[vtkusers] vtkCaptionActor2D not filling its prop correctly

[Tiago Nobrega]

Hi David,

Looks like you were right on the money. After some consideration here we
ended up agreeing with you guys so we'll just update the images on our end.
For reference, I did pull master and try the new 'tight' bounding box
setting and it did indeed generate my base image. Do we have a ballpark for
7.1's release date?

Thank you for your help,

Tiago

On Fri, Sep 23, 2016 at 12:08 PM, David Lonie <david.lonie at kitware.com>
wrote:

> "That's not a bug, it's a feature" ;)
>
> VTK previously used a "tight" bounding box for aligning/sizing text, which
> gives better results in cases like this. However, this caused issues with
> animations in ParaView, since if a string changed height by gaining/losing
> ascenders (e.g. "T" vs "n") or descenders (e.g. "j" vs "i"), the text would
> jump around. So the change was made to have all strings always account for
> ascenders/descenders to keep the baseline consistent in such cases.
>
> Dan Lipsa very recently added the option to vtkTextProperty to use a tight
> bounding box:
>
> https://gitlab.kitware.com/vtk/vtk/merge_requests/1925
>
> This is available in master, and should be in the upcoming 7.1 release. It
> should allow you to render strings like in the "before" image.
>
> HTH,
> Dave
>
> On Fri, Sep 23, 2016 at 7:27 AM, Tiago Nobrega <tigarmo at gmail.com> wrote:
>
>> Hello,
>>
>> I apologize for not reading the guidelines properly and submitting an
>> issue on Gitlab before trying the mailing list. Here's my issue:
>>
>> We are in the process of updating VTK from 6.3 to 7.0 and some of our
>> tests are failing because text actors are being rendered differently. This
>> usually happens when we update the library (minor differences are to be
>> expected) but in this particular case it looks like a regression.
>>
>> The following code (python):
>>
>> ```python
>> import vtk
>>
>> ren1 = vtk.vtkRenderer()
>> renWin = vtk.vtkRenderWindow()
>> renWin.AddRenderer(ren1)
>> iren = vtk.vtkRenderWindowInteractor()
>> iren.SetRenderWindow(renWin)
>>
>> prop_1 = vtk.vtkCaptionActor2D()
>> prop_1.SetCaption('Hello')
>> prop_1.SetAttachmentPoint((-0.1, 0.0, 0.0))
>>
>> prop_1.GetCaptionTextProperty().Modified()
>>
>> ren1.AddActor(prop_1)
>> ren1.SetBackground(0, 0, 0)
>> ren1.GetActiveCamera().SetFocalPoint(0,0,0)
>> ren1.GetActiveCamera().SetPosition(1,0,0)
>> ren1.GetActiveCamera().SetViewUp(0,0,1)
>> ren1.ResetCamera()
>> renWin.SetSize(500, 500)
>>
>> iren.Start()
>> ```
>>
>> ... generates two different renderings depending on the version, as shown
>> on the following image:
>>
>> http://imgur.com/w8VXM8z
>>
>> The left side is VTK 6.3, and the right one is 7.0. Both ran on a Windows
>> 10 machine, but the issue was replicated on our Linux boxes too. In all
>> cases we're still using the old OpenGL backend and not the new OpenGL2 one.
>> The behavior in version 6.3 seems more "correct" in the sense that the text
>> is more fully filling up the rectangle, with the default scaling mode being
>> to scale to the prop. I've investigated the commit history for the classes
>> that seem relevant - vtkCaptionActor2D, vtkTextActor, vtkTextProperty, etc
>> - but nothing stood out as possible "culprits".
>>
>> Let me know if you need further info or clarifications. Thanks.
>>
>> Tiago Nobrega
>>
>>
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