At QWindowPrivate::init time we initialize the cached device pixel ratio
from the target screen's device pixel ratio. Once the window is created
we then pick it up from the platform window, but at that point the
window may not yet be part of a UIWindow hierarchy with a UIScreen,
in which case the UIView reports a contentScale of 1. Once the window
is shown, the content scale starts reflecting the UISCreen.
To avoid the intermediate step of reflecting a DPR of 1, which also
triggers a warning from QGuiApplicationPrivate::processExposeEvent,
we reflect the window's QScreen DPR as long as it doesn't have an
associated UISCreen.
Fixes: QTBUG-125479
Pick-to: 6.7
Change-Id: I0e038e3c3f0bfff116e0910d24e85cc817c890d4
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
(cherry picked from commit 31f9f80ad38177605a3011b6fde70e3a8d536d47)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
8e61693bea