/*
 * SharkLine.java
 *	A java program to make a shark line, similar to <hr>, but with fin
 *	Usage:	<applet code="SharkLine.class" width=500 height=10>
 *		</applet>
 *
 * Ken Shirriff		ken.shirriff@eng.sun.com
 *
 */
import java.awt.*;
import java.awt.image.*;
import java.io.*;
import java.net.*;
import java.applet.Applet;

public class SharkLine extends java.applet.Applet implements Runnable {

	// Double buffer for output
	Image outimage;
	Graphics outgraphics;
	// Animation thread
	Thread sharkthread = null;
	// Parameters for the applet and fin sizes
	int width = 500;
	int delay = 60;
	int maxfinheight=5, offset=1;
	int height = 10;
	// pixels, image, color model, and colors for the line image
	int pix[];
	Image line_img;
	IndexColorModel icm;
	byte r[] = new byte[3];
	byte g[] = new byte[3];
	byte b[] = new byte[3];

	// Start up the applet
	public void init() {
		int i,j;
		if (getParameter("width") != null) {
			width = Integer.parseInt(getParameter("width"));
		}
		if (getParameter("height") != null) {
			height = Integer.parseInt(getParameter("height"));
		}
		if (getParameter("delay") != null) {
			delay = Integer.parseInt(getParameter("delay"));
		}

		// color 0 is the screen background
		r[0] = (byte) 192; g[0] = (byte) 192; b[0] = (byte) 192;
		// color 1 is the dark part of the line
		r[1] = (byte) 112; g[1] = (byte) 112; b[1] = (byte) 112;
		// color 2 is the light part of the line
		r[2] = (byte) 231; g[2] = (byte) 231; b[2] = (byte) 231;
		icm = new IndexColorModel(8,3,r,g,b);

		// Fill pix with the appropriate pixels for a shadowed line
		pix = new int[width*height];
		for (i=0;i<width;i++) {
			for (j=0;j<height-3;j++) {
				pix[j*width+i] = 0;
			}
		}
		pix[(height-2)*width] = 1;
		pix[(height-1)*width] = 1;
		for (i=1;i<width-1;i++) {
			pix[(height-2)*width+i] = 1;
			pix[(height-1)*width+i] = 2;
		}
		// Now make the pixels into an image
		line_img = createImage(new MemoryImageSource(width,
			height, icm, pix, 0, width));

		resize(width,height);
		outimage = createImage(width,height);
		outgraphics = outimage.getGraphics();
		outgraphics.setColor(Color.black); // Fin color
		//outgraphics.drawImage(line_img,0,0,this);

	}

	public void start() {
		// If we don't have a thread running, start one.
		if (sharkthread == null) {
			sharkthread = new Thread(this);
			sharkthread.start();
		}
	}

	// Stop the thread
	public void stop() {
		if (sharkthread != null) {
			sharkthread.stop();
		}
		sharkthread = null;
	}


	public void update(Graphics g) {
		paint(g);
	}

	public void paint(Graphics g) {
		// Put the double buffered image on the screen
		g.drawImage(outimage,0,0,this);
	}

	// This is the run thread that does the actual work
	// It's basically a loop of waiting for the shark to surface,
	// (while visiblefin is false)
	// and then a loop of moving the shark around (visiblefin true).
	public void run() {
		// x position of fin, height of fin, and turn count
		int x=1, finheight=0, cnt=0;
		// Controls for shark movement:
		// visiblefin true when fin is up
		// goingup, goingdown indicate the fin is ascending/descending
		// right is true if the fin is moving to the right
		boolean visiblefin=false, goingup=false, goingdown=false,
			right=false;
		while (sharkthread == Thread.currentThread()) {
			// Draw the current shark line image
			paint(this.getGraphics());
			// Reset the dubble buffered image to just the line
			outgraphics.drawImage(line_img,0,0,this);
			if (!visiblefin) {
				// Shark waiting underwater
				try {
					// Wait a few seconds
					sharkthread.sleep((int)(Math.random()*10000)+2000);
				} catch (InterruptedException e) { }
				// Shark appears at a random location
				x=(int)(Math.random()*width);
				finheight=0;
				// Shark will turn a random number of times
				cnt = (int)(Math.random()*8)+2;
				visiblefin = true;
				goingup = true;
				// Shark goes either right or left
				right = (Math.random()<.5);
			} else {
				// Shark swimming

				// Draw triangular fin
				for (int i=0;i<finheight;i++) {
					outgraphics.drawLine(x,height-offset-finheight+i,
					x+(right?i:-i),height-offset-finheight+i);
				}

				// Move to next location
				if (goingup) {
					// Fin moving up
					finheight++;
					if (finheight>=maxfinheight) {
						goingup=false;
					}
				} else if (goingdown) {
					// Fin going down
					finheight--;
					if (finheight<0) {
						goingdown=false;
						visiblefin = false;
					}
				}
				if (right) {
					// Fin moving to the right
					x++;
				} else {
					// Fin moving to the left
					x--;
				}
				// Turn at edge or randomly
				if (x>=width-10 || x<=10 || Math.random()<.03) {
					cnt--;
					if (cnt==0) {
						goingdown = true;
					} else {
						right = !right;
					}
				}
				// Animation delay
				try {
					sharkthread.sleep(delay);
				} catch (Exception e) { }
			}
		}
	}

	public String getAppletInfo() {
		return "SharkLine by Ken Shirriff  shirriff@eng.sun.com";
	}

	public String[][] getParameterInfo() {
		String [][] info = {
			{"width      ","int        ", "image width"},
			{"height     ","int        ", "image height"},
			{"delay      ","int        ", "delay"},
		};
		return info;

	}

} // SharkLine