D29397: KPreviewJob : Support for DeviceRatioPixel

[Méven Car]

meven added a comment.


  In D29397#666153 <https://phabricator.kde.org/D29397#666153>, @kossebau wrote:
  
  > In D29397#666134 <https://phabricator.kde.org/D29397#666134>, @meven wrote:
  >
  > > In D29397#666132 <https://phabricator.kde.org/D29397#666132>, @kossebau wrote:
  > >
  > > > For another stupid question (the first one was already asked by someone else and answered :) ):
  > > >  Given some generated thumbnails are cached, does the thumbnail cache specification support logical resolution?
  > >
  > >
  > > I am evolving here the specification : the images stored are stored with their HiDpi size (width * dpr, height * dpr), and then some metadata is written.
  >
  >
  > Specification as in, https://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-latest.html? So there is some work on extending the specs not yet reflected on that page?
  
  
  Thanks for the reference.
  I meant I am beyond the spec, adding some by facts, that is not great :/
  This spec is showing its age, and would need to evolve to cover HiDPi use case, but I am not editing it ATM.
  
  > How is the metadata written?
  
  line 751 of PreviewJob.
  
  >>> How would cached thumbnails work cross-screen?
  >> 
  >> Cache thumbnails with low dpr will look blurry on hidpi screen, other than that's not an issue.
  > 
  > Cached thumbnails rendered for hidpi (so e.g. being 256x256 with bigger details due to hidpi context) , but used for lowdpi elsewhere will be an issue as well. E.g. when it comes to text rendered with minfontsize like in case of plain text documents, it will be too large then.
  > 
  > I wonder if the thumbnail cache would not need the same extension like the icon spec had, with a @2x variant, to make up for that. There are still a lot of lowdpi devices out there, and they are getting mixed.
  
  That looks like the way to go, I would favor adding normal at 2x and large at 2x in .cache/thumbnails

REPOSITORY
  R241 KIO

REVISION DETAIL
  https://phabricator.kde.org/D29397

To: meven, dfaure, broulik, #frameworks
Cc: kossebau, davidedmundson, kde-frameworks-devel, LeGast00n, cblack, michaelh, ngraham, bruns
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