public class C extends Applet implements MouseListener, MouseMotionListener
{
private final int MAX = 256;
private final double SX = -1.0; // 实部的最小值
private final double SY = -1.5; // 虚部的最小值
private final double EX = 2.0; // 实部的最大值
private final double EY = 1.5; // 虚部的最大值
private static int picX, picY, xs, ys, xe, ye;
private static double x1, y1, x2, y2, p, q,xb,yb;
private static boolean action, rechteck, fertig, stopit;
private static float xy;
private Image bild;
private Graphics g1;
private Cursor c1, c2;
public void init() // 初始化所有实例
{
p = -0.46;
q = 0.57;

fertig = false;
addMouseListener(this);
addMouseMotionListener(this);
c1 = new Cursor(Cursor.WAIT_CURSOR);
c2 = new Cursor(Cursor.CROSSHAIR_CURSOR);
picX = getSize().width;
picY = getSize().height;
xy = (float)picX / (float)picY;
bild = createImage(picX, picY);
g1 = bild.getGraphics();
fertig = true;
}
public void destroy() // 删除所有实例
{
if (fertig)
{
removeMouseListener(this);
removeMouseMotionListener(this);
bild = null;
g1 = null;
c1 = null;
c2 = null;
System.gc();
}
}
public void start()
{
action = false;
rechteck = false;
stopit = false;
startwerte();
xb = (x2 - x1) / (double)picX;
yb = (y2 - y1) / (double)picY;

julia();
}
public void stop()
{
}

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

public void update(Graphics g)
{
g.drawImage(bild, 0, 0, this);
if (rechteck)
{
g.setColor(Color.white);
if (xs < xe)
{
if (ys < ye) g.drawRect(xs, ys, (xe - xs), (ye - ys));
else g.drawRect(xs, ye, (xe - xs), (ys - ye));
}
else
{
if (ys < ye) g.drawRect(xe, ys, (xs - xe), (ye - ys));
else g.drawRect(xe, ye, (xs - xe), (ys - ye));
}
}
}

private void julia() // 计算所有的点
{
int x, y;
float h, b, alt = 0.0f;

action = false;
setCursor(c1);
showStatus("正在计算julia集，请等待...");
p = -0.46;
q = 0.57;
for (x = 0; x < picX; x+=2) {
for (y = 0; y < picY; y++)
{
h = punktfarbe(x1 + xb * (double)x, y1 + yb * (double)y,p,q); // 颜色值
if (h != alt)
{
b = 1.0f - h * h;
g1.setColor(Color.getHSBColor( h,1,b));

alt = h;
}
g1.drawLine(x, y, x + 1, y);
}
showStatus( "At " + x + " of " + picX );
if (stopit) x = picX;
}

if (stopit) {
showStatus("Aborted");
stopit = false;
} else {
showStatus("julia集已准备好，请用鼠标选择放大区域.");
}
setCursor(c2);
action = true;
}
// 由迭代产生的0.0到1.0的颜色值
private float punktfarbe(double x0, double y0,double p,double q)
{
double r = 0.0, xk = 0, yk = 0;
int j = 0;

while ((j < MAX) && (r < 4.0))
{

xk = x0 * x0 - y0 * y0 + p;
yk = 2.0 * x0 * y0 + q;
j++;
r = yk * yk + xk * xk;
x0 = xk;
y0 = yk;

 

}
return (float)j / (float)MAX;
}

private void startwerte() // 重新开始值
{
x1 = SX;
y1 = SY;
x2 = EX;
y2 = EY;
if ((float)((x2 - x1) / (y2 - y1)) != xy )
x1 = x2 - (y2 - y1) * (double)xy;
}
public void mousePressed(MouseEvent e)
{
e.consume();
if (action)
{
xs = e.getX();
ys = e.getY();
}
}

public void mouseReleased(MouseEvent e)
{
int z, w;

e.consume();
if (action)
{
xe = e.getX();
ye = e.getY();
if (xs > xe)
{
z = xs;
xs = xe;
xe = z;
}
if (ys > ye)
{
z = ys;
ys = ye;
ye = z;
}
w = (xe - xs);
z = (ye - ys);
if ((w < 2) && (z < 2)) startwerte();
else
{
if (((float)w > (float)z * xy)) ye = (int)((float)ys + (float)w / xy);
else xe = (int)((float)xs + (float)z * xy);
x2 = x1 + xb* (double)xe;
y2 = y1 + yb * (double)ye;
x1 += xb * (double)xs;
y1 += yb * (double)ys;
}
xb = (x2 - x1) / (double)picX;
yb = (y2 - y1) / (double)picY;
julia();
rechteck = false;
repaint();
} else {
stopit = true;
}
}
public void mouseEntered(MouseEvent e)
{
}
public void mouseExited(MouseEvent e)
{
}
public void mouseClicked(MouseEvent e)
{
}

public void mouseDragged(MouseEvent e)
{
e.consume();
if (action)
{
xe = e.getX();
ye = e.getY();
rechteck = true;
repaint();
}
}

public void mouseMoved(MouseEvent e)
{
}

}