[Qt-interest] Screen coordinates inQGraphicsItem::hoverEnterEvent() ?

[Atlant Schmidt]

Ross:

> That is to say, all QDesktopWidget::screenGeometry(x) rects
> are part of a continuous plane.
>
> Perhaps this is not the case on X11?

  I can't say for sure for early Windows, but this definitely
  *WASN'T* the case for X-Windows; each X-Windows physical
  display was an entirely separate entity with a separate
  coordinate system and windows *COULD NOT* span across
  multiple monitors.

  Later, a bit of software called Xinerama (a pun on the
  motion picture format called Cinerama) allowed the fusing
  of multiple X physical displays into a single virtual display.

    http://en.wikipedia.org/wiki/Xinerama

    http://en.wikipedia.org/wiki/Cinerama


  For a while, it had the amusing bug that I referred to in
  my immediately-previous reply where dialog boxes and other
  pop-ups would appear in the exact center of the virtual
  display. If you had two identical physical displays, that
  meant the dialog box was split into two parts by the bezels
  of the monitors. If you had four identical displays arranged
  as a rectangle (as some stock trading stations did), the dialog
  box appeared split into quarters spread across the four displays.

  Ahh, Xinerama!

                                Atlant


-----Original Message-----
From: qt-interest-bounces+aschmidt=dekaresearch.com at qt.nokia.com [mailto:qt-interest-bounces+aschmidt=dekaresearch.com at qt.nokia.com] On Behalf Of Ross Bencina
Sent: Thursday, June 02, 2011 03:14
To: bdaunas at free.fr; qt-interest at qt.nokia.com
Subject: Re: [Qt-interest] Screen coordinates inQGraphicsItem::hoverEnterEvent() ?

Hello Bertrand

You wrote:
> Unfortunately, I feel, but hopefully will be proven wrong, that your
> suggestion will not work in a multi-screen environment, and that is a
> requirement for my app.
>
> In such an environment, the same global screen pos can refer to
> different screens, hence different widgets, and again I have no way
> that I am aware of, to differentiate between those screens.

This has not been my experience (on Windows and Mac OS) perhaps I am
mistaken, however my understanding is that:

"screenPos()" always refers to a position in a single, unified, global
coordinate system that spans all screens.

That is to say, all QDesktopWidget::screenGeometry(x) rects are part of a
continuous plane.

Perhaps this is not the case on X11?

Perhaps this behavior is dependent on the result of
QDesktopWidget::isVirtualDesktop()?

I suspect (but am not sure) that you are discussing the case where
(QDesktopWidget::isVirtualDesktop() == false) -- can you clarify please?

Thanks

Ross.

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