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Drag from a view, drop onto the diagram, and create a node [message #143513]

Thu, 19 July 2007 10:52

Eclipse User

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Hi. 
 
I have read the messages related to drag and drop in GMF, in particular
this <a
href=" http://dev.eclipse.org/newslists/news.eclipse.technology.gmf /msg01281.html">one</a>,
but I'm still in trouble. 
 
Let me introduce what I want to do. 
First, I have a diagram editor, built with GMF. And then, I have a
custom view (nothing to do with GMF), defined in another plugin and
made with SWT. What I want to do is drag an element from my view and
drop it on the diagram. When I drop my element, I would like to create
a new element (model and view). 
 
There are two points: catch a drop event on the diagram, and create a
new node. 
 
For the moment, I just transfer text data. I will see later for more
complex objects. 
So, I created a DragSource, with a Text TypeTransfer and a DragListener
in my view. 
And in my diagram, I added in my *DiagramEditor file a
DropTargetListener. Here is the code: 
<blockquote>protected void initializeGraphicalViewer() { 
         super.initializeGraphicalViewer(); 
         getDiagramGraphicalViewer().addDropTargetListener( 
                 new DiagramDropTargetListener(
getDiagramGraphicalViewer(), LocalTransfer.getInstance() ) { 
 
                     @Override 
                    protected List getObjectsBeingDropped() { 
                        System.out.println( "Dropped !" ); 
                        return null; 
                    }  
                     
                 }); 
    } 
 
</blockquote>
But the drop event is not detected. So, in *EditPart (the one which
corresponds to the root element of my meta-model), I installed an
EditPolicy as follows: 
 
<blockquote>installEditPolicy(EditPolicyRoles.DRAG_DROP_ROLE, 
                new DiagramDragDropEditPolicy()); 
 
</blockquote>
But it's still not working. Anyone to help me please ? 
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Re: Drag from a view, drop onto the diagram, and create a node [message #144157 is a reply to message #143513]

Wed, 25 July 2007 11:30

Eclipse User

Hello Vincent,

You have to create DropTargetListener passing correct transfer instance as
a parameter. AFAIU, you are using TextTransfer in source of you D&D and installing
listener with the LocalTransfer.getInstance() on diagram.. You should use
same TextTransfer there.

-----------------
Alex Shatalin

Re: Drag from a view, drop onto the diagram, and create a node [message #144793 is a reply to message #144157]

Mon, 30 July 2007 12:21

Eclipse User

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Hello Alex. 
 
Thanks for your reply. It doesn't change the result, but I think you're
right. :) 
 
In fact, the use "DiagramDragDropEditPolicy" is maybe not a good thing,
since it is said that it allows the drop of semantic objects (meaning -
for me - = objects from the meta-model). I've tried to install a custom
edit policy, extending "DragDropEditPolicy" : 
 
<blockquote>public class UddiOrchestrationDragDropEditPolicy extends
DragDropEditPolicy { 
 private OrchestrationEditPart editPart; 
 
 public UddiOrchestrationDragDropEditPolicy() { 
 super(); 
 System.out.println(" installé "); 
 } 
 
 protected Command getDropCommand(ChangeBoundsRequest request) { 
 System.out.println("get drop command"); 
 return null; 
 } 
 
 protected Command getDropElementCommand(EObject element,
DropObjectsRequest request) { 
 System.out.println("get dropped element command"); 
 return null; 
 } 
 
 public Command getCommand( Request request ) { 
 if (RequestConstants.REQ_DROP.equals(request.getType())) { 
 System.out.println("send request"); 
 return getDropCommand((ChangeBoundsRequest) request); 
 } 
 return null; 
 } 
 
 protected Command getDropObjectsCommand(DropObjectsRequest
request) { 
 System.out.println("get drop objects command"); 
 return null; 
 } 
} 
</blockquote>
But still no printing. 
I also tried another thing in my "initializeGraphicalViewer" method of
the *DiagramEditor. I added a "new TransferDropTargetListener" to my
viewer instead of a a "DiagramDropTargetListener". 
 
<blockquote>getDiagramGraphicalViewer().addDropTargetListener( 
 new TransferDropTargetListener() { 
 
 public Transfer getTransfer() { 
 System.out.println( "Orchestration got
transfer" ); 
 return TextTransfer.getInstance(); 
 } 
 
 public boolean isEnabled(DropTargetEvent event) { 
 System.out.println( "Orchestration is enabled"
); 
 return true; 
 } 
 
 public void dragEnter(DropTargetEvent event) { 
 System.out.println( "enter"); 
 if (event.detail == DND.DROP_DEFAULT) { 
 event.detail = (event.operations &
DND.DROP_COPY) != 0 ? DND.DROP_COPY : DND.DROP_NONE; 
 } 
 
 // Allow dropping text only 
 for (int i = 0, n = event.dataTypes.length; i
< n; i++) { 
 if
(TextTransfer.getInstance().isSupportedType(event.dataTypes[ i])) { 
 event.currentDataType =
event.dataTypes[i]; 
 } 
 } 
 } 
 
 public void dragLeave(DropTargetEvent event) { 
 System.out.println( "Orchestration drag leave"
); 
 } 
 
 public void dragOperationChanged(DropTargetEvent
event) { 
 System.out.println( "Orchestration operation
changed" ); 
 } 
 
 public void dragOver(DropTargetEvent event) { 
 System.out.println( "Orchestration drag over"
); 
 } 
 
 public void drop(DropTargetEvent event) { 
 if
(TextTransfer.getInstance().isSupportedType(event.currentDat aType)) { 
 System.out.println("Orchestration drop"); 
 } else 
 System.out.println("Orchestration drop
failed"); 
 } 
 
 public void dropAccept(DropTargetEvent event) { 
 System.out.println( "Orchestration drop
accepted" ); 
 } 
 }); 
</blockquote>
 
But still nothing. I don't understand why the editor does not detect
any drop action, since I added printings everywhere. Besides, I'm
working with Linux, and the drag source calls the "dragSetData" method
only on a drop event. But with a drop on the editor, this method is not
called. I think the problem is that I don't drag and drop semantic
elements. But I don't understand why it would be a problem, since GMF
is built on top of SWT and that I didn't encounter any problem with DnD
in SWT. 
 
Any help is welcome. 
 
Regards, 
 
 Vincent. 
 
 
 
Alex Shatalin wrote:
<blockquote cite="mid3c3172e6164fb8c99cf8ad80aa0f@news.eclipse.org"
type="cite">Hello Vincent,
 
 
You have to create DropTargetListener passing correct transfer instance
as a parameter. AFAIU, you are using TextTransfer in source of you
D&D and installing listener with the LocalTransfer.getInstance() on
diagram.. You should use same TextTransfer there.
 
 
-----------------
 
Alex Shatalin
 
 
 
</blockquote>
 
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