[vtkusers] Creating annotation/caption system - which widgets best to use?

[David Tidmarsh]

Hello all,

I am relatively new to VTK so I will describe my question and then perhaps
those with ideas can contribute.

In the program I am working on, users can visualize and work with 2D images
and 3D meshes. I want to create an annotation/caption system so that users
can mark parts of the object, enter text, and then save those annotations
for later reference. I want to have it so that the captions are not always
visible, but can be viewed by hovering over or clicking on a particular
annotation.

>From what I can tell, some possible classes to use for this would be
vtkCornerAnnotation, vtkBalloonWidget, vtkSeedWidget, and vtkCaptionWidget.
I have looked at the demos for each of these items and none of the demos
are exactly what I want in their current form.

For example, when I use the seed widget demo, the seeds don't stick to the
sphere; their position on the screen stays the same regardless of how far
I'm zoomed in. What I want to do is to have a caption map or "stick" to a
particular pixel or polygon so that I can save its place, its position will
change when the user changes the camera angle, etc. Also, is it possible to
change the appearance of the seed widget? I can anticipate the red cross
being problematic for images with lots of red colors.

The balloon widget is also appealing for users to view their saved
captions, but I would like to change the default font, font size, and
color. Another problem is that at certain positions the text in the balloon
may go off the screen - is there a way to have the text in the balloon
automatically wrap, or for the balloon to change its shape? These
annotations may be longer than a couple sentences, so this is an important
concern for me.

Sorry for the long email and thanks for any advice or suggestions you can
give.

David
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