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Graphics drawing problem

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  Graphics drawing problem "sydpolen" <sydpolen@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
    Re: Graphics drawing prob "Knute Johnson" <knute.johnson@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
      Re: Graphics drawing prob "sydpolen" <sydpolen@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
        Re: Graphics drawing prob "Judy Szikora" <judy.szikora@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000
          Re: Graphics drawing prob "Jul" <jul@THRWHITE.remove-dii-this> - 2011-04-27 15:35 +0000

#1834 — Graphics drawing problem

  To: comp.lang.java.gui
Hi,

I'm a java gui newbie. I have this problem;

I made a class "Gui" I want to use as a template for future Gui
builds. I want to draw lines in the center. I made a "test" method
which I call from main class. For some reason the line I attempt to
draw is not visible. When I call sleep between the initiate() and the
test() methods the line will sometimes be visible.

I would appreciate any pointers of what I'm doing wrong. I paste the
source ...

import java.awt.*;
import javax.swing.*;
public class StartGui {
    public static void main(String[] args) throws Exception{
		Gui gui = new Gui();
		gui.initiate();
        //Thread.sleep(2000);
        gui.test(100,100,300,300);
    }
}

import javax.swing.*;
import java.awt.*;
public class Gui extends JFrame{

	Color cN = Color.LIGHT_GRAY;
	Color cW = Color.LIGHT_GRAY;
	Color cC = Color.LIGHT_GRAY;
	Color cE = Color.LIGHT_GRAY;
	Color cS = Color.LIGHT_GRAY;
	Color cGap = Color.BLACK;

	int widthW = 200;
	int widthC = 400;
	int widthE = 200;
	int heightN = 150;
	int heightC = 400;
	int heightS = 150;

	Graphics graphics;
	JPanel n;
	JPanel s;
	JPanel e;
	JPanel w;
	JPanel c;

	public Gui() {
		new JFrame("Gui");
		n = new JPanel();
		w = new JPanel();
		e = new JPanel();
		s = new JPanel();
		c = new JPanel();
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		pack();
		setVisible(true);
	}
	public void initiate() {
		getContentPane().setLayout(new BorderLayout(2,2));
		getContentPane().setBackground(cGap);
		n.setBackground(cN);
		n.setPreferredSize(new Dimension(widthE+widthC+widthW,heightN));
		w.setBackground(cW);
		w.setPreferredSize(new Dimension(widthW,heightC));
		c.setBackground(cC);
		c.setPreferredSize(new Dimension(widthC,heightC));
		e.setBackground(cE);
		e.setPreferredSize(new Dimension(widthE,heightC));
		s.setBackground(cS);
		s.setPreferredSize(new Dimension(widthE+widthC+widthW,heightS));
		getContentPane().add(e,BorderLayout.EAST);
		getContentPane().add(w,BorderLayout.WEST);
		getContentPane().add(n,BorderLayout.NORTH);
		getContentPane().add(s,BorderLayout.SOUTH);
		getContentPane().add(c,BorderLayout.CENTER);
		pack();
	}
	public void test(int x1, int y1, int x2, int y2){
		c.setBackground(Color.BLACK);
		graphics = c.getGraphics();
		graphics.setColor(Color.GREEN);
		graphics.drawLine(x1,y1,x2,x2);
	}
}

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#1836 — Re: Graphics drawing prob

  To: comp.lang.java.gui
sydpolen@gmail.com wrote:
> Hi,
> 
> I'm a java gui newbie. I have this problem;
> 
> I made a class "Gui" I want to use as a template for future Gui
> builds. I want to draw lines in the center. I made a "test" method
> which I call from main class. For some reason the line I attempt to
> draw is not visible. When I call sleep between the initiate() and the
> test() methods the line will sometimes be visible.
> 
> I would appreciate any pointers of what I'm doing wrong. I paste the
> source ...
> 

Drawing needs to be done in the paintComponent() method for Swing 
components.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class XComponent extends JComponent {
     public XComponent() {
         setPreferredSize(new Dimension(40,40));
     }

     public void paintComponent(Graphics g) {
         g.drawLine(0,0,getWidth(),getHeight());
         g.drawLine(getWidth(),0,0,getHeight());
     }

     public static void main(String[] args) {
         Runnable r = new Runnable() {
             public void run() {
                 JFrame f = new JFrame();
                 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                 XComponent x = new XComponent();
                 f.add(x);
                 f.pack();
                 f.setVisible(true);
             }
         };
         EventQueue.invokeLater(r);
     }
}

-- 

Knute Johnson
email s/nospam/knute/

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#1841 — Re: Graphics drawing prob

  To: comp.lang.java.gui
On 14 Jun., 19:39, Knute Johnson <nos...@rabbitbrush.frazmtn.com>
wrote:
> sydpo...@gmail.com wrote:
> > Hi,
>
> > I'm a java gui newbie. I have this problem;
>
> > I made a class "Gui" I want to use as a template for future Gui
> > builds. I want to draw lines in the center. I made a "test" method
> > which I call from main class. For some reason the line I attempt to
> > draw is not visible. When I call sleep between the initiate() and the
> > test() methods the line will sometimes be visible.
>
> > I would appreciate any pointers of what I'm doing wrong. I paste the
> > source ...
>
> Drawing needs to be done in the paintComponent() method for Swing
> components.
>
> import java.awt.*;
> import java.awt.event.*;
> import javax.swing.*;
>
> public class XComponent extends JComponent {
>      public XComponent() {
>          setPreferredSize(new Dimension(40,40));
>      }
>
>      public void paintComponent(Graphics g) {
>          g.drawLine(0,0,getWidth(),getHeight());
>          g.drawLine(getWidth(),0,0,getHeight());
>      }
>
>      public static void main(String[] args) {
>          Runnable r = new Runnable() {
>              public void run() {
>                  JFrame f = new JFrame();
>                  f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
>                  XComponent x = new XComponent();
>                  f.add(x);
>                  f.pack();
>                  f.setVisible(true);
>              }
>          };
>          EventQueue.invokeLater(r);
>      }
>
> }
>
> --
>
> Knute Johnson
> email s/nospam/knute/

Ok, thx a lot Knute, with your advice I made it work.

Can someone recommend a link where I can find something about how the
graphical elements of Java works explained in a short and precise way
(both high level and low level topics). Since I'm a newbie with regard
to graphics, I also seek information about the basics, e.g. when I
read some stuff mentioning the word "render", I would like to know
what actually happens on the underlying levels when graphics are
rendered.

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#1846 — Re: Graphics drawing prob

  To: comp.lang.java.gui
sydpolen@gmail.com wrote:
...
> 
> Can someone recommend a link where I can find something about how the
> graphical elements of Java works explained in a short and precise way
> (both high level and low level topics). Since I'm a newbie with regard
> to graphics, I also seek information about the basics, e.g. when I
> read some stuff mentioning the word "render", I would like to know
> what actually happens on the underlying levels when graphics are
> rendered.
> 
The API doc for java.awt.Graphics and java.awt.Graphics2D has important 
information but may be too concise. The docs/index.html page in your JDK 
installation has a link to Java2D and Imaging with pointers to more doc, 
including the Java tutorial. Google and a good bookseller are worth a 
look too.

-- 
Judy Szikora, Apprisant Technologies Inc.
http://www.apprisant.com

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#1850 — Re: Graphics drawing prob

  To: comp.lang.java.gui
> The API doc for java.awt.Graphics and java.awt.Graphics2D has important
> information but may be too concise. The docs/index.html page in your JDK
> installation has a link to Java2D and Imaging with pointers to more doc,
> including the Java tutorial. Google and a good bookseller are worth a
> look too.

Thanks Judy, I already looked at these docs, good material, but I was
hoping someone would have a link to an outstanding site about the
topics in question, which might not pop-up at the first 1-5 Google
search pages.

Cheers,
Jul

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