Exercise 14-1. The DigitalClock class of Example 14-2 uses a MouseMotionListener
to initiate a drag when the user drags the mouse. It initiates a drag
even when the user meant to click but jiggled the mouse a pixel or
two. Modify the example so that a drag is not initiated unless the
mouse has actually moved four pixels from where the button was
pressed down. You'll need a
MouseListener in addition to the
MouseMotionListener.
Exercise 14-2. Define a custom Swing component, named
ColorSwatch, with a read/write property named
"color" that displays a color
swatch and allows that color to be dragged. Use a
TransferHandler to transfer the value of the
"color" property. Next, modify
ColorSwatch to add a property named
"allowsDrop". If this property is
false, then the ColorSwatch
should not allow colors to be dropped onto itself. To do this,
you'll need to subclass
TransferHandler to modify the canImport(
) and importData( ) methods.
Exercise 14-3. The copy( ) method of Example 14-5
defines an anonymous implementation of the
ClipboardOwner interface that has an empty
lostOwnership( ) method. Provide an implementation
of this method to deselect the currently selected line: this provides
visual feedback to the user that indicates the line is no longer
available for pasting. Test your method by selecting and copying a
line in one instance of the component, and then doing the same thing
in another instance. Next, modify your method so that it only
deselects the selected line if it is the same one that was
transferred to the clipboard.
