[vtkusers] VTK+JAVA Crash in mouse events

[Jeff Lee]

Shyam Prakash wrote:

>Jeff,
>	The program that I sent you was just to demonstrate my problem.
>Your idea of actors getting gc'ed while they are still in renderer could
>be a possibility. But then I can not convince my self how this could
>happen as the actor still has a reference to the renderer. Do you have
>any idea?
>  
>
The way you coded it, as I recall, was to assign an ivar called actor = 
new vtkActor() and then added it to the renderer.  The next time you do 
this, the previous actor has no more references (even though the 
Renderer in c++ added a consumer, this is not the same as adding a 
reference).  Since you added the old one, but did not remove it, the 
object was finalized while still in the renderer, causing the errors.  
In short, the actor doesn't have a reference to the renderer, only a 
list of consumers.
-Jeff

>Thanks
>Shyam
>
>-----Original Message-----
>From: vtkusers-admin at vtk.org [mailto:vtkusers-admin at vtk.org] On Behalf
>Of Jeff Lee
>Sent: Tuesday, November 18, 2003 8:06 PM
>To: Shyam Prakash
>Cc: vtkusers at public.kitware.com
>Subject: Re: [vtkusers] VTK+JAVA Crash in mouse events
>
>I think the main problem was that your actors were getting gc'ed while 
>the mouse was moving.  You should be careful to remove actors from the 
>renderer which might be garbage collected for any reason.  Furthermore, 
>you were creating a new plane widget every time the action was triggered
>
>- was that your intent?  If so, you need to remove the old one from the 
>renderer first.  In the future, if you see this type of behavior, it is 
>almost guaranteed to be related to some object unwittingly being a 
>candidate for garbage collection, and the object gets deleted while 
>still in the renderer.  I attached a better-behaving version of your 
>code, but it may not be what you intended.
>-Jeff
>
>Shyam Prakash wrote:
>
>  
>
>>Hello,
>>
>>            I had encountered this problem earlier too. The program 
>>suddenly crashes in mouseMove, mouseDrag,mousePress or mouseRelease 
>>events with a message similar to the message given below.
>>
>> 
>>
>>Current Java thread:
>>
>>      at vtk.vtkGenericRenderWindowInteractor.MouseMoveEvent_2(Native 
>>Method)
>>
>>      at 
>>
>>    
>>
>vtk.vtkGenericRenderWindowInteractor.MouseMoveEvent(vtkGenericRenderWind
>owInteractor.java:19)
>  
>
>>      at vtk.vtkCanvas.mouseDragged(vtkCanvas.java:209)
>>
>>      at
>>    
>>
>java.awt.Component.processMouseMotionEvent(Component.java:5182)
>  
>
>>      at java.awt.Component.processEvent(Component.java:4935)
>>
>> 
>>
>>I am not sure what exactly could be the problem. I am using vtk 4.2.2 
>>on Windows2k with jdk 1.4.1_02. Attached is a sample code. When I run 
>>this code, it often crashes in my machine when I rotate the model 
>>vigorously(in combination with resizing the window). My gut feeling is
>>    
>>
>
>  
>
>>it could be because of the presence of vtkImplicitPlaneWidget. Is 
>>there anyway I can avoid this?
>>
>> 
>>
>>Thanks
>>
>>Shyam
>>
>>    
>>
>
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