I am following the examples from Java : The complete reference 8th edition (JDK 7) on AWT and I cannot succeed to display a string on the window that appears. The size and title are set correctly and the window shows up. If I output a string on the console in the paint() method I see that it actually gets called a few times but the string does not appear on the window of my application. I can't see where I diverged from the example; I actually have a bit less code (they added a mouse listener and a key listener) :\
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
public class Main {
public static void main(String[] args) {
Application app = new Application();
app.setSize(new Dimension(640, 480));
app.setTitle("This is a test");
app.setVisible(true);
}
}
class MyWindowAdapter extends WindowAdapter {
public void windowClosing(WindowEvent we) {
System.exit(0);
}
}
class Application extends Frame {
public Application() {
addWindowListener(new MyWindowAdapter());
}
public void paint(Graphics g) {
System.out.println("Hey hey !");
g.drawString("Test", 10, 10);
}
}
The problem you're having is the fact that you are painting directly on top of the frame. The frame also includes the frame border, so position 0, 0 (or in your case 10, 10) is actually hidden UNDER the frame border.
You can see more about that here.
Instead, you should draw onto a Canvas and add that to the frame
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
public class BadFrame {
public static void main(String[] args) {
new BadFrame();
}
public BadFrame() {
Application app = new Application();
app.setSize(new Dimension(640, 480));
app.setTitle("This is a test");
app.setLayout(new BorderLayout());
app.add(new MyCanvas());
app.setVisible(true);
}
class MyWindowAdapter extends WindowAdapter {
public void windowClosing(WindowEvent we) {
System.exit(0);
}
}
public class MyCanvas extends Component {
#Override
public void paint(Graphics g) {
super.paint(g);
System.out.println("Hey hey !");
g.drawString("Test", 10, 10);
}
}
class Application extends Frame {
public Application() {
addWindowListener(new MyWindowAdapter());
}
}
}
The next question that comes to mind is, why AWT? The API has being moth balled in favor of Swing. If nothing else, it's automatically double buffered ;)
ps- You may also find 2D Graphics of some interest, especially the discussion on text
Your string gets drawn but is hidden under the title bar of the window. Just use e.g.
g.drawString("Test", 10, 200);
and you'll see it appear
Related
Take the example from Oracle, there are some examples in your documentation.
My idea is the following:
I have achieved that my application has a transparent background, but the minimize and close application buttons do not appear
This is my code:
main
import javax.swing.JFrame;
import java.awt.*;
import javax.swing.*;
import static java.awt.GraphicsDevice.WindowTranslucency.*;
public class Textmovie extends JFrame {
/*
public Textmovie() {
//setLayout(new GridBagLayout());
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
*/
public static void main(String[] args) {
JFrame jf = new JFrame("");
jf.setUndecorated(true);
jf.setBackground(new Color(0,0,0,10));
//jf.setOpacity(0.55f);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.add(new texscroll());
jf.setSize(720,480);
jf.setVisible(true);
}
}
Part 2
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JPanel;
/**
*
* #author inide
*/
public class texscroll extends JPanel {
int x =510 , y = 25;
public texscroll() {
setOpaque(false);
}
#Override
public void paint(Graphics g){
super.paint(g);
Graphics2D g2 = (Graphics2D)g;
Font font = new Font("Arial",Font.BOLD + Font.PLAIN,15);
g2.setFont(font);
g2.setColor(Color.BLACK);
String string = "stackoverflow stackoverflow stackoverflow stackoverflow";
g2.drawString(string ,x,y);
try{Thread.sleep(14);}
catch(Exception ex)
{
};
x-=1;
if(x==-10*string.length()){
x= 510;
}
repaint();
// System.out.println(string.length() );
}
}
And this is shown when running in NetBeans IDE 8.0.2
They can explain to me what I have to do to make the buttons appear (minimize and close application).
If you actually dig into the code based on the exception:
Exception in thread "AWT-EventQueue-0" java.awt.IllegalComponentStateException: The frame is decorated
at java.desktop/java.awt.Frame.setBackground(Frame.java:989)
You'll find that it's impossible to make a frame transparent AND be decorated...
#Override
public void setBackground(Color bgColor) {
synchronized (getTreeLock()) {
if ((bgColor != null) && (bgColor.getAlpha() < 255) && !isUndecorated()) {
throw new IllegalComponentStateException("The frame is decorated");
}
super.setBackground(bgColor);
}
}
The fact that the tutorials show it working is irrelevant and an error on the part of the tutorials.
It "might" have been possible in earlier "unreleased" versions of the API (using AWTUtilities), but it simply no longer possible
Now, we've got that out the way, this, inside paint...
try {
Thread.sleep(14);
} catch (Exception ex) {
};
x -= 1;
if (x == -10 * string.length()) {
x = 510;
}
repaint();
is not how you do animation in Swing
This is just going to cause you no end of issues, as nothing is committed to the native peer until AFTER the paintComponent exist (this is how double buffering works)
See Concurrency in Swing for more details.
A more appropriate solution might look something like...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Textmovie extends JFrame {
public static void main(String[] args) {
new Textmovie();
}
public Textmovie() throws HeadlessException {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame jf = new JFrame("");
jf.setUndecorated(true);
jf.setBackground(new Color(0, 0, 0, 10));
//jf.setOpacity(0.55f);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.add(new texscroll());
jf.pack();
jf.setLocationRelativeTo(null);
jf.setVisible(true);
}
});
}
public static class texscroll extends JPanel {
private int x = 510, y = 25;
private String string = "stackoverflow stackoverflow stackoverflow stackoverflow";
public texscroll() {
Font font = new Font("Arial", Font.BOLD + Font.PLAIN, 15);
setFont(font);
setForeground(Color.BLACK);
setOpaque(false);
Timer timer = new Timer(14, new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
x -= 1;
if (x == -10 * string.length()) {
x = 510;
}
repaint();
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(720, 480);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g); //To change body of generated methods, choose Tools | Templates.
Graphics2D g2 = (Graphics2D) g;
g2.drawString(string, x, y);
}
}
}
See How to Use Swing Timers for more details
jf.setUndecorated(true);
makes the title bar invisible and that includes the minimize and close buttons so you should remove that line (because it's false by default)
It’s because you’re calling jf.setUndecorated(true). This method removes the the title bar, which contains the minimize and maximize buttons.
Unfortunately, the window have to be undecorated to have a system title bar, but the look and feel can provide a title bar. To enable it, you have to call this before your frame is made visible:
JFrame.setDefaultLookAndFeelDecorated(true);
I am learning how to work with Gui's in java. Currently I'm trying to make a simple program that opens a Gui and draws an image to the background. The problem is that the background is completely white instead of the image.
Code:
Main.java:
package com.flaghacker.buckygame;
public class Main
{
public static void main(String[] args)
{
GuiFrame guiFrame = new GuiFrame();
}
}
GuiFrame.java:
package com.flaghacker.buckygame;
import javax.swing.JFrame;
public class GuiFrame extends JFrame
{
private GuiPanel guiPanel;
public GuiFrame()
{
//General
super("Title");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Size
this.setSize(1100, 650);
this.setResizable(true);
//Components
guiPanel = new GuiPanel();
this.add(guiPanel);
//Final
this.setVisible(true);
}
}
GuiPane.java:
package com.flaghacker.buckygame;
import javax.swing.ImageIcon;
import javax.swing.JPanel;
import java.awt.Graphics;
import java.awt.Image;
public class GuiPanel extends JPanel
{
private Image backGround;
public GuiPanel()
{
backGround = new ImageIcon("D:\\Install\\Java Projects\\Testing\\Bucky\\Back.jpg").getImage();
}
#Override
public void paint(Graphics g)
{
super.paint(g);
g.drawImage(backGround, 0, 0, null);
}
}
I test your code and it works ... the possible problem are two
first) your image isn't in
"D:\\Install\\Java Projects\\Testing\\Bucky\\Back.jpg"
i suggested you to use
"D:/Install/Java Projects/Testing/Bucky/Back.jpg"
and verify
Case insensitive.
second) the image Back.jpg have width and height more high of 1100 650 so you display only a top left angle of image
In Swing, there are several ways to capture the event of minimizing a frame (iconifying), but the event happens when the frame is ICONIFIED which means after the frame becomes invisible from the screen.
Now I wish to run some code before disappearance of the frame -- immediately when I click the taskbar button.
In other words, do something when the JFrame is "about to" (NOT AFTER) be minimized. Is it possible to do this?
Use WindowStateListener, and call WindowEvent#getNewState() and check against Frame.ICONIFIED.
Here is an example:
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Frame;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Test {
public Test() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel() {
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
};
frame.add(panel);
frame.addWindowStateListener(new WindowAdapter() {
#Override
public void windowStateChanged(WindowEvent we) {
if (we.getNewState() == Frame.ICONIFIED) {
System.out.println("Here");
}
}
});
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Test();
}
});
}
}
Create your own JFrame and override setExtendedState method.
public class MyFrame extends JFrame{
....
setExtendedState(JFrame.ICONIFIED);
....
#Override
public void setExtendedState(int state) {
// your code
super.setExtendedState(state);
};
}
Answer to the question "Is it possible to perform some action BEFORE a JFrame is minimized?"
I would say no unfortunately, I checked the native code for openjdk (windows) for frame and window that sends these events to java-space. And as I understand it, it is a callback from the windows API VM_SIZE message. And the SIZE_MINIMIZED is sent when "The window has been minimized" and is not getting any messages before the actual minimization.
A few days ago I posted a question about a program that caused text on screen to change color when the mousewheel was scrolled. It was unfortunately a badly put together question with too much code posted to be particularly useful.
I had several responses, one of which was from the user trashdog who posted something that fixed the problem (which can be found at the bottom of this page here: Window going blank during MouseWheelMotion event) , however having read the class descriptions of all the things I didn't know about in the program he posted and gone through its execution I don't understand why his achieves a different effect from mine.
His seems to log every mouse wheel movement where as mine only does the initial movement. Also several people commented that they couldn't replicate the effect of my program probably because it was so big.
Below is an extremely simplified version which still elicits the same effect (I hope).
Question: What is the fundamental difference between the two programs that fixes the screen going blank when the mouse wheel events are being processed?
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import java.util.LinkedList;
import javax.swing.JFrame;
public class WheelPrinter implements MouseWheelListener, Runnable {
JFrame frame;
LinkedList colorList;
int colorCount;
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
WheelPrinter w = new WheelPrinter();
w.run();
}
public WheelPrinter() {
frame = new JFrame();
frame.setSize(500, 500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.addMouseWheelListener(this);
frame.setVisible(true);
frame.setBackground(Color.WHITE);
colorList = new LinkedList();
colorList.add(Color.BLACK);
colorList.add(Color.BLUE);
colorList.add(Color.YELLOW);
colorList.add(Color.GREEN);
colorList.add(Color.PINK);
}
#Override
public void mouseWheelMoved(MouseWheelEvent e) {
colorChange();
}
#Override
public void run() {
while(true) {
draw(frame.getGraphics());
try {
Thread.sleep(20);
} catch (Exception ex) {
}
}
}
public void draw(Graphics g) {
g.setColor(frame.getBackground());
g.fillRect(0,0,frame.getWidth(),frame.getHeight());
g.setFont(new Font("sansserif", Font.BOLD, 32));
g.setColor(frame.getForeground());
g.drawString("yes", 50, 50);
}
public void colorChange() {
colorCount++;
if (colorCount > 4) {
colorCount = 0;
}
frame.setForeground((Color) colorList.get(colorCount));
}
}
(Try spinning your mouse wheel really hard if you try running my code and it will become even more obvious)
while(true) { is endless loop, without break; f.e.
use Swing Timer instead of Runnable#Thread delayed by Thread.Sleep()
paint to the JPanel or JComponent, not directly to the JFrame
all painting to the Swing JComponent should be done in paintComponent()
more in the 2D Graphics tutorial
edit
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseWheelEvent;
import java.util.LinkedList;
import java.util.Queue;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
/**
* based on example by #trashgod
*
* #see http://stackoverflow.com/a/10970892/230513
*/
public class ColorWheel extends JPanel {
private static final int N = 32;
private static final long serialVersionUID = 1L;
private final Queue<Color> clut = new LinkedList<Color>();
private final JLabel label = new JLabel();
public ColorWheel() {
for (int i = 0; i < N; i++) {
clut.add(Color.getHSBColor((float) i / N, 1, 1));
}
//clut.add(Color.BLACK);
//clut.add(Color.BLUE);
//clut.add(Color.YELLOW);
//clut.add(Color.GREEN);
//clut.add(Color.PINK);
label.setFont(label.getFont().deriveFont(36f));
label.setForeground(clut.peek());
label.setText("#see http://stackoverflow.com/a/10970892/230513");
setBackground(Color.white);
add(label);
label.addMouseWheelListener(new MouseAdapter() {
#Override
public void mouseWheelMoved(MouseWheelEvent e) {
label.setForeground(clut.peek());
clut.add(clut.remove());
}
});
}
#Override
public Dimension getPreferredSize() {
int w = SwingUtilities.computeStringWidth(label.getFontMetrics(
label.getFont()), label.getText());
return new Dimension(w + 20, 80);
}
private void display() {
JFrame f = new JFrame("ColorWheel");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new ColorWheel().display();
}
});
}
}
The fundamental difference is that you are trying to interact with the Graphics object from the wrong thread and without knowing anything about the state the Graphics object is in at the time.
The generally correct way to interact with a Graphics object in Swing is by making a custom component which overrides the paintComponent(Graphics) method. You do your drawing while inside that method.
Your colorChange() method can tell your component to re-draw itself by calling repaint(), which will eventually lead to a call to paintComponent(Graphics) on the correct thread at the correct time.
See tutorial here
I am experiencing a problem with Swing that only occurs when the computer monitor is powered off, but my Swing application continues to run in the background. It seems that whenever the monitor is off, Swing/AWT cancels all painting operations, leading to a number of display issues in the GUI that are visible as soon as the monitor turns back on.
For example, when I turn off the monitor using a custom JNI function and subsequently open a simple message dialog, the message dialog is blank when the monitor turns back on:
But it paints correctly after the next repaint:
Is this the expected behavior of Swing? Is there a way to instruct Swing to continue drawing to the screen even if the monitor is powered off?
EDIT: Here is an SSCCE:
package test;
import javax.swing.JOptionPane;
import javax.swing.SwingUtilities;
public class App {
public static void main(String[] args) throws Throwable {
System.out.println("***** Please turn off the monitor in the next 70 seconds *****");
Thread.sleep(1000L * 70);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JOptionPane.showMessageDialog(null, "Test");
}
});
}
}
I am using 64-bit Windows 7 Home Premium SP1 and 64-bit Java 1.6.0_24.
EDIT 2: Here is another program with which I experience the effect of "canceled painting operations":
package test;
import static com.mycompany.Util.turnOffMonitors;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
public class DialogTest extends JDialog {
private final JLabel label;
public DialogTest() {
setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
label = new JLabel("Test", JLabel.CENTER);
label.setOpaque(true);
Container contentPane = getContentPane();
contentPane.setLayout(new BorderLayout());
contentPane.add(BorderLayout.CENTER, label);
this.setPreferredSize(new Dimension(200, 110));
pack();
setLocationRelativeTo(null);
setVisible(true);
Thread t = new Thread() {
#Override
public void run() {
turnOffMonitors();
try {
Thread.sleep(3000L);
} catch (InterruptedException ex) { }
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
label.setBackground(Color.YELLOW);
}
});
}
};
t.start();
}
public static void main(String[] args) throws Throwable {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new DialogTest();
}
});
}
}
Before the monitor shuts off, I see:
With the monitor off, the label background color is changed to yellow in the background. I then move the mouse to turn the monitor back on. The dialog is visually unchanged. It is only after I force a repaint (by ALT-TABbing, for example) do I see the yellow:
EDIT 3: Reported to Oracle as Bug ID 7049597.
I then started the program and stopped
moving the mouse/typing. After one
minute, the screen turned off. I
waited another 20 seconds to move the
mouse. The monitor turned back on and
I saw a blank message dialog.
Using your example, I don't see this on my (non-Windows) platform. You might try the example below, which should alternate between WINDOW_ACTIVATED on wake and WINDOW_DEACTIVATED on sleep. If so, you could extend JDialog and repaint() in windowActivated().
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JLabel;
/** #see http://stackoverflow.com/questions/6163606 */
public class DialogEventTest extends JDialog {
public DialogEventTest() {
this.setLayout(new GridLayout(0, 1));
this.add(new JLabel("Dialog event test.", JLabel.CENTER));
this.add(new JButton(new AbstractAction("Close") {
#Override
public void actionPerformed(ActionEvent e) {
DialogEventTest.this.setVisible(false);
DialogEventTest.this.dispatchEvent(new WindowEvent(
DialogEventTest.this, WindowEvent.WINDOW_CLOSING));
}
}));
}
private static class WindowHandler extends WindowAdapter {
#Override
public void windowActivated(WindowEvent e) {
System.out.println(e);
}
#Override
public void windowDeactivated(WindowEvent e) {
System.out.println(e);
}
}
private void display() {
this.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
this.addWindowListener(new WindowHandler());
this.pack();
this.setLocationRelativeTo(null);
this.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new DialogEventTest().display();
}
});
}
}
The problem probably has more to do with how it repaints when the screen comes on rather than what happens while it's off. You could check by running a screen recorder.