michael-jeulinl/MSVTK — comment on commit d742be7395cc01dec9c016b5eae1a80597f5415b
File:  line 0
By finetjul:

typo in the commit title:
Add module Qt::Widgets::TimePlayerWidget with ITS UI and unit test

I think you didn't fully understand how (time) information travels within the VTK pipeline.
At the end of the pipeline (mappers), they are aware about the entire time range, time step and current time.
The application changes the mapper to have a different current time, it is then propagated up the pipeline, up to the reader who returns the new current time image data, which are processed down the pipeline.