touch-packages team mailing list archive

[Michi Henning <michi.henning@xxxxxxxxxxxxx>]

OK, so that explains the video thumbnails, thanks!

I think it's OK to ask for whatever images you actually want to display.
I mean, after all, that's what the thumbnailer is for. If you were to
always ask for some fixed size, then each and every time the thumbnail
needs to be displayed, the GPU has to re-scale it. I suspect that's
going to be harder on the battery and on performance than to simply ask
for whatever size you want to show. That way, we scale each image only
once.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to gallery-app in Ubuntu.
https://bugs.launchpad.net/bugs/1467743

Title:
  Lots of thumbnail requests with invalid size

Status in Canonical System Image:
  In Progress
Status in gallery-app package in Ubuntu:
  In Progress
Status in thumbnailer package in Ubuntu:
  New

Bug description:
  When using the ballery app, the thumbnailer gets loads of requests
  with QSize(-1,-1), for example, when opening the gallery app.

  The problem with this is that the thumbnailer interprets this to mean
  "give me the largest size you can (limited to a 1920x1920 bounding
  box). That's very expensive, especially in terms of disk space,
  because that 1920 "thumbnail" ends up going into the cache, needlessly
  hogging space.

  We are about to add a qWarning message to the QML side that reports
  invalid QSize requests. For now, we are going to retain the old
  behavior, but this will turn into an error soon.

  The most effective way to use the thumbnailer is to simply ask for an
  image in the desired size, with neither width nor height of -1. The
  thumbnailer will efficiently produce a thumbnail for that. (We do lots
  of internal caching to avoid extracting or downloading a thumbnail
  unnecessarily.)

  The thumbnailer may deliver a thumbnail that is smaller than what was
  asked for (because it never up-scales) so, if asked for a thumbnail of
  size 256, it's guaranteed not to be larger, but might be smaller (if
  the original image is smaller than what was asked for).

  Could you please adjust the gallery app behavior to ask for specific,
  valid sizes only?

  Running a tail -f on ~/.cache/upstart/dbus.log allows you to see the
  requests as they are made. Each request shows the size that was asked
  for.

To manage notifications about this bug go to:
https://bugs.launchpad.net/canonical-devices-system-image/+bug/1467743/+subscriptions