[vtk-developers] an abstract class to manage groups of widgets?

[Nicole Aucoin]

Hello,

In 3D Slicer we're currently using a vtkSeedWidget to represent a list 
of points, and I'd like to extend my module[1] to work with lists of 
rulers, angles, bidimensional widgets etc. I want to eventually have 
many types of lists that contain elements with >1 points and have VTK 
widgets to interact with them. In the code that manages the mapping 
between the widgets and the stored point values, having one 
vtkSeedWidget per list of points is working well, but I'm finding that I 
have many special cases when trying to use many vtkDistanceWidgets to 
represent a list of pairs of points. I need a generalisation of a 
vtkSeedWidget that will manage a set of general widgets rather than 
being restricted to a set of handle widgets.
I noticed that in VTK 6 there's a new class called vtkWidgetSet, but the 
documentation[2] states that it synchronises a set of widgets across 
render windows, which is not quite what I need (I have separate widgets 
in each render window, synchronised via the point(s) list).

I was going to start working on the abstract widget group (list?) class 
and representation[3] that I need and at first integrate it into 
Slicer's fork of VTK then contribute it back into VTK. Before I start, I 
wanted to ask if there was any effort in this direction already, or if 
there's a grouping method in VTK6 that might work out of the box.

thanks,
Nicole

[1] 
http://www.slicer.org/slicerWiki/index.php/Documentation/4.3/Modules/Markups
[2] http://www.vtk.org/doc/nightly/html/classvtkWidgetSet.html#details
[3]  Working from the example of the seed representation as the base and 
extending to support Nth point set/get, which will probably require some 
superclass additions to generalise the representations. 
DistanceRepresentation uses [Get|Set]Point[1|2][World|Display]Position 
which could be updated to call a new virtual method 
[Get|Set]NthPoint[World|Display]Position(unsigned int n, ...). The 
vtkContourRepresentation has some generalisation already in 
[Get|Set]NthNode[World|Display]Position(int n, ...), while the 
vtkSeedRepresentation uses [Get|Set]Seed[World|Display]Position(unsigned 
int n, ...), so an effort to make it uniform could be worthwhile, but 
would likely be phase 2 of my project.



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