Java Source Codes

squares with mouse

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

class MousePanel extends JPanel
implements MouseMotionListener
{ public MousePanel()
{ addMouseListener(new MouseAdapter()
{ public void mousePressed(MouseEvent evt)
{ int x = evt.getX();
int y = evt.getY();
current = find(x, y);
if (current < 0) // not inside a square
add(x, y);
}

public void mouseClicked(MouseEvent evt)
{ int x = evt.getX();
int y = evt.getY();

if (evt.getClickCount() >= 2)
{ remove(current);
}
}
});
addMouseMotionListener(this);
}

public void paintComponent(Graphics g)
{ super.paintComponent(g);
for (int i = 0; i < nsquares; i++)
draw(g, i);
}

public int find(int x, int y)
{ for (int i = 0; i < nsquares; i++)
if (squares[i].x - SQUARELENGTH / 2 <= x &&
x <= squares[i].x + SQUARELENGTH / 2
&& squares[i].y - SQUARELENGTH / 2 <= y
&& y <= squares[i].y + SQUARELENGTH / 2)
return i;
return -1;
}

public void draw(Graphics g, int i)
{ g.drawRect(squares[i].x - SQUARELENGTH / 2,
squares[i].y - SQUARELENGTH / 2,
SQUARELENGTH,
SQUARELENGTH);
}

public void add(int x, int y)
{ if (nsquares < MAXNSQUARES)
{ squares[nsquares] = new Point(x, y);
current = nsquares;
nsquares++;
repaint();
}
}

public void remove(int n)
{ if (n < 0 '' n >= nsquares) return;
nsquares--;
squares[n] = squares[nsquares];
if (current == n) current = -1;
repaint();
}

public void mouseMoved(MouseEvent evt)
{ int x = evt.getX();
int y = evt.getY();

if (find(x, y) >= 0)
setCursor(Cursor.getPredefinedCursor
(Cursor.CROSSHAIR_CURSOR));
else
setCursor(Cursor.getDefaultCursor());
}

public void mouseDragged(MouseEvent evt)
{ int x = evt.getX();
int y = evt.getY();

if (current >= 0)
{ Graphics g = getGraphics();
g.setXORMode(getBackground());
draw(g, current);
squares[current].x = x;
squares[current].y = y;
draw(g, current);
g.dispose();
}
}

private static final int SQUARELENGTH = 10;
private static final int MAXNSQUARES = 100;
private Point[] squares = new Point[MAXNSQUARES];
private int nsquares = 0;
private int current = -1;
}

class MouseFrame extends JFrame
{ public MouseFrame()
{ setTitle("MouseTest");
setSize(300, 200);
addWindowListener(new WindowAdapter()
{ public void windowClosing(WindowEvent e)
{ System.exit(0);
}
} );

Container contentPane = getContentPane();
contentPane.add(new MousePanel());
}
}

public class MouseTest
{ public static void main(String[] args)
{ JFrame frame = new MouseFrame();
frame.show();
}
}

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