first commit

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/DarkerFilter.ctxt

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+#BlueJ class context
+comment0.params=name
+comment0.target=DarkerFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ DarkerFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/DarkerFilter.java

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+/**
+ * An image filter to make the image a bit darker.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class DarkerFilter extends Filter
+{
+    /**
+     * Constructor for objects of class DarkerFilter.
+     * @param name The name of the filter.
+     */
+    public DarkerFilter(String name)
+    {
+        super(name);
+    }
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                image.setPixel(x, y, image.getPixel(x, y).darker());
+            }
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/EdgeFilter.ctxt

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+#BlueJ class context
+comment0.params=name
+comment0.target=EdgeFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ EdgeFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+comment1.params=image
+comment1.target=void\ apply(OFImage)
+comment1.text=\n\ Apply\ this\ filter\ to\ an\ image.\n\ \n\ @param\ \ image\ \ The\ image\ to\ be\ changed\ by\ this\ filter.\n
+comment2.params=xpos\ ypos
+comment2.target=java.awt.Color\ edge(int,\ int)
+comment2.text=\n\ Return\ a\ new\ color\ that\ is\ the\ smoothed\ color\ of\ a\ given\n\ position.\ The\ "smoothed\ color"\ is\ the\ color\ value\ that\ is\ the\n\ average\ of\ this\ pixel\ and\ all\ the\ adjacent\ pixels.\n\ @param\ xpos\ The\ x\ position\ of\ the\ pixel.\n\ @param\ ypos\ The\ y\ position\ of\ the\ pixel.\n\ @return\ The\ smoothed\ color.\n
+comment3.params=pixels
+comment3.target=int\ diffRed(java.util.List)
+comment3.text=\n\ @param\ pixels\ The\ list\ of\ pixels\ to\ be\ averaged.\n\ @return\ The\ average\ of\ all\ the\ red\ values\ in\ the\ given\ list\ of\ pixels.\n
+comment4.params=pixels
+comment4.target=int\ diffGreen(java.util.List)
+comment4.text=\n\ @param\ pixels\ The\ list\ of\ pixels\ to\ be\ averaged.\n\ @return\ The\ average\ of\ all\ the\ green\ values\ in\ the\ given\ list\ of\ pixels.\n
+comment5.params=pixels
+comment5.target=int\ diffBlue(java.util.List)
+comment5.text=\n\ @param\ pixels\ The\ list\ of\ pixels\ to\ be\ averaged.\n\ @return\ The\ average\ of\ all\ the\ blue\ values\ in\ the\ given\ list\ of\ pixels.\n
+numComments=6

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/EdgeFilter.java

@@ -0,0 +1,143 @@
+import java.awt.Color;
+
+import java.util.List;
+import java.util.ArrayList;
+
+/**
+ * An image filter to detect edges and highlight them, a bit like 
+ * a colored pencil drawing.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class EdgeFilter extends Filter
+{
+    private static final int TOLERANCE = 20;
+    
+    private OFImage original;
+    private int width;
+    private int height;
+
+    /**
+     * Constructor for objects of class EdgeFilter.
+     * @param name The name of the filter.
+     */
+    public EdgeFilter(String name)
+    {
+        super(name);
+    }
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        original = new OFImage(image);
+        width = original.getWidth();
+        height = original.getHeight();
+        
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                image.setPixel(x, y, edge(x, y));
+            }
+        }
+    }
+
+    /**
+     * Return a new color that is the smoothed color of a given
+     * position. The "smoothed color" is the color value that is the
+     * average of this pixel and all the adjacent pixels.
+     * @param xpos The x position of the pixel.
+     * @param ypos The y position of the pixel.
+     * @return The smoothed color.
+     */
+    private Color edge(int xpos, int ypos)
+    {
+        List<Color> pixels = new ArrayList<>(9);
+        
+        for(int y = ypos-1; y <= ypos+1; y++) {
+            for(int x = xpos-1; x <= xpos+1; x++) {
+                if( x >= 0 && x < width && y >= 0 && y < height ) {
+                    pixels.add(original.getPixel(x, y));
+                }
+            }
+        }
+
+        return new Color(255 - diffRed(pixels), 255 - diffGreen(pixels), 255 - diffBlue(pixels));
+    }
+
+    /**
+     * @param pixels The list of pixels to be averaged.
+     * @return The average of all the red values in the given list of pixels.
+     */
+    private int diffRed(List<Color> pixels)
+    {
+        int max = 0;
+        int min = 255;
+        for(Color color : pixels) {
+            int val = color.getRed();
+            if(val > max) {
+                max = val;
+            }
+            if(val < min) {
+                min = val;
+            }
+        }
+        int difference = max - min - TOLERANCE;
+        if(difference < 0) {
+            difference = 0;
+        }
+        return difference;
+    }
+
+    /**
+     * @param pixels The list of pixels to be averaged.
+     * @return The average of all the green values in the given list of pixels.
+     */
+    private int diffGreen(List<Color> pixels)
+    {
+        int max = 0;
+        int min = 255;
+        for(Color color : pixels) {
+            int val = color.getGreen();
+            if(val > max) {
+                max = val;
+            }
+            if(val < min) {
+                min = val;
+            }
+        }
+        int difference = max - min - TOLERANCE;
+        if(difference < 0) {
+            difference = 0;
+        }
+        return difference;
+    }
+
+    /**
+     * @param pixels The list of pixels to be averaged.
+     * @return The average of all the blue values in the given list of pixels.
+     */
+    private int diffBlue(List<Color> pixels)
+    {
+        int max = 0;
+        int min = 255;
+        for(Color color : pixels) {
+            int val = color.getBlue();
+            if(val > max) {
+                max = val;
+            }
+            if(val < min) {
+                min = val;
+            }
+        }
+        int difference = max - min - TOLERANCE;
+        if(difference < 0) {
+            difference = 0;
+        }
+        return difference;
+    }
+
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/Filter.ctxt

@@ -0,0 +1,8 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=Filter(java.lang.String)
+comment0.text=\n\ Create\ a\ new\ filter\ with\ a\ given\ name.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+comment1.params=
+comment1.target=java.lang.String\ getName()
+comment1.text=\n\ Return\ the\ name\ of\ this\ filter.\n\ \n\ @return\ \ The\ name\ of\ this\ filter.\n
+numComments=2

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/Filter.java

@@ -0,0 +1,38 @@
+/**
+ * Filter is an abstract superclass for all image filters in this
+ * application. Filters can be applied to OFImages by invoking the apply 
+ * method.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public abstract class Filter
+{
+    private String name;
+
+    /**
+     * Create a new filter with a given name.
+     * @param name The name of the filter.
+     */
+    public Filter(String name)
+    {
+        this.name = name;
+    }
+    
+    /**
+     * Return the name of this filter.
+     * 
+     * @return  The name of this filter.
+     */
+    public String getName()
+    {
+        return name;
+    }
+    
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public abstract void apply(OFImage image);
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/FishEyeFilter.ctxt

@@ -0,0 +1,11 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=FishEyeFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ LensFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+comment1.params=width
+comment1.target=int[]\ computeXArray(int)
+comment1.text=\n\ Compute\ and\ return\ an\ array\ of\ horizontal\ offsets\ for\ each\ pixel\ column.\n\ These\ can\ then\ be\ applied\ as\ the\ horizontal\ offset\ for\ each\ pixel.\n
+comment2.params=height
+comment2.target=int[]\ computeYArray(int)
+comment2.text=\n\ Compute\ and\ return\ an\ array\ of\ vertical\ offsets\ for\ each\ pixel\ row.\n\ These\ can\ then\ be\ applied\ as\ the\ vertical\ offset\ for\ each\ pixel.\n
+numComments=3

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/FishEyeFilter.java

@@ -0,0 +1,73 @@
+import java.awt.Color;
+
+/**
+ * An image filter to create an effect similar to a fisheye camera lens.
+ * (Works especially well on portraits.)
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class FishEyeFilter extends Filter
+{
+    // constants:
+    private final static int SCALE = 20;   // this defines the strenght of the filter
+    private final static double TWO_PI = 2 * Math.PI;
+
+    /**
+     * Constructor for objects of class LensFilter.
+     * @param name The name of the filter.
+     */
+    public FishEyeFilter(String name)
+    {
+        super(name);
+    }
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        OFImage original = new OFImage(image);
+
+        int[] xa = computeXArray(width);
+        int[] ya = computeYArray(height);
+        
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                image.setPixel(x, y, original.getPixel(x + xa[x], y + ya[y]));
+            }
+        }
+    }
+
+    /**
+     * Compute and return an array of horizontal offsets for each pixel column.
+     * These can then be applied as the horizontal offset for each pixel.
+     */
+    private int[] computeXArray(int width)
+    {
+        int[] xArray = new int[width];
+        
+        for(int i=0; i < width; i++) {
+            xArray[i] = (int)(Math.sin( ((double)i / width) * TWO_PI) * SCALE);
+        }
+        return xArray;
+    }
+
+    /**
+     * Compute and return an array of vertical offsets for each pixel row.
+     * These can then be applied as the vertical offset for each pixel.
+     */
+    private int[] computeYArray(int height)
+    {
+        int[] yArray = new int[height];
+        
+        for(int i=0; i < height; i++) {
+            yArray[i] = (int)(Math.sin( ((double)i / height) * TWO_PI) * SCALE);
+        }
+        return yArray;
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/GrayScaleFilter.ctxt

@@ -0,0 +1,5 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=GrayScaleFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ GrayScaleFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/GrayScaleFilter.java

@@ -0,0 +1,37 @@
+import java.awt.Color;
+
+/**
+ * An image filter to remove color from an image.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class GrayScaleFilter extends Filter
+{
+	/**
+	 * Constructor for objects of class GrayScaleFilter.
+	 * @param name The name of the filter.
+	 */
+	public GrayScaleFilter(String name)
+    {
+        super(name);
+	}
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                Color pix = image.getPixel(x, y);
+                int avg = (pix.getRed() + pix.getGreen() + pix.getBlue()) / 3;
+                image.setPixel(x, y, new Color(avg, avg, avg));
+            }
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/ImageFileManager.ctxt

@@ -0,0 +1,8 @@
+#BlueJ class context
+comment0.params=imageFile
+comment0.target=OFImage\ loadImage(java.io.File)
+comment0.text=\n\ Read\ an\ image\ file\ from\ disk\ and\ return\ it\ as\ an\ image.\ This\ method\n\ can\ read\ JPG\ and\ PNG\ file\ formats.\ In\ case\ of\ any\ problem\ (e.g\ the\ file\ \n\ does\ not\ exist,\ is\ in\ an\ undecodable\ format,\ or\ any\ other\ read\ error)\ \n\ this\ method\ returns\ null.\n\ \n\ @param\ imageFile\ \ The\ image\ file\ to\ be\ loaded.\n\ @return\ \ \ \ \ \ \ \ \ \ \ The\ image\ object\ or\ null\ if\ it\ could\ not\ be\ read.\n
+comment1.params=image\ file
+comment1.target=void\ saveImage(OFImage,\ java.io.File)
+comment1.text=\n\ Write\ an\ image\ file\ to\ disk.\ The\ file\ format\ is\ JPG.\ In\ case\ of\ any\ \n\ problem\ the\ method\ just\ silently\ returns.\n\ \n\ @param\ image\ \ The\ image\ to\ be\ saved.\n\ @param\ file\ \ \ The\ file\ to\ save\ to.\n
+numComments=2

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/ImageFileManager.java

@@ -0,0 +1,61 @@
+import java.awt.image.*;
+import javax.imageio.*;
+import java.io.*;
+
+/**
+ * ImageFileManager is a small utility class with static methods to load
+ * and save images.
+ * 
+ * The files on disk can be in JPG or PNG image format. For files written
+ * by this class, the format is determined by the constant IMAGE_FORMAT.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 2.0
+ */
+public class ImageFileManager
+{
+    // A constant for the image format that this writer uses for writing.
+    // Available formats are "jpg" and "png".
+    private static final String IMAGE_FORMAT = "jpg";
+    
+    /**
+     * Read an image file from disk and return it as an image. This method
+     * can read JPG and PNG file formats. In case of any problem (e.g the file 
+     * does not exist, is in an undecodable format, or any other read error) 
+     * this method returns null.
+     * 
+     * @param imageFile  The image file to be loaded.
+     * @return           The image object or null if it could not be read.
+     */
+    public static OFImage loadImage(File imageFile)
+    {
+        try {
+            BufferedImage image = ImageIO.read(imageFile);
+            if(image == null || (image.getWidth(null) < 0)) {
+                // we could not load the image - probably invalid file format
+                return null;
+            }
+            return new OFImage(image);
+        }
+        catch(IOException exc) {
+            return null;
+        }
+    }
+
+    /**
+     * Write an image file to disk. The file format is JPG. In case of any 
+     * problem the method just silently returns.
+     * 
+     * @param image  The image to be saved.
+     * @param file   The file to save to.
+     */
+    public static void saveImage(OFImage image, File file)
+    {
+        try {
+            ImageIO.write(image, IMAGE_FORMAT, file);
+        }
+        catch(IOException exc) {
+            return;
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/ImagePanel.ctxt

@@ -0,0 +1,14 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImagePanel()
+comment0.text=\n\ Create\ a\ new,\ empty\ ImagePanel.\n
+comment1.params=
+comment1.target=void\ clearImage()
+comment1.text=\n\ Clear\ the\ image\ on\ this\ panel.\n
+comment2.params=
+comment2.target=java.awt.Dimension\ getPreferredSize()
+comment2.text=\n\ Tell\ the\ layout\ manager\ how\ big\ we\ would\ like\ to\ be.\n\ (This\ method\ gets\ called\ by\ layout\ managers\ for\ placing\n\ the\ components.)\n\ \n\ @return\ The\ preferred\ dimension\ for\ this\ component.\n
+comment3.params=g
+comment3.target=void\ paintComponent(java.awt.Graphics)
+comment3.text=\n\ This\ component\ needs\ to\ be\ redisplayed.\ Copy\ the\ internal\ image\ \n\ to\ screen.\ (This\ method\ gets\ called\ by\ the\ Swing\ screen\ painter\ \n\ every\ time\ it\ want\ this\ component\ displayed.)\n\ \n\ @param\ g\ The\ graphics\ context\ that\ can\ be\ used\ to\ draw\ on\ this\ component.\n
+numComments=4

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/ImagePanel.java

@@ -0,0 +1,89 @@
+import java.awt.*;
+import javax.swing.*;
+import java.awt.image.*;
+
+/**
+ * An ImagePanel is a Swing component that can display an OFImage.
+ * It is constructed as a subclass of JComponent with the added functionality
+ * of setting an OFImage that will be displayed on the surface of this
+ * component.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class ImagePanel extends JComponent
+{
+    // The current width and height of this panel
+    private int width, height;
+
+    // An internal image buffer that is used for painting. For
+    // actual display, this image buffer is then copied to screen.
+    private OFImage panelImage;
+
+    /**
+     * Create a new, empty ImagePanel.
+     */
+    public ImagePanel()
+    {
+        width = 360;    // arbitrary size for empty panel
+        height = 240;
+        panelImage = null;
+    }
+
+    /**
+     * Set the image that this panel should show.
+     * 
+     * @param image  The image to be displayed.
+     */
+    public void setImage(OFImage image)
+    {
+        if(image != null) {
+            width = image.getWidth();
+            height = image.getHeight();
+            panelImage = image;
+            repaint();
+        }
+    }
+    
+    /**
+     * Clear the image on this panel.
+     */
+    public void clearImage()
+    {
+        Graphics imageGraphics = panelImage.getGraphics();
+        imageGraphics.setColor(Color.LIGHT_GRAY);
+        imageGraphics.fillRect(0, 0, width, height);
+        repaint();
+    }
+    
+    // The following methods are redefinitions of methods
+    // inherited from superclasses.
+    
+    /**
+     * Tell the layout manager how big we would like to be.
+     * (This method gets called by layout managers for placing
+     * the components.)
+     * 
+     * @return The preferred dimension for this component.
+     */
+    public Dimension getPreferredSize()
+    {
+        return new Dimension(width, height);
+    }
+    
+    /**
+     * This component needs to be redisplayed. Copy the internal image 
+     * to screen. (This method gets called by the Swing screen painter 
+     * every time it want this component displayed.)
+     * 
+     * @param g The graphics context that can be used to draw on this component.
+     */
+    public void paintComponent(Graphics g)
+    {
+        Dimension size = getSize();
+        g.clearRect(0, 0, size.width, size.height);
+        if(panelImage != null) {
+            g.drawImage(panelImage, 0, 0, null);
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/ImageViewer.ctxt

@@ -0,0 +1,47 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImageViewer()
+comment0.text=\n\ Create\ an\ ImageViewer\ and\ display\ its\ GUI\ on\ screen.\n
+comment1.params=
+comment1.target=void\ openFile()
+comment1.text=\n\ Open\ function\:\ open\ a\ file\ chooser\ to\ select\ a\ new\ image\ file,\n\ and\ then\ display\ the\ chosen\ image.\n
+comment10.params=text
+comment10.target=void\ showStatus(java.lang.String)
+comment10.text=\n\ Show\ a\ message\ in\ the\ status\ bar\ at\ the\ bottom\ of\ the\ screen.\n\ @param\ text\ The\ status\ message.\n
+comment11.params=status
+comment11.target=void\ setButtonsEnabled(boolean)
+comment11.text=\n\ Enable\ or\ disable\ all\ toolbar\ buttons.\n\ \n\ @param\ status\ \ 'true'\ to\ enable\ the\ buttons,\ 'false'\ to\ disable.\n
+comment12.params=
+comment12.target=java.util.List\ createFilters()
+comment12.text=\n\ Create\ a\ list\ with\ all\ the\ known\ filters.\n\ @return\ The\ list\ of\ filters.\n
+comment13.params=
+comment13.target=void\ makeFrame()
+comment13.text=\n\ Create\ the\ Swing\ frame\ and\ its\ content.\n
+comment14.params=frame
+comment14.target=void\ makeMenuBar(javax.swing.JFrame)
+comment14.text=\n\ Create\ the\ main\ frame's\ menu\ bar.\n\ \n\ @param\ frame\ \ \ The\ frame\ that\ the\ menu\ bar\ should\ be\ added\ to.\n
+comment2.params=
+comment2.target=void\ close()
+comment2.text=\n\ Close\ function\:\ close\ the\ current\ image.\n
+comment3.params=
+comment3.target=void\ saveAs()
+comment3.text=\n\ Save\ As\ function\:\ save\ the\ current\ image\ to\ a\ file.\n
+comment4.params=
+comment4.target=void\ quit()
+comment4.text=\n\ Quit\ function\:\ quit\ the\ application.\n
+comment5.params=filter
+comment5.target=void\ applyFilter(Filter)
+comment5.text=\n\ Apply\ a\ given\ filter\ to\ the\ current\ image.\n\ \n\ @param\ filter\ \ \ The\ filter\ object\ to\ be\ applied.\n
+comment6.params=
+comment6.target=void\ showAbout()
+comment6.text=\n\ 'About'\ function\:\ show\ the\ 'about'\ box.\n
+comment7.params=
+comment7.target=void\ makeLarger()
+comment7.text=\n\ Make\ the\ current\ picture\ larger.\n
+comment8.params=
+comment8.target=void\ makeSmaller()
+comment8.text=\n\ Make\ the\ current\ picture\ smaller.\n
+comment9.params=filename
+comment9.target=void\ showFilename(java.lang.String)
+comment9.text=\n\ Show\ the\ file\ name\ of\ the\ current\ image\ in\ the\ fils\ display\ label.\n\ 'null'\ may\ be\ used\ as\ a\ parameter\ if\ no\ file\ is\ currently\ loaded.\n\ \n\ @param\ filename\ \ The\ file\ name\ to\ be\ displayed,\ or\ null\ for\ 'no\ file'.\n
+numComments=15

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/ImageViewer.java

@@ -0,0 +1,381 @@
+import java.awt.*;
+import java.awt.event.*;
+import java.awt.image.*;
+import javax.swing.*;
+import javax.swing.border.*;
+
+import java.io.File;
+
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Iterator;
+
+/**
+ * ImageViewer is the main class of the image viewer application. It builds and
+ * displays the application GUI and initialises all other components.
+ * 
+ * To start the application, create an object of this class.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 3.1
+ */
+public class ImageViewer
+{
+    // static fields:
+    private static final String VERSION = "Version 3.1";
+    private static JFileChooser fileChooser = new JFileChooser(System.getProperty("user.dir"));
+
+    // fields:
+    private JFrame frame;
+    private ImagePanel imagePanel;
+    private JLabel filenameLabel;
+    private JLabel statusLabel;
+    private JButton smallerButton;
+    private JButton largerButton;
+    private OFImage currentImage;
+    
+    private List<Filter> filters;
+    
+    /**
+     * Create an ImageViewer and display its GUI on screen.
+     */
+    public ImageViewer()
+    {
+        currentImage = null;
+        filters = createFilters();
+        makeFrame();
+    }
+
+
+    // ---- implementation of menu functions ----
+    
+    /**
+     * Open function: open a file chooser to select a new image file,
+     * and then display the chosen image.
+     */
+    private void openFile()
+    {
+        int returnVal = fileChooser.showOpenDialog(frame);
+
+        if(returnVal != JFileChooser.APPROVE_OPTION) {
+            return;  // cancelled
+        }
+        File selectedFile = fileChooser.getSelectedFile();
+        currentImage = ImageFileManager.loadImage(selectedFile);
+        
+        if(currentImage == null) {   // image file was not a valid image
+            JOptionPane.showMessageDialog(frame,
+                    "The file was not in a recognized image file format.",
+                    "Image Load Error",
+                    JOptionPane.ERROR_MESSAGE);
+            return;
+        }
+
+        imagePanel.setImage(currentImage);
+        setButtonsEnabled(true);
+        showFilename(selectedFile.getPath());
+        showStatus("File loaded.");
+        frame.pack();
+    }
+
+    /**
+     * Close function: close the current image.
+     */
+    private void close()
+    {
+        currentImage = null;
+        imagePanel.clearImage();
+        showFilename(null);
+        setButtonsEnabled(false);
+    }
+
+    /**
+     * Save As function: save the current image to a file.
+     */
+    private void saveAs()
+    {
+        if(currentImage != null) {
+            int returnVal = fileChooser.showSaveDialog(frame);
+    
+            if(returnVal != JFileChooser.APPROVE_OPTION) {
+                return;  // cancelled
+            }
+            File selectedFile = fileChooser.getSelectedFile();
+            ImageFileManager.saveImage(currentImage, selectedFile);
+            
+            showFilename(selectedFile.getPath());
+        }
+    }
+
+    /**
+     * Quit function: quit the application.
+     */
+    private void quit()
+    {
+        System.exit(0);
+    }
+
+    /**
+     * Apply a given filter to the current image.
+     * 
+     * @param filter   The filter object to be applied.
+     */
+    private void applyFilter(Filter filter)
+    {
+        if(currentImage != null) {
+            filter.apply(currentImage);
+            frame.repaint();
+            showStatus("Applied: " + filter.getName());
+        }
+        else {
+            showStatus("No image loaded.");
+        }
+    }
+
+    /**
+     * 'About' function: show the 'about' box.
+     */
+    private void showAbout()
+    {
+        JOptionPane.showMessageDialog(frame, 
+                    "ImageViewer\n" + VERSION,
+                    "About ImageViewer", 
+                    JOptionPane.INFORMATION_MESSAGE);
+    }
+
+    /**
+     * Make the current picture larger.
+     */
+    private void makeLarger()
+    {
+        if(currentImage != null) {
+            // create new image with double size
+            int width = currentImage.getWidth();
+            int height = currentImage.getHeight();
+            OFImage newImage = new OFImage(width * 2, height * 2);
+
+            // copy pixel data into new image
+            for(int y = 0; y < height; y++) {
+                for(int x = 0; x < width; x++) {
+                    Color col = currentImage.getPixel(x, y);
+                    newImage.setPixel(x * 2, y * 2, col);
+                    newImage.setPixel(x * 2 + 1, y * 2, col);
+                    newImage.setPixel(x * 2, y * 2 + 1, col);
+                    newImage.setPixel(x * 2+1, y * 2 + 1, col);
+                }
+            }
+            
+            currentImage = newImage;
+            imagePanel.setImage(currentImage);
+            frame.pack();
+        }
+    }
+    
+
+    /**
+     * Make the current picture smaller.
+     */
+    private void makeSmaller()
+    {
+        if(currentImage != null) {
+            // create new image with double size
+            int width = currentImage.getWidth() / 2;
+            int height = currentImage.getHeight() / 2;
+            OFImage newImage = new OFImage(width, height);
+
+            // copy pixel data into new image
+            for(int y = 0; y < height; y++) {
+                for(int x = 0; x < width; x++) {
+                    newImage.setPixel(x, y, currentImage.getPixel(x * 2, y * 2));
+                }
+            }
+            
+            currentImage = newImage;
+            imagePanel.setImage(currentImage);
+            frame.pack();
+        }
+    }
+    
+    // ---- support methods ----
+
+    /**
+     * Show the file name of the current image in the fils display label.
+     * 'null' may be used as a parameter if no file is currently loaded.
+     * 
+     * @param filename  The file name to be displayed, or null for 'no file'.
+     */
+    private void showFilename(String filename)
+    {
+        if(filename == null) {
+            filenameLabel.setText("No file displayed.");
+        }
+        else {
+            filenameLabel.setText("File: " + filename);
+        }
+    }
+    
+    
+    /**
+     * Show a message in the status bar at the bottom of the screen.
+     * @param text The status message.
+     */
+    private void showStatus(String text)
+    {
+        statusLabel.setText(text);
+    }
+    
+    
+    /**
+     * Enable or disable all toolbar buttons.
+     * 
+     * @param status  'true' to enable the buttons, 'false' to disable.
+     */
+    private void setButtonsEnabled(boolean status)
+    {
+        smallerButton.setEnabled(status);
+        largerButton.setEnabled(status);
+    }
+    
+    
+    /**
+     * Create a list with all the known filters.
+     * @return The list of filters.
+     */
+    private List<Filter> createFilters()
+    {
+        List<Filter> filterList = new ArrayList<>();
+        filterList.add(new DarkerFilter("Darker"));
+        filterList.add(new LighterFilter("Lighter"));
+        filterList.add(new ThresholdFilter("Threshold"));
+        filterList.add(new InvertFilter("Invert"));
+        filterList.add(new SolarizeFilter("Solarize"));
+        filterList.add(new SmoothFilter("Smooth"));
+        filterList.add(new PixelizeFilter("Pixelize"));
+        filterList.add(new MirrorFilter("Mirror"));
+        filterList.add(new GrayScaleFilter("Grayscale"));
+        filterList.add(new EdgeFilter("Edge Detection"));
+        filterList.add(new FishEyeFilter("Fish Eye"));
+       
+        return filterList;
+    }
+    
+    // ---- Swing stuff to build the frame and all its components and menus ----
+    
+    /**
+     * Create the Swing frame and its content.
+     */
+    private void makeFrame()
+    {
+        frame = new JFrame("ImageViewer");
+        JPanel contentPane = (JPanel)frame.getContentPane();
+        contentPane.setBorder(new EmptyBorder(12, 12, 12, 12));
+
+        makeMenuBar(frame);
+        
+        // Specify the layout manager with nice spacing
+        contentPane.setLayout(new BorderLayout(6, 6));
+        
+        // Create the image pane in the center
+        imagePanel = new ImagePanel();
+        imagePanel.setBorder(new EtchedBorder());
+        contentPane.add(imagePanel, BorderLayout.CENTER);
+
+        // Create two labels at top and bottom for the file name and status messages
+        filenameLabel = new JLabel();
+        contentPane.add(filenameLabel, BorderLayout.NORTH);
+
+        statusLabel = new JLabel(VERSION);
+        contentPane.add(statusLabel, BorderLayout.SOUTH);
+        
+        // Create the toolbar with the buttons
+        JPanel toolbar = new JPanel();
+        toolbar.setLayout(new GridLayout(0, 1));
+        
+        smallerButton = new JButton("Smaller");
+        smallerButton.addActionListener(e -> makeSmaller());
+        toolbar.add(smallerButton);
+        
+        largerButton = new JButton("Larger");
+        largerButton.addActionListener(e -> makeLarger());
+        toolbar.add(largerButton);
+
+        // Add toolbar into panel with flow layout for spacing
+        JPanel flow = new JPanel();
+        flow.add(toolbar);
+        
+        contentPane.add(flow, BorderLayout.WEST);
+        
+        // building is done - arrange the components      
+        showFilename(null);
+        setButtonsEnabled(false);
+        frame.pack();
+        
+        // place the frame at the center of the screen and show
+        Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
+        frame.setLocation(d.width/2 - frame.getWidth()/2, d.height/2 - frame.getHeight()/2);
+        frame.setVisible(true);
+    }
+    
+    /**
+     * Create the main frame's menu bar.
+     * 
+     * @param frame   The frame that the menu bar should be added to.
+     */
+    private void makeMenuBar(JFrame frame)
+    {
+        final int SHORTCUT_MASK =
+            Toolkit.getDefaultToolkit().getMenuShortcutKeyMask();
+
+        JMenuBar menubar = new JMenuBar();
+        frame.setJMenuBar(menubar);
+        
+        JMenu menu;
+        JMenuItem item;
+        
+        // create the File menu
+        menu = new JMenu("File");
+        menubar.add(menu);
+        
+        item = new JMenuItem("Open...");
+            item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O, SHORTCUT_MASK));
+            item.addActionListener(e -> openFile());
+        menu.add(item);
+
+        item = new JMenuItem("Close");
+            item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_W, SHORTCUT_MASK));
+            item.addActionListener(e -> close());
+        menu.add(item);
+        menu.addSeparator();
+
+        item = new JMenuItem("Save As...");
+            item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S, SHORTCUT_MASK));
+            item.addActionListener(e -> saveAs());
+        menu.add(item);
+        menu.addSeparator();
+        
+        item = new JMenuItem("Quit");
+            item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK));
+            item.addActionListener(e -> quit());
+        menu.add(item);
+
+
+        // create the Filter menu
+        menu = new JMenu("Filter");
+        menubar.add(menu);
+        
+        for(Filter filter : filters) {
+            item = new JMenuItem(filter.getName());
+            item.addActionListener(e -> applyFilter(filter));
+             menu.add(item);
+         }
+
+        // create the Help menu
+        menu = new JMenu("Help");
+        menubar.add(menu);
+        
+        item = new JMenuItem("About ImageViewer...");
+            item.addActionListener(e -> showAbout());
+        menu.add(item);
+
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/InvertFilter.ctxt

@@ -0,0 +1,5 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=InvertFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ InvertFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/InvertFilter.java

@@ -0,0 +1,38 @@
+import java.awt.Color;
+
+/**
+ * An image filter to invert colors.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class InvertFilter extends Filter
+{
+    /**
+     * Constructor for objects of class InvertFilter.
+     * @param name The name of the filter.
+     */
+    public InvertFilter(String name)
+    {
+        super(name);
+    }
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                Color pix = image.getPixel(x, y);
+                image.setPixel(x, y, new Color(255 - pix.getRed(),
+                                               255 - pix.getGreen(),
+                                               255 - pix.getBlue()));
+            }
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/LighterFilter.ctxt

@@ -0,0 +1,5 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=LighterFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ LighterFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/LighterFilter.java

@@ -0,0 +1,34 @@
+/**
+ * An image filter to make the image a bit lighter.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class LighterFilter extends Filter
+{
+	/**
+	 * Constructor for objects of class LighterFilter.
+     * @param name The name of the filter.
+	 */
+	public LighterFilter(String name)
+    {
+        super(name);
+	}
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                image.setPixel(x, y, image.getPixel(x, y).brighter());
+            }
+        }
+    }
+
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/MirrorFilter.ctxt

@@ -0,0 +1,5 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=MirrorFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ MirrorFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/MirrorFilter.java

@@ -0,0 +1,37 @@
+import java.awt.Color;
+
+/**
+ * An image filter to mirror (flip) the image horizontally.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class MirrorFilter extends Filter
+{
+	/**
+	 * Constructor for objects of class MirrorFilter.
+     * @param name The name of the filter.
+	 */
+	public MirrorFilter(String name)
+    {
+        super(name);
+	}
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width / 2; x++) {
+                Color left = image.getPixel(x, y);
+                image.setPixel(x, y, image.getPixel(width - 1 - x, y));
+                image.setPixel(width - 1 - x, y, left);
+            }
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/OFImage.ctxt

@@ -0,0 +1,14 @@
+#BlueJ class context
+comment0.params=image
+comment0.target=OFImage(java.awt.image.BufferedImage)
+comment0.text=\n\ Create\ an\ OFImage\ copied\ from\ a\ BufferedImage.\n\ @param\ image\ The\ image\ to\ copy.\n
+comment1.params=width\ height
+comment1.target=OFImage(int,\ int)
+comment1.text=\n\ Create\ an\ OFImage\ with\ specified\ size\ and\ unspecified\ content.\n\ @param\ width\ The\ width\ of\ the\ image.\n\ @param\ height\ The\ height\ of\ the\ image.\n
+comment2.params=x\ y\ col
+comment2.target=void\ setPixel(int,\ int,\ java.awt.Color)
+comment2.text=\n\ Set\ a\ given\ pixel\ of\ this\ image\ to\ a\ specified\ color.\ The\n\ color\ is\ represented\ as\ an\ (r,g,b)\ value.\n\ @param\ x\ The\ x\ position\ of\ the\ pixel.\n\ @param\ y\ The\ y\ position\ of\ the\ pixel.\n\ @param\ col\ The\ color\ of\ the\ pixel.\n
+comment3.params=x\ y
+comment3.target=java.awt.Color\ getPixel(int,\ int)
+comment3.text=\n\ Get\ the\ color\ value\ at\ a\ specified\ pixel\ position.\n\ @param\ x\ The\ x\ position\ of\ the\ pixel.\n\ @param\ y\ The\ y\ position\ of\ the\ pixel.\n\ @return\ The\ color\ of\ the\ pixel\ at\ the\ given\ position.\n
+numComments=4

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/OFImage.java

@@ -0,0 +1,57 @@
+import java.awt.*;
+import java.awt.image.*;
+import javax.swing.*;
+
+/**
+ * OFImage is a class that defines an image in OF (Objects First) format.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 2.0
+ */
+public class OFImage extends BufferedImage
+{
+    /**
+     * Create an OFImage copied from a BufferedImage.
+     * @param image The image to copy.
+     */
+    public OFImage(BufferedImage image)
+    {
+         super(image.getColorModel(), image.copyData(null), 
+               image.isAlphaPremultiplied(), null);
+    }
+
+    /**
+     * Create an OFImage with specified size and unspecified content.
+     * @param width The width of the image.
+     * @param height The height of the image.
+     */
+    public OFImage(int width, int height)
+    {
+        super(width, height, TYPE_INT_RGB);
+    }
+
+    /**
+     * Set a given pixel of this image to a specified color. The
+     * color is represented as an (r,g,b) value.
+     * @param x The x position of the pixel.
+     * @param y The y position of the pixel.
+     * @param col The color of the pixel.
+     */
+    public void setPixel(int x, int y, Color col)
+    {
+        int pixel = col.getRGB();
+        setRGB(x, y, pixel);
+    }
+    
+    /**
+     * Get the color value at a specified pixel position.
+     * @param x The x position of the pixel.
+     * @param y The y position of the pixel.
+     * @return The color of the pixel at the given position.
+     */
+    public Color getPixel(int x, int y)
+    {
+        int pixel = getRGB(x, y);
+        return new Color(pixel);
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/PixelizeFilter.ctxt

@@ -0,0 +1,5 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=PixelizeFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ PixelizeFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/PixelizeFilter.java

@@ -0,0 +1,44 @@
+import java.awt.Color;
+
+/**
+ * An image filter to create a pixelization effect, like an enlarged
+ * low-resolution digital image.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class PixelizeFilter extends Filter
+{
+    /**
+     * Constructor for objects of class PixelizeFilter.
+     * @param name The name of the filter.
+     */
+    public PixelizeFilter(String name)
+    {
+        super(name);
+    }
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        final int PIXEL_SIZE = 5;
+        int width = image.getWidth();
+        int height = image.getHeight();
+        
+        for(int y = 0; y < height; y += PIXEL_SIZE) {
+            for(int x = 0; x < width; x += PIXEL_SIZE) {
+                Color pix = image.getPixel(x, y);
+                for(int dy = y; dy < y + PIXEL_SIZE; dy++) {
+                    for(int dx = x; dx < x + PIXEL_SIZE; dx++) {
+                        if( dx < width && dy < height )
+                            image.setPixel(dx, dy, pix);
+                    }
+                }
+            }
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/README.TXT

@@ -0,0 +1,25 @@
+Project "imageviewer-final" (version 3.1)
+Authors: David Barnes and Michael Kölling
+
+This project is part of the material for the book
+
+   Objects First with Java - A Practical Introduction using BlueJ
+   Sixth edition
+   David J. Barnes and Michael Kölling
+   Pearson Education, 2016
+
+It is discussed in chapter 13.
+
+This project demonstrates the building of a simple GUI (including labels, 
+buttons, layout managers, event handling, menus, dialogs) as well as a bit of 
+image processing.
+
+This project is started by creating an object of class ImageViewer. This will 
+automatically display the application's GUI - no further interaction with the 
+object on the object bench is necessary.
+
+WARNING: 
+
+It sometimes happens (unfortunately) that the image viewer window opens BEHIND the
+BlueJ window. This can be confusing, since it initially appears as if nothing 
+is happening.

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/SmoothFilter.ctxt

@@ -0,0 +1,20 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=SmoothFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ SmoothFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+comment1.params=image
+comment1.target=void\ apply(OFImage)
+comment1.text=\n\ Apply\ this\ filter\ to\ an\ image.\n\ \n\ @param\ \ image\ \ The\ image\ to\ be\ changed\ by\ this\ filter.\n
+comment2.params=xpos\ ypos
+comment2.target=java.awt.Color\ smooth(int,\ int)
+comment2.text=\n\ Return\ a\ new\ color\ that\ is\ the\ smoothed\ color\ of\ a\ given\n\ position.\ The\ "smoothed\ color"\ is\ the\ color\ value\ that\ is\ the\n\ average\ of\ this\ pixel\ and\ all\ the\ adjacent\ pixels.\n\ @param\ xpos\ The\ xposition\ of\ the\ pixel.\n\ @param\ ypos\ The\ yposition\ of\ the\ pixel.\n\ @return\ The\ smoothed\ color.\n
+comment3.params=pixels
+comment3.target=int\ avgRed(java.util.List)
+comment3.text=\n\ @param\ pixels\ The\ list\ of\ pixels.\n\ @return\ The\ average\ of\ all\ the\ red\ values\ in\ the\ given\ list\ of\ pixels.\n
+comment4.params=pixels
+comment4.target=int\ avgGreen(java.util.List)
+comment4.text=\n\ @param\ pixels\ The\ list\ of\ pixels.\n\ @return\ The\ average\ of\ all\ the\ green\ values\ in\ the\ given\ list\ of\ pixels.\n
+comment5.params=pixels
+comment5.target=int\ avgBlue(java.util.List)
+comment5.text=\n\ @param\ pixels\ The\ list\ of\ pixels.\n\ @return\ The\ average\ of\ all\ the\ blue\ values\ in\ the\ given\ list\ of\ pixels.\n
+numComments=6

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/SmoothFilter.java

@@ -0,0 +1,105 @@
+import java.awt.Color;
+import java.util.List;
+import java.util.ArrayList;
+
+/**
+ * An image filter to reduce sharp edges and pixelization. A bit like
+ * a soft lens.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class SmoothFilter extends Filter
+{
+    private OFImage original;
+    private int width;
+    private int height;
+    
+    /**
+     * Constructor for objects of class SmoothFilter.
+     * @param name The name of the filter.
+     */
+    public SmoothFilter(String name)
+    {
+        super(name);
+    }
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        original = new OFImage(image);
+        width = original.getWidth();
+        height = original.getHeight();
+        
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                image.setPixel(x, y, smooth(x, y));
+            }
+        }
+    }
+    
+    /**
+     * Return a new color that is the smoothed color of a given
+     * position. The "smoothed color" is the color value that is the
+     * average of this pixel and all the adjacent pixels.
+     * @param xpos The xposition of the pixel.
+     * @param ypos The yposition of the pixel.
+     * @return The smoothed color.
+     */
+    private Color smooth(int xpos, int ypos)
+    {
+        List<Color> pixels = new ArrayList<>(9);
+        
+        for(int y = ypos - 1; y <= ypos + 1; y++) {
+            for(int x = xpos - 1; x <= xpos + 1; x++) {
+                if( x >= 0 && x < width && y >= 0 && y < height )
+                    pixels.add(original.getPixel(x, y));
+            }
+        }
+
+        return new Color(avgRed(pixels), avgGreen(pixels), avgBlue(pixels));
+    }
+
+    /**
+     * @param pixels The list of pixels.
+     * @return The average of all the red values in the given list of pixels.
+     */
+    private int avgRed(List<Color> pixels)
+    {
+        int total = 0;
+        for(Color color : pixels) {
+            total += color.getRed();
+        }
+        return total / pixels.size();
+    }
+
+    /**
+     * @param pixels The list of pixels.
+     * @return The average of all the green values in the given list of pixels.
+     */
+    private int avgGreen(List<Color> pixels)
+    {
+        int total = 0;
+        for(Color color : pixels) {
+            total += color.getGreen();
+        }
+        return total / pixels.size();
+    }
+
+    /**
+     * @param pixels The list of pixels.
+     * @return The average of all the blue values in the given list of pixels.
+     */
+    private int avgBlue(List<Color> pixels)
+    {
+        int total = 0;
+        for(Color color : pixels) {
+            total += color.getBlue();
+        }
+        return total / pixels.size();
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/SolarizeFilter.ctxt

@@ -0,0 +1,5 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=SolarizeFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ Solarize.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/SolarizeFilter.java

@@ -0,0 +1,49 @@
+import java.awt.Color;
+
+/**
+ * An image filter to create a solarization effect.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class SolarizeFilter extends Filter
+{
+    /**
+     * Constructor for objects of class Solarize.
+     * @param name The name of the filter.
+     */
+    public SolarizeFilter(String name)
+    {
+        super(name);
+    }
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                Color pix = image.getPixel(x, y);
+                int red = pix.getRed();
+                if(red <= 127) {
+                    red = 255 - red;
+                }
+                int green = pix.getGreen();
+                if(green <= 127) {
+                    green = 255 - green;
+                }
+                int blue = pix.getBlue();
+                if(blue <= 127) {
+                    blue = 255 - blue;
+                }
+                image.setPixel(x, y, new Color(red, green, blue));
+            }
+        }
+    }
+
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/ThresholdFilter.ctxt

@@ -0,0 +1,5 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=ThresholdFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ ThresholdFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/ThresholdFilter.java

@@ -0,0 +1,45 @@
+import java.awt.Color;
+
+/**
+ * An three-level gray-based threshold filter.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class ThresholdFilter extends Filter
+{
+	/**
+	 * Constructor for objects of class ThresholdFilter.
+     * @param name The name of the filter.
+	 */
+	public ThresholdFilter(String name)
+    {
+        super(name);
+	}
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                Color pixel = image.getPixel(x, y);
+                int brightness = (pixel.getRed() + pixel.getBlue() + pixel.getGreen()) / 3;
+                if(brightness <= 85) {
+                    image.setPixel(x, y, Color.BLACK);
+                }
+                else if(brightness <= 170) {
+                    image.setPixel(x, y, Color.GRAY);
+                }
+                else {
+                    image.setPixel(x, y, Color.WHITE);
+                }
+            }
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer-final/package.bluej

@@ -0,0 +1,311 @@
+#BlueJ package file
+dependency1.from=EdgeFilter
+dependency1.to=OFImage
+dependency1.type=UsesDependency
+dependency10.from=ImageViewer
+dependency10.to=LighterFilter
+dependency10.type=UsesDependency
+dependency11.from=ImageViewer
+dependency11.to=SolarizeFilter
+dependency11.type=UsesDependency
+dependency12.from=ImageViewer
+dependency12.to=MirrorFilter
+dependency12.type=UsesDependency
+dependency13.from=ImageViewer
+dependency13.to=ThresholdFilter
+dependency13.type=UsesDependency
+dependency14.from=ImageViewer
+dependency14.to=FishEyeFilter
+dependency14.type=UsesDependency
+dependency15.from=ImageViewer
+dependency15.to=Filter
+dependency15.type=UsesDependency
+dependency16.from=ImageViewer
+dependency16.to=InvertFilter
+dependency16.type=UsesDependency
+dependency17.from=SolarizeFilter
+dependency17.to=OFImage
+dependency17.type=UsesDependency
+dependency18.from=LighterFilter
+dependency18.to=OFImage
+dependency18.type=UsesDependency
+dependency19.from=DarkerFilter
+dependency19.to=OFImage
+dependency19.type=UsesDependency
+dependency2.from=SmoothFilter
+dependency2.to=OFImage
+dependency2.type=UsesDependency
+dependency20.from=PixelizeFilter
+dependency20.to=OFImage
+dependency20.type=UsesDependency
+dependency21.from=MirrorFilter
+dependency21.to=OFImage
+dependency21.type=UsesDependency
+dependency22.from=ThresholdFilter
+dependency22.to=OFImage
+dependency22.type=UsesDependency
+dependency23.from=ImagePanel
+dependency23.to=OFImage
+dependency23.type=UsesDependency
+dependency24.from=FishEyeFilter
+dependency24.to=OFImage
+dependency24.type=UsesDependency
+dependency25.from=Filter
+dependency25.to=OFImage
+dependency25.type=UsesDependency
+dependency26.from=InvertFilter
+dependency26.to=OFImage
+dependency26.type=UsesDependency
+dependency27.from=GrayScaleFilter
+dependency27.to=OFImage
+dependency27.type=UsesDependency
+dependency28.from=ImageFileManager
+dependency28.to=OFImage
+dependency28.type=UsesDependency
+dependency29.from=ImageViewer
+dependency29.to=ImageFileManager
+dependency29.type=UsesDependency
+dependency3.from=ImageViewer
+dependency3.to=SmoothFilter
+dependency3.type=UsesDependency
+dependency4.from=ImageViewer
+dependency4.to=DarkerFilter
+dependency4.type=UsesDependency
+dependency5.from=ImageViewer
+dependency5.to=PixelizeFilter
+dependency5.type=UsesDependency
+dependency6.from=ImageViewer
+dependency6.to=OFImage
+dependency6.type=UsesDependency
+dependency7.from=ImageViewer
+dependency7.to=ImagePanel
+dependency7.type=UsesDependency
+dependency8.from=ImageViewer
+dependency8.to=GrayScaleFilter
+dependency8.type=UsesDependency
+dependency9.from=ImageViewer
+dependency9.to=EdgeFilter
+dependency9.type=UsesDependency
+objectbench.height=76
+objectbench.width=1074
+package.editor.height=636
+package.editor.width=966
+package.editor.x=70
+package.editor.y=80
+package.numDependencies=29
+package.numTargets=16
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+readme.editor.height=642
+readme.editor.width=871
+readme.editor.x=41
+readme.editor.y=67
+target1.editor.height=731
+target1.editor.width=850
+target1.editor.x=50
+target1.editor.y=60
+target1.height=60
+target1.name=SolarizeFilter
+target1.naviview.expanded=true
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=110
+target1.x=780
+target1.y=190
+target10.editor.height=734
+target10.editor.width=889
+target10.editor.x=50
+target10.editor.y=60
+target10.height=60
+target10.name=Filter
+target10.naviview.expanded=true
+target10.showInterface=false
+target10.type=AbstractTarget
+target10.typeParameters=
+target10.width=100
+target10.x=600
+target10.y=260
+target11.editor.height=730
+target11.editor.width=976
+target11.editor.x=50
+target11.editor.y=60
+target11.height=60
+target11.name=EdgeFilter
+target11.naviview.expanded=true
+target11.showInterface=false
+target11.type=ClassTarget
+target11.typeParameters=
+target11.width=90
+target11.x=450
+target11.y=120
+target12.editor.height=731
+target12.editor.width=890
+target12.editor.x=50
+target12.editor.y=60
+target12.height=60
+target12.name=FishEyeFilter
+target12.naviview.expanded=true
+target12.showInterface=false
+target12.type=ClassTarget
+target12.typeParameters=
+target12.width=100
+target12.x=550
+target12.y=120
+target13.editor.height=730
+target13.editor.width=869
+target13.editor.x=50
+target13.editor.y=60
+target13.height=60
+target13.name=MirrorFilter
+target13.naviview.expanded=true
+target13.showInterface=false
+target13.type=ClassTarget
+target13.typeParameters=
+target13.width=110
+target13.x=780
+target13.y=260
+target14.editor.height=699
+target14.editor.width=1004
+target14.editor.x=41
+target14.editor.y=23
+target14.height=60
+target14.name=ImageViewer
+target14.naviview.expanded=true
+target14.showInterface=false
+target14.type=ClassTarget
+target14.typeParameters=
+target14.width=130
+target14.x=230
+target14.y=30
+target15.editor.height=724
+target15.editor.width=877
+target15.editor.x=50
+target15.editor.y=60
+target15.height=60
+target15.name=SmoothFilter
+target15.naviview.expanded=true
+target15.showInterface=false
+target15.type=ClassTarget
+target15.typeParameters=
+target15.width=110
+target15.x=780
+target15.y=330
+target16.editor.height=728
+target16.editor.width=885
+target16.editor.x=50
+target16.editor.y=60
+target16.height=60
+target16.name=ImagePanel
+target16.naviview.expanded=true
+target16.showInterface=false
+target16.type=ClassTarget
+target16.typeParameters=
+target16.width=140
+target16.x=60
+target16.y=270
+target2.editor.height=720
+target2.editor.width=946
+target2.editor.x=50
+target2.editor.y=60
+target2.height=60
+target2.name=ThresholdFilter
+target2.naviview.expanded=true
+target2.showInterface=false
+target2.type=ClassTarget
+target2.typeParameters=
+target2.width=120
+target2.x=650
+target2.y=400
+target3.editor.height=728
+target3.editor.width=858
+target3.editor.x=50
+target3.editor.y=60
+target3.height=60
+target3.name=InvertFilter
+target3.naviview.expanded=true
+target3.showInterface=false
+target3.type=ClassTarget
+target3.typeParameters=
+target3.width=110
+target3.x=780
+target3.y=400
+target4.editor.height=732
+target4.editor.width=895
+target4.editor.x=50
+target4.editor.y=60
+target4.height=60
+target4.name=GrayScaleFilter
+target4.naviview.expanded=true
+target4.showInterface=false
+target4.type=ClassTarget
+target4.typeParameters=
+target4.width=110
+target4.x=660
+target4.y=120
+target5.editor.height=731
+target5.editor.width=858
+target5.editor.x=50
+target5.editor.y=60
+target5.height=60
+target5.name=DarkerFilter
+target5.naviview.expanded=true
+target5.showInterface=false
+target5.type=ClassTarget
+target5.typeParameters=
+target5.width=100
+target5.x=430
+target5.y=400
+target6.editor.height=729
+target6.editor.width=878
+target6.editor.x=50
+target6.editor.y=60
+target6.height=60
+target6.name=PixelizeFilter
+target6.naviview.expanded=true
+target6.showInterface=false
+target6.type=ClassTarget
+target6.typeParameters=
+target6.width=110
+target6.x=780
+target6.y=120
+target7.editor.height=737
+target7.editor.width=846
+target7.editor.x=50
+target7.editor.y=60
+target7.height=60
+target7.name=ImageFileManager
+target7.naviview.expanded=true
+target7.showInterface=false
+target7.type=ClassTarget
+target7.typeParameters=
+target7.width=140
+target7.x=60
+target7.y=190
+target8.editor.height=718
+target8.editor.width=872
+target8.editor.x=50
+target8.editor.y=60
+target8.height=60
+target8.name=LighterFilter
+target8.naviview.expanded=true
+target8.showInterface=false
+target8.type=ClassTarget
+target8.typeParameters=
+target8.width=100
+target8.x=540
+target8.y=400
+target9.editor.height=700
+target9.editor.width=863
+target9.editor.x=0
+target9.editor.y=22
+target9.height=90
+target9.name=OFImage
+target9.naviview.expanded=true
+target9.showInterface=false
+target9.type=ClassTarget
+target9.typeParameters=
+target9.width=110
+target9.x=90
+target9.y=510

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-1/ImageViewer.ctxt

@@ -0,0 +1,8 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImageViewer()
+comment0.text=\n\ Create\ an\ ImageViewer\ show\ it\ on\ screen.\n
+comment1.params=
+comment1.target=void\ makeFrame()
+comment1.text=\n\ Create\ the\ Swing\ frame\ and\ its\ content.\n
+numComments=2

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-1/ImageViewer.java

@@ -0,0 +1,42 @@
+import java.awt.*;
+import java.awt.event.*;
+import javax.swing.*;
+
+/**
+ * ImageViewer is the main class of the image viewer application. It builds
+ * and displays the application GUI and initialises all other components.
+ * 
+ * To start the application, create an object of this class.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 0.1
+ */
+public class ImageViewer
+{
+    private JFrame frame;
+    
+    /**
+     * Create an ImageViewer show it on screen.
+     */
+    public ImageViewer()
+    {
+        makeFrame();
+    }
+    
+    // ---- swing stuff to build the frame and all its components ----
+    
+    /**
+     * Create the Swing frame and its content.
+     */
+    private void makeFrame()
+    {
+        frame = new JFrame("ImageViewer");        
+        Container contentPane = frame.getContentPane();
+        
+        JLabel label = new JLabel("I am a label. I can display some text.");
+        contentPane.add(label);
+
+        frame.pack();
+        frame.setVisible(true);
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-1/README.TXT

@@ -0,0 +1,14 @@
+Project: imageviewer, version 0.1
+Authors: David Barnes and Michael Kölling
+
+This project is part of the material for the book
+
+   Objects First with Java - A Practical Introduction using BlueJ
+   Sixth edition
+   David J. Barnes and Michael Kölling
+   Pearson Education, 2016
+
+It is discussed in chapter 13.
+
+To use this project, create an instance of class ImageViewer.
+For details, refer to the book chapter.

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-1/package.bluej

@@ -0,0 +1,29 @@
+#BlueJ package file
+objectbench.height=76
+objectbench.width=682
+package.editor.height=368
+package.editor.width=574
+package.editor.x=70
+package.editor.y=80
+package.numDependencies=0
+package.numTargets=1
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+readme.editor.height=565
+readme.editor.width=787
+readme.editor.x=53
+readme.editor.y=23
+target1.editor.height=777
+target1.editor.width=945
+target1.editor.x=427
+target1.editor.y=23
+target1.height=60
+target1.name=ImageViewer
+target1.naviview.expanded=true
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=110
+target1.x=170
+target1.y=100

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-1a/ImageViewer.ctxt

@@ -0,0 +1,8 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImageViewer()
+comment0.text=\n\ Create\ an\ ImageViewer\ show\ it\ on\ screen.\n
+comment1.params=
+comment1.target=void\ makeFrame()
+comment1.text=\n\ Create\ the\ Swing\ frame\ and\ its\ content.\n
+numComments=2

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-1a/ImageViewer.java

@@ -0,0 +1,41 @@
+import java.awt.*;
+import java.awt.event.*;
+import javax.swing.*;
+
+/**
+ * ImageViewer is the main class of the image viewer application. It builds
+ * and displays the application GUI and initialises all other components.
+ * 
+ * To start the application, create an object of this class.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 0.1a
+ */
+public class ImageViewer extends JFrame
+{
+    
+    /**
+     * Create an ImageViewer show it on screen.
+     */
+    public ImageViewer()
+    {
+        super("ImageViewer");
+        makeFrame();
+    }
+    
+    // ---- swing stuff to build the frame and all its components ----
+    
+    /**
+     * Create the Swing frame and its content.
+     */
+    private void makeFrame()
+    {
+        Container contentPane = getContentPane();
+        
+        JLabel label = new JLabel("I am a label. I can display some text.");
+        contentPane.add(label);
+
+        pack();
+        setVisible(true);
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-1a/README.TXT

@@ -0,0 +1,14 @@
+Project: imageviewer, version 0.1a
+Authors: David Barnes and Michael Kölling
+
+This project is part of the material for the book
+
+   Objects First with Java - A Practical Introduction using BlueJ
+   Sixth edition
+   David J. Barnes and Michael Kölling
+   Pearson Education, 2016
+
+It is discussed in chapter 13.
+
+To use this project, create an instance of class ImageViewer.
+For details, refer to the book chapter.

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-1a/package.bluej

@@ -0,0 +1,29 @@
+#BlueJ package file
+objectbench.height=76
+objectbench.width=665
+package.editor.height=395
+package.editor.width=557
+package.editor.x=70
+package.editor.y=80
+package.numDependencies=0
+package.numTargets=1
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+readme.editor.height=571
+readme.editor.width=843
+readme.editor.x=53
+readme.editor.y=23
+target1.editor.height=819
+target1.editor.width=890
+target1.editor.x=963
+target1.editor.y=71
+target1.height=60
+target1.name=ImageViewer
+target1.naviview.expanded=false
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=110
+target1.x=170
+target1.y=120

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-2/ImageViewer.ctxt

@@ -0,0 +1,14 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImageViewer()
+comment0.text=\n\ Create\ an\ ImageViewer\ show\ it\ on\ screen.\n
+comment1.params=event
+comment1.target=void\ actionPerformed(java.awt.event.ActionEvent)
+comment1.text=\n\ Receive\ notification\ of\ an\ action.\n\ @param\ event\ Details\ of\ the\ action.\n
+comment2.params=
+comment2.target=void\ makeFrame()
+comment2.text=\n\ Create\ the\ Swing\ frame\ and\ its\ content.\n
+comment3.params=frame
+comment3.target=void\ makeMenuBar(javax.swing.JFrame)
+comment3.text=\n\ Create\ the\ main\ frame's\ menu\ bar.\n\ @param\ frame\ \ \ The\ frame\ that\ the\ menu\ bar\ should\ be\ added\ to.\n
+numComments=4

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-2/ImageViewer.java

@@ -0,0 +1,78 @@
+import java.awt.*;
+import java.awt.event.*;
+import javax.swing.*;
+
+/**
+ * ImageViewer is the main class of the image viewer application. It builds 
+ * and displays the application GUI.
+ * 
+ * To start the application, create an object of this class.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 0.2
+ */
+public class ImageViewer
+    implements ActionListener
+{
+    private JFrame frame;
+    
+    /**
+     * Create an ImageViewer show it on screen.
+     */
+    public ImageViewer()
+    {
+        makeFrame();
+    }
+
+    /**
+     * Receive notification of an action.
+     * @param event Details of the action.
+     */
+    public void actionPerformed(ActionEvent event) 
+    { 
+        System.out.println("Menu item: " + event.getActionCommand());
+    }
+
+    
+    // ---- swing stuff to build the frame and all its components ----
+    
+    /**
+     * Create the Swing frame and its content.
+     */
+    private void makeFrame()
+    {
+        frame = new JFrame("ImageViewer");
+        makeMenuBar(frame);
+        
+        Container contentPane = frame.getContentPane();
+        
+        JLabel label = new JLabel("I am a label. I can display some text.");
+        contentPane.add(label);
+
+        // building is done - arrange the components and show        
+        frame.pack();
+        frame.setVisible(true);
+    }
+    
+    /**
+     * Create the main frame's menu bar.
+     * @param frame   The frame that the menu bar should be added to.
+     */
+    private void makeMenuBar(JFrame frame)
+    {
+        JMenuBar menubar = new JMenuBar();
+        frame.setJMenuBar(menubar);
+        
+        // create the File menu
+        JMenu fileMenu = new JMenu("File");
+        menubar.add(fileMenu);
+        
+        JMenuItem openItem = new JMenuItem("Open");
+        openItem.addActionListener(this);
+        fileMenu.add(openItem);
+
+        JMenuItem quitItem = new JMenuItem("Quit");
+        quitItem.addActionListener(this);
+        fileMenu.add(quitItem);
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-2/README.TXT

@@ -0,0 +1,14 @@
+Project: imageviewer, version 0.2
+Authors: David Barnes and Michael Kölling
+
+This project is part of the material for the book
+
+   Objects First with Java - A Practical Introduction using BlueJ
+   Sixth edition
+   David J. Barnes and Michael Kölling
+   Pearson Education, 2016
+
+It is discussed in chapter 13.
+
+To use this project, create an instance of class ImageViewer.
+For details, refer to the book chapter.

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-2/package.bluej

@@ -0,0 +1,29 @@
+#BlueJ package file
+objectbench.height=76
+objectbench.width=683
+package.editor.height=364
+package.editor.width=575
+package.editor.x=70
+package.editor.y=80
+package.numDependencies=0
+package.numTargets=1
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+readme.editor.height=543
+readme.editor.width=810
+readme.editor.x=53
+readme.editor.y=23
+target1.editor.height=714
+target1.editor.width=892
+target1.editor.x=53
+target1.editor.y=36
+target1.height=60
+target1.name=ImageViewer
+target1.naviview.expanded=true
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=120
+target1.x=180
+target1.y=120

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-3/ImageViewer.ctxt

@@ -0,0 +1,17 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImageViewer()
+comment0.text=\n\ Create\ an\ ImageViewer\ show\ it\ on\ screen.\n
+comment1.params=
+comment1.target=void\ openFile()
+comment1.text=\n\ Open\ function\:\ open\ a\ file\ chooser\ to\ select\ a\ new\ image\ file.\n
+comment2.params=
+comment2.target=void\ quit()
+comment2.text=\n\ Quit\ function\:\ quit\ the\ application.\n
+comment3.params=
+comment3.target=void\ makeFrame()
+comment3.text=\n\ Create\ the\ Swing\ frame\ and\ its\ content.\n
+comment4.params=frame
+comment4.target=void\ makeMenuBar(javax.swing.JFrame)
+comment4.text=\n\ Create\ the\ main\ frame's\ menu\ bar.\n\ @param\ frame\ \ \ The\ frame\ that\ the\ menu\ bar\ should\ be\ added\ to.\n
+numComments=5

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-3/ImageViewer.java

@@ -0,0 +1,87 @@
+import java.awt.*;
+import java.awt.event.*;
+import javax.swing.*;
+
+/**
+ * ImageViewer is the main class of the image viewer application. It builds 
+ * and displays the application GUI.
+ * 
+ * To start the application, create an object of this class.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 0.3
+ */
+public class ImageViewer
+{
+    private JFrame frame;
+    
+    /**
+     * Create an ImageViewer show it on screen.
+     */
+    public ImageViewer()
+    {
+        makeFrame();
+    }
+
+
+    // ---- implementation of menu functions ----
+    
+    /**
+     * Open function: open a file chooser to select a new image file.
+     */
+    private void openFile()
+    {
+        // this is some test output, until we do this properly
+        System.out.println("open file");
+    }
+    
+    /**
+     * Quit function: quit the application.
+     */
+    private void quit()
+    {
+        System.exit(0);
+    }
+    
+    // ---- swing stuff to build the frame and all its components ----
+    
+    /**
+     * Create the Swing frame and its content.
+     */
+    private void makeFrame()
+    {
+        frame = new JFrame("ImageViewer");
+        makeMenuBar(frame);
+        
+        Container contentPane = frame.getContentPane();
+        
+        JLabel label = new JLabel("I am a label. I can display some text.");
+        contentPane.add(label);
+
+        // building is done - arrange the components and show
+        frame.pack();
+        frame.setVisible(true);
+    }
+    
+    /**
+     * Create the main frame's menu bar.
+     * @param frame   The frame that the menu bar should be added to.
+     */
+    private void makeMenuBar(JFrame frame)
+    {
+        JMenuBar menubar = new JMenuBar();
+        frame.setJMenuBar(menubar);
+        
+        // create the File menu
+        JMenu fileMenu = new JMenu("File");
+        menubar.add(fileMenu);
+        
+        JMenuItem openItem = new JMenuItem("Open");
+        openItem.addActionListener(e -> openFile());
+        fileMenu.add(openItem);
+
+        JMenuItem quitItem = new JMenuItem("Quit");
+        quitItem.addActionListener(e -> quit());
+        fileMenu.add(quitItem);
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-3/README.TXT

@@ -0,0 +1,14 @@
+Project: imageviewer, version 0.3
+Authors: David Barnes and Michael Kölling
+
+This project is part of the material for the book
+
+   Objects First with Java - A Practical Introduction using BlueJ
+   Sixth edition
+   David J. Barnes and Michael Kölling
+   Pearson Education, 2016
+
+It is discussed in chapter 13.
+
+To use this project, create an instance of class ImageViewer.
+For details, refer to the book chapter.

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-3/package.bluej

@@ -0,0 +1,29 @@
+#BlueJ package file
+objectbench.height=76
+objectbench.width=679
+package.editor.height=369
+package.editor.width=571
+package.editor.x=70
+package.editor.y=80
+package.numDependencies=0
+package.numTargets=1
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+readme.editor.height=534
+readme.editor.width=776
+readme.editor.x=53
+readme.editor.y=23
+target1.editor.height=736
+target1.editor.width=938
+target1.editor.x=231
+target1.editor.y=58
+target1.height=60
+target1.name=ImageViewer
+target1.naviview.expanded=true
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=120
+target1.x=210
+target1.y=130

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-4/ImageFileManager.ctxt

@@ -0,0 +1,11 @@
+#BlueJ class context
+comment0.params=
+comment0.target=OFImage\ getImage()
+comment0.text=\n\ Open\ a\ file\ chooser\ and\ let\ the\ user\ select\ an\ image\ file\ in\ the\ file\n\ system.\ Then\ read\ an\ image\ file\ from\ disk\ and\ return\ it\ as\ an\ image.\ This\ method\n\ can\ read\ JPG\ and\ PNG\ file\ formats.\ In\ case\ of\ any\ problem\ (e.g\ the\ file\ does\n\ not\ exist,\ is\ in\ an\ undecodable\ format,\ or\ any\ other\ read\ error)\ this\ method\n\ returns\ null.\n\ \n\ @return\ \ \ \ \ \ \ The\ image\ object\ or\ null\ is\ it\ was\ not\ a\ valid\ image\ file.\n
+comment1.params=imageFile
+comment1.target=OFImage\ loadImage(java.io.File)
+comment1.text=\n\ Read\ an\ image\ file\ from\ disk\ and\ return\ it\ as\ a\ BufferedImage.\ This\ method\n\ can\ read\ JPG\ and\ PNG\ file\ formats.\ In\ case\ of\ any\ problem\ (e.g\ the\ file\ does\n\ not\ exist,\ is\ in\ an\ undecodable\ format,\ or\ any\ other\ read\ error)\ this\ method\n\ returns\ null.\n\ \n\ @param\ imageFile\ \ The\ image\ file\ to\ be\ loaded.\n\ @return\ \ \ \ \ \ \ \ \ \ \ The\ image\ object\ or\ null\ if\ it\ was\ not\ a\ valid\ image\ file.\n
+comment2.params=image\ file
+comment2.target=void\ saveImage(OFImage,\ java.io.File)
+comment2.text=\n\ Write\ an\ image\ file\ to\ disk.\ The\ file\ format\ is\ JPG.\ In\ case\ of\ any\ problem\n\ the\ method\ just\ silently\ returns.\n\ \n\ @param\ image\ \ The\ image\ to\ be\ saved.\n\ @param\ file\ \ \ The\ file\ to\ save\ to.\n
+numComments=3

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-4/ImageFileManager.java

@@ -0,0 +1,83 @@
+import java.awt.image.*;
+import javax.imageio.*;
+import javax.swing.*;
+import java.io.*;
+
+/**
+ * ImageFileManager is a small utility class with static methods to load
+ * and save images.
+ * 
+ * The files on disk can be in JPG or PNG image format. For files written
+ * by this class, the format is determined by the constant IMAGE_FORMAT.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class ImageFileManager
+{
+    // A constant for the image format that this writer uses for writing.
+    // Available formats are "jpg" and "png".
+    private static final String IMAGE_FORMAT = "jpg";
+    private static JFileChooser fileChooser = new JFileChooser(System.getProperty("user.dir"));
+    
+    /**
+     * Open a file chooser and let the user select an image file in the file
+     * system. Then read an image file from disk and return it as an image. This method
+     * can read JPG and PNG file formats. In case of any problem (e.g the file does
+     * not exist, is in an undecodable format, or any other read error) this method
+     * returns null.
+     * 
+     * @return       The image object or null is it was not a valid image file.
+     */
+    public static OFImage getImage()
+    {
+        int returnVal = fileChooser.showOpenDialog(null);
+
+        if(returnVal != JFileChooser.APPROVE_OPTION) {
+            return null;  // cancelled
+        }
+        File selectedFile = fileChooser.getSelectedFile();
+        return loadImage(selectedFile);
+    }
+
+    /**
+     * Read an image file from disk and return it as a BufferedImage. This method
+     * can read JPG and PNG file formats. In case of any problem (e.g the file does
+     * not exist, is in an undecodable format, or any other read error) this method
+     * returns null.
+     * 
+     * @param imageFile  The image file to be loaded.
+     * @return           The image object or null if it was not a valid image file.
+     */
+    public static OFImage loadImage(File imageFile)
+    {
+        try {
+            BufferedImage image = ImageIO.read(imageFile);
+            if(image == null || (image.getWidth(null) < 0)) {
+                // we could not load the image - probably invalid file format
+                return null;
+            }
+            return new OFImage(image);
+        }
+        catch(IOException exc) {
+            return null;
+        }
+    }
+
+    /**
+     * Write an image file to disk. The file format is JPG. In case of any problem
+     * the method just silently returns.
+     * 
+     * @param image  The image to be saved.
+     * @param file   The file to save to.
+     */
+    public static void saveImage(OFImage image, File file)
+    {
+        try {
+            ImageIO.write(image, IMAGE_FORMAT, file);
+        }
+        catch(IOException exc) {
+            return;
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-4/ImagePanel.ctxt

@@ -0,0 +1,17 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImagePanel()
+comment0.text=\n\ Create\ a\ new,\ empty\ ImagePanel.\n
+comment1.params=image
+comment1.target=void\ setImage(OFImage)
+comment1.text=\n\ Set\ the\ image\ that\ this\ panel\ should\ show.\n\ \n\ @param\ image\ \ The\ image\ to\ be\ displayed.\n
+comment2.params=
+comment2.target=void\ clearImage()
+comment2.text=\n\ Clear\ the\ image\ on\ this\ panel.\n
+comment3.params=
+comment3.target=java.awt.Dimension\ getPreferredSize()
+comment3.text=\n\ Tell\ the\ layout\ manager\ how\ big\ we\ would\ like\ to\ be.\n\ (This\ method\ gets\ called\ by\ layout\ managers\ for\ placing\n\ the\ components.)\n\ \n\ @return\ The\ preferred\ dimension\ for\ this\ component.\n
+comment4.params=g
+comment4.target=void\ paintComponent(java.awt.Graphics)
+comment4.text=\n\ This\ component\ needs\ to\ be\ redisplayed.\ Copy\ the\ internal\ image\ \n\ to\ screen.\ (This\ method\ gets\ called\ by\ the\ Swing\ screen\ painter\ \n\ every\ time\ it\ want\ this\ component\ displayed.)\n\ \n\ @param\ g\ The\ graphics\ context\ that\ can\ be\ used\ to\ draw\ on\ this\ component.\n
+numComments=5

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-4/ImagePanel.java

@@ -0,0 +1,89 @@
+import java.awt.*;
+import javax.swing.*;
+import java.awt.image.*;
+
+/**
+ * An ImagePanel is a Swing component that can display an OFImage.
+ * It is constructed as a subclass of JComponent with the added functionality
+ * of setting an OFImage that will be displayed on the surface of this
+ * component.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class ImagePanel extends JComponent
+{
+    // The current width and height of this panel
+    private int width, height;
+
+    // An internal image buffer that is used for painting. For
+    // actual display, this image buffer is then copied to screen.
+    private OFImage panelImage;
+
+    /**
+     * Create a new, empty ImagePanel.
+     */
+    public ImagePanel()
+    {
+        width = 360;    // arbitrary size for empty panel
+        height = 240;
+        panelImage = null;
+    }
+
+    /**
+     * Set the image that this panel should show.
+     * 
+     * @param image  The image to be displayed.
+     */
+    public void setImage(OFImage image)
+    {
+        if(image != null) {
+            width = image.getWidth();
+            height = image.getHeight();
+            panelImage = image;
+            repaint();
+        }
+    }
+    
+    /**
+     * Clear the image on this panel.
+     */
+    public void clearImage()
+    {
+        Graphics imageGraphics = panelImage.getGraphics();
+        imageGraphics.setColor(Color.LIGHT_GRAY);
+        imageGraphics.fillRect(0, 0, width, height);
+        repaint();
+    }
+    
+    // The following methods are redefinitions of methods
+    // inherited from superclasses.
+    
+    /**
+     * Tell the layout manager how big we would like to be.
+     * (This method gets called by layout managers for placing
+     * the components.)
+     * 
+     * @return The preferred dimension for this component.
+     */
+    public Dimension getPreferredSize()
+    {
+        return new Dimension(width, height);
+    }
+    
+    /**
+     * This component needs to be redisplayed. Copy the internal image 
+     * to screen. (This method gets called by the Swing screen painter 
+     * every time it want this component displayed.)
+     * 
+     * @param g The graphics context that can be used to draw on this component.
+     */
+    public void paintComponent(Graphics g)
+    {
+        Dimension size = getSize();
+        g.clearRect(0, 0, size.width, size.height);
+        if(panelImage != null) {
+            g.drawImage(panelImage, 0, 0, null);
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-4/ImageViewer.ctxt

@@ -0,0 +1,17 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImageViewer()
+comment0.text=\n\ Create\ an\ ImageViewer\ show\ it\ on\ screen.\n
+comment1.params=
+comment1.target=void\ openFile()
+comment1.text=\n\ Open\ function\:\ open\ a\ file\ chooser\ to\ select\ a\ new\ image\ file.\n
+comment2.params=
+comment2.target=void\ quit()
+comment2.text=\n\ Quit\ function\:\ quit\ the\ application.\n
+comment3.params=
+comment3.target=void\ makeFrame()
+comment3.text=\n\ Create\ the\ Swing\ frame\ and\ its\ content.\n
+comment4.params=frame
+comment4.target=void\ makeMenuBar(javax.swing.JFrame)
+comment4.text=\n\ Create\ the\ main\ frame's\ menu\ bar.\n\ @param\ frame\ \ \ The\ frame\ that\ the\ menu\ bar\ should\ be\ added\ to.\n
+numComments=5

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-4/ImageViewer.java

@@ -0,0 +1,96 @@
+import java.awt.*;
+import java.awt.event.*;
+import javax.swing.*;
+
+/**
+ * ImageViewer is the main class of the image viewer application. It builds and
+ * displays the application GUI and initialises all other components.
+ * 
+ * To start the application, create an object of this class.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 0.4
+ */
+public class ImageViewer
+{
+    private JFrame frame;
+    private ImagePanel imagePanel;
+    
+    /**
+     * Create an ImageViewer show it on screen.
+     */
+    public ImageViewer()
+    {
+        makeFrame();
+    }
+
+
+    // ---- implementation of menu functions ----
+    
+    /**
+     * Open function: open a file chooser to select a new image file.
+     */
+    private void openFile()
+    {
+        OFImage image = ImageFileManager.getImage();
+        imagePanel.setImage(image);
+        frame.pack();
+    }
+    
+    /**
+     * Quit function: quit the application.
+     */
+    private void quit()
+    {
+        System.exit(0);
+    }
+    
+    // ---- swing stuff to build the frame and all its components ----
+    
+    /**
+     * Create the Swing frame and its content.
+     */
+    private void makeFrame()
+    {
+        frame = new JFrame("ImageViewer");
+        makeMenuBar(frame);
+        
+        Container contentPane = frame.getContentPane();
+        
+        imagePanel = new ImagePanel();
+        contentPane.add(imagePanel);
+
+        // building is done - arrange the components and show        
+        frame.pack();
+        frame.setVisible(true);
+    }
+    
+    /**
+     * Create the main frame's menu bar.
+     * @param frame   The frame that the menu bar should be added to.
+     */
+    private void makeMenuBar(JFrame frame)
+    {
+        final int SHORTCUT_MASK =
+            Toolkit.getDefaultToolkit().getMenuShortcutKeyMask();
+
+
+        JMenuBar menubar = new JMenuBar();
+        frame.setJMenuBar(menubar);
+        
+        // create the File manu
+        JMenu fileMenu = new JMenu("File");
+        menubar.add(fileMenu);
+        
+        JMenuItem openItem = new JMenuItem("Open");
+            openItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O, SHORTCUT_MASK));
+            openItem.addActionListener(e -> openFile());
+        fileMenu.add(openItem);
+
+        JMenuItem quitItem = new JMenuItem("Quit");
+            quitItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK));
+            quitItem.addActionListener(e -> quit());
+        fileMenu.add(quitItem);
+
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-4/OFImage.ctxt

@@ -0,0 +1,14 @@
+#BlueJ class context
+comment0.params=image
+comment0.target=OFImage(java.awt.image.BufferedImage)
+comment0.text=\n\ Create\ an\ OFImage\ copied\ from\ a\ BufferedImage.\n\ @param\ image\ The\ image\ to\ copy.\n
+comment1.params=width\ height
+comment1.target=OFImage(int,\ int)
+comment1.text=\n\ Create\ an\ OFImage\ with\ specified\ size\ and\ unspecified\ content.\n\ @param\ width\ The\ width\ of\ the\ image.\n\ @param\ height\ The\ height\ of\ the\ image.\n
+comment2.params=x\ y\ col
+comment2.target=void\ setPixel(int,\ int,\ java.awt.Color)
+comment2.text=\n\ Set\ a\ given\ pixel\ of\ this\ image\ to\ a\ specified\ color.\ The\n\ color\ is\ represented\ as\ an\ (r,g,b)\ value.\n\ @param\ x\ The\ x\ position\ of\ the\ pixel.\n\ @param\ y\ The\ y\ position\ of\ the\ pixel.\n\ @param\ col\ The\ color\ of\ the\ pixel.\n
+comment3.params=x\ y
+comment3.target=java.awt.Color\ getPixel(int,\ int)
+comment3.text=\n\ Get\ the\ color\ value\ at\ a\ specified\ pixel\ position.\n\ @param\ x\ The\ x\ position\ of\ the\ pixel.\n\ @param\ y\ The\ y\ position\ of\ the\ pixel.\n\ @return\ The\ color\ of\ the\ pixel\ at\ the\ given\ position.\n
+numComments=4

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-4/OFImage.java

@@ -0,0 +1,57 @@
+import java.awt.*;
+import java.awt.image.*;
+import javax.swing.*;
+
+/**
+ * OFImage is a class that defines an image in OF (Objects First) format.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class OFImage extends BufferedImage
+{
+    /**
+     * Create an OFImage copied from a BufferedImage.
+     * @param image The image to copy.
+     */
+    public OFImage(BufferedImage image)
+    {
+         super(image.getColorModel(), image.copyData(null), 
+               image.isAlphaPremultiplied(), null);
+    }
+
+    /**
+     * Create an OFImage with specified size and unspecified content.
+     * @param width The width of the image.
+     * @param height The height of the image.
+     */
+    public OFImage(int width, int height)
+    {
+        super(width, height, TYPE_INT_RGB);
+    }
+
+    /**
+     * Set a given pixel of this image to a specified color. The
+     * color is represented as an (r,g,b) value.
+     * @param x The x position of the pixel.
+     * @param y The y position of the pixel.
+     * @param col The color of the pixel.
+     */
+    public void setPixel(int x, int y, Color col)
+    {
+        int pixel = col.getRGB();
+        setRGB(x, y, pixel);
+    }
+    
+    /**
+     * Get the color value at a specified pixel position.
+     * @param x The x position of the pixel.
+     * @param y The y position of the pixel.
+     * @return The color of the pixel at the given position.
+     */
+    public Color getPixel(int x, int y)
+    {
+        int pixel = getRGB(x, y);
+        return new Color(pixel);
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-4/README.TXT

@@ -0,0 +1,14 @@
+Project: imageviewer, version 0.4
+Authors: David Barnes and Michael Kölling
+
+This project is part of the material for the book
+
+   Objects First with Java - A Practical Introduction using BlueJ
+   Sixth edition
+   David J. Barnes and Michael Kölling
+   Pearson Education, 2016
+
+It is discussed in chapter 13.
+
+To use this project, create an instance of class ImageViewer.
+For details, refer to the book chapter.

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer0-4/package.bluej

@@ -0,0 +1,83 @@
+#BlueJ package file
+dependency1.from=ImageViewer
+dependency1.to=ImagePanel
+dependency1.type=UsesDependency
+dependency2.from=ImageViewer
+dependency2.to=OFImage
+dependency2.type=UsesDependency
+dependency3.from=ImageViewer
+dependency3.to=ImageFileManager
+dependency3.type=UsesDependency
+dependency4.from=ImageFileManager
+dependency4.to=OFImage
+dependency4.type=UsesDependency
+dependency5.from=ImagePanel
+dependency5.to=OFImage
+dependency5.type=UsesDependency
+objectbench.height=76
+objectbench.width=782
+package.editor.height=445
+package.editor.width=674
+package.editor.x=70
+package.editor.y=80
+package.numDependencies=5
+package.numTargets=4
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+readme.editor.height=557
+readme.editor.width=820
+readme.editor.x=53
+readme.editor.y=23
+target1.editor.height=714
+target1.editor.width=889
+target1.editor.x=50
+target1.editor.y=60
+target1.height=60
+target1.name=OFImage
+target1.naviview.expanded=true
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=120
+target1.x=320
+target1.y=320
+target2.editor.height=733
+target2.editor.width=961
+target2.editor.x=532
+target2.editor.y=42
+target2.height=60
+target2.name=ImageFileManager
+target2.naviview.expanded=true
+target2.showInterface=false
+target2.type=ClassTarget
+target2.typeParameters=
+target2.width=140
+target2.x=430
+target2.y=180
+target3.editor.height=674
+target3.editor.width=938
+target3.editor.x=69
+target3.editor.y=90
+target3.height=60
+target3.name=ImageViewer
+target3.naviview.expanded=true
+target3.showInterface=false
+target3.type=ClassTarget
+target3.typeParameters=
+target3.width=120
+target3.x=220
+target3.y=70
+target4.editor.height=726
+target4.editor.width=907
+target4.editor.x=50
+target4.editor.y=60
+target4.height=60
+target4.name=ImagePanel
+target4.naviview.expanded=true
+target4.showInterface=false
+target4.type=ClassTarget
+target4.typeParameters=
+target4.width=120
+target4.x=60
+target4.y=180

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer1-0/ImageFileManager.ctxt

@@ -0,0 +1,8 @@
+#BlueJ class context
+comment0.params=imageFile
+comment0.target=OFImage\ loadImage(java.io.File)
+comment0.text=\n\ Read\ an\ image\ file\ from\ disk\ and\ return\ it\ as\ an\ image.\ This\ method\n\ can\ read\ JPG\ and\ PNG\ file\ formats.\ In\ case\ of\ any\ problem\ (e.g\ the\ file\ \n\ does\ not\ exist,\ is\ in\ an\ undecodable\ format,\ or\ any\ other\ read\ error)\ \n\ this\ method\ returns\ null.\n\ \n\ @param\ imageFile\ \ The\ image\ file\ to\ be\ loaded.\n\ @return\ \ \ \ \ \ \ \ \ \ \ The\ image\ object\ or\ null\ if\ it\ could\ not\ be\ read.\n
+comment1.params=image\ file
+comment1.target=void\ saveImage(OFImage,\ java.io.File)
+comment1.text=\n\ Write\ an\ image\ file\ to\ disk.\ The\ file\ format\ is\ JPG.\ In\ case\ of\ any\ \n\ problem\ the\ method\ just\ silently\ returns.\n\ \n\ @param\ image\ \ The\ image\ to\ be\ saved.\n\ @param\ file\ \ \ The\ file\ to\ save\ to.\n
+numComments=2

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer1-0/ImageFileManager.java

@@ -0,0 +1,61 @@
+import java.awt.image.*;
+import javax.imageio.*;
+import java.io.*;
+
+/**
+ * ImageFileManager is a small utility class with static methods to load
+ * and save images.
+ * 
+ * The files on disk can be in JPG or PNG image format. For files written
+ * by this class, the format is determined by the constant IMAGE_FORMAT.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 2.0
+ */
+public class ImageFileManager
+{
+    // A constant for the image format that this writer uses for writing.
+    // Available formats are "jpg" and "png".
+    private static final String IMAGE_FORMAT = "jpg";
+    
+    /**
+     * Read an image file from disk and return it as an image. This method
+     * can read JPG and PNG file formats. In case of any problem (e.g the file 
+     * does not exist, is in an undecodable format, or any other read error) 
+     * this method returns null.
+     * 
+     * @param imageFile  The image file to be loaded.
+     * @return           The image object or null if it could not be read.
+     */
+    public static OFImage loadImage(File imageFile)
+    {
+        try {
+            BufferedImage image = ImageIO.read(imageFile);
+            if(image == null || (image.getWidth(null) < 0)) {
+                // we could not load the image - probably invalid file format
+                return null;
+            }
+            return new OFImage(image);
+        }
+        catch(IOException exc) {
+            return null;
+        }
+    }
+
+    /**
+     * Write an image file to disk. The file format is JPG. In case of any 
+     * problem the method just silently returns.
+     * 
+     * @param image  The image to be saved.
+     * @param file   The file to save to.
+     */
+    public static void saveImage(OFImage image, File file)
+    {
+        try {
+            ImageIO.write(image, IMAGE_FORMAT, file);
+        }
+        catch(IOException exc) {
+            return;
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer1-0/ImagePanel.ctxt

@@ -0,0 +1,14 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImagePanel()
+comment0.text=\n\ Create\ a\ new,\ empty\ ImagePanel.\n
+comment1.params=
+comment1.target=void\ clearImage()
+comment1.text=\n\ Clear\ the\ image\ on\ this\ panel.\n
+comment2.params=
+comment2.target=java.awt.Dimension\ getPreferredSize()
+comment2.text=\n\ Tell\ the\ layout\ manager\ how\ big\ we\ would\ like\ to\ be.\n\ (This\ method\ gets\ called\ by\ layout\ managers\ for\ placing\n\ the\ components.)\n\ \n\ @return\ The\ preferred\ dimension\ for\ this\ component.\n
+comment3.params=g
+comment3.target=void\ paintComponent(java.awt.Graphics)
+comment3.text=\n\ This\ component\ needs\ to\ be\ redisplayed.\ Copy\ the\ internal\ image\ \n\ to\ screen.\ (This\ method\ gets\ called\ by\ the\ Swing\ screen\ painter\ \n\ every\ time\ it\ want\ this\ component\ displayed.)\n\ \n\ @param\ g\ The\ graphics\ context\ that\ can\ be\ used\ to\ draw\ on\ this\ component.\n
+numComments=4

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer1-0/ImagePanel.java

@@ -0,0 +1,89 @@
+import java.awt.*;
+import javax.swing.*;
+import java.awt.image.*;
+
+/**
+ * An ImagePanel is a Swing component that can display an OFImage.
+ * It is constructed as a subclass of JComponent with the added functionality
+ * of setting an OFImage that will be displayed on the surface of this
+ * component.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class ImagePanel extends JComponent
+{
+    // The current width and height of this panel
+    private int width, height;
+
+    // An internal image buffer that is used for painting. For
+    // actual display, this image buffer is then copied to screen.
+    private OFImage panelImage;
+
+    /**
+     * Create a new, empty ImagePanel.
+     */
+    public ImagePanel()
+    {
+        width = 360;    // arbitrary size for empty panel
+        height = 240;
+        panelImage = null;
+    }
+
+    /**
+     * Set the image that this panel should show.
+     * 
+     * @param image  The image to be displayed.
+     */
+    public void setImage(OFImage image)
+    {
+        if(image != null) {
+            width = image.getWidth();
+            height = image.getHeight();
+            panelImage = image;
+            repaint();
+        }
+    }
+    
+    /**
+     * Clear the image on this panel.
+     */
+    public void clearImage()
+    {
+        Graphics imageGraphics = panelImage.getGraphics();
+        imageGraphics.setColor(Color.LIGHT_GRAY);
+        imageGraphics.fillRect(0, 0, width, height);
+        repaint();
+    }
+    
+    // The following methods are redefinitions of methods
+    // inherited from superclasses.
+    
+    /**
+     * Tell the layout manager how big we would like to be.
+     * (This method gets called by layout managers for placing
+     * the components.)
+     * 
+     * @return The preferred dimension for this component.
+     */
+    public Dimension getPreferredSize()
+    {
+        return new Dimension(width, height);
+    }
+    
+    /**
+     * This component needs to be redisplayed. Copy the internal image 
+     * to screen. (This method gets called by the Swing screen painter 
+     * every time it want this component displayed.)
+     * 
+     * @param g The graphics context that can be used to draw on this component.
+     */
+    public void paintComponent(Graphics g)
+    {
+        Dimension size = getSize();
+        g.clearRect(0, 0, size.width, size.height);
+        if(panelImage != null) {
+            g.drawImage(panelImage, 0, 0, null);
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer1-0/ImageViewer.ctxt

@@ -0,0 +1,38 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImageViewer()
+comment0.text=\n\ Create\ an\ ImageViewer\ show\ it\ on\ screen.\n
+comment1.params=
+comment1.target=void\ openFile()
+comment1.text=\n\ Open\ function\:\ open\ a\ file\ chooser\ to\ select\ a\ new\ image\ file.\n
+comment10.params=
+comment10.target=void\ makeFrame()
+comment10.text=\n\ Create\ the\ Swing\ frame\ and\ its\ content.\n
+comment11.params=frame
+comment11.target=void\ makeMenuBar(javax.swing.JFrame)
+comment11.text=\n\ Create\ the\ main\ frame's\ menu\ bar.\n\ @param\ frame\ \ \ The\ frame\ that\ the\ menu\ bar\ should\ be\ added\ to.\n
+comment2.params=
+comment2.target=void\ close()
+comment2.text=\n\ Close\ function\:\ close\ the\ current\ image.\n
+comment3.params=
+comment3.target=void\ quit()
+comment3.text=\n\ Quit\ function\:\ quit\ the\ application.\n
+comment4.params=
+comment4.target=void\ makeDarker()
+comment4.text=\n\ 'Darker'\ function\:\ make\ the\ picture\ darker.\n
+comment5.params=
+comment5.target=void\ makeLighter()
+comment5.text=\n\ 'Lighter'\ function\:\ make\ the\ picture\ lighter\n
+comment6.params=
+comment6.target=void\ threshold()
+comment6.text=\n\ 'threshold'\ function\:\ apply\ the\ threshold\ filter\n
+comment7.params=
+comment7.target=void\ showAbout()
+comment7.text=\n\ Show\ the\ 'About...'\ dialog.\n
+comment8.params=filename
+comment8.target=void\ showFilename(java.lang.String)
+comment8.text=\n\ Display\ a\ file\ name\ on\ the\ appropriate\ label.\n\ @param\ filename\ The\ file\ name\ to\ be\ displayed.\n
+comment9.params=text
+comment9.target=void\ showStatus(java.lang.String)
+comment9.text=\n\ Display\ a\ status\ message\ in\ the\ frame's\ status\ bar.\n\ @param\ text\ The\ status\ message\ to\ be\ displayed.\n
+numComments=12

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer1-0/ImageViewer.java

@@ -0,0 +1,266 @@
+import java.awt.*;
+import java.awt.event.*;
+import java.awt.image.*;
+import javax.swing.*;
+
+import java.io.File;
+
+/**
+ * ImageViewer is the main class of the image viewer application. It builds and
+ * displays the application GUI and initialises all other components.
+ * 
+ * To start the application, create an object of this class.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class ImageViewer
+{
+    // static fields:
+    private static final String VERSION = "Version 1.0";
+    private static JFileChooser fileChooser = new JFileChooser(System.getProperty("user.dir"));
+
+    // fields:
+    private JFrame frame;
+    private ImagePanel imagePanel;
+    private JLabel filenameLabel;
+    private JLabel statusLabel;
+    private OFImage currentImage;
+    
+    /**
+     * Create an ImageViewer show it on screen.
+     */
+    public ImageViewer()
+    {
+        currentImage = null;
+        makeFrame();
+    }
+
+
+    // ---- implementation of menu functions ----
+    
+    /**
+     * Open function: open a file chooser to select a new image file.
+     */
+    private void openFile()
+    {
+        int returnVal = fileChooser.showOpenDialog(frame);
+
+        if(returnVal != JFileChooser.APPROVE_OPTION) {
+            return;  // cancelled
+        }
+        File selectedFile = fileChooser.getSelectedFile();
+        currentImage = ImageFileManager.loadImage(selectedFile);
+
+        if(currentImage == null) {   // image file was not a valid image
+            JOptionPane.showMessageDialog(frame,
+                    "The file was not in a recognized image file format.",
+                    "Image Load Error",
+                    JOptionPane.ERROR_MESSAGE);
+            return;
+        }
+        
+        imagePanel.setImage(currentImage);
+        showFilename(selectedFile.getPath());
+        showStatus("File loaded.");
+        frame.pack();
+    }
+    
+    /**
+     * Close function: close the current image.
+     */
+    private void close()
+    {
+        currentImage = null;
+        imagePanel.clearImage();
+        showFilename(null);
+    }
+    
+    /**
+     * Quit function: quit the application.
+     */
+    private void quit()
+    {
+        System.exit(0);
+    }
+    
+    
+    /**
+     * 'Darker' function: make the picture darker.
+     */
+    private void makeDarker()
+    {
+        if(currentImage != null) {
+            currentImage.darker();
+            frame.repaint();
+            showStatus("Applied: darker");
+        }
+        else {
+            showStatus("No image loaded.");
+        }
+    }
+    
+    /**
+     * 'Lighter' function: make the picture lighter
+     */
+    private void makeLighter()
+    {
+        if(currentImage != null) {
+            currentImage.lighter();
+            frame.repaint();
+            showStatus("Applied: lighter");
+        }
+        else {
+            showStatus("No image loaded.");
+        }
+    }
+    
+    /**
+     * 'threshold' function: apply the threshold filter
+     */
+    private void threshold()
+    {
+        if(currentImage != null) {
+            currentImage.threshold();
+            frame.repaint();
+            showStatus("Applied: threshold");
+        }
+        else {
+            showStatus("No image loaded.");
+        }
+    }
+    
+    /**
+     * Show the 'About...' dialog.
+     */
+    private void showAbout()
+    {
+        JOptionPane.showMessageDialog(frame, 
+                    "ImageViewer\n" + VERSION,
+                    "About ImageViewer", 
+                    JOptionPane.INFORMATION_MESSAGE);
+    }
+    
+    
+    // ---- support methods ----
+
+    /**
+     * Display a file name on the appropriate label.
+     * @param filename The file name to be displayed.
+     */
+    private void showFilename(String filename)
+    {
+        if(filename == null) {
+            filenameLabel.setText("No file displayed.");
+        }
+        else {
+            filenameLabel.setText("File: " + filename);
+        }
+    }
+    
+    /**
+     * Display a status message in the frame's status bar.
+     * @param text The status message to be displayed.
+     */
+    private void showStatus(String text)
+    {
+        statusLabel.setText(text);
+    }
+    
+    // ---- swing stuff to build the frame and all its components ----
+    
+    /**
+     * Create the Swing frame and its content.
+     */
+    private void makeFrame()
+    {
+        frame = new JFrame("ImageViewer");
+        makeMenuBar(frame);
+        
+        Container contentPane = frame.getContentPane();
+        
+        // Specify the layout manager with nice spacing
+        contentPane.setLayout(new BorderLayout(6, 6));
+        
+        filenameLabel = new JLabel();
+        contentPane.add(filenameLabel, BorderLayout.NORTH);
+
+        imagePanel = new ImagePanel();
+        contentPane.add(imagePanel, BorderLayout.CENTER);
+
+        statusLabel = new JLabel(VERSION);
+        contentPane.add(statusLabel, BorderLayout.SOUTH);
+        
+        // building is done - arrange the components and show        
+        showFilename(null);
+        frame.pack();
+        
+        Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
+        frame.setLocation(d.width/2 - frame.getWidth()/2, d.height/2 - frame.getHeight()/2);
+        frame.setVisible(true);
+    }
+    
+    /**
+     * Create the main frame's menu bar.
+     * @param frame   The frame that the menu bar should be added to.
+     */
+    private void makeMenuBar(JFrame frame)
+    {
+        final int SHORTCUT_MASK =
+            Toolkit.getDefaultToolkit().getMenuShortcutKeyMask();
+
+
+        JMenuBar menubar = new JMenuBar();
+        frame.setJMenuBar(menubar);
+        
+        JMenu menu;
+        JMenuItem item;
+        
+        // create the File menu
+        menu = new JMenu("File");
+        menubar.add(menu);
+        
+        item = new JMenuItem("Open");
+            item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O, SHORTCUT_MASK));
+            item.addActionListener(e -> openFile());
+        menu.add(item);
+
+        item = new JMenuItem("Close");
+            item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_W, SHORTCUT_MASK));
+            item.addActionListener(e -> close());
+        menu.add(item);
+        menu.addSeparator();
+        
+        item = new JMenuItem("Quit");
+            item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK));
+            item.addActionListener(e -> quit());
+        menu.add(item);
+
+
+        // create the Filter menu
+        menu = new JMenu("Filter");
+        menubar.add(menu);
+        
+        item = new JMenuItem("Darker");
+            item.addActionListener(e -> makeDarker());
+        menu.add(item);
+
+        item = new JMenuItem("Lighter");
+            item.addActionListener(e -> makeLighter());
+        menu.add(item);
+
+        item = new JMenuItem("Threshold");
+            item.addActionListener(e -> threshold());
+        menu.add(item);
+
+        
+        // create the Help menu
+        menu = new JMenu("Help");
+        menubar.add(menu);
+        
+        item = new JMenuItem("About ImageViewer...");
+            item.addActionListener(e -> showAbout());
+        menu.add(item);
+
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer1-0/OFImage.ctxt

@@ -0,0 +1,23 @@
+#BlueJ class context
+comment0.params=image
+comment0.target=OFImage(java.awt.image.BufferedImage)
+comment0.text=\n\ Create\ an\ OFImage\ copied\ from\ a\ BufferedImage.\n\ @param\ image\ The\ image\ to\ copy.\n
+comment1.params=width\ height
+comment1.target=OFImage(int,\ int)
+comment1.text=\n\ Create\ an\ OFImage\ with\ specified\ size\ and\ unspecified\ content.\n\ @param\ width\ The\ width\ of\ the\ image.\n\ @param\ height\ The\ height\ of\ the\ image.\n
+comment2.params=x\ y\ col
+comment2.target=void\ setPixel(int,\ int,\ java.awt.Color)
+comment2.text=\n\ Set\ a\ given\ pixel\ of\ this\ image\ to\ a\ specified\ color.\ The\n\ color\ is\ represented\ as\ an\ (r,g,b)\ value.\n\ @param\ x\ The\ x\ position\ of\ the\ pixel.\n\ @param\ y\ The\ y\ position\ of\ the\ pixel.\n\ @param\ col\ The\ color\ of\ the\ pixel.\n
+comment3.params=x\ y
+comment3.target=java.awt.Color\ getPixel(int,\ int)
+comment3.text=\n\ Get\ the\ color\ value\ at\ a\ specified\ pixel\ position.\n\ @param\ x\ The\ x\ position\ of\ the\ pixel.\n\ @param\ y\ The\ y\ position\ of\ the\ pixel.\n\ @return\ The\ color\ of\ the\ pixel\ at\ the\ given\ position.\n
+comment4.params=
+comment4.target=void\ darker()
+comment4.text=\n\ Make\ this\ image\ a\ bit\ darker.\n
+comment5.params=
+comment5.target=void\ lighter()
+comment5.text=\n\ Make\ this\ image\ a\ bit\ lighter.\n
+comment6.params=
+comment6.target=void\ threshold()
+comment6.text=\n\ Perform\ a\ three\ level\ threshold\ operation.\n\ That\ is\:\ repaint\ the\ image\ with\ only\ three\ color\ values\:\n\ \ \ \ \ \ \ \ \ \ white,\ gray,\ and\ black.\n
+numComments=7

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer1-0/OFImage.java

@@ -0,0 +1,111 @@
+import java.awt.*;
+import java.awt.image.*;
+import javax.swing.*;
+
+/**
+ * OFImage is a class that defines an image in OF (Objects First) format.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.1
+ */
+public class OFImage extends BufferedImage
+{
+    /**
+     * Create an OFImage copied from a BufferedImage.
+     * @param image The image to copy.
+     */
+    public OFImage(BufferedImage image)
+    {
+         super(image.getColorModel(), image.copyData(null), 
+               image.isAlphaPremultiplied(), null);
+    }
+
+    /**
+     * Create an OFImage with specified size and unspecified content.
+     * @param width The width of the image.
+     * @param height The height of the image.
+     */
+    public OFImage(int width, int height)
+    {
+        super(width, height, TYPE_INT_RGB);
+    }
+
+    /**
+     * Set a given pixel of this image to a specified color. The
+     * color is represented as an (r,g,b) value.
+     * @param x The x position of the pixel.
+     * @param y The y position of the pixel.
+     * @param col The color of the pixel.
+     */
+    public void setPixel(int x, int y, Color col)
+    {
+        int pixel = col.getRGB();
+        setRGB(x, y, pixel);
+    }
+    
+    /**
+     * Get the color value at a specified pixel position.
+     * @param x The x position of the pixel.
+     * @param y The y position of the pixel.
+     * @return The color of the pixel at the given position.
+     */
+    public Color getPixel(int x, int y)
+    {
+        int pixel = getRGB(x, y);
+        return new Color(pixel);
+    }
+
+    /**
+     * Make this image a bit darker.
+     */
+    public void darker()
+    {
+        int height = getHeight();
+        int width = getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                setPixel(x, y, getPixel(x, y).darker());
+            }
+        }
+    }
+
+    /**
+     * Make this image a bit lighter.
+     */
+    public void lighter()
+    {
+        int height = getHeight();
+        int width = getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                setPixel(x, y, getPixel(x, y).brighter());
+            }
+        }
+    }
+
+    /**
+     * Perform a three level threshold operation.
+     * That is: repaint the image with only three color values:
+     *          white, gray, and black.
+     */
+    public void threshold()
+    {
+        int height = getHeight();
+        int width = getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                Color pixel = getPixel(x, y);
+                int brightness = (pixel.getRed() + pixel.getBlue() + pixel.getGreen()) / 3;
+                if(brightness <= 85) {
+                    setPixel(x, y, Color.BLACK);
+                }
+                else if(brightness <= 170) {
+                    setPixel(x, y, Color.GRAY);
+                }
+                else {
+                    setPixel(x, y, Color.WHITE);
+                }
+            }
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer1-0/README.TXT

@@ -0,0 +1,17 @@
+Project: imageviewer, version 1.0
+Authors: David Barnes and Michael Kölling
+
+This project is part of the material for the book
+
+   Objects First with Java - A Practical Introduction using BlueJ
+   Sixth edition
+   David J. Barnes and Michael Kölling
+   Pearson Education, 2016
+
+It is discussed in chapter 13.
+
+To use this project, create an instance of class ImageViewer.
+This version is the first completed version of this project. It is not 
+perfect, but at least it can display some images.
+
+For details, refer to the book chapter.

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer1-0/package.bluej

@@ -0,0 +1,83 @@
+#BlueJ package file
+dependency1.from=ImageViewer
+dependency1.to=OFImage
+dependency1.type=UsesDependency
+dependency2.from=ImageViewer
+dependency2.to=ImagePanel
+dependency2.type=UsesDependency
+dependency3.from=ImageFileManager
+dependency3.to=OFImage
+dependency3.type=UsesDependency
+dependency4.from=ImagePanel
+dependency4.to=OFImage
+dependency4.type=UsesDependency
+dependency5.from=ImageViewer
+dependency5.to=ImageFileManager
+dependency5.type=UsesDependency
+objectbench.height=76
+objectbench.width=784
+package.editor.height=456
+package.editor.width=676
+package.editor.x=70
+package.editor.y=80
+package.numDependencies=5
+package.numTargets=4
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+readme.editor.height=492
+readme.editor.width=809
+readme.editor.x=53
+readme.editor.y=95
+target1.editor.height=727
+target1.editor.width=966
+target1.editor.x=53
+target1.editor.y=23
+target1.height=60
+target1.name=OFImage
+target1.naviview.expanded=true
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=120
+target1.x=310
+target1.y=330
+target2.editor.height=730
+target2.editor.width=911
+target2.editor.x=520
+target2.editor.y=51
+target2.height=60
+target2.name=ImageFileManager
+target2.naviview.expanded=true
+target2.showInterface=false
+target2.type=ClassTarget
+target2.typeParameters=
+target2.width=140
+target2.x=410
+target2.y=160
+target3.editor.height=777
+target3.editor.width=989
+target3.editor.x=55
+target3.editor.y=23
+target3.height=60
+target3.name=ImageViewer
+target3.naviview.expanded=true
+target3.showInterface=false
+target3.type=ClassTarget
+target3.typeParameters=
+target3.width=120
+target3.x=200
+target3.y=60
+target4.editor.height=731
+target4.editor.width=903
+target4.editor.x=53
+target4.editor.y=60
+target4.height=60
+target4.name=ImagePanel
+target4.naviview.expanded=true
+target4.showInterface=false
+target4.type=ClassTarget
+target4.typeParameters=
+target4.width=110
+target4.x=80
+target4.y=200

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/DarkerFilter.ctxt

@@ -0,0 +1,5 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=DarkerFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ DarkerFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/DarkerFilter.java

@@ -0,0 +1,33 @@
+/**
+ * An image filter to make the image a bit darker.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class DarkerFilter extends Filter
+{
+    /**
+     * Constructor for objects of class DarkerFilter.
+     * @param name The name of the filter.
+     */
+    public DarkerFilter(String name)
+    {
+        super(name);
+    }
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                image.setPixel(x, y, image.getPixel(x, y).darker());
+            }
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/Filter.ctxt

@@ -0,0 +1,8 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=Filter(java.lang.String)
+comment0.text=\n\ Create\ a\ new\ filter\ with\ a\ given\ name.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+comment1.params=
+comment1.target=java.lang.String\ getName()
+comment1.text=\n\ Return\ the\ name\ of\ this\ filter.\n\ \n\ @return\ \ The\ name\ of\ this\ filter.\n
+numComments=2

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/Filter.java

@@ -0,0 +1,38 @@
+/**
+ * Filter is an abstract superclass for all image filters in this
+ * application. Filters can be applied to OFImages by invoking the apply 
+ * method.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public abstract class Filter
+{
+    private String name;
+
+    /**
+     * Create a new filter with a given name.
+     * @param name The name of the filter.
+     */
+    public Filter(String name)
+    {
+        this.name = name;
+    }
+    
+    /**
+     * Return the name of this filter.
+     * 
+     * @return  The name of this filter.
+     */
+    public String getName()
+    {
+        return name;
+    }
+    
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public abstract void apply(OFImage image);
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/ImageFileManager.ctxt

@@ -0,0 +1,2 @@
+#BlueJ class context
+numComments=0

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/ImageFileManager.java

@@ -0,0 +1,61 @@
+import java.awt.image.*;
+import javax.imageio.*;
+import java.io.*;
+
+/**
+ * ImageFileManager is a small utility class with static methods to load
+ * and save images.
+ * 
+ * The files on disk can be in JPG or PNG image format. For files written
+ * by this class, the format is determined by the constant IMAGE_FORMAT.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 2.0
+ */
+public class ImageFileManager
+{
+    // A constant for the image format that this writer uses for writing.
+    // Available formats are "jpg" and "png".
+    private static final String IMAGE_FORMAT = "jpg";
+    
+    /**
+     * Read an image file from disk and return it as an image. This method
+     * can read JPG and PNG file formats. In case of any problem (e.g the file 
+     * does not exist, is in an undecodable format, or any other read error) 
+     * this method returns null.
+     * 
+     * @param imageFile  The image file to be loaded.
+     * @return           The image object or null is it could not be read.
+     */
+    public static OFImage loadImage(File imageFile)
+    {
+        try {
+            BufferedImage image = ImageIO.read(imageFile);
+            if(image == null || (image.getWidth(null) < 0)) {
+                // we could not load the image - probably invalid file format
+                return null;
+            }
+            return new OFImage(image);
+        }
+        catch(IOException exc) {
+            return null;
+        }
+    }
+
+    /**
+     * Write an image file to disk. The file format is JPG. In case of any 
+     * problem the method just silently returns.
+     * 
+     * @param image  The image to be saved.
+     * @param file   The file to save to.
+     */
+    public static void saveImage(OFImage image, File file)
+    {
+        try {
+            ImageIO.write(image, IMAGE_FORMAT, file);
+        }
+        catch(IOException exc) {
+            return;
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/ImagePanel.ctxt

@@ -0,0 +1,14 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImagePanel()
+comment0.text=\n\ Create\ a\ new,\ empty\ ImagePanel.\n
+comment1.params=
+comment1.target=void\ clearImage()
+comment1.text=\n\ Clear\ the\ image\ on\ this\ panel.\n
+comment2.params=
+comment2.target=java.awt.Dimension\ getPreferredSize()
+comment2.text=\n\ Tell\ the\ layout\ manager\ how\ big\ we\ would\ like\ to\ be.\n\ (This\ method\ gets\ called\ by\ layout\ managers\ for\ placing\n\ the\ components.)\n\ \n\ @return\ The\ preferred\ dimension\ for\ this\ component.\n
+comment3.params=g
+comment3.target=void\ paintComponent(java.awt.Graphics)
+comment3.text=\n\ This\ component\ needs\ to\ be\ redisplayed.\ Copy\ the\ internal\ image\ \n\ to\ screen.\ (This\ method\ gets\ called\ by\ the\ Swing\ screen\ painter\ \n\ every\ time\ it\ want\ this\ component\ displayed.)\n\ \n\ @param\ g\ The\ graphics\ context\ that\ can\ be\ used\ to\ draw\ on\ this\ component.\n
+numComments=4

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/ImagePanel.java

@@ -0,0 +1,89 @@
+import java.awt.*;
+import javax.swing.*;
+import java.awt.image.*;
+
+/**
+ * An ImagePanel is a Swing component that can display an OFImage.
+ * It is constructed as a subclass of JComponent with the added functionality
+ * of setting an OFImage that will be displayed on the surface of this
+ * component.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class ImagePanel extends JComponent
+{
+    // The current width and height of this panel
+    private int width, height;
+
+    // An internal image buffer that is used for painting. For
+    // actual display, this image buffer is then copied to screen.
+    private OFImage panelImage;
+
+    /**
+     * Create a new, empty ImagePanel.
+     */
+    public ImagePanel()
+    {
+        width = 360;    // arbitrary size for empty panel
+        height = 240;
+        panelImage = null;
+    }
+
+    /**
+     * Set the image that this panel should show.
+     * 
+     * @param image  The image to be displayed.
+     */
+    public void setImage(OFImage image)
+    {
+        if(image != null) {
+            width = image.getWidth();
+            height = image.getHeight();
+            panelImage = image;
+            repaint();
+        }
+    }
+    
+    /**
+     * Clear the image on this panel.
+     */
+    public void clearImage()
+    {
+        Graphics imageGraphics = panelImage.getGraphics();
+        imageGraphics.setColor(Color.LIGHT_GRAY);
+        imageGraphics.fillRect(0, 0, width, height);
+        repaint();
+    }
+    
+    // The following methods are redefinitions of methods
+    // inherited from superclasses.
+    
+    /**
+     * Tell the layout manager how big we would like to be.
+     * (This method gets called by layout managers for placing
+     * the components.)
+     * 
+     * @return The preferred dimension for this component.
+     */
+    public Dimension getPreferredSize()
+    {
+        return new Dimension(width, height);
+    }
+    
+    /**
+     * This component needs to be redisplayed. Copy the internal image 
+     * to screen. (This method gets called by the Swing screen painter 
+     * every time it want this component displayed.)
+     * 
+     * @param g The graphics context that can be used to draw on this component.
+     */
+    public void paintComponent(Graphics g)
+    {
+        Dimension size = getSize();
+        g.clearRect(0, 0, size.width, size.height);
+        if(panelImage != null) {
+            g.drawImage(panelImage, 0, 0, null);
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/ImageViewer.ctxt

@@ -0,0 +1,35 @@
+#BlueJ class context
+comment0.params=
+comment0.target=ImageViewer()
+comment0.text=\n\ Create\ an\ ImageViewer\ show\ it\ on\ screen.\n
+comment1.params=
+comment1.target=void\ openFile()
+comment1.text=\n\ Open\ function\:\ open\ a\ file\ chooser\ to\ select\ a\ new\ image\ file.\n
+comment10.params=frame
+comment10.target=void\ makeMenuBar(javax.swing.JFrame)
+comment10.text=\n\ Create\ the\ main\ frame's\ menu\ bar.\n\ @param\ frame\ \ \ The\ frame\ that\ the\ menu\ bar\ should\ be\ added\ to.\n
+comment2.params=
+comment2.target=void\ close()
+comment2.text=\n\ Close\ function\:\ close\ the\ current\ image.\n
+comment3.params=
+comment3.target=void\ quit()
+comment3.text=\n\ Quit\ function\:\ quit\ the\ application.\n
+comment4.params=filter
+comment4.target=void\ applyFilter(Filter)
+comment4.text=\n\ Apply\ a\ given\ filter\ to\ the\ current\ image.\n\ @param\ filter\ The\ filter\ to\ be\ applied.\n
+comment5.params=
+comment5.target=void\ showAbout()
+comment5.text=\n\ Show\ the\ 'About...'\ dialog.\n
+comment6.params=filename
+comment6.target=void\ showFilename(java.lang.String)
+comment6.text=\n\ Display\ a\ file\ name\ on\ the\ appropriate\ label.\n\ @param\ filename\ The\ file\ name\ to\ be\ displayed.\n
+comment7.params=text
+comment7.target=void\ showStatus(java.lang.String)
+comment7.text=\n\ Display\ a\ status\ message\ in\ the\ frame's\ status\ bar.\n
+comment8.params=
+comment8.target=java.util.List\ createFilters()
+comment8.text=\n\ Create\ and\ return\ a\ list\ with\ all\ the\ known\ filters.\n\ @return\ The\ list\ of\ filters.\n
+comment9.params=
+comment9.target=void\ makeFrame()
+comment9.text=\n\ Create\ the\ Swing\ frame\ and\ its\ content.\n
+numComments=11

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/ImageViewer.java

@@ -0,0 +1,248 @@
+import java.awt.*;
+import java.awt.event.*;
+import java.awt.image.*;
+import javax.swing.*;
+
+import java.io.File;
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Iterator;
+
+/**
+ * ImageViewer is the main class of the image viewer application. It builds and
+ * displays the application GUI and initialises all other components.
+ * 
+ * To start the application, create an object of this class.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 2.0
+ */
+public class ImageViewer
+{
+    // static fields:
+    private static final String VERSION = "Version 2.0";
+    private static JFileChooser fileChooser = new JFileChooser(System.getProperty("user.dir"));
+
+    // fields:
+    private JFrame frame;
+    private ImagePanel imagePanel;
+    private JLabel filenameLabel;
+    private JLabel statusLabel;
+    private OFImage currentImage;
+    
+    private List<Filter> filters;
+    
+    /**
+     * Create an ImageViewer show it on screen.
+     */
+    public ImageViewer()
+    {
+        currentImage = null;
+        filters = createFilters();
+        makeFrame();
+    }
+
+
+    // ---- implementation of menu functions ----
+    
+    /**
+     * Open function: open a file chooser to select a new image file.
+     */
+    private void openFile()
+    {
+        int returnVal = fileChooser.showOpenDialog(frame);
+
+        if(returnVal != JFileChooser.APPROVE_OPTION) {
+            return;  // cancelled
+        }
+        File selectedFile = fileChooser.getSelectedFile();
+        currentImage = ImageFileManager.loadImage(selectedFile);
+
+        if(currentImage == null) {   // image file was not a valid image
+            JOptionPane.showMessageDialog(frame,
+                    "The file was not in a recognized image file format.",
+                    "Image Load Error",
+                    JOptionPane.ERROR_MESSAGE);
+            return;
+        }
+        
+        imagePanel.setImage(currentImage);
+        showFilename(selectedFile.getPath());
+        showStatus("File loaded.");
+        frame.pack();
+    }
+    
+    /**
+     * Close function: close the current image.
+     */
+    private void close()
+    {
+        currentImage = null;
+        imagePanel.clearImage();
+        showFilename(null);
+    }
+    
+    /**
+     * Quit function: quit the application.
+     */
+    private void quit()
+    {
+        System.exit(0);
+    }
+    
+    
+    /**
+     * Apply a given filter to the current image.
+     * @param filter The filter to be applied.
+     */
+    private void applyFilter(Filter filter)
+    {
+        if(currentImage != null) {
+            filter.apply(currentImage);
+            frame.repaint();
+            showStatus("Applied: " + filter.getName());
+        }
+        else {
+            showStatus("No image loaded.");
+        }
+    }
+    
+    /**
+     * Show the 'About...' dialog.
+     */
+    private void showAbout()
+    {
+        JOptionPane.showMessageDialog(frame, 
+                    "ImageViewer\n" + VERSION,
+                    "About ImageViewer", 
+                    JOptionPane.INFORMATION_MESSAGE);
+    }
+    
+    
+    // ---- support methods ----
+
+    /**
+     * Display a file name on the appropriate label.
+     * @param filename The file name to be displayed.
+     */
+    private void showFilename(String filename)
+    {
+        if(filename == null) {
+            filenameLabel.setText("No file displayed.");
+        }
+        else {
+            filenameLabel.setText("File: " + filename);
+        }
+    }
+    
+    /**
+     * Display a status message in the frame's status bar.
+     */
+    private void showStatus(String text)
+    {
+        statusLabel.setText(text);
+    }
+    
+    /**
+     * Create and return a list with all the known filters.
+     * @return The list of filters.
+     */
+    private List<Filter> createFilters()
+    {
+        List<Filter> filterList = new ArrayList<>();
+        filterList.add(new DarkerFilter("Darker"));
+        filterList.add(new LighterFilter("Lighter"));
+        filterList.add(new ThresholdFilter("Threshold"));
+        
+        return filterList;
+    }
+    
+    // ---- swing stuff to build the frame and all its components ----
+    
+    /**
+     * Create the Swing frame and its content.
+     */
+    private void makeFrame()
+    {
+        frame = new JFrame("ImageViewer");
+        Container contentPane = frame.getContentPane();
+        
+        makeMenuBar(frame);
+        
+        // Specify the layout manager with nice spacing
+        contentPane.setLayout(new BorderLayout(6, 6));
+        
+        filenameLabel = new JLabel();
+        contentPane.add(filenameLabel, BorderLayout.NORTH);
+
+        imagePanel = new ImagePanel();
+        contentPane.add(imagePanel, BorderLayout.CENTER);
+
+        statusLabel = new JLabel(VERSION);
+        contentPane.add(statusLabel, BorderLayout.SOUTH);
+        
+        // building is done - arrange the components and show        
+        showFilename(null);
+        frame.pack();
+        
+        // center the frame on screen
+        Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
+        frame.setLocation(d.width/2 - frame.getWidth()/2, d.height/2 - frame.getHeight()/2);
+        frame.setVisible(true);
+    }
+    
+    /**
+     * Create the main frame's menu bar.
+     * @param frame   The frame that the menu bar should be added to.
+     */
+    private void makeMenuBar(JFrame frame)
+    {
+        final int SHORTCUT_MASK = Toolkit.getDefaultToolkit().getMenuShortcutKeyMask();
+
+        JMenuBar menubar = new JMenuBar();
+        frame.setJMenuBar(menubar);
+        
+        JMenu menu;
+        JMenuItem item;
+        
+        // create the File menu
+        menu = new JMenu("File");
+        menubar.add(menu);
+        
+        item = new JMenuItem("Open");
+            item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O, SHORTCUT_MASK));
+            item.addActionListener(e -> openFile());
+        menu.add(item);
+
+        item = new JMenuItem("Close");
+            item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_W, SHORTCUT_MASK));
+            item.addActionListener(e -> close());
+        menu.add(item);
+        menu.addSeparator();
+        
+        item = new JMenuItem("Quit");
+            item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK));
+            item.addActionListener(e -> quit());
+        menu.add(item);
+
+
+        // create the Filter menu
+        menu = new JMenu("Filter");
+        menubar.add(menu);
+        
+        for(Filter filter : filters) {
+            item = new JMenuItem(filter.getName());
+            item.addActionListener(e -> applyFilter(filter));
+            menu.add(item);
+        }
+
+        // create the Help menu
+        menu = new JMenu("Help");
+        menubar.add(menu);
+        
+        item = new JMenuItem("About ImageViewer...");
+            item.addActionListener(e -> showAbout());
+        menu.add(item);
+
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/LighterFilter.ctxt

@@ -0,0 +1,5 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=LighterFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ LighterFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/LighterFilter.java

@@ -0,0 +1,34 @@
+/**
+ * An image filter to make the image a bit lighter.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class LighterFilter extends Filter
+{
+	/**
+	 * Constructor for objects of class LighterFilter.
+     * @param name The name of the filter.
+	 */
+	public LighterFilter(String name)
+    {
+        super(name);
+	}
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                image.setPixel(x, y, image.getPixel(x, y).brighter());
+            }
+        }
+    }
+
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/OFImage.ctxt

@@ -0,0 +1,14 @@
+#BlueJ class context
+comment0.params=image
+comment0.target=OFImage(java.awt.image.BufferedImage)
+comment0.text=\n\ Create\ an\ OFImage\ copied\ from\ a\ BufferedImage.\n\ @param\ image\ The\ image\ to\ copy.\n
+comment1.params=width\ height
+comment1.target=OFImage(int,\ int)
+comment1.text=\n\ Create\ an\ OFImage\ with\ specified\ size\ and\ unspecified\ content.\n\ @param\ width\ The\ width\ of\ the\ image.\n\ @param\ height\ The\ height\ of\ the\ image.\n
+comment2.params=x\ y\ col
+comment2.target=void\ setPixel(int,\ int,\ java.awt.Color)
+comment2.text=\n\ Set\ a\ given\ pixel\ of\ this\ image\ to\ a\ specified\ color.\ The\n\ color\ is\ represented\ as\ an\ (r,g,b)\ value.\n\ @param\ x\ The\ x\ position\ of\ the\ pixel.\n\ @param\ y\ The\ y\ position\ of\ the\ pixel.\n\ @param\ col\ The\ color\ of\ the\ pixel.\n
+comment3.params=x\ y
+comment3.target=java.awt.Color\ getPixel(int,\ int)
+comment3.text=\n\ Get\ the\ color\ value\ at\ a\ specified\ pixel\ position.\n\ @param\ x\ The\ x\ position\ of\ the\ pixel.\n\ @param\ y\ The\ y\ position\ of\ the\ pixel.\n\ @return\ The\ color\ of\ the\ pixel\ at\ the\ given\ position.\n
+numComments=4

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/OFImage.java

@@ -0,0 +1,57 @@
+import java.awt.*;
+import java.awt.image.*;
+import javax.swing.*;
+
+/**
+ * OFImage is a class that defines an image in OF (Objects First) format.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 2.0
+ */
+public class OFImage extends BufferedImage
+{
+    /**
+     * Create an OFImage copied from a BufferedImage.
+     * @param image The image to copy.
+     */
+    public OFImage(BufferedImage image)
+    {
+         super(image.getColorModel(), image.copyData(null), 
+               image.isAlphaPremultiplied(), null);
+    }
+
+    /**
+     * Create an OFImage with specified size and unspecified content.
+     * @param width The width of the image.
+     * @param height The height of the image.
+     */
+    public OFImage(int width, int height)
+    {
+        super(width, height, TYPE_INT_RGB);
+    }
+
+    /**
+     * Set a given pixel of this image to a specified color. The
+     * color is represented as an (r,g,b) value.
+     * @param x The x position of the pixel.
+     * @param y The y position of the pixel.
+     * @param col The color of the pixel.
+     */
+    public void setPixel(int x, int y, Color col)
+    {
+        int pixel = col.getRGB();
+        setRGB(x, y, pixel);
+    }
+    
+    /**
+     * Get the color value at a specified pixel position.
+     * @param x The x position of the pixel.
+     * @param y The y position of the pixel.
+     * @return The color of the pixel at the given position.
+     */
+    public Color getPixel(int x, int y)
+    {
+        int pixel = getRGB(x, y);
+        return new Color(pixel);
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/README.TXT

@@ -0,0 +1,16 @@
+Project: imageviewer, version 2.0
+Authors: David Barnes and Michael Kölling
+
+This project is part of the material for the book
+
+   Objects First with Java - A Practical Introduction using BlueJ
+   Sixth edition
+   David J. Barnes and Michael Kölling
+   Pearson Education, 2016
+
+It is discussed in chapter 13.
+
+To use this project, create an instance of class ImageViewer.
+This version refactors some of the code to improve its structure.
+
+For details, refer to the book chapter.

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/ThresholdFilter.ctxt

@@ -0,0 +1,5 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=ThresholdFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ ThresholdFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/ThresholdFilter.java

@@ -0,0 +1,45 @@
+import java.awt.Color;
+
+/**
+ * An three-level gray-based threshold filter.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class ThresholdFilter extends Filter
+{
+	/**
+	 * Constructor for objects of class ThresholdFilter.
+     * @param name The name of the filter.
+	 */
+	public ThresholdFilter(String name)
+    {
+        super(name);
+	}
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                Color pixel = image.getPixel(x, y);
+                int brightness = (pixel.getRed() + pixel.getBlue() + pixel.getGreen()) / 3;
+                if(brightness <= 85) {
+                    image.setPixel(x, y, Color.BLACK);
+                }
+                else if(brightness <= 170) {
+                    image.setPixel(x, y, Color.GRAY);
+                }
+                else {
+                    image.setPixel(x, y, Color.WHITE);
+                }
+            }
+        }
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer2-0/package.bluej

@@ -0,0 +1,159 @@
+#BlueJ package file
+dependency1.from=Filter
+dependency1.to=OFImage
+dependency1.type=UsesDependency
+dependency10.from=DarkerFilter
+dependency10.to=OFImage
+dependency10.type=UsesDependency
+dependency11.from=ImageFileManager
+dependency11.to=OFImage
+dependency11.type=UsesDependency
+dependency12.from=ThresholdFilter
+dependency12.to=OFImage
+dependency12.type=UsesDependency
+dependency13.from=ImagePanel
+dependency13.to=OFImage
+dependency13.type=UsesDependency
+dependency2.from=ImageViewer
+dependency2.to=ImagePanel
+dependency2.type=UsesDependency
+dependency3.from=ImageViewer
+dependency3.to=OFImage
+dependency3.type=UsesDependency
+dependency4.from=ImageViewer
+dependency4.to=ImageFileManager
+dependency4.type=UsesDependency
+dependency5.from=ImageViewer
+dependency5.to=Filter
+dependency5.type=UsesDependency
+dependency6.from=ImageViewer
+dependency6.to=DarkerFilter
+dependency6.type=UsesDependency
+dependency7.from=ImageViewer
+dependency7.to=LighterFilter
+dependency7.type=UsesDependency
+dependency8.from=ImageViewer
+dependency8.to=ThresholdFilter
+dependency8.type=UsesDependency
+dependency9.from=LighterFilter
+dependency9.to=OFImage
+dependency9.type=UsesDependency
+objectbench.height=76
+objectbench.width=948
+package.editor.height=514
+package.editor.width=840
+package.editor.x=70
+package.editor.y=80
+package.numDependencies=13
+package.numTargets=8
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+readme.editor.height=560
+readme.editor.width=828
+readme.editor.x=53
+readme.editor.y=23
+target1.editor.height=734
+target1.editor.width=935
+target1.editor.x=50
+target1.editor.y=60
+target1.height=60
+target1.name=ThresholdFilter
+target1.naviview.expanded=true
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=110
+target1.x=690
+target1.y=290
+target2.editor.height=728
+target2.editor.width=880
+target2.editor.x=50
+target2.editor.y=60
+target2.height=60
+target2.name=LighterFilter
+target2.naviview.expanded=true
+target2.showInterface=false
+target2.type=ClassTarget
+target2.typeParameters=
+target2.width=100
+target2.x=570
+target2.y=290
+target3.editor.height=700
+target3.editor.width=900
+target3.editor.x=0
+target3.editor.y=22
+target3.height=60
+target3.name=OFImage
+target3.naviview.expanded=true
+target3.showInterface=false
+target3.type=ClassTarget
+target3.typeParameters=
+target3.width=110
+target3.x=90
+target3.y=420
+target4.editor.height=728
+target4.editor.width=856
+target4.editor.x=317
+target4.editor.y=35
+target4.height=60
+target4.name=Filter
+target4.naviview.expanded=true
+target4.showInterface=false
+target4.type=AbstractTarget
+target4.typeParameters=
+target4.width=100
+target4.x=570
+target4.y=180
+target5.editor.height=726
+target5.editor.width=851
+target5.editor.x=327
+target5.editor.y=36
+target5.height=60
+target5.name=DarkerFilter
+target5.naviview.expanded=true
+target5.showInterface=false
+target5.type=ClassTarget
+target5.typeParameters=
+target5.width=100
+target5.x=450
+target5.y=290
+target6.editor.height=732
+target6.editor.width=926
+target6.editor.x=50
+target6.editor.y=60
+target6.height=60
+target6.name=ImageFileManager
+target6.naviview.expanded=true
+target6.showInterface=false
+target6.type=ClassTarget
+target6.typeParameters=
+target6.width=140
+target6.x=60
+target6.y=130
+target7.editor.height=739
+target7.editor.width=875
+target7.editor.x=41
+target7.editor.y=23
+target7.height=60
+target7.name=ImageViewer
+target7.naviview.expanded=true
+target7.showInterface=false
+target7.type=ClassTarget
+target7.typeParameters=
+target7.width=110
+target7.x=240
+target7.y=40
+target8.editor.height=726
+target8.editor.width=879
+target8.editor.x=50
+target8.editor.y=60
+target8.height=60
+target8.name=ImagePanel
+target8.naviview.expanded=true
+target8.showInterface=false
+target8.type=ClassTarget
+target8.typeParameters=
+target8.width=140
+target8.x=60
+target8.y=210

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer3-0/DarkerFilter.ctxt

@@ -0,0 +1,5 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=DarkerFilter(java.lang.String)
+comment0.text=\n\ Constructor\ for\ objects\ of\ class\ DarkerFilter.\n\ @param\ name\ The\ name\ of\ the\ filter.\n
+numComments=1

Semester 1/Programming 1/Java/examples/projects/chapter13/imageviewer3-0/DarkerFilter.java

@@ -0,0 +1,33 @@
+/**
+ * An image filter to make the image a bit darker.
+ * 
+ * @author Michael Kölling and David J. Barnes.
+ * @version 1.0
+ */
+public class DarkerFilter extends Filter
+{
+    /**
+     * Constructor for objects of class DarkerFilter.
+     * @param name The name of the filter.
+     */
+    public DarkerFilter(String name)
+    {
+        super(name);
+    }
+
+    /**
+     * Apply this filter to an image.
+     * 
+     * @param  image  The image to be changed by this filter.
+     */
+    public void apply(OFImage image)
+    {
+        int height = image.getHeight();
+        int width = image.getWidth();
+        for(int y = 0; y < height; y++) {
+            for(int x = 0; x < width; x++) {
+                image.setPixel(x, y, image.getPixel(x, y).darker());
+            }
+        }
+    }
+}