Swing Hacks

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Chapter 12, Miscellany

#88 Display a Busy Cursor

HACK

First, you need to build an AnimatedCursor class and generate the images in

the constructor. In this case, the images are instances of the

java.awt.Cursor

object. I used standard, predefined cursors to keep the code easy, but you

could also use cursors derived from custom images. A

JFrame

is passed into

the constructor and stored for later use, as you can see in Example 12-1.

AnimatedCursor implements Runnable because it will be threaded, and it

accepts action events to turn on and off the animation. You can reuse the

standard directional cursors, one for each compass direction, stored in a

Cursor array, which is eight items long.

Running the Animation

Next, you need to build the actual animation thread:

public void run( ) {

int count = 0;

while(animate) {

try {

Thread.currentThread( ).sleep(200);

} catch (Exception ex) { }

frame.setCursor(cursors[count % cursors.length]);

count++;

}

frame.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));

}

Example 12-1. A simple animated cursor

public class AnimatedCursor implements Runnable, ActionListener {

private boolean animate;

private Cursor[] cursors;

private JFrame frame;

public AnimatedCursor(JFrame frame) {

animate = false;

cursors = new Cursor[8];

this.frame = frame;

cursors[0] = Cursor.getPredefinedCursor(Cursor.N_RESIZE_CURSOR);

cursors[1] = Cursor.getPredefinedCursor(Cursor.NE_RESIZE_CURSOR);

cursors[2] = Cursor.getPredefinedCursor(Cursor.E_RESIZE_CURSOR);

cursors[3] = Cursor.getPredefinedCursor(Cursor.SE_RESIZE_CURSOR);

cursors[4] = Cursor.getPredefinedCursor(Cursor.S_RESIZE_CURSOR);

cursors[5] = Cursor.getPredefinedCursor(Cursor.SW_RESIZE_CURSOR);

cursors[6] = Cursor.getPredefinedCursor(Cursor.W_RESIZE_CURSOR);

cursors[7] = Cursor.getPredefinedCursor(Cursor.NW_RESIZE_CURSOR);

}

}