Hi!
I see that the first decisive commit is already merged but I'd like to
comment on it anyway:
On Mon, 2 Mar 2015, Rutledge Shawn wrote:
It may be a surprise though, for some applications, that
QGuiApplication::primaryScreen() can return null in the case where there
is really no screen attached. It’s a rare use case, but it’s possible
that some applications could crash if they are using that pointer at the
wrong time, without checking. And there are also some platforms where a
dummy screen will normally exist even if no actual monitors are
connected. It’s just that it doesn’t seem to be necessary to have one
on xcb, so we are trying to avoid needing to create one artificially.
It seems right to have the code modeling the real world: if there is
nothing on which you can view the graphical output of your application,
then there should not be a QScreen instance.
Does anyone have any objection?
I would favor an "invalid" QScreen instance to be returned instead. At
least from the public QGuiApplication API.
A function that "maybe" returns null on "some platforms" puts an onus on a
diligent developer using this function. Thus work is created for everyone
to cover a scenario that will happen for a very few in very seldom cases.
Our own software was not prepared for a similar case until last week: we
relied on the xcb plugin returning an X11 Display pointer when querying it
for "display". Until the first customer had build Qt without xlib
support...
Harri.
PS: The documentation of the (internal) QPlatformWindow::screen()
implementation would need updating too:
https://codereview.qt-project.org/#/c/87885/20/src/gui/kernel/qplatformwindow.cpp
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