[9/8u40] Review request for RT-37149 and JDK-8049065 : Implement DnD for SwingNode

[Anthony Petrov]

Hi Petr, Anton, Artem, Steve,

Please review the fix at https://javafx-jira.kenai.com/browse/RT-37149

Webrevs:

JDK: http://cr.openjdk.java.net/~anthony/9-5.2/

FX: http://cr.openjdk.java.net/~anthony/g-522-swingNodeDnD-RT-37149.3/


JavaFX implements the DragSourceContextPeer and DragGestureRecognizer so 
that SwingNode content could pose as a drag source. In order to support 
a drop target, the DropTargetContextPeer is implemented in SwingNode and 
the add/removeDropTarget() methods register/unregister the drop target 
listeners.

The changes in JDK are mostly technical. We simply delegate the 
Toolkit.createDragSourceContextPeer() and 
Toolkit.createDragGestureRecognizer() factory methods to SwingNode. 
Similarly, we delegate the DropTargetPeer.add/removeDropTarget() 
operations to SwingNode as well.

In FX I've factored out the CachingTransferable class from the 
SwingDragSource class so as to share the implementation with the 
SwingNode DnD support. Also I've added a few utility methods to 
DataFlavorUtils and SwingFXUtils. The main fix is the new code in 
FXDnD.java which actually implements the AWT interfaces, installs 
appropriate event handlers on the SwingNode node in FX, and handles all 
the DnD events.

Note that the JDK <-> FX interface is loose because I use default 
methods in the LightweightContent interface, so that you can run new FX 
with the old JDK, or old FX with the new JDK, and nothing should break. 
Obviously, the DnD in SwingNode will only work if both JDK and FX are 
patched.

I've tested these changes on Windows and Mac with the sample code from 
this JIRA as well as a JFXPanel DnD test application from RT-34283. The 
DnD works fine for me in both intra- and inter-process modes.

Please post your review comments in JIRA.

--
best regards,
Anthony