Re: [gef-dev] Draw2d Mouse Events Mechanism

[Anthony Hunter <anthonyh@xxxxxxxxxx>]

Hi,

Please post questions to the GEF newsgroup
news://news.eclipse.org/eclipse.tools.gef


Cheers...
Anthony
--
Anthony Hunter mailto:anthonyh@xxxxxxxxxx
Software Development Manager: Eclipse Open Source Components
IBM Rational Software: Aurora / Modeling Tools 
Phone: 613-591-7037

From:	Manuel SELVA <manuel.selva@xxxxxx>
To:	GEF development <gef-dev@xxxxxxxxxxx>
Date:	10/16/2007 02:58 AM
Subject:	[gef-dev] Draw2d Mouse Events Mechanism

---

Hi all,

I am Working a lot with Draw2d, and finally got a Draw2d figure 
hierarchy quit complex. In fact, the important thing is just that i have
a "transparent figure" on top of several others. A transparent
rectangle 
for example just override the fillShape method of RectangleFigure in 
order to set the alpha transparency of the underlying Graphics and of 
course of the underlying GC.

My problem is the following one : Figures "semi-hidden" by the
transparent rectangle don't received MouseEvents !!!

After looking inside Draw2d's code it seems that the SWTEventDispatcher
delegates to its root figure to find the "target figure" of a
MouseDown 
event for example. All the work is happening in findMouseEventTargetAt
and in findMouseEventTargetInDescendantsAt methods of the Figure class.
The findMouseEventTargetInDescendantsAt method start from the top most
figure (the figure at the top right in children list) and check if it 
contains the "looking point", if yes it looks in its own children
and 
then return.

In my case The transparent rectangle contains point and does not accept
MouseEvents so the findMouseEventTargetInDescendantsAt returns Null 
without looking into figures that are "behind" this transparent
rectangle.

Does anybody already encountered this need and how do you fixed it ? 
Maybe it will be nice to have a way to tell Draw2d figures "exclude
this 
figure from MouseEvents look path ...

Let me know if you have any suggestions, comments or critics on the subject

Manu
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