Problems with Opacity

[Kazie]

Hi I'm working on a little project that lets me draw on my desktop. The main idea is to have a button that lets you switch the background from being fully transparent (only showing what I have drawn) to 50% transparent (at wich i am supposed to draw).

My 2 Main problems is:

1. I can't make the background 50% transparent, only fully transparent or fully opaque.

2. While drawing too fast the line becomes dotted.

This is my Main class:

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.GeneralPath;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Main extends JFrame implements MouseMotionListener, MouseListener, KeyListener {

    boolean stop = false;
    int currentX, currentY;
    ArrayList<Line> list = new ArrayList();

    public Main() {
        super("PaintOnScreen");

        addMouseListener(this);
        addMouseMotionListener(this);
        addKeyListener(this);

        setExtendedState(Frame.MAXIMIZED_BOTH);
        setUndecorated(true);
        setAlwaysOnTop(true);

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);



        JPanel panel = new JPanel() {

            public void paintComponent(Graphics g) {               
                for (Line line : list) {
                    line.paint(g);
                }
            }
        };

        panel.setOpaque(false);
        setGlassPane(panel);

        getGlassPane().setVisible(true);
        setVisible(true);
    }

    // Toggles the paintmode off to make the fram translucent
    void Paintmodeoff() {
        com.sun.awt.AWTUtilities.setWindowOpaque(this, false);
        stop = true;
        repaint();
    }
    // Toggles the paintmode on to make the area drawable
    void Paintmodeon() {
        com.sun.awt.AWTUtilities.setWindowOpaque(this, true);
        stop = false;
    }

    public static void main(String[] args) {
        new Main();
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        currentX = e.getX();
        currentY = e.getY();

        list.add(new Line(currentX, currentY));
        
        repaint();
    }

    @Override
    public void mouseMoved(MouseEvent e) {
    }

    @Override
    public void mouseClicked(MouseEvent e) {
    }

    @Override
    public void mousePressed(MouseEvent e) {
        currentX = e.getX();
        currentY = e.getY();
        list.add(new Line(currentX, currentY));
    }

    @Override
    public void mouseReleased(MouseEvent e) {
        list.add(new Line(currentX, currentY));
        repaint();
        System.out.println("added line");
    }

    @Override
    public void mouseEntered(MouseEvent e) {
    }

    @Override
    public void mouseExited(MouseEvent e) {
    }

    @Override
    public void keyTyped(KeyEvent e) {
    }

    @Override
    public void keyPressed(KeyEvent e) {
        if (e.getKeyChar() == KeyEvent.VK_ESCAPE) {
            System.exit(0);
        }
        if (e.getKeyCode() == KeyEvent.VK_A) {
            Paintmodeoff();
            System.out.println("exit Drawing mode");
        }
        if (e.getKeyCode() == KeyEvent.VK_S) {
            Paintmodeon();
            System.out.println("enter Drawing mode");
        }

    }

    @Override
    public void keyReleased(KeyEvent e) {
    }
}

[DarrylBurke]

        com.sun.awt.AWTUtilities.setWindowOpaque(this, false);
:
:
        com.sun.awt.AWTUtilities.setWindowOpaque(this, true);

You do know that code is liable to break ... or don't you? And now that Java 7 is out, there's no need to write such fragile code.

db

[Kazie]

No, I didn't know that. :P
How am I supposed to code it?

[DarrylBurke]

Read the Java 7 API for JFrame. Pay attention to the methods inherited from Window. Or go straight to the API for Window, you'll find a few set... methods that weren't there in Java 6.

All classes that aren't a part of the public API are subject to change or removal.

db

[Amali]

//This is transparent simple example. Try to applly to ur project.
//I'm using setOpacity method.
public class TransparentDemo extends JFrame {
public TransparentDemo() {
setLayout(new FlowLayout());
setSize(400,300);
add(new JButton("OK"));
}

public static void main(String[] args) {
JFrame.setDefaultLookAndFeelDecorated(true);
TransparentDemo frame = new TransparentDemo();
frame.setOpacity(0.50f);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOS E);
}
}

[Kazie]

Ok, after downloading the latest jdk i finally got it working with setOpacity(0.5f);
However that gave me a new problem, when making the window transparent the lines which I have drawn becomes transparent too :/

[DarrylBurke]

//This is transparent simple example. Try to applly to ur project.

Don't spoonfeed here. You're possibly denying the questioner the opportunity to acquire the very necessary skill of reading and understanding the API.

And that's bad code. All Swing components should be constructed and their methods called only on the EDT. Find and go through the tutorial on Concurrency in Swing, and search the net for articles on Swing's single threaded rule.

Also bad is that you didn't bother to find out how people post formatted code. This forum has a FAQs section, which should have been the first place to look. Or you could have clicked "Reply with Quote" below a post that does have properly formatted code to see how it's done.

In summary, posting a few lines of code that 'works' is not helpful. Please don't do it again.

db