Weird rendering issue with 2 screens (Mac OS)

[gillesfernandez]

First of all, thank you for this ! It's been a while I wanted to code this and never took the time for it...

I tried it and everything worked really nice until I connected an external screen. I ran into a really weird issue : the content is downscaled and uses a quarter of the available size.

The issue only appears on one of the screen, with the lowest DPI. The weird part is that if I log the width in QML, it's the width of the window. And we can't see my mouse cursor on the screenshot, but it reacts normally.

So, only the rendering isn't what it should... I googled a bit and didn't find anything valuable... Any idea where to look at?

[gillesfernandez]

Took me a while but finally found something relevant... Looks like it's on Qt side : https://bugreports.qt.io/browse/QTBUG-58626

[dfct]

Wow, nice bug find on qt.io! Have you tried a pre Qt 5.8.0 version? While I wasn't using QML as you are, I otherwise haven't seen this in pre 5.8.0 projects on macOS.

[gillesfernandez]

Same issue with 5.7, we'll see for 5.9 !

[dfct]

Any luck with Qt 5.9? I can confirm that non-QML works in Qt 5.9 on macOS, just tested that today while fixing a bug introduced on the Windows side. (In related news, they reworked a lot of their DPI code, so 5.9 may very well have helped this!)

[coooooooorey]

I can confirm that non-QML works in Qt 5.9 on macOS

does that mean I can't use it in a qml application?
: (

thanks for your work~

[dfct]

@coooooooooorey I'm not sure if the bug linked above is still present as of 5.9. I don't use QML myself, so I don't have anything on hand to test with. Please do let me know if you have trouble if you give it a try!

[gillesfernandez]

I just installed Qt 5.9, I'll try it out this week and give you feedback but given the bug report, it is not fixed yet :(

[gillesfernandez]

Tested with Qt 5.9.1, same issue...

[dfct]

Ugh, dang. Do you have any simple sample code to repro it by chance?

[gillesfernandez]

There is a simple sample code attached here: https://bugreports.qt.io/browse/QTBUG-58626