Screen.pixelDensity is incorrect on all devices

[Olivier Tilloy]

I’m testing the Screen.pixelDensity attached property (http://doc.qt.io/qt-5/qml-qtquick-window-screen.html#pixelDensity-attached-prop) in a QML app on various devices (krillin, arale, flo), and the screen always reports the same incorrect value: 3.93701 px/mm.

I had a quick look at how this is implemented in QtQuick, and it calls into QScreen::physicalDotsPerInch(), which itself calls into QPlatformScreen::physicalSize(), which doesn’t appear to be reimplemented in QtUbuntu (UbuntuScreen).

For reference, I want to use that property to calculate the physical size of the screen, as a heuristic to determine the most suitable form factor.

[Olivier Tilloy (osomon)]

With the linked branch, I’m getting correct pixel density values for 3 devices:

  arale: 19.104950495049504 px/mm
  krillin: 9.48931735278791 px/mm
  flo: 12.673405367723944 px/mm

[Bill Filler (bfiller)]

@kgunn, grayback,
can we get a landing on this - looks like MR has been approved already
we need this fix for a browser bug we have

[Launchpad Janitor (janitor)]

This bug was fixed in the package qtubuntu - 0.62+16.04.20151105-0ubuntu1

---------------
qtubuntu (0.62+16.04.20151105-0ubuntu1) xenial; urgency=medium

  [ Nick Dedekind ]
  * Support server->client visibility change to stop rendering
    (lp:#1475678) (LP: #1475678)

  [ Olivier Tilloy ]
  * Re-implement QPlatformScreen::physicalSize(). (LP: #1504293)

 -- Michał Sawicz <email address hidden> Thu, 05 Nov 2015 16:56:48 +0000