SplashScreen.java

package org.vorthmann.ui;


import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.Window;
import java.net.URL;

/**
* Present a simple graphic to the user upon launch of the application, to 
* provide a faster initial response than is possible with the main window.
* 
* <P>Adapted from an 
* <a href=http://developer.java.sun.com/developer/qow/archive/24/index.html>item</a> 
* on Sun's Java Developer Connection.
*
* <P>This splash screen appears within about 2.5 seconds on a development 
* machine. The main screen takes about 6.0 seconds to load, so use of a splash 
* screen cuts down the initial display delay by about 55 percent. 
*
* @used.By {@link stocksmonitor.ApplicationUI}
* @to.do Can the performance be improved to 1.0 second?
* @author <a href="http://www.javapractices.com/">javapractices.com</a>
*/
public final class SplashScreen extends Frame {

  /**
  * @param aImageId must have content, and is used by  
  * <code>Class.getResource</code> to retrieve the splash screen image.
  */
  public SplashScreen(String aImageId) {
    /* Implementation Note
    * Args.checkForContent is not called here, in an attempt to minimize 
    * class loading.
    */
    if ( aImageId == null || aImageId.trim().length() == 0 ){
      throw new IllegalArgumentException("Image Id does not have content.");
    }
    fImageId = aImageId;
  }
   
  /**
  * Show the splash screen to the end user.
  *
  * <P>Once this method returns, the splash screen is realized, which means 
  * that almost all work on the splash screen should proceed through the event 
  * dispatch thread. In particular, any call to <code>dispose</code> for the 
  * splash screen must be performed in the event dispatch thread.
  */
  public void splash(){
    initImageAndTracker();
    setSize(fImage.getWidth(null), fImage.getHeight(null));
    center();
    
    fMediaTracker.addImage(fImage, 0);
    try {
      fMediaTracker.waitForID(0);
    }
    catch(InterruptedException ie){
      System.out.println("Cannot track image load.");
    }

    SplashWindow splashWindow = new SplashWindow(this,fImage);
  }
  
  
  // PRIVATE//
  private final String fImageId;
  private MediaTracker fMediaTracker;
  private Image fImage;

  private void initImageAndTracker(){
    fMediaTracker = new MediaTracker(this);
    URL imageURL = Thread .currentThread() .getContextClassLoader() .getResource(fImageId);
    fImage = Toolkit.getDefaultToolkit().getImage(imageURL);
  }

  /**
  * Centers the frame on the screen.
  *
  * This centering service is more or less in {@link UiUtil}; this duplication 
  * is justified only because the use of {@link UiUtil} would entail more 
  * class loading, which is not desirable for a splash screen.
  */
  private void center(){
    Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
    Rectangle frame = getBounds();
    setLocation((screen.width - frame.width)/2, (screen.height - frame.height)/2);
  }
 
  private class SplashWindow extends Window {
    SplashWindow(Frame aParent, Image aImage) {
       super(aParent);
       fImage = aImage;
       setSize(fImage.getWidth(null), fImage.getHeight(null));
       Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
       Rectangle window = getBounds();
       setLocation((screen.width - window.width) / 2, (screen.height - window.height) / 2);
       setVisible(true);
    }
    @Override
    public void paint(Graphics graphics) {
      if (fImage != null) {
        graphics.drawImage(fImage,0,0,this);
      }
    }
    private Image fImage;
  }
  
  /**
  * Developer test harness shows the splash screen for a fixed length of 
  * time, without launching the full application.
  */
  private static void main(String[] args){
    SplashScreen splashScreen = new SplashScreen( "testSplash.gif");
    splashScreen.splash();
    try {
      Thread.sleep(2000);
    }
    catch(InterruptedException ex) {
      System.out.println(ex);
    }
    System.exit(0);
  }
}