Draw bitmap in Canvas

[Jonathas Carrijo]

I have to show a bmp image in a Canvas, inside a frame. I tried to use Toolkit's getImage(String <filename> , but it didn't work... Actually I copied the code from an old post here at this forum. Here it is:

import java.awt.*;
import java.awt.event.*;
import java.io.File;
public class ImageFrame extends Frame{   
  private ImageCanvas c;
  private Image i;
  ImageFrame( Image i ) {
    this.i = i;
    c = new ImageCanvas( i );
    add( c );
  }

  public static void main( String[] args ) {
    Toolkit tk = Toolkit.getDefaultToolkit();
    //for debug
    File file = new File("c:\\juba\\used.bmp");
    System.out.println(file.exists());
    Image im = tk.getImage("c:\\juba\\used.bmp");
    ImageFrame f = new ImageFrame( im );
    f.addWindowListener( new WindowAdapter() { 
      public void windowClosing( WindowEvent e ) {
        System.exit( 0 );
      }
    });
    f.setSize( 300, 300 );
    f.show();
  }
  private class ImageCanvas extends Canvas {
    Image i;
    public ImageCanvas( Image i ) {
      this.i = i;
    }

    public void paint( Graphics g ) {
      g.drawImage( i, 0, 0, this );
    }

    public Dimension getPreferredSize() {
      int w = i.getWidth( this );
      int h = i.getHeight( this );
      return new Dimension( w, h );
    }
  }
}

It compiles and run fine, but the image simply is not painted, and it actually exists (i get a true printed in the console). Why doesn't it work? How can it be done (without using an applet) ?
Thanks in advance...
JUBA d-_-b

[Amanda Weber]

The drawImage method of the graphics class returns a boolean if the image displayed. Try using it in a while loop:
while (!g.drawImage(......))
repaint;

[Jonathas Carrijo]

I changed the paint() method as follows:

  public void paint( Graphics g ) {
    boolean b = g.drawImage( i, 0, 0, this );
    System.out.println("drawImage: "+b);
    if (!b) repaint();
  }

And all I got is hundreds of thousands of:
drawImage: false
drawImage: false
drawImage: false
drawImage: false
drawImage: false
Why??? What can be done? I really need this working! Please help me...
Thanks,
Juba d-_-b

[Amanda Weber]

You are trying to draw the image before it is fully loaded. Use the MediaTracker to get when the image will be loaded, then draw it. Sun's documentation on java.awt.MediaTracker explains it very well.

[Jonathas Carrijo]

I added this to my code. Everything compiled and ran fine, but still didn't show my image...

MediaTracker mt = new MediaTracker(this);
mt.addImage(i, 0);
try {
  mt.waitForAll();
} catch (InterruptedException e) {
  e.printStackTrace();
  System.out.println("Couldn't wait for load!");
}
System.out.println("Error loading: "
                   +mt.isErrorAny());

I got as output:
Error loading: true
which means that there was an error loading the image... I tried to use the getImage() method which takes an URL as parameter, like this:

 URL url;
 Image im;
 try {
    url = new URL("file:///c:/juba/used.bmp");
    im = tk.getImage(url);
 } catch (MalformedURLException e) {
    e.printStackTrace();
    System.exit(5);
 }

instead of the tk.getImage("c:\\juba\\used.bmp");
Didn`t work yet... I think I'm gonna migrate to Swing... or even to C# (hehehe)
Am I attacking it the right way? I mean, is the problem actually in the path specification?
Anybody help, I need it deployed till tomorrow...
Thanks much!
Juba d-_-b
[ November 21, 2002: Message edited by: Jonathas Carrijo ]

[Jonathas Carrijo]

Please guys... I really need help on this!
Haven't anybody ever had a happy experience loading images?? Please share with me
Thanks a lot

[Cindy Glass]

Try this. Note that Balloon.jpg is in the same directory with ImageFrame.class.

import java.awt.*;
import java.awt.event.*;
import java.io.File;
public class ImageFrame extends Frame{
  private ImageCanvas c;
  private Image i;
  ImageFrame( Image i ) {
    this.i = i;
    c = new ImageCanvas( i );
    add( c );
  }
  public static void main( String[] args ) {
    ImageFrame f = new ImageFrame(Toolkit.getDefaultToolkit().createImage("Balloon.jpg"));
    f.setSize( 300, 300 );
    f.show();
  }
  private class ImageCanvas extends Canvas {
    Image i;
    public ImageCanvas( Image i ) {
      this.i = i;
    }
    public void paint( Graphics g ) {
      g.drawImage( i, 0, 0, this );
    }
    public Dimension getPreferredSize() {
      int w = i.getWidth( this );
      int h = i.getHeight( this );
      return new Dimension( w, h );
    }
  }
}

[O Nulano]

I had the same problem (images not loading) and I found this: Official Java Tutorial on loading Images

[Campbell Ritchie]

Welcome to the Ranch

Did you notice the thread was labelled urgent? I hope ten years wasn’t too long to wait That tutorial might not even have been available in 2002!

[O Nulano]

Campbell Ritchie wrote:Welcome to the Ranch

Did you notice the thread was labelled urgent? I hope ten years wasn’t too long to wait That tutorial might not even have been available in 2002!

It was urgent for me too. I couln't find anything of value except this, and I thought it wold be valuable information for other people who find this forum as well.

[Campbell Ritchie]

Yes, it is valuable information. Thank you, It is just that we sometimes wonder whether people realise they are reopening such old threads.

[Rob Spoor]

Campbell Ritchie wrote:Did you notice the thread was labelled urgent?

Emphasis on "was"

[Campbell Ritchie]

No, emphasis on“”