Re: [platform-ui-dev] Question about JFace, wrapped objects, and objectC

[Markus Keller <markus_keller@xxxxxxxxxx>]

I don't know exactly how you intended
to implement 3. We had a similar problem in the Call Hierarchy and solved
it like this in CallHierarchyViewPart:

Instead of passing the viewer to ViewPart#getSite().setSelectionProvider(..),
we pass our own IPostSelectionProvider, which does the unwrapping in getSelection()
and otherwise just delegates the selection listeners.

HTH,
Markus

Michael Valenta <Michael_Valenta@xxxxxxxxxx>
Sent by: platform-ui-dev-bounces@xxxxxxxxxxx

2005-08-24 15:59

Please respond to
"Eclipse Platform UI component developers list." <platform-ui-dev@xxxxxxxxxxx>

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Subject	Re: [platform-ui-dev] Question about JFace, wrapped objects,        and        objectContributions

Brian, 

The only other option I can think of is for JDT to make their objectComntributions
adaptable. I can't comment on whether they would agree to do this and it
wouldn't help you in the short term anyway. Other than that, I think 2
would be your best option (although there may be some gotchas that I don't
know about). 

The thing that is getting you here is the need to show the same model object
multiple times. If you could get ride of that requirement, you could just
implement a custom content provider (i.e. the intended way to handle this
situation). 

Michael

Brian de Alwis <bsd@xxxxxxxxx>
Sent by: platform-ui-dev-bounces@xxxxxxxxxxx

22/08/2005 04:54 PM

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Subject	[platform-ui-dev] Question about JFace, wrapped objects,        and objectContributions

Hi everybody.  I have a question about the interaction of
objectContributions and selections when dealing with custom models
managed through JFace.  My apologies if this isn't seen as appropriate
for this list, but it seemed that there is a deeper issue here.

I'm using a JFace TreeViewer to provide a view on a model.  As my
model doesn't directly correspond to a tree, I've created a projection
of the model using a structure similar to the TreeParent / TreeObject
as provided by the JFace generated templates.  I've modified my
LabelProvider to unwrap these objects appropriately.

My problem is this: although my wrappers are an internal thing,
meant only to impose a structure, they are bleeding through, becoming
the actual objects exposed to the workbench.  As a result, some of
the workbench's objectContributions are not being properly applied,
such as when building context menus.

For example, some of my model objects are actually JDT IJavaElements.
But because the JDT objectContributions don't specify "adaptable=true"
(e.g. org.eclipse.jdt.internal.ui.compare.JavaReplaceActions and
org.eclipse.jdt.internal.ui.compare.JavaCompareActions), they never
appear in the context menus, even when the wrappers can be adapted.
I think they should apply as my wrapper objects exist only to
support imposing a viewing structure; the `real' objects are the
model objects.

I can't return the actual model objects (e.g. the IJavaElements),
as they may occur multiple places in my model (which causes problems
with implementing ITreeContentProvider.getParent()).

I see three solutions to this problem, but I'm hoping there is a
better way?

1. My hacked solution for the moment is to explicitly call
   ObjectActionContributorManager.contributeObjectActions() in in
   my menuAboutToShow(IMenuManager) callback and provide an
   explicitly unwrapped selection.  This solves the immediate
   problem, but it's an undesirable, short-term solution.

2. Subclass TreeViewer and override the getSelection() to do the
   rewrapping.  This seems the better immediate option, but I'm
   not sure about the consequences, and the same problem will occur
   with other types of structured viewers.

3. Add another level of indirection with an additional method to
   IStructuredContentProvider.getModelObject(), called appropriately?

I apologize if this has been discussed before, but I couldn't find
anything appropriate.

Brian.

-- 
 Brian de Alwis | Software Practices Lab | UBC | http://www.cs.ubc.ca/~bsd/
"There is much pleasure to be gained in useless knowledge." -
Bertrand Russell
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