There is a mix between screen device pixel ratio. Currently we store the
property on a per-window basis, but the change notifications are still
on a per screen basis which can fall apart on edge cases.
On wayland we are getting per window DPR changes without as useful
screen change events so it's important to fix. It also has potential to
clean up the Windows backend in the future where the backend is
currently papering over the two concepts.
This patch introduces two new events:
A QWindowSystemInterface to trigger a window DPR change
independently of a screen change.
An event to notify windows the new DPR rather than needing to track
signals on the screen. This happens either when the window dpr changes
or implicitly through a screen change. This can deprecate an existing
event ScreenChangeInternal so the value is reused and renamed for
clarity.
Change-Id: I637a07fd4520ba3184ccc2c987c29d8d23a65ad3
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
ab449c205c