Java Foundation Classes in a Nutshell

Example 6−2: ColorSour ce.java (continued)

Image colorblock = this.createImage(25,25);

Graphics g = colorblock.getGraphics();

g.setColor(color);

g.fillRect(0,0,25,25);

// Start dragging our transferable color object

e.startDrag(DragSource.DefaultMoveDrop, // The initial drag cursor

colorblock, new Point(0,0), // The image to drag

tcolor, // The data being dragged

this); // Who to notify during drag

}

// These methods implement DragSourceListener.

// Since we passed this object to startDrag, these methods will be

// called at interesting points during the drag. We could use them,

// for example, to implement custom cursors or other "drag-over" effects.

public void dragEnter(DragSourceDragEvent e) {}

public void dragExit(DragSourceEvent e) {}

public void dragDropEnd(DragSourceDropEvent e) {}

public void dragOver(DragSourceDragEvent e) {}

public void dropActionChanged(DragSourceDragEvent e) {}

}

A Data Sink

Example 6-3 shows the ColorSink class, which is a simple subclass of the Swing

JTextArea class. ColorSink allows color objects to be pasted or dropped on it.

When either event occurs,

ColorSink sets its background color to the transferred

color object. In addition, the class allows the pasting of textual data, which it

inserts at the current cursor position. Finally,

ColorSink accepts drops of the

DataFlavor.javaFileListFlavor type. This data flavor is used when the user

drags and drops a file icon. When ...