Nasty Old Dog: Graphics Based Black Jack

AP Computer Science: After the Exam: Graphical BlackJack

The AP COMP SCI test is done

Congratulations to every one that took the 2013 AP Exam. This is probably the last series AP Computer Science Articles I write (at least until another one of my kids decides to take the course). Whatever score you end up getting I hope you pursue a few computer courses in college. Computers are involved in every aspect of business and manufacturing and understanding the concepts of building working programs will make you better managers and business owners. Too many managers in the 21st Century think that understanding how to use a spreadsheet is all they require to manage a 21st Century business. Instead I propose that great managers understand what it takes to get things accomplished and understand what goes into making a great product. My hope for the new generation of entrepreneurs is that you persue your talents with passion and take us forward in ways the spreadsheet jockeys can't even dream of, much less understand.

Now that you have some time and aren't worried about taking tests. I wanted to take the BlackJack Program to its next evolutionary step and add a Graphical User Interface to the BlackJack Program. I haven't used the Java Swing classes in a long time and have never considered myself a User Interface Programmer so I will step you through the process as an example of how at least one programmer treads into uncharted territory.

Spicing up BlackJack

First things first I'm going to steal some pictures and code. It seems legal because the developer has placed them on his(or her) website for free. So go to http://www.jfitz.com/cards/index.html and download the classic-cards.zip. That file contains a .png file of all the card faces needed to implement the game. The picture of all the cards in one file is there to. You are viewing it at the above site. By using your browser to do a "Copy Image Location" you can save the http address for use in the program.

Now go to the following message board site: stackoverflow.com There you will find a piece of code that uses the cards you downloaded. The code there shows you how to use them directly from the web without downloading prior to using them. Feel free to cut and paste the code into your IDE and see how it works. For this project I'm going to adapt one portion of that code: there is a "Factory" class called CreateCards. This grabs portions of the .png file to cut out single card images and store them in objects in a list.

class CreateCards {
   private static final int SUIT_COUNT = 4;
   private static final int RANK_COUNT = 13;

   public static List<ImageIcon> createCardIconList(String pathToDeck)
         throws MalformedURLException, IOException {
      BufferedImage fullDeckImg = ImageIO.read(new URL(pathToDeck));
      int width = fullDeckImg.getWidth();
      int height = fullDeckImg.getHeight();
      List<ImageIcon> iconList = new ArrayList<ImageIcon>();

      for (int suit = 0; suit < SUIT_COUNT; suit++) {
         for (int rank = 0; rank < RANK_COUNT; rank++) {
            int x = (rank * width) / RANK_COUNT;
            int y = (suit * height) / SUIT_COUNT;
            int w = width / RANK_COUNT;
            int h = height / SUIT_COUNT;
            BufferedImage cardImg = fullDeckImg.getSubimage(x, y, w, h);
            iconList.add(new ImageIcon(cardImg));
         }
      }
      Collections.shuffle(iconList);
      return iconList;
   }
}

Now the above code is not quite what we will use but it is informative. The author (pseudonym: Hovercraft Full of Eels) shows how to take the full deck image and divide it up into individual card images. The BlackJack program we created has a bit of a problem because we used modulo to create card face values and suits.

Instead of looping through the suits and "rank" (rank is what I originally termed face_value), use modulo to get the rank and suit. Change the text model order for the suits:

was: private String suit = "HDSC";
now: private String suit = "CSHD";

Now the card images get set up in a one to one correspondence image to text. Pretty simple change for some borrowed code.

This program doesn't really need the ImageIcon object. That provides some capabilities to move the image around on the screen. For a simple blackjack program there isn't really a need for this functionality. The code has been adapted further to use the BufferedImage class directly.

Hide the Image Down Deep Inside

To adapt the above code the question arises where do you store the image? The PlayingCard object is the obvious choice. A PlayingCard should know how to display itself.

The CardDeck object already loops 52 times to create all the PlayingCard's by calling the PlayingCard constructor method. By creating a BufferedImage field in the PlayingCard object and using the CardImageFactory method makeCardImage in the constructor, all the images will be associated with the PlayingCard Objects with very little coding. All that is needed is to properly map from our cardno in a PlayingCard to the appropriate image in the large image file.

First the new factory class CardImageFactory:

package blackjack;

import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;

/**
 * Factory class to create images for each card so it may be displayed 
 * graphically. Everything is static but initCardImageFactory method 
 * must be called first to set up the full image of all the cards in memory
 * this way the call to makeCardIcon does not make 52 web accesses
 * 
 * @author Nasty Old Dog
 */
public class CardImageFactory {
   private static final int SUIT_COUNT = 4;
   private static final int RANK_COUNT = 13;
   private  static BufferedImage fullDeckImg = null;
   public static   int width = 0;
   public static   int height = 0;

      /**
    * Initialized the .png image in memory and sets up width and height 
    * readying size parameters to cut the image up into icons. This also
    * isolates IO exceptions to this method so the individual calls 
    * do not have to have exception handling.
    * 
    * @param pathToDeck the http address of the full card image file
    * @throws MalformedURLException
    * @throws IOException 
    */
   public static void initCardImageFactory(String pathToDeck) 
           throws MalformedURLException, IOException{
      fullDeckImg = ImageIO.read(new URL(pathToDeck));
      width = fullDeckImg.getWidth();
      height = fullDeckImg.getHeight();
   }

   /**
    * For the structure of the current Black Jack program this returns 
    * individual card images instead of a full list. This allows you to 
    * develop a class hierarchy where the image is stored at the individual
    * PlayingCard object level.
    * 
    * @param rank card face value number 0 - 12
    * @param suit suits 0 - 4
    * @return 
    */
   public static BufferedImage makeCardIcon(int rank, int suit) {
            int x = (rank * width) / PlayingCard.RANK;
            int y = (suit * height) / PlayingCard.SUIT;
            int w = width / PlayingCard.RANK;
            int h = height / PlayingCard.SUIT;
            return fullDeckImg.getSubimage(x, y, w, h);
            // BufferedImage cardImg = fullDeckImg.getSubimage(x, y, w, h);
           // return new ImageIcon(cardImg);
   } 

   /**
    * The original image list created from the example found at: 
    * http://stackoverflow.com/questions/9692465/java-how-do-i-drag-and-drop-a-control-to-a-new-location-instead-of-its-data
    * created by author who goes by pseudonym: "Hovercraft Full of Eels"
    * @return
    * @throws MalformedURLException
    * @throws IOException 
    */
   public static List<ImageIcon> createCardIconList()
         throws MalformedURLException, IOException {
      //BufferedImage fullDeckImg = ImageIO.read(new URL(pathToDeck));
      width = fullDeckImg.getWidth();
      height = fullDeckImg.getHeight();
      List<ImageIcon> iconList = new ArrayList<ImageIcon>();

      for (int suit = 0; suit < SUIT_COUNT; suit++) {
         for (int rank = 0; rank < RANK_COUNT; rank++) {
            int x = (rank * width) / RANK_COUNT;
            int y = (suit * height) / SUIT_COUNT;
            int w = width / RANK_COUNT;
            int h = height / SUIT_COUNT;
            BufferedImage cardImg = fullDeckImg.getSubimage(x, y, w, h);
            iconList.add(new ImageIcon(cardImg));
         }
      }
      Collections.shuffle(iconList);
      return iconList;
   }

}

I left the "Eels" original method in the class as a reminder of where all the code came from. I split the file access from the image chopping because the file access routines throw exceptions. I want to handle those right away. So they have been placed in the "initCardImageFactory" method. This method is called in the main method to set up images in memory to be cut up when calls to the PlayingCard constructor are made. There's no sense trying to even create PlayingCards or running the program further if the program can't access the image file. As a rule I don't like to have exceptions in constructors the code becomes ugly when trying to create an object.

The other problem with creating a CardImageFactory object is where will the object reside so that the PlayingCard object has access to it. It could be set up in CardDeck and then passed in to the PlayingCard constructor but this again makes the code ugly. It is better to make it a set of static fields and method calls and limit where they are called from.

Java Swing and Graphics2D Libraries

Now that the decision has been made about where the image creation will be done one more thing that is needed is some code that will open a window for all this great graphics to be displayed in. Once that is in place the code changes can be added to the PlayingCard object so that PlayingCard instances (the objects created by CardDeck) get displayed properly.

The Java Swing Library is a graphics API. It provides windows for the program to run in. It has a call to "add" graphic objects into the window. The blackjack program needs a window object and a class that the window object knows how to display.

JFrame class: from the Swing API provides a graphics window
JComponent class: Swing API class that can be displayed in a JFrame

Any object that has a graphical representation will need to extend JComponent. This gives the object the ability to be used within a JFrame. It also needs a paint method. JFrame will call the paint method on all the objects that have been added to it when 2 method calls take place:

frame.pack();
frame.setVisible(true);

Assuming the PlayingCard object has been modified the following code is all we need to display a card:

JFrame frame = new JFrame("BlackJack");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
PlayingCard p1 = new PlayingCard(2);
frame.getContentPane().add(p1);
frame.pack();
frame.setVisible(true);

The PlayingCard Class

The PlayingCard Object is where most of the action takes place. The constructors have the calls to makeCardIcon have been placed. The next changes that are necessary is the object must extend JComponent and have a "paint" method. The paint method takes a "Graphics" object as a parameter. This will ultimately be supplied by JFrame after we add the PlayingCard to the list of objects to be displayed.

There is some ugly casting of the "Graphics" object to the "Graphics2D" object. This harkens back to the early days of Java and the use of the AWT drawing classes. The Swing drawing classes are an improvement over the AWT classes because the Swing classes make calls directly to the windowing system of the computer. So windows computers will see MS Windows style windows and Mac users will see Mac style windows. To make this change happen without killing off the AWT API and all the programs that were created the idea of supplying a Graphics2D object came about. It implements everything that the AWT had so you can send it to an old AWT style program and it will think it the old "Graphics" object. But in newer code where you know your using a version of Java that supports Graphics2D you can cast the graphics object to Graphics2D and get all the extra functionality that the new class provides.

Without further ado the PlayingCard Class now looks like:

/*
 * PlayingCard.java - Playing card class for BlackJack
 */
package blackjack;

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import javax.swing.JComponent;

/**
 * Object model of a simple playing card. Class has been adapted to be displayed
 * in a JFrame 
 * 
 * @author Nasty Old Dog
 */
public class PlayingCard extends JComponent{
    public static final int RANK=13;
    public static final int SUIT=4;
    private int cardno;
    private int card_score[] = {11, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10};
    private BufferedImage img = null;

    private String faceVal = "A23456789TJQK";
    private String suit = "CSHD";

    public PlayingCard(int cardno)
    {
        this.cardno = cardno;
        this.img = CardImageFactory.makeCardIcon(cardno%RANK, cardno%SUIT);
    }

    public PlayingCard(int cardno, int[] card_score)
    {
        this.cardno = cardno;
        this.card_score = card_score;
        this.img = CardImageFactory.makeCardIcon(cardno%RANK, cardno%SUIT);
    }

    /**
     * Get the card scoring value for blackjack face cards = 10 ace = 11 
     * all other cards equal their face value. Aces can equal 1 at times and 
     * is handled elsewhere
     * @return 
     */
    public int card_value()
    {
        return card_score[cardno % 13];
    }

    /**
     * convert cardno into text string of face value and suit
     * @return 
     */
    public String getCardText() {
        int card_val = this.cardno % 13;
        int card_suit = this.cardno % 4;
        return this.faceVal.substring(card_val, card_val + 1)
                + this.suit.substring(card_suit, card_suit + 1);
    }

    /**
     * paint the image for the Playing card as Graphics2D image
     * @param _g 
     */
    @Override
    public void paint(Graphics _g) {
        Graphics2D g = (Graphics2D) _g;
        g.drawImage(img,10,10,null);
    }
}

Testing the program so far

The BlackJack class (the main class for this project) looks like this:

/*
 * BlackJack a simple implementation upgrade for graphical card display
 */
package blackjack;

import java.io.IOException;
import java.net.MalformedURLException;
import java.util.Scanner;
import javax.swing.JFrame;

/**
 * This class controls the game logic of this simple implementation of 
 * Black Jack. A more profession version would allow for multiplayer games
 * via a game server so you could play your friends on the internet. 
 * Some improvements would be:
 * <p>
 *    Adding insurance (players could insure bets against a dealer having blackjack) <p>
 *    Increase the payout for a blackjack hand to 1.5 x the original bet <p>
 *    Double Down <p>
 *    Splitting pairs <p>
 * 
 * @author Nasty Old Dog
 */
public class BlackJack {

    int card_score[] = {11, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10};
    CardDeck card;
    Hand player;
    Hand dealer;

    public BlackJack()
    {
        this.card = new CardDeck();
    }

    /**
     * run method that does all the work of this class
     */
    public void run() {
// **************************************************************
//   Added graphics code
        JFrame frame = new JFrame("BlackJack");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        PlayingCard p1 = new PlayingCard(2);
        frame.getContentPane().add(p1);
        frame.pack();
        frame.setVisible(true);
// **************************************************************
        this.card.display();
        this.card.shuffle();
        this.card.display();

        // Now I just need to create the hand objects
        this.player = new Hand("Player Hand");
        this.dealer = new Hand("Dealer Hand");
/*
 *               .
 *               .
 *               .
 *      The rest of the code for run() remains unchanged from it's 
 *      previous incantation
 *               .
 *               .
 *               .
 */

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        try {
            // initialize the CardImageFactory to use the full card image file
            CardImageFactory.initCardImageFactory("http://www.jfitz.com/cards/classic-playing-cards.png");
            BlackJack game = new BlackJack();

            game.run();
        } catch (MalformedURLException ex) {
            System.out.println(ex.getMessage());
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }        
    }
}

The call to init the CardImageFactory has been placed in the main routine. The calls to the JFrame have been added and one PlayingCard object is created to see if we can create a window that displays a PlayingCard as a graphic instead of the text we have been doing before.

The Graphics

For this project I took the 4 BlackJack Classes created earlier (BlackJack, CardDeck, PlayingCards, and Hand) and added the CardImageFactory class and put them all into a new project. This helps to isolate the program so it can be packaged as a stand alone program. When you make the changes to BlackJack and PlayingCards you should see a window pop up.

It needs to be enlarged and the window is responsive to mouse commands. When it is enlarged we see a card was created and displayed using the PlayingCard.

Conclusion

The small window that opens up when the program is run is annoying. Nobody wants to have to reset the size with the mouse to see what is going on. The addition of one more method call on the JFrame object will fix the problem:

frame.setPreferredSize(new Dimension(300,300));

Adding this will open a window where the full card is displayed.

The other interesting behavior this program has is that the window is in control of terminating the program. If you kill the window the whole program terminates. For a graphics program this is the expected behavior. Right now the BlackJack program lives in a text based world that is separated from the graphics based world. It would be nice as the program transitions to span both worlds at the same time so a direct comparison between the graphics presentation and the text based presentation can be made. This may be beyond the scope of this project as JFrame objects are meant to run in a multi-threaded environment and weaving control back and forth may not be the best way forward.

For the entire source code download the following and unzip:

blackjacksrc.zip

NEXT STEPS

Modify CardDeck so it displays the entire deck of cards as a test to see that all images have been accounted for
Modify Hand so it displays it's cards graphically
Add graphic controls for the user to control the game
Weave in the blackjack control code into the graphics code to complete the game

References

stackoverflow.com "Java: How do I drag and drop a control to a new location instead of its data?" answer by author pseudonym "Hovercraft Full of Eels" stackoverflow.com Link
The Java Tutorials (oracle.com) "Using Swing Components: Using Top-Level Containers" Top-level Containers Link
Hardy, Vincent J. "Java 2D API Graphics" Palo Alto, CA: Sun Microsystems, 2000.

Author: Nasty Old Dog

Validate XHTML 1.0

Nasty Old Dog

Nasty Pages

Sunday, May 12, 2013

Graphics Based Black Jack