import java.lang.Thread;

public class Mandelbrot extends Thread {
    public Mandelbrot(int width, int height, 
                      double left, double right, 
                      double top, double bottom) {
        setSize(width, height);
        setBoundaries(left, right, top, bottom);
        setMaxIterations(10000);
    }
    
    public void run() {
        while (true) {
            if (_recalculate) {
                calculate();
                _recalculate = false;
            }
        }
    }
    
    public void setBoundaries(double left, double right, 
                              double top, double bottom) {
        // Which bit of the set to view.
        _left = left;
        _right = right;
        _top = top;
        _bottom = bottom;
        _recalculate = true;
    }
    
    public void setSize(int width, int height) {
        // Size of our view (zoom).
        _width = width;
        _height = height;
        _set = new int[width][height];
        _recalculate = true;
    }
    
    public void setMaxIterations(int n) {
        _iterations = n;
        _recalculate = true;
    }
    
    public int getMaxIterations() {
        return _iterations;
    }
    
    public int value(int x, int y) {
        return _set[x][y];
    }
    
    private void calculate() {
        for (int x = 0; x < _width; x++) {
            for (int y = 0; y < _height; y++) {
                double zr = 0.0, zi = 0.0;
                double cr = _left + x * (_right - _left) / _width;
                double ci = _top + y * (_bottom - _top) / _height;
                
                double zrsq = zr * zr;
                double zisq = zi * zi;
                
                for (_set[x][y] = 0; (zrsq + zisq <= 4.0) 
                        && (_set[x][y] < _iterations); _set[x][y]++) {
                    zr = zrsq - zisq + cr;
                    zi = 2 * zr * zi + ci;
                    zrsq = zr * zr;
                    zisq = zi * zi;
                }
            }
        }
    }
    
    private int[][] _set;
    private boolean _recalculate;
    
    private double _left;
    private double _right;
    private double _top;
    private double _bottom;
    private int _width;
    private int _height;
    private int _iterations;
}