[Paraview] useful plugin: how to do it, really?

[Utkarsh Ayachit]

Bertwim,

I agree the developer docs are little scattered right now. My plan is
to start writing blog posts that make this easier to digest. One of
these, hopefully, I get around to it :). In the mean time, my replies
are inline.


> 1. Suppose I have created, interactively, a box, a sphere and a cone,
> using the corresponding entries in the "Sources" menu.
>
> 2. Now I would like to *programmatically* (i.e. in  a c++ plugin) loop
> over the sources (here: the box, sphere and cone) and for each of the
> elements
> get hold of the parameters that were used to define these sources (i.e.
> the box dimensions, center, radii etc.). With these parameters I can
> then do other things to build my own extension, but those details do not
> matter here.


Several ways for getting to the "proxies" for the sphere, box, etc.
created. One way it using the vtkSMSessionProxyManager.

a. Using vtkSMSessionProxyManager:
a.1 Get access to the active session's proxy manager using
pqActiveObjects::instance().proxyManager() [1]
a.2 Use vtkSMProxyIterator[2] to iterate over the "sources" group.
    vtkNew<vtkSMProxyIterator> iter;
    iter->SetSessionProxyManager(pqActiveObjects::instance().proxyManager());
    iter->SetModeToOneGroup();
    for (iter->Begin("sources"); ! iter->IsAtEndt(); iter->Next())
      {
      iter->GetKey() ---> is the "label" for the proxy you see in the
pipeline browser
      iter->GetProxy() -- > will be the actual proxy object,
      }

To access parameters defined on them, you can access the "properties"
on these proxies. If you know which property you're looking for using
vtkSMPropertyHelper[3] to get the values e.g.

   sphereProxy = ..
   vtkSMPropertyHelper(sphereProxy, "Radius").GetAsDouble() --> the radius

To iterate over all properties on the proxy, you can use
vtkSMProxy::NewPropertyIterator [4] which will give you a new iterator
(don't forget to call iter->Delete() once you're done with the
iterator). You can use that to iterate over all properties on the
proxy,

Hope that helps,
Utkarsh

[1] http://www.paraview.org/ParaView3/Doc/Nightly/www/cxx-doc/classpqActiveObjects.html#a547a93dececb0d5ac7a35f373e5c68ab
[2] http://www.paraview.org/ParaView3/Doc/Nightly/www/cxx-doc/classvtkSMProxyIterator.html
[3] http://www.paraview.org/ParaView3/Doc/Nightly/www/cxx-doc/classvtkSMPropertyHelper.html
[4] http://www.paraview.org/ParaView3/Doc/Nightly/www/cxx-doc/classvtkSMProxy.html#ab0eee37fc2a021334964e9ffcd682a4c