bounds).execute();
}
public class SnapShotWorker extends SwingWorker<BufferedImage, BufferedImage> {
private JFrame frame;
private PrintPane pane;
private Rectangle captureBounds;
public SnapShotWorker(JFrame frame, PrintPane pane, Rectangle bounds) {
this.frame = frame;
this.pane = pane;
captureBounds = bounds;
}
@Override
protected BufferedImage doInBackground() throws Exception {
Thread.sleep(125);
BufferedImage snapShot = null;
try {
Robot bot = new Robot();
snapShot = bot.createScreenCapture(captureBounds);
} catch (AWTException ex) {
ex.printStackTrace();
}
Thread.sleep(125);
return snapShot;
}
@Override
protected void done() {
try {
BufferedImage snapShot = get();
pane.setSnapShot(snapShot);
frame.setVisible(true);
} catch (InterruptedException ex) {
ex.printStackTrace();
} catch (ExecutionException ex) {
ex.printStackTrace();
}
}
}
public class PrintPane extends JPanel {
private BufferedImage background;
public PrintPane() {
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
public void setSnapShot(BufferedImage img) {
background = img;
repaint();
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (background != null) {
Graphics2D g2d = (Graphics2D) g.create();
g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
g2d.drawImage(background, 0, 0, this);
g2d.dispose();
}
}
}
}
May help...
Now, I had some issues with the timing of Robot, it would seem that part of the operation is threaded in some way, meaning that unless you got the timing of the frame changing between invisible and visible "just" right, you would actually recapture the frame...annoying...
To try and fix this, and reduce the amount of times I tried capturing the screen, I employed a javax.swing.Timer (to reduce the capture attempts) and a SwingWorker to control the actual snapshot process, taking it out of the Event Dispatching Thread, there by ensuring (to some degree) that the window will be invisible.
I also added some additional lag to ensure that the frame was off the screen long enough to prevent it been capture by the snapshot...
来源：https://stackoverflow.com/questions/26319646/print-screen-without-jframe