drawImage not getting the image drawn before printing!

[Stephen Huey]

This is not an applet, and I'm not displaying the image for the user, either. I've got an image (my oCanvas object is a Graphics2D) that I'm drawing by calling drawString and fillRect to put stuff on it, and then I'm writing it out to a file. I've been using this for a long time and am trying to simply modify it by calling drawImage on it. I have a local image file that I want to add to this image, and here's the code that's not working:

 
      try {
        String logoLocation = GlobalSettings.getSetting("imagedir") + "AE89x35.BMP";
        Image logo = Toolkit.getDefaultToolkit().getImage(logoLocation);
        System.out.println("logoLocation is " + logoLocation);
        oCanvas.drawImage(logo, 180, 190, this);
      } catch (Exception e) {
        System.err.println(e);
      }
    }
   oCanvas.drawString("DESCRIPTION:", 10, 215);  
 

The class I'm in extends Component, which is why I have this in there, but I also tried it by overriding the imageUpdate method, and I've also tried it with null in there. drawImage is returning false, meaning the image is not yet loaded. I need my program to wait for that image to be drawn before going on, and I've been Googling around for a while trying to figure out a good way to do this, b/c I'm finding wading around this particular section of the API to be a bit hairy for me (being that I rarely do anything with graphics).
Thanks for any help!

[Jose Botella]

Hello.
From the old AWT tutorial:

The MediaTracker class lets you easily download data for a group of images and find out when the images are fully loaded. Ordinarily, an image's data isn't downloaded until the image is drawn for the first time. To request that the data for a group of images be preloaded asynchronously, you can use the forms of checkID() and checkAll() that take a boolean argument, setting the argument to true. To load data synchronously (waiting for the data to arrive), use the waitForID() and waitForAll() methods. The MediaTracker methods that load data use several background threads to download the data, resulting in increased speed.
To check on the status of image loading, you can use the MediaTracker statusID() and statusAll() methods. To simply check whether any image data remains to be loaded, you can use the checkID() and checkAll() methods.

/*
 * 1.0 code.
 */
import java.awt.*;
import java.applet.Applet;
/* 
 * This applet displays several images in a row.  It prevents
 * flashing by double buffering.  MediaTracker preloads the image
 * data using multiple background threads.  The program doesn't
 * draw until all the images are fully loaded.
 */
public class MTImageSequence extends Applet implements Runnable {
    int frameNumber = -1;
    int delay;
    Thread animatorThread;
    boolean frozen = false;
    Dimension offDimension;
    Image offImage;
    Graphics offGraphics;
    Image[] images;
    MediaTracker tracker;
    public void init() {
        String str;
        int fps = 10;
        //How many milliseconds between frames?
        str = getParameter("fps");
        try {
            if (str != null) {
                fps = Integer.parseInt(str);
            }
        } catch (Exception e) {}
        delay = (fps > 0) ? (1000 / fps) : 100;
        //Load all the images.
        images = new Image[10];
        tracker = new MediaTracker(this);
        for (int i = 1; i <= 10; i++) {
            images[i-1] = getImage(getCodeBase(),
                          "T"+i+".gif");
            tracker.addImage(images[i-1], 0);
        }
    }
    public void start() {
        if (frozen) {
            //Do nothing.  The user has requested that we
            //stop changing the image.
        } else {
            //Start animating!
            if (animatorThread == null) {
                animatorThread = new Thread(this);
            }
            animatorThread.start();
        }
    }
    public void stop() {
        //Stop the animating thread.
        animatorThread = null;
        //Get rid of the objects necessary for double buffering.
        offGraphics = null;
        offImage = null;
    }
    public boolean mouseDown(Event e, int x, int y) {
        if (frozen) {
            frozen = false;
            start();
        } else {
            frozen = true;
            //Instead of calling stop(), which destroys the
            //backbuffer, just stop the animating thread.
            animatorThread = null;
        }
        return true;
    }
    public void run() {
        try {
            //Start downloading the images. Wait until they're loaded
    //before requesting repaints.
            tracker.waitForAll();
        } catch (InterruptedException e) {}
        //Just to be nice, lower this thread's priority
        //so it can't interfere with other processing going on.
        Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
 
        //Remember the starting time.
        long startTime = System.currentTimeMillis();
        //This is the animation loop.
        while (Thread.currentThread() == animatorThread) {
            //Advance the animation frame.
            frameNumber++;
            //Display it.
            repaint();
            //Delay depending on how far we are behind.
            try {
                startTime += delay;
                Thread.sleep(Math.max(0, 
                                      startTime-System.currentTimeMillis()));
            } catch (InterruptedException e) {
                break;
            }
        }
    }
    public void paint(Graphics g) {
        update(g);
    }
    public void update(Graphics g) {
        Dimension d = size();
        //If not all the images are loaded, just clear the background
        //and display a status string.
        if (!tracker.checkAll()) {
            g.clearRect(0, 0, d.width, d.height);
            g.drawString("Please wait...", 0, d.height/2);
        }
        //If all images are loaded, draw.
        else {
            //Create the offscreen graphics context, if no good one exists.
            if ( (offGraphics == null)
              || (d.width != offDimension.width)
              || (d.height != offDimension.height) ) {
                offDimension = d;
                offImage = createImage(d.width, d.height);
                offGraphics = offImage.getGraphics();
            }
            //Erase the previous image.
            offGraphics.setColor(getBackground());
            offGraphics.fillRect(0, 0, d.width, d.height);
            offGraphics.setColor(Color.black);
            //Paint the frame into the image.
            offGraphics.drawImage(images[frameNumber % 10], 0, 0, this);
            //Paint the image onto the screen.
            g.drawImage(offImage, 0, 0, this);
        }
    }
}

[Brian Pipa]

From the javadocs:

public abstract Image getImage(URL url)
   Returns an image which gets pixel data from the specified URL. The pixel data referenced by the specified URL must be in one of the following formats: GIF, JPEG or PNG.

Try converting your .bmp image to one of the supported formats.
Brian

[Stephen Huey]

Duh! Thanks so much. I was *really* tired yesterday!
:roll:

Originally posted by Brian Pipa:
From the javadocs:

public abstract Image getImage(URL url)
   Returns an image which gets pixel data from the specified URL. The pixel data referenced by the specified URL must be in one of the following formats: GIF, JPEG or PNG.

Try converting your .bmp image to one of the supported formats.
Brian