int QDesktopWidget::numScreens() const
{
QScreen *screen = QScreen::instance();
if (!screen)
return 0;
const QList<QScreen*> subScreens = screen->subScreens();
return qMax(subScreens.size(), 1);
}
static inline QScreen *getPrimaryScreen()
{
QScreen *screen = QScreen::instance();
if (!screen->base()) {
QList<QScreen*> subScreens = screen->subScreens();
if (subScreens.size() < 1)
return 0;
screen = subScreens.at(0);
}
return screen;
}
QT_BEGIN_NAMESPACE
static QScreen *screenForDevice(QPaintDevice *device)
{
QScreen *screen = qt_screen;
if (!screen)
return 0;
if (screen->classId() == QScreen::MultiClass) {
int screenNumber;
if (device && device->devType() == QInternal::Widget)
screenNumber = qApp->desktop()->screenNumber(static_cast<QWidget *>(device));
else
screenNumber = 0;
screen = screen->subScreens()[screenNumber];
}
while (screen->classId() == QScreen::ProxyClass ||
screen->classId() == QScreen::TransformedClass) {
screen = static_cast<QProxyScreen *>(screen)->screen();
}
return screen;
}
QT_BEGIN_NAMESPACE
#ifdef Q_WS_QWS
#ifndef QT_NO_DIRECTPAINTER
/*!
\class QDirectPainter
\ingroup painting
\ingroup qws
\brief The QDirectPainter class provides direct access to the
underlying hardware in Qt for Embedded Linux.
Note that this class is only available in \l{Qt for Embedded Linux}.
QDirectPainter allows a client application to reserve a region of
the framebuffer and render directly onto the screen. There are two
ways of using the QDirectPainter class: You can either reserve a
region using the provided static functions, or you can instantiate
an object and make use of its more dynamic API.
\tableofcontents
\section1 Dynamic Allocation
By instantiating a QDirectPainter object using the default
QDirectPainter::NonReserved surface flag, the client application
only gets some control over the reserved region, i.e., it can
still render directly onto the screen but the allocated region may
change (for example, if a window with a higher focus requests
parts of the same region). The currently allocated region can be
retrieved using the allocatedRegion() function, while the
requestedRegion() function returns the originally reserved
region.
\section1 Static Allocation
Using the static approach, the client application gets complete
control over the reserved region, i.e., the affected region will
never be modified by the screen driver.
To create a static region, pass the QDirectPainter::Reserved
surface flag to the constructor. After the reserved region is
reported through regionChanged(), the allocated region will not
change, unless setRegion() is called.
If QDirectPainter::ReservedSynchronous is passed to the
constructor, calls to setRegion() will block until the region is
reserved, meaning that allocatedRegion() will be available immediately.
Note that in the current version setRegion() will cause the application
event loop to be entered, potentially causing reentrancy issues.
\section1 Rendering
To draw on a given region, the application must first get hold of
a pointer to the framebuffer. In most cases, this pointer can be
retrieved using the QDirectPainter::frameBuffer() function. But
note that if the current screen has subscreens, you must query the
screen driver instead to identify the correct subscreen. A pointer
to the current screen driver can always be retrieved using the
static QScreen::instance() function. Then use QScreen's \l
{QScreen::}{subScreenIndexAt()} and \l {QScreen::}{subScreens()}
functions to access the correct subscreen, and the subscreen's \l
{QScreen::}{base()} function to retrieve a pointer to the
framebuffer.
Depending on the hardware, it might be necessary to lock the
framebuffer for exclusive use while writing to it. This is
possible using the lock() and unlock() functions. Note that
calling lock() will prevent all other applications from working
until unlock() is called.
In addition, QDirectPainter provides several functions returning
information about the framebuffer: the linestep() function returns
the length (in bytes) of each scanline of the framebuffer while
the screenDepth(), screenWidth() and screenHeight() function
return the screen metrics.
\sa QScreen, QWSEmbedWidget, {Qt for Embedded Linux Architecture}
*/
/*!
\enum QDirectPainter::SurfaceFlag
This enum describes the behavior of the region reserved by this
QDirectPainter object.
\value NonReserved The allocated region may change, e.g., if a
window with a higher focus requests parts of the same region. See
also \l {Dynamic Allocation}.
\value Reserved The allocated region will never change. See also
\l {Static Allocation}.
\value ReservedSynchronous The allocated region will never change and
each function that changes the allocated region will be blocking.
\sa allocatedRegion()
*/
/*!
\fn QRegion QDirectPainter::region()
\obsolete
Use QDirectPainter::allocatedRegion() instead.
*/
static inline QScreen *getPrimaryScreen()
{
QScreen *screen = QScreen::instance();
if (!screen->base()) {
QList<QScreen*> subScreens = screen->subScreens();
if (subScreens.size() < 1)
return 0;
screen = subScreens.at(0);
}
return screen;
}
