| Proper usage of diagram node selection and subsequent command processing [message #64725] |
Tue, 17 October 2006 17:44  |
Eclipse User |
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Hi,
due to some bug that has turned out to be quite mysterious, I would like
to clarify some things:
(1)
Why get methods like e.g. PackageEditHelper.getMoveCommand(MoveRequest
req) executed 3-5 times in a row when I do a drag'n'drop operation (with
a single diagram element!) in my diagram?
Not only I wonder why that method is called multiple times, but also the
fact that the number of subsequent calls varies.
Further, I do expect that method to be called not earlier then the
"release mouse button event". Instead, it's called on mouse hover (with
dragged elements glued to the mouse pointer).
(2)
I feel that there are some things to know concerning proper selection of
multiple diagram nodes. In particular, how do I access the set of
currently active diagram elements?
(3, as a consequence of 1+2)
When will the runtime documentation and related docs be reviewed to
cover these nasty things?
Thanks a lot for your advice,
Martin Herbort
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| Re: Proper usage of diagram node selection and subsequent command processing [message #64750 is a reply to message #64725] |
Tue, 17 October 2006 18:39  |
| Eclipse User |
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Originally posted by: vcciubot.uwaterloo.ca
> (1)
> Why get methods like e.g. PackageEditHelper.getMoveCommand(MoveRequest
> req) executed 3-5 times in a row when I do a drag'n'drop operation (with
> a single diagram element!) in my diagram?
> Not only I wonder why that method is called multiple times, but also the
> fact that the number of subsequent calls varies.
Tools/Actions etc call getCommand() on an EditPart to update the mouse
pointer or their icon (enabled/disabled). As such, when you drag the tool
updates the target edit part and calls getCommand() on that edit part
which in turn calls the semantic policy which calls your edit helper.
>
> Further, I do expect that method to be called not earlier then the
> "release mouse button event". Instead, it's called on mouse hover (with
> dragged elements glued to the mouse pointer).
Those commands are checked for being executable but are only executed when
the dragging ends.
>
> (2)
> I feel that there are some things to know concerning proper selection of
> multiple diagram nodes. In particular, how do I access the set of
> currently active diagram elements?
EditPartViewer#getSelection
You can get the viewer from an edit part.
>
> (3, as a consequence of 1+2)
> When will the runtime documentation and related docs be reviewed to
> cover these nasty things?
It's hard at the beginning :)
Some of these topics have already been covered in the GEF programmer's
manual.
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