Why Graphics.drawImage() can't work?

Question

Hi Veterans,
I met some problems when I create an image by calling the Graphics.drawImage() method. Firstly, I created an off-screen image by calling the method frame.createImage(800, 640), then I was drawing some graphical elements on the the graphics acquired from the offscreen image, like drawString(), drawLine. And the most important step is as follows, I want to append another image from the file system to the current one by calling drawImage(Image img, int x, int y, ImageObserver frame), but it can't work, I got the appended image by calling Toolkit.getDefaultToolkit().createImage("D:\\abc.gif"). But I am not sure if it is a correct way to get an image from the file system. After that, I will use a 3rd party utitliy to generate new gif image. But when I view the new generated image, it only include the grahpical elements I drew by drawString(), drawLine, and the drawImage() seems can't work. Why?
I post the code snippet for reference.
Any help is appreciated!
               frame=new Frame();
               frame.addNotify();
               Image offscreen = frame.createImage(800, 800);
               g = (Graphics2D) offscreen.getGraphics();
               g.setFont(new Font("Dialog",Font.PLAIN,12));
               g.drawString("Owner ID:",10,10);
               g.drawString("2238",90,10);
               g.drawString("Order No.:",10,40);
               Image image = Toolkit.getDefaultToolkit().createImage("D:\\barcode.gif");
               System.out.println("[Image Width:] " + image.getWidth(frame)); //the output is -1, why?
g.drawImage(image, 0, 0, frame); //seems can't work

Answer 1

This isn't right. The Toolkit returned by getDefaultToolkit has an implementation for all these methods. The issue here is that you are calling getWidth on the Image before the Image has been loaded from your gif file. What you need to do is to call getWidth(ImageObserver) and then, if the width comes back as -1 wait for the ImageObserver to notify you that it has loaded the width attribute of the image. Take a look at
http://java.sun.com/docs/books/tutorial/uiswing/painting/loadingImages.html
Huw