import java.applet.Applet;
import java.awt.*;
import java.util.*;

public class mandelbrot extends Applet
{
	int Ybordersize = 30, accuracy;
	double xrange, yrange, xoffset, yoffset;
	int Xwindowsize, Ywindowsize;
	int Xdrawsize, Ydrawsize, dragx, dragy;
	static int x1, y1, x2, y2;
	String raise_accuracy_text = "Accuracy X2", reset_button_text = "Reset";
	String constrain_ratio_text = "Maintain Aspect Ratio";
	boolean constrain_ratio = true;
	Checkbox constrain_checkbox;
	boolean mouseReleased = true;

	public void init(){
		Button increase_accuracy, reset;
		reset = new Button (reset_button_text);
		increase_accuracy = new Button (raise_accuracy_text);
		constrain_checkbox = new Checkbox (constrain_ratio_text, null, true);

		/**
		Later use object.reshape(x, y, xsize, ysize);
		**/
		add(reset);
		add(increase_accuracy);
		add(constrain_checkbox);

		initialize_values();

		Xwindowsize = size().width;
		Ywindowsize = size().height;
		Xdrawsize = Xwindowsize;
		Ydrawsize = Ywindowsize - Ybordersize;
	}

	public void initialize_values()
	{
		accuracy = 256;
		xrange = 4;
		yrange = 4;
		xoffset = -2;
		yoffset = -2;
	}

	public void paint(Graphics g){
		if(!mouseReleased){
/*
			if(constrain_ratio){
				if(dragx - x1 > dragy - y1){
					g.drawRect(x1, y1 + Ybordersize, dragx - x1, y1 + (dragx - x1) - Ybordersize);
				}else{
					g.drawRect(x1, y1 + Ybordersize, x1 + (dragy - y1), dragy - y1 - Ybordersize);
				}
			}else
*/
				g.drawRect(x1, y1 + Ybordersize, dragx - x1, dragy - y1 - Ybordersize);
		}else{
			render_image(g);
		}
	}

	public void update(Graphics g)
	{
		if(mouseReleased)
			render_image(g);
		else{
			g.drawRect(x1, y1 + Ybordersize, dragx - x1, dragy - y1 - Ybordersize);
		}
		//g.drawLine(x1, y1, dragx, dragy);
	}

	public boolean mouseDrag(Event evt, int x, int y){
		dragx = x - 1;
		dragy = y - 2;
		repaint();
		return true;
	}

	public boolean mouseDown (Event evt, int x, int y)
	{
		mouseReleased = false;
		x1 = x - 1;
		y1 = y - 2 - Ybordersize;
		return (true);
	}

	public boolean mouseUp (Event evt, int x, int y)
	{
		int deltax, deltay;
		mouseReleased = true;
		x2 = x;
		y2 = y - Ybordersize;
		if(x2 < x1){ x2 ^= x1; x1 ^= x2; x2 ^= x1; }
		if(y2 < y1){ y2 ^= y1; y1 ^= y2; y2 ^= y1; }

		if(constrain_ratio){
			deltax = x2 - x1;
			deltay = y2 - y1;
			if(deltax > deltay)
				y2 = y1 + deltax;
			else if(deltay > deltax)
				x2 = x1 + deltay;
		}

		if(x2 - x1 != 0 && y2 - y1 != 0){
			xoffset += xrange * (double)x1 / (double)Xdrawsize;
			yoffset += yrange * (double)y1 / (double)Ydrawsize;
			xrange *= (double)(x2 - x1) / (double)Xdrawsize;
			yrange *= (double)(y2 - y1) / (double)Ydrawsize;
			repaint();
		}
		
		return (true);
	}

	private void render_image(Graphics g){
		int x, y;
		Color c;

		for(x = 0; x < Xdrawsize; x++){
			for(y = 0; y < Ydrawsize; y++){
				c = calc_colour(x, y);
				g.setColor(c);
				g.drawLine(x, y + Ybordersize, x, y + Ybordersize);
			}
		}
	}

	private Color calc_colour(int x, int y){
		Color returnval;
		double c = (xrange / (double)Xdrawsize) * (double)x + (double)xoffset;
		double ci = (yrange / (double)Ydrawsize) * (double)y + (double)yoffset;
		int count = 0;
		double z = 0, zi = 0, zsq = 0;
		double zisq = 0, nz = 0, nzi = 0;

		while((count <= accuracy) && ((zsq + zisq) < 4.)){
			nz = zsq - zisq;
			nzi = (z * zi) * 2.;
			z = nz + c;
			zi = nzi + ci;
			zsq = z * z;
			zisq = zi * zi;
			count++;
		}

		if(count > accuracy)
			returnval = new Color(0, 0, 0);
		else
			returnval = new Color(
				128 - (int)(128. * Math.sin((float)count / 20.)),
				128 - (int)(128. * Math.cos((float)count / 20.)),
				128 + (int)(128. * Math.sin((float)count / 20.))
			);
		return returnval;
	}

	public boolean handleEvent(Event evt)
	{
		Rectangle rect;
		rect = constrain_checkbox.bounds();

		if((evt.id == Event.ACTION_EVENT) && (evt.arg == raise_accuracy_text)){
			accuracy *= 2;
			repaint();
		}else if((evt.id == Event.ACTION_EVENT) && (evt.arg == reset_button_text)){
			initialize_values();
			repaint();
		}else if((evt.id == Event.ACTION_EVENT) && (evt.x == rect.x) && (evt.y == rect.y)){
			constrain_ratio = !constrain_ratio;
		}

		return super.handleEvent(evt);
	}

}