D28935: Reduce memory use when zooming in fitsviewer

murveit created this revision.
murveit added a reviewer: mutlaqja.
Herald added a project: KDE Edu.
Herald added a subscriber: kde-edu.
murveit requested review of this revision.

REVISION SUMMARY
  Instead of creating a scaled image, let Qt do the work.
  This saves half the memory when zooming 200% or 300%.
  I also limited the zoom to 300% running out of memory has been
  an issue for users. This change was relatively straight-forward
  for the image rendering, but there was complexity with the
  overlays drawn, espcially those rendering text.

TEST PLAN
  Load an image, zoom in. You should be limited to 300%. You should notice less than 
  1Gb of memory use from a ~20megapixel camera, whereas this would be over 2.5Gb 
  previously. Try the various overlays. They should work the same as before (some line
  widths may be slightly different, but I tried to match the previous rendering.
  Similarly, test focus, align, guide views, zooming in and so forth.

REPOSITORY
  R321 KStars

BRANCH
  fitsviewer-zoom-memory (branched from master)

REVISION DETAIL
  https://phabricator.kde.org/D28935

AFFECTED FILES
  kstars/fitsviewer/fitsview.cpp
  kstars/fitsviewer/fitsview.h

To: murveit, mutlaqja
Cc: kde-edu, narvaez, apol