51 images by ls723a4r

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									Images




         4-Oct-12
        Drawing images
   Java can display .gif, .jpg (or .jpeg), and .png images
       These are the only kinds it can display
   Displaying them is (relatively) easy:
       Get the Graphics of the panel you want to display them in
       Call this method of your Graphics object:
        boolean drawImage(Image img, int x, int y,
                              ImageObserver observer)
        where:
            img is the image
            x, y are the coordinates of the upper left-hand corner
            observer – the enclosing JFrame works well for this argument
   Example:
    myPanel.getGraphics().drawImage(myImage, 0, 0, this);
        Why an ImageObserver?
   boolean drawImage(Image img, int x, int y,
                            ImageObserver observer)
   This method “Draws as much of the specified image as
    is currently available.”
       It returns true if the entire image is available
       It notifies the ImageObserver if more has become available

   In general, it would be nice if the images were loaded
    before attempting to display them
       In particular, attempting to display a null image is an error
         Loading images
   This is ridiculously difficult. Here goes...
        Get a Toolkit that can load the image
             Toolkit toolkit = Toolkit.getDefaultToolkit();
        Get a MediaTracker that can watch images being loaded
             MediaTracker tracker = new MediaTracker(owner);
                 A JFrame makes a perfectly good owner

        Tell the toolkit that you want to load the image
             Image image = toolkit.getImage(fileName);
        Tell the MediaTracker to track the image
             tracker.addImage(image, 0);
             A MediaTracker can track any number of images at once
        Tell the MediaTracker to start loading the images (bet you thought
         getImage did this!) and wait for them to finish loading
             tracker.waitForAll();
        Finally, handle the Exceptions that might occur
The End

								
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