[vtkusers] vtkDistanceWidget and vtkCanvas

[Sebastien Jourdain]

Hi Marco,

the reason why the vtk garbage collector kick the widget off is
because the Java one think that that class is not used anymore.
To solve the problem, you have to keep a reference of the widget
around in the global context...

Seb

On Wed, Jan 18, 2012 at 11:42 AM, Marco Sambin <m.sambin at gmail.com> wrote:
> Sure Seb,
>
> I will keep the list in the loop. Actually, I did not realize I was
> replying to you directly, sorry (I am using a web client I am not used
> to...).
> Please consider that everything works as expected if I remove the
> following call from my code:
>
> vtkObject.JAVA_OBJECT_MANAGER.getAutoGarbageCollector().SetAutoGarbageCollection(true);
>
> So, it seems strange to me that I am missing something fundamental in the code.
> However, I will review once again all the documentation.
>
> Please let me know if I shall post again the test case to the list.
>
> Thanks,
>
> Marco
>
>
> 2012/1/18 Sebastien Jourdain <sebastien.jourdain at kitware.com>:
>> Hi Marco,
>>
>> keep the list in the loop so other could benefit from our discussion.
>>
>> Moreover, I'm sure you are still missing what I'm saying, but as I
>> haven't done such thing in a while I can not tell you exactly how to
>> do it, unless I do it myself.
>>
>> Seb
>>
>> On Wed, Jan 18, 2012 at 11:30 AM, Marco Sambin <m.sambin at gmail.com> wrote:
>>> Hi Seb,
>>>
>>> thank you for your message.
>>>
>>> Actually, it looks like there is no PlaceWidget() call in vtkDistanceWidget.
>>> I think the job of adding the appropriate actor(s) to the renderer is
>>> carried out by the .On() call on the widget (corresponding to
>>> .SetEnabled(1)). Am I correct?
>>>
>>> In any case, I am quite convinced I have found a (strange) issue in
>>> VTK (I am using a nightly build dated 2011.12.15, Win 64-bit): don't
>>> ask me why, but the vtkDistanceWidget seems not to work in vtkCanvas
>>> when VTK's Java auto garbage collector is enabled.
>>>
>>> I attach a reproducible test case demonstrating the issue.
>>> Maybe it could help you (VTK team) in fixing a possible bug.
>>>
>>> Best regards,
>>>
>>> Marco Sambin
>>>
>>>
>>> 2012/1/18 Sebastien Jourdain <sebastien.jourdain at kitware.com>:
>>>> Hi Marco,
>>>>
>>>> I reply directly in your comment.
>>>>
>>>> On Wed, Jan 18, 2012 at 5:06 AM, Marco Sambin <m.sambin at gmail.com> wrote:
>>>>> Hi Seb,
>>>>>
>>>>> first of all, thanks for your reply.
>>>>>
>>>>> What do you mean by "add your widget actor into the renderer"?
>>>>> It is my understanding that calling "SetInteractor(iren)" on the
>>>>> vtkDistanceWidget should be enough to see it working on screen. Am I
>>>>> correct, or I am missing some calls?
>>>>
>>>> Yes, you are missing something, the interactor is needed so the widget
>>>> could interpret the user interaction (mouse), but this not change the
>>>> content of your 3d scene... Therefore, you still need to add
>>>> "something" to your renderer and even size your widget in the scene.
>>>> (PlaceWidget)
>>>>
>>>> For more informations, you can look at that :
>>>> http://www.vtk.org/Wiki/VTK/Examples/Cxx#Widgets
>>>> and http://www.vtk.org/Wiki/VTK/Examples/Java
>>>>
>>>> Hope this could help,
>>>>
>>>> Seb
>>>>
>>>>>
>>>>> Regarding the camera, well, I actually make a call to
>>>>> GetRenderer().ResetCamera() on my vtkCanvas, but since the
>>>>> vtkDistanceWidget is interaction-driven, shouldn't it appear in any
>>>>> case in the position where I am pressing my mouse (hence, within the
>>>>> viewing range of the camera)?
>>>>> In any case, calling ResetCamera() before or after I pressed my mouse
>>>>> buttons does not show anything.
>>>>>
>>>>> Do you have further suggestions?
>>>>>
>>>>> Thanks again for your time.
>>>>>
>>>>> Regards,
>>>>>
>>>>> Marco
>>>>>
>>>>>
>>>>> 2012/1/17 Sebastien Jourdain <sebastien.jourdain at kitware.com>:
>>>>>> Just quickly... Did you add your widget actor into the renderer ?
>>>>>> Did you reset the camera to be sure it is looking in the right direction ?
>>>>>>
>>>>>> Seb
>>>>>>
>>>>>> On Tue, Jan 17, 2012 at 1:10 PM, Marco Sambin <m.sambin at gmail.com> wrote:
>>>>>>> Hi all.
>>>>>>> I am trying to use a vtkDistanceWidget in my vtkCanvas-derived class.
>>>>>>>
>>>>>>> In the constructor of my vtkCanvas-derived class, I have the following code:
>>>>>>>
>>>>>>> [...]
>>>>>>>    // Initialize the measurements widget
>>>>>>>    vtkDistanceWidget distWidget = new vtkDistanceWidget();
>>>>>>>    distWidget.SetInteractor(iren);
>>>>>>>    vtkPointHandleRepresentation2D handle = new
>>>>>>> vtkPointHandleRepresentation2D();
>>>>>>>    handle.GetProperty().SetColor(1, 0, 0);
>>>>>>>    vtkDistanceRepresentation2D rep = new vtkDistanceRepresentation2D();
>>>>>>>    rep.SetHandleRepresentation(handle);
>>>>>>>    rep.GetAxis().SetNumberOfMinorTicks(4);
>>>>>>>    rep.GetAxis().SetTickLength(9);
>>>>>>>    rep.GetAxis().SetTitlePosition(0.2);
>>>>>>>    distWidget.SetRepresentation(rep);
>>>>>>>    distWidget.On();
>>>>>>> [...]
>>>>>>>
>>>>>>> For now, my vtkCanvas is empty, and there is no other relevant code in
>>>>>>> the constructor.
>>>>>>>
>>>>>>> I cannot get the vtkDistanceWidget to work. Nothing appears on screen
>>>>>>> when I left-press on my vtkCanvas.
>>>>>>>
>>>>>>> Am I missing something fundamental in order to have the
>>>>>>> vtkDistanceWidget to work?
>>>>>>>
>>>>>>> Thanks in advance for any hint.
>>>>>>>
>>>>>>> Best regards,
>>>>>>>
>>>>>>> Marco
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