Problems displaying fonts in 4k monitors

[lornat75]

All guis have problems displaying fonts in high-res monitors.

The problems is probably this one:
http://doc.qt.io/qt-5/highdpi.html

can be fixed by adding qputenv("QT_DEVICE_PIXEL_RATIO", QByteArray("2")); in the main.

Thanks @aitek4iit

[lornat75]

Checking the documentation more carefully we need to ensure that the line:

qputenv("QT_DEVICE_PIXEL_RATIO",QByteArray("2"));

does not cause problems to systems with low-resolution. More importantly this feature is deprecated in qt 5.6, so we need to make it version specific and remove it once we stop supporting qt 5.4 and (probably) 5.5.

[lornat75]

These commits have been reverted because did mess up the visualization on normal screens. As reported by @pattacini for testing. They did work on my VM Linux unbuntu 10.04.

[lornat75]

Looks like the safest solution at the moment is to leave to the user to set the environment variable:

QT_DEVICE_PIXEL_RATIO = 2

This can be done at the system level (recommended) in the control panel or on each terminal.

[lornat75]

Proper fix should be done using new features in qt-5.6.

@mbrunettini maybe in the next release of the binaries we should replace qt-5.4 with qt-5.6 .

@drdanz, @aitek4iit what do you think?

[pattacini]

Quick update: together with @lornat75 we've tested that QT_DEVICE_PIXEL_RATIO = auto works for both high-res and normal systems.

[lornat75]

@pattacini I have updated the pull request, would you mind give it a try?

[pattacini]

@lornat75 it works nicely; just merged!

(devel updated too)

[lornat75]

Ok. Thanks, leaving this open until we fix the problem in Qt 5.6 using appropriate functions.

[mbrunettini]

Ok, I will update to Qt 5.6 where it is supported.

[aitek4iit]

Yes the AUTO flag should do the trick for both resolution and I think Qt 5.6 wolud manage better the high dpi resolutions beacuse in the 5.4 version this feature was only a beta.

[mbrunettini]

QT 5.6 is only avavilabe on windows with the following versions:
-VS 2013 (V12) 32 and 64 bit
-VS 2015 (V14) 32 and 64 bit

[claudiofantacci]

I'm writing here concerning about QT_DEVICE_PIXEL_RATIO qtputenv option.

Under macOS, QT version 5.7.0 (from brew), launching yaprdataplayer, yaprview, yarpmotorgui, the following warning is raised:

Warning: QT_DEVICE_PIXEL_RATIO is deprecated. Instead use: 
    QT_AUTO_SCREEN_SCALE_FACTOR to enable platform plugin controlled per-screen factors. 
    QT_SCREEN_SCALE_FACTORS to set per-screen factors. 
    QT_SCALE_FACTOR to set the application global scale factor.

Probably QT_AUTO_SCREEN_SCALE_FACTOR set to 1 (boolean true) will make the job done.

Ref: http://doc.qt.io/qt-5/highdpi.html#high-dpi-support-in-qt

[drdanz]

@claudiofantacci Opened a new issue, see #1038

[Nicogene]

Changes introduced in #1200 should solve, for now I close this issue, if someone encounter some problems I will re-open it