touch-packages team mailing list archive

[Michi Henning <michi.henning@xxxxxxxxxxxxx>]

It looks like this seriously affects the user experience too.

Take about 40-50 photos. Run gallery-app. Go to the photo roll.

Scroll up and down until all the thumbnails have been generated. (This
loads up the cache.)

Run tail -f ~/.cache/upstart/dbus.log on the phone.

Now scroll up and down in the photo roll.

The trace shows that all the thumbnail requests are made with
QSize(-1,-1). The thumbnailer delivers each thumbnail in around 1.5
msec. But the screen shows lots of spinners for quite some time.
Presumably, that's happening because all the thumbnails are 1920 in
size, but need to be scaled down to the size required on-screen. Asking
for the thumbnails in the correct size would make things go considerably
faster, I suspect.

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Touch seeded packages, which is subscribed to thumbnailer in Ubuntu.
https://bugs.launchpad.net/bugs/1467743

Title:
  Lots of thumbnail requests with invalid size

Status in Gallery App:
  New
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.

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