Kaleidoscope

/*
 *     Kaleidoscope Ver 1.0
 *
 * Created by Tsutomu Ishikura <ishikura@tky.threewebnet.or.jp>
 *            1996 Mar 12
 *
 */

import java.awt.*;
import java.awt.image.*;
import java.net.URL;
import java.lang.Math;
import java.applet.Applet;
import java.util.StringTokenizer;

/* 
 * An applet that displays repeated triangular image like 
 * Kaleidoscope. the triangular image unit is randomly clipped 
 * from an image that is specified by URL.
 */

public class Kaleidoscope extends Applet implements Runnable {
    KaleidoscopeCanvas canvas;
    KaleidoscopeControl control;
    TriangleCreator triangleCreator;
    Label message;
    Thread kicker;

    public void init () {
	setLayout (new BorderLayout ());
	control = new KaleidoscopeControl (this);
	canvas = new KaleidoscopeCanvas (control.getCanvasSize ());
	message = new Label (" ");
	message.setAlignment (Label.CENTER);
	message.setForeground (Color.blue);
	add ("North", canvas);
	add ("Center", message);
	add ("South", control);
    }

    public void resetCreator () {
	triangleCreator = null;
    }
    
    void setNewTriangle () {
	if (triangleCreator == null) {
	    switch (control.getMethod ()) {
	    case 0:
	    default:
		triangleCreator = new Method0 (control, this);
		break;
	    }
	}
	if ((triangleCreator != null) && (triangleCreator.next ())) {
	    Image image = triangleCreator.getImage ();
	    canvas.setBaseTriangle (image, triangleCreator.getSize ());
	} else {
	    imageProcessError ();
	}
    }

    public void run () {
	displayMessage ("");
	Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
	while (true) {
	    try {
		setNewTriangle ();
		Thread.sleep (control.getUpdateInterval ());
	    }
	    catch (Exception ex) {
	    }
//	    System.err.println ("next");
	}
    }

    public void start() {
	if (kicker == null) {
	    kicker = new Thread(this);
	    kicker.start();
	}
    }

    public void stop() {
	if ((kicker != null) && (kicker.isAlive ())) {
	    kicker.stop();
	}
	kicker = null;
    }

    public void displayMessage (String s) {
	message.setText (s);
    }

    public void imageLoadError () {
	System.err.println ("image load error");
	showStatus ("image load error");
	displayMessage ("image load error");
	stop ();
    }
    
    public void imageProcessError () {
	System.err.println ("image convert error");
	showStatus ("image convert error");
	displayMessage ("image convert error");
	stop ();
    }
}

/*
 * This class is the heart of the kaleidoscope. 
 * it displays repeated images of a given triangle.
 */

class KaleidoscopeCanvas extends Canvas {

    final double SQRT3 = Math.sqrt (3);
    
    Dimension preferredSize;

    Image baseTriangle;
    int triangleWidth;
    int triangleHeight;

    Image repeatRectangle;
    int rectangleWidth;
    int rectangleHeight;
    
    Image imageBuff;

    public KaleidoscopeCanvas (Dimension size) {
	preferredSize = size;
    }
    
    public void setBaseTriangle (Image img, int width) {
	baseTriangle = img;
	triangleWidth = (width - 1) / 2 * 2 + 1; // force width to odd.
	triangleHeight = (int) (triangleWidth * SQRT3 / 2);
	createRepeatRectangle ();
    }

    void createRepeatRectangle () {
	int tw = triangleWidth;
	int th = triangleHeight;
	int rw = rectangleWidth = triangleWidth + (triangleWidth - 1 ) / 2;
	int rh = rectangleHeight = 2 * triangleHeight - 1;
	int trianglePixels[] = new int[tw * th];
	PixelGrabber pg = new PixelGrabber (baseTriangle, 0, 0, tw, th, trianglePixels, 0, tw);
	try {
	    pg.grabPixels ();
	} catch (Exception ex) {
	    System.err.println ("interrupted waiting for pixels");
	    return;
	}
	if ((pg.status () & ImageObserver.ABORT) != 0 ) {
	    System.err.println ("image fetch aborted or errored");
	    return;
	}
	int rectanglePixels[] = new int[rw * rh];
	int x, y, x2, y2, aw;
	aw = tw -1;
	for (y = 0; y < rh / 2 + 1; y++) {
	    for (x = 0; x < aw / 2; x++) {
		if (y > SQRT3 * x) {
		    x2 = (int)((-x + SQRT3 * y) / 2);
		    y2 = (int)((SQRT3 * x + y) / 2);
		} else {
		    x2 = x;
		    y2 = y;
		}
		rectanglePixels[x + rw * (rh - 1 - y)]
		    = rectanglePixels[x + rw * y] = trianglePixels[x2 + y2 * tw];
	    }
	    for (x = aw / 2; x < aw; x++) {
		if (y > (aw - x) * SQRT3) {
		    x2 = (int)((-x - SQRT3 * y + 3 * aw) / 2);
		    y2 = (int)((-SQRT3 * x + y + SQRT3 * aw) / 2);
		} else {
		    x2 = x;
		    y2 = y;
		}
		rectanglePixels[x + rw * (rh - 1 - y)]
		    = rectanglePixels[x + rw * y] = trianglePixels[x2 + y2 * tw];
	    }
	    for (x = aw; x < rw; x++) {
		if (y > (x - aw) * SQRT3) {
		    x2 = (int)((-x - SQRT3 * y + 3 * aw) / 2);
		    y2 = (int)((-SQRT3 * x + y + SQRT3 * aw) / 2);
		} else {
		    x2 = (int)((-x - SQRT3 * y + 3 * aw) / 2);
		    y2 = (int)((SQRT3 * x - y - SQRT3 * aw) / 2);
		}
		rectanglePixels[x + rw * (rh - 1 - y)]
		    = rectanglePixels[x + rw * y] = trianglePixels[x2 + y2 * tw];
	    }
	}
	repeatRectangle
	    = createImage (new MemoryImageSource (rw, rh, rectanglePixels, 0, rw));
	repaint ();
    }

    public void update (Graphics g) {
	paint (g);
    }
    
    public synchronized void paint (Graphics g) {
	int i,j;
	int h = size().height;
	int w = size().width;

	if (repeatRectangle != null) {
	    for (i = 0 ; i * (rectangleWidth - 1)< w ; i++ ) {
		if ((i % 2) == 0) {
		    j = 0;
		} else {
		    j = - rectangleHeight / 2;
		}
		for (; j < h ; j += rectangleHeight - 1) {
		    g.drawImage (repeatRectangle, i * (rectangleWidth - 1), j,
				 rectangleWidth, rectangleHeight, this);
		}
	    }
	}
    }

    public Dimension preferredSize () {
	return preferredSize;
    }
}

class KaleidoscopeControl extends Panel {
    Kaleidoscope applet;
    URL imageURL;
    String imageURLString;
    Dimension canvasSize;
    int triangleSize;
    int updateInterval;
    String imageFileList[];
    Choice imageSelector;
    TextField userImageURL;
    TextField updateIntervalText;
    TextField triangleSizeText;

    KaleidoscopeControl (Kaleidoscope applet0)
    {
	applet = applet0;
	initVariable ();
	Panel panel1 = new Panel ();
	Panel panel2 = new Panel ();
	Panel panel3 = new Panel ();
	panel1.add (new Button ("start"));
	panel1.add (new Button ("stop"));
	panel1.add (new Button ("restart"));
	panel1.add (new Label ("  update interval (ms):"));
	updateIntervalText = new TextField (Integer.toString (updateInterval));
	panel1.add (updateIntervalText);
	panel2.add (new Label ("select image:"));
	imageSelector = new Choice ();
	int i;
	for (i = 0 ; i < imageFileList.length ; i++) {
	    imageSelector.addItem (imageFileList [i]);
	}
	imageSelector.addItem ("From URL");
	panel2.add (imageSelector);
	panel2.add (new Label ("triangle size:"));
	triangleSizeText = new TextField (Integer.toString (triangleSize));
	panel2.add (triangleSizeText);
	panel3.add (new Label ("Image from URL:"));
	userImageURL = new TextField (imageURLString, 40);
	panel3.add (userImageURL);
	add (panel1);
	add (panel2);
	add (panel3);
    }

    void initVariable () {
	int canvasWidth, canvasHeight;
	try {
	    updateInterval 
		= Integer.valueOf (
		    applet.getParameter ("interval")).intValue ();
	} catch (Exception e) {
	    updateInterval = 1000;
	}
	try {
	    triangleSize
		= Integer.valueOf (
		    applet.getParameter ("trianglesize")).intValue ();
	} catch (Exception e) {
	    triangleSize = 76;
	}
	try {
	    imageURLString = applet.getParameter ("imageURL");
	} catch (Exception e) {
	    imageURLString = "";
	}
	try {
	    String files = applet.getParameter ("localfiles");
	    StringTokenizer t = new StringTokenizer (files);
	    imageFileList = new String[t.countTokens ()];
	    int i = 0;
	    for (i = 0 ; t.hasMoreTokens () ; i++) {
		imageFileList [i] = t.nextToken ();
	    }
	} catch (Exception e) {
	    String nullArray[] = {};
	    imageFileList = nullArray;
	}
	try {
	    canvasWidth
		= Integer.valueOf (
		    applet.getParameter ("canvaswidth")).intValue ();
	} catch (Exception e) {
	    canvasWidth = 400;
	}
	try {
	    canvasHeight
		= Integer.valueOf (
		    applet.getParameter ("canvasheight")).intValue ();
	} catch (Exception e) {
	    canvasHeight = 300;
	}
	canvasSize = new Dimension (canvasWidth, canvasHeight);
    }

    public boolean action (Event e, Object o) {
	if (e.target instanceof Button) {
	    if ("start".equals (o)) {
		applet.start ();
		return true;
	    } else if ("stop".equals (o)) {
		applet.stop ();
		return true;
	    } else if ("restart".equals (o)) {
		applet.stop ();
		applet.resetCreator ();
		applet.start ();
		return true;
	    }
	} else if (e.target instanceof Choice) {
		applet.stop ();
		applet.resetCreator ();
		applet.start ();
		return true;
	} else if (e.target instanceof TextField) {
	    if (e.target == updateIntervalText) {
		try {
		    updateInterval = Integer.valueOf ((String)o).intValue ();
		} catch (Exception ex) {
		    updateInterval = 1000;
		    updateIntervalText.setText (Integer.toString (updateInterval));
		}
	    } else if (e.target == triangleSizeText) {
		try {
		    triangleSize = Integer.valueOf ((String)o).intValue ();
		} catch (Exception ex) {
		    triangleSize = 0;
		}
		if (triangleSize < 10) {
		    triangleSize = 76;
		    triangleSizeText.setText (Integer.toString (triangleSize));
		}
		applet.stop ();
		applet.resetCreator ();
		applet.start ();
		return true;
	    } else if (e.target == userImageURL) {
		imageSelector.select("From URL");
		applet.stop ();
		applet.resetCreator ();
		applet.start ();
		return true;
	    }
	}
	return false;
    }

    public URL getImageURL () {
	String s = imageSelector.getSelectedItem ();
	if ("From URL".equals (s)){
	    s = userImageURL.getText ();
	    try {
		imageURL = new URL (s);
	    } catch (Exception ex) {
		System.err.println ("user URL is not valid");
		return null;
	    }
	} else {
	    try {
		imageURL = new URL (applet.getDocumentBase (), s);
	    } catch (Exception ex) {
		System.err.println ("filename " + s + " is not valid");
		return null;
	    }
	}
	return imageURL;
    }
    
    public Dimension getCanvasSize () {
	return canvasSize;
    }
    
    public int getUpdateInterval () {
	return updateInterval;
    }

    public int getTriangleSize () {
	return triangleSize;
    }

    public int getMethod () {
	return 0;
    }

    public Dimension preferredSize () {
	return new Dimension (400,130);
    }
}

/*
 * An abstract class that generates triangular images 
 * for KaleidoscopeCanvas.
 */

abstract class TriangleCreator extends Object {

    abstract public boolean next ();

    abstract public Image getImage ();

    abstract public int getSize ();
}

/*
 * This class clips triangular images from a given image.
 */

class Method0 extends TriangleCreator implements ImageObserver {
    Kaleidoscope applet;
    KaleidoscopeControl control;
    int x,y;
    int ox,oy;
    int iw,ih;
    int tw,th;
    Image triangleImage;
    Image image;
    int step;
    int interval;
    int counter;
    volatile boolean imageReadError;

    Method0 (KaleidoscopeControl control0, Kaleidoscope applet0) {
	applet = applet0;
	control = control0;
	init ();
    }
    
    synchronized void init () {
	tw = control.getTriangleSize ();
        th = (int) (Math.sqrt(3) * tw / 2);
	try {
	    image = applet.getImage (control.getImageURL ());
	} catch (Exception e) {
	    applet.imageLoadError ();
	    return;
	}
	if (image == null) { 
	    applet.imageLoadError ();
	    return;
	}
	imageReadError = false;
	while (((iw = image.getWidth (this)) < 0) && !imageReadError) {
	    try {
		wait ();
	    } catch (InterruptedException ex) {
	    }
	}
	if (imageReadError) {
	    applet.imageLoadError ();
	    return;
	}
	ih = image.getHeight (this);
	if ((ih < th - 10) || (iw < tw - 10)) {
	    applet.imageProcessError ();
	    return;
	}
	x = (int) (((Math.random() - 0.5) * 0.6 + 0.5)*(iw - tw));
	y = (int) (((Math.random() - 0.5) * 0.6 + 0.5)*(ih - th));

	interval = 10;
	counter = 0;
	step = 5;
	do {
	    ox = (int)((Math.random () - 0.5) * 2 * step);
	    oy = (int)((Math.random () - 0.5) * 2 * step);
	} while ((ox == 0) && (oy == 0));
    }
    
    public synchronized boolean imageUpdate (Image img, int infoFlags,
					     int x, int y,
					     int width, int height) {
        if ((infoFlags & ERROR) != 0) {
	    imageReadError = true;
	}
	notifyAll ();
	return true;
    }

    public boolean next () {
	if (counter++ >= interval) {
	    counter = 0;
	    do {
		ox = (int)((Math.random () - 0.5) * 2 * step);
		oy = (int)((Math.random () - 0.5) * 2 * step);
	    } while ((ox == 0) && (oy == 0));
	}
	x += ox;
	y += oy;
	if ((x < 0) || (x + tw >= iw -1) || (y < 0) || (y + th >= ih - 1)) {
	    ox = -ox;
	    oy = -oy;
	    x += 2 * ox;
	    y += 2 * oy;
	}
	triangleImage
	    = applet.createImage (new FilteredImageSource 
				  (image.getSource (),
				   new CropImageFilter(x, y, tw, th)));
	return (triangleImage != null);
    }
    
    public Image getImage () {
	return triangleImage;
    }
    
    public int getSize () {
	return tw;
    }
}

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