23-Jun-15 Images

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 Exception s that might occur

The End