Pick screen color

[fabiencastan]

http://qt-project.org/doc/qt-5/qscreen.html#grabWindow

Sample code from QColorDialogPrivate:

QColor QColorDialogPrivate::grabScreenColor(const QPoint &p)
{ const QDesktopWidget *desktop = QApplication::desktop(); const QPixmap pixmap = QGuiApplication::screens().at(desktop->screenNumber())->grabWindow(desktop->winId(), p.x(), p.y(), 1, 1); QImage i = pixmap.toImage(); return i.pixel(0, 0); }

See grabScreenColor:
https://qt.gitorious.org/qt/qtbase/source/73a1e8c60d894701f34806cc4b847aa2814bf389:src/widgets/dialogs/qcolordialog.cpp#L1500

See _q_pickScreenColor:
https://qt.gitorious.org/qt/qtbase/source/73a1e8c60d894701f34806cc4b847aa2814bf389:src/widgets/dialogs/qcolordialog.cpp#L1540

See QColorPickingEventFilter:
https://qt.gitorious.org/qt/qtbase/source/73a1e8c60d894701f34806cc4b847aa2814bf389:src/widgets/dialogs/qcolordialog.cpp#L432