//
// another example of the Java AWT, showing loading and display of
//      an image.
// see class definition for details.
//
import java.awt.* ;
import java.io.* ;

//
// a ShowImage object is a DrawingFrame that displays an image
//      loaded from a file (GIF and JPEG formats are supported).
//      the initial size of the display is just big enough to
//      contain the image; if the window is resized, the image is
//      scaled to fit.
//
class ShowImage extends DrawingFrame {

        private Image frameImage ;

        ShowImage(String imageFile) {
                super("ShowImage") ;

                // start loading image.
                frameImage = getToolkit().getImage(imageFile) ;
                System.out.println("loading image ....") ;

                // wait for completion.
                waitForImage(frameImage) ;
                System.out.println("done") ;

                // get size of loaded image and use to set
                //      initial size.
                int w = frameImage.getWidth(this) ;
                int h = frameImage.getHeight(this) ;
                setDrawingSize(new Dimension(w, h)) ;

                show() ;
        }

        // waits for image to finish loading.
        private void waitForImage(Image im) {
                MediaTracker tracker = new MediaTracker(this) ;
                // add desired image to list of things the
                //      MediaTracker is tracking, with id = 0.
                tracker.addImage(im, 0) ;
                try {
                        // wait for loading of image we just
                        //      added to MediaTracker's list.
                        tracker.waitForID(0) ;
                } catch(InterruptedException e) { }
        }

        // creates onscreen image by scaling image from file.
        public void paint(Graphics g) {

                System.out.println("paint called") ;
                if (frameImage != null) {

                        // position origin to avoid frame borders.
                        translateDrawingArea(g) ;

                        // get size of frame, minus borders.
                        Dimension d = getDrawingSize() ;

                        // draw scaled version of image.
                        g.drawImage(frameImage, 0, 0, d.width, d.height,
                                this) ;
                }
        }

        // updates onscreen image (no need to clear first, just paint).
        public void update(Graphics g) {
                System.out.println("update called") ;
                paint(g) ;
        }

        //
        // ---- main ---------------------------------------------------
        //
        // command-line argument:  file from which to load image.
        //
        public static void main(String[] args) {

                if (args.length < 1) {
                        System.out.println("Argument is filename") ;
                        System.exit(-1) ;
                }

                File f = new File(args[0]) ;
                if (!f.exists() || !f.canRead()) {
                        System.out.println("Filename not found") ;
                        System.exit(-1) ;
                }

                ShowImage s = new ShowImage(args[0]) ;
        }
}