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IDProjectCategoryView StatusDate SubmittedLast Update
0015603VTK(No Category)public2015-07-29 08:232016-08-12 09:55
ReporterMarc Ruiz 
Assigned ToKitware Robot 
PrioritynormalSeverityminorReproducibilityhave not tried
StatusclosedResolutionmoved 
PlatformOSOS Version
Product Version6.1.0 
Target VersionFixed in Version 
ProjectTBD
Typeperformance
Summary0015603: Slow text rendering with vtkCornerAnnotation and big windows
DescriptionHi, I'm the developer of a medical viewer that uses vtkCornerAnnotation to display image-related information in the corners of the window. I have found that updating the text for each frame is slow when the window is very big, like for example in a 5 MPixel medical display.

With the default vtkTextRenderer implementation in the vtkRenderingFreeType module, when the window is very big, vtkCornerAnnotation updates take a considerable amount of time, to the point of making the application very laggy when scrolling through images. I have tried to limit the text size to a small number, but even then with a big window text rendering is slow and with a small window it's fast, so it's not directly related to text size. In comparison, the old ftgl approach in the vtkRenderingFreeTypeOpenGL module is instantaneous no matter the window size.

A profiler points to vtkFreeTypeTools::RenderCharacter() as the hotspot, but according to David Lonie's answer in the mailing list[1], the real issue may be in vtkCornerAnnotation::RenderOpaqueGeometry(), which has two loops that resize the text repeatedly to decide the best size.

Possible improvements: "At the very least the initial fontsize should be able to be set, and at best this class should be refactored to use newer text renderering APIs like vtkTextRenderer::GetBoundingBox, which won't actually generate a texture but just compute the dimensions of the resulting image."

[1] http://public.kitware.com/pipermail/vtkusers/2015-July/091690.html [^]
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Issue History
Date ModifiedUsernameFieldChange
2015-07-29 08:23Marc RuizNew Issue
2016-08-12 09:55Kitware RobotNote Added: 0037405
2016-08-12 09:55Kitware RobotStatusbacklog => closed
2016-08-12 09:55Kitware RobotResolutionopen => moved
2016-08-12 09:55Kitware RobotAssigned To => Kitware Robot

Notes
(0037405)
Kitware Robot   
2016-08-12 09:55   
Resolving issue as `moved`.

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