[問題]如何設定圖形移動的邊界?

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請問各位大大
要如何讓圖形的移動範圍限制在，設定的框框內呢？
以下的程式碼是小弟目前的進度，請指教一下..........謝謝!!
import java.awt.event.*;
import java.applet.*;
import java.awt.*;

public class B9003070 extends Applet implements MouseListener, MouseMotionListener
{
int mx, my, onaroll;
int ix, iy;
Image ti;

public void init()
{
onaroll = 0;
setSize(500, 500);
addMouseListener(this);
addMouseMotionListener(this);
ti=getImage(getDocumentBase(),"tigi.gif");
}

public void destroy()
{
removeMouseListener(this);
removeMouseMotionListener(this);
}

public void paint(Graphics g)
{
ix=mx;
iy=my;
g.drawImage(ti,ix,iy,this);
g.setColor(Color.blue);
g.drawRect(10,10,410,410);
g.setColor(Color.green);
g.drawString("X="+mx+" Y="+my,25,30);
}

public void mouseDragged(MouseEvent e)
{
}

public void mouseMoved(MouseEvent e)
{
mx = e.getX();
my = e.getY();
e.consume();
repaint();
}

public void mousePressed(MouseEvent e)
{
}

public void mouseReleased(MouseEvent e)
{
//repaint();
}

public void mouseEntered(MouseEvent e)
{
//repaint();
}

public void mouseExited(MouseEvent e)
{
//onaroll = 0;
//repaint();
}

public void mouseClicked(MouseEvent e)
{
//repaint();
}
}
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