Uses the information provided by the Wayland outputs to setup the data
about the available screens.
In order to properly work together with the X Server the implementation
syncs the data to the X system using XRandR. If XRandR is not available
this is most likely going to not work correctly.
Screens provides a size which is constructed from the size of
the bounding geometry of all screens and provides an overload taking
an int to return the size of a specified screen. For geometry() a new
ovload is added without an argument, which is just a convenient wrapper
for QRect(QPoint(0, 0), size()).
Both new methods are exported to effects and scripting as new
properties there called virtualScreenSize and virtualScreenGeometry.
The (virtual) size gets cached in screens and is updated whenever the
count or geometry changes.
Construction of Screens is slightly changed by moving the init code
from ctor into a virtual method init(). Reason is that we ended in
a loop with accessing the singleton pointer before it was set.
REVIEW: 116114
largely reverts b164e9912c9b5f9c9ae619bbd79355d317174115
which prevented the crash but due to early screen updating
causes issues with scene/overlay update on at least intel chips
BUG: 322970
FIXED-IN: 4.11
CCBUG: 322156
REVIEW: https://git.reviewboard.kde.org/r/111811/
Following the approaches of other split out functionality Screens is a
singleton class created by Workspace.
The class takes over the responsibility for:
* screenChanged signal delayed by timer
* number of screens
* geometry of given screen
* active screen
* config option for active screen follows mouse
The class contains a small abstraction layer and has a concrete subclass
wrapping around QDesktopWidget, but the idea is to go more low level and
interact with XRandR directly to get more detailed information.
All over KWin the usage from QDesktopWidget is ported over to the new
Screens class.
REVIEW: 109839
