Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.gui > #5030

Re: How do I paint on an existing Panel?

Show all headers | View raw

On 2/16/2012 1:05 PM, A B wrote:
> Sorry, I'm stumped, again. I really have been trying to sort it out
> myself, but no luck. I've done it by adapting Knute Johnson's code
> (which works fine in itself). Mine now defines a line and calls
> repaint() as nice as you like, but there's no answer.
>
> I've chopped the code back to just the bits directly involved with the
> drawing and sprinkled debugging statements everywhere, which established
> that the bit that calls paintComponent() (via repaint() - that's right
> isn't it?) is firing but paintComponent() itself isn't. Here's what's
> left, if you're interested. Sorry if anyone finds it hard to read, I
> don't know how you like it formatted.
>
> ------------------------
> import java.awt.*;
> import java.awt.event.*;
> import java.awt.geom.*;
> import java.util.*;
> import javax.swing.*;
>
> public class Vectorine extends JFrame implements MouseListener
> {
> private static final long serialVersionUID = 159L;
> // List to contain all the lines generated
> private final java.util.List<ColoredLine> lineList = new
> java.util.ArrayList<ColoredLine>();
>
> public static void main() {Vectorine v = new Vectorine();}
>
> public Vectorine()
> {
> super("Vectorine");
> setSize(200, 200);
> setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
> setVisible(true);
>
> // Set up window's initial contents
> Container contentArea = getContentPane();
> FlowLayout layout = new FlowLayout();
> contentArea.setLayout(layout);
> JPanel panelA = new JPanel();
> panelA.addMouseListener(this);
> contentArea.add(panelA);
> setContentPane(contentArea);
>
> System.out.println("If you click anywhere in the box, 3 random lines
> should appear in it.");
> }
>
> public void paintComponent(Graphics g2d)
> {
> Graphics2D g = (Graphics2D)g2d;
> System.out.println("Painting...");
> for (ColoredLine hand : lineList)
> {
> System.out.println("Drawing line...");
> BasicStroke pen = new BasicStroke(hand.getThickness());
> g.setStroke(pen);
> g.setColor(hand.getColor());
> g.draw(hand);
> }
> }
>
> public void mouseClicked(MouseEvent event)
> {
> System.out.println("Mouse clicked");
> double xcoord = 0, ycoord = 0;
> for (int count=0; count<3; count++)
> {
> xcoord = 100 * Math.random();
> ycoord = 100 * Math.random();
> System.out.println("xcoord="+xcoord+", ycoord="+ycoord);
> ColoredLine hand = new ColoredLine(0F, 0F, (float)xcoord, (float)ycoord,
> Color.red, 2);
> lineList.add(hand);
> System.out.println("Calling repaint()...");
> repaint();
> }
> }
>
> /** Blank methods to keep MouseListener happy. */
> public void mousePressed(MouseEvent event) {}
> public void mouseReleased(MouseEvent event) {}
> public void mouseEntered(MouseEvent event) {}
> public void mouseExited(MouseEvent event) {}
> }
>
> /** The actual lines drawn are instances of the ColoredLine class. */
> class ColoredLine extends Line2D.Double
> { private static final long serialVersionUID = 149L;
> private final Color color;
> private final int thickness;
> public ColoredLine(double x,double y,double w,double h,Color color,int
> thickness)
> {
> super(x,y,w,h);
> this.color = color;
> this.thickness = thickness;
> }
>
> public Color getColor() {return color;}
> public int getThickness() {return thickness;}
> }
>

You need to follow the example I gave you a little closer.  I would 
extend JPanel rather than JFrame.  You can draw on the JPanel.  I would 
put the MouseListener into the JPanel rather than implementing it on the 
JPanel.  That you can do with a MouseAdapter and you don't have to 
create all of the methods.  You need to change the order in which you 
set up your GUI.  You do not want to make it visible until you have 
created all of the part.  You also need to wrap all Swing GUI creation 
code in EventQueue.invokeLater() so that it will be created on the Event 
Dispatch Thread.  The example I gave you shows that.

Note also that you rarely need the ContentPane of a JFrame anymore. 
JFrame.add() has been modified to add the Component to the JFrame's 
ContentPane.

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.io.*;
import java.net.*;
import java.util.*;
import javax.imageio.*;
import javax.swing.*;

public class test extends JPanel {
     private final Random random =
      new Random(System.currentTimeMillis());
     private BufferedImage image;
     private final java.util.List<ColoredShape> shapeList =
      new java.util.ArrayList<ColoredShape>();

     public test() {
         try {
             URL url =
              new URL("http://rabbitbrush.frazmtn.com/kittens.jpg");
             image = ImageIO.read(url);
             setPreferredSize(new Dimension(
              image.getWidth(),image.getHeight()));
         } catch (MalformedURLException murle) {
              // you need to catch these
         } catch (IOException ioe) {
         }

         addMouseListener(new MouseAdapter() {
             public void mousePressed(MouseEvent me) {
                 double w = random.nextDouble() * getWidth();
                 double h = random.nextDouble() * getHeight();
                 double x = me.getX() - w / 2.0;
                 double y = me.getY() - h / 2.0;
                 Color color = new Color(
                  random.nextInt(256),
                  random.nextInt(256),
                  random.nextInt(256));
                 ColoredShape shape = new ColoredShape(x,y,w,h,color);
                 shapeList.add(shape);
                 repaint();
             }
         });
     }

     // do all of your drawing in the overridden method paintComponent()
     public void paintComponent(Graphics g2d) {
         Graphics2D g = (Graphics2D)g2d;

         if (image != null)
             g.drawImage(image,0,0,null);

         for (ColoredShape shape : shapeList) {
             g.setColor(shape.getColor());
             g.fill(shape);
         }
     }

     class ColoredShape extends Ellipse2D.Double {
         private final Color color;

         public ColoredShape(double x,double y,double w,double h,
          Color color) {
             super(x,y,w,h);
             this.color = color;
         }

         public Color getColor() {
             return color;
         }
     }

     public static void main(String[] args) {
         // create GUI on EDT (event dispatch thread)
         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 JFrame f = new JFrame();
                 f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                 test t = new test();
                 f.add(t,BorderLayout.CENTER);
                 f.pack();
                 f.setVisible(true);
             }
         });
     }
}

Back to comp.lang.java.gui | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-01-18 16:55 +0000
  Re: How do I paint on an existing Panel? Knute Johnson <nospam@knutejohnson.com> - 2012-01-18 09:29 -0800
    Re: How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-01-18 18:12 +0000
      Re: How do I paint on an existing Panel? Knute Johnson <nospam@knutejohnson.com> - 2012-01-18 15:00 -0800
  Re: How do I paint on an existing Panel? markspace <-@.> - 2012-01-18 10:55 -0800
  Re: How do I paint on an existing Panel? Roedy Green <see_website@mindprod.com.invalid> - 2012-01-20 19:54 -0800
  Re: How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-01-30 17:59 +0000
  Re: How do I paint on an existing Panel? Neil Morris <neil.morris4@googlemail.com> - 2012-02-04 20:58 +0000
    Re: How do I paint on an existing Panel? Lew <lewbloch@gmail.com> - 2012-02-05 01:01 -0800
    Re: How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-02-10 12:10 +0000
    Re: How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-02-16 20:55 +0000
      Re: How do I paint on an existing Panel? Lew <lewbloch@gmail.com> - 2012-02-16 13:04 -0800
        Re: How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-02-16 21:33 +0000
  Re: How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-02-16 21:05 +0000
    Re: How do I paint on an existing Panel? Lew <lewbloch@gmail.com> - 2012-02-16 13:28 -0800
      Re: How do I paint on an existing Panel? "John B. Matthews" <nospam@nospam.invalid> - 2012-02-16 21:18 -0500
      Re: How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-02-17 18:20 +0000
        Re: How do I paint on an existing Panel? Lew <lewbloch@gmail.com> - 2012-02-17 10:45 -0800
        Re: How do I paint on an existing Panel? Lew <lewbloch@gmail.com> - 2012-02-17 10:49 -0800
          Re: How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-02-19 19:31 +0000
            Re: How do I paint on an existing Panel? Lew <noone@lewscanon.com> - 2012-02-19 14:41 -0800
              Re: How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-03-04 16:51 +0000
                Re: How do I paint on an existing Panel? Jeff Higgins <jeff@invalid.invalid> - 2012-03-04 12:36 -0500
                Re: How do I paint on an existing Panel? Lew <noone@lewscanon.com> - 2012-03-04 10:47 -0800
                Re: How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-03-14 17:39 +0000
                Re: How do I paint on an existing Panel? Lew <lewbloch@gmail.com> - 2012-03-14 11:07 -0700
                Re: How do I paint on an existing Panel? "John B. Matthews" <nospam@nospam.invalid> - 2012-03-14 23:01 -0400
                Re: How do I paint on an existing Panel? markspace <-@.> - 2012-03-15 09:30 -0700
        Re: How do I paint on an existing Panel? Knute Johnson <nospam@knutejohnson.com> - 2012-02-17 17:01 -0800
    Re: How do I paint on an existing Panel? Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2012-02-16 13:59 -0800
      Re: How do I paint on an existing Panel? "A B" <@bleBaker.uk> - 2012-02-17 18:07 +0000
        Re: How do I paint on an existing Panel? Knute Johnson <nospam@knutejohnson.com> - 2012-02-17 17:04 -0800
        Re: How do I paint on an existing Panel? Knute Johnson <nospam@knutejohnson.com> - 2012-02-17 17:08 -0800

csiph-web