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QScreen ClassThe QScreen class is used to query screen properties. More... #include <QScreen>Inherits: QObject. This class was introduced in Qt 5.0. Properties
Public Functions
Signals
Additional Inherited Members
Detailed DescriptionThe QScreen class is used to query screen properties. A note on logical vs physical dots per inch: physical DPI is based on the actual physical pixel sizes when available, and is useful for print preview and other cases where it's desirable to know the exact physical dimensions of screen displayed contents. Logical dots per inch are used to convert font and user interface elements from point sizes to pixel sizes, and might be different from the physical dots per inch. The logical dots per inch are sometimes user-settable in the desktop environment's settings panel, to let the user globally control UI and font sizes in different applications. Property Documentation
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| QRect | availableGeometry() const |
Notifier signal:
| void | availableGeometryChanged(const QRect & rect) |
availableSize : const QSize
This property holds the screen's available size in pixels.
The available size is the size excluding window manager reserved areas such as task bars and system menus.
Access functions:
| QSize | availableSize() const |
Notifier signal:
| void | availableSizeChanged(const QSize & size) |
depth : const int
This property holds the color depth of the screen.
Access functions:
| int | depth() const |
geometry : const QRect
This property holds the screen's geometry in pixels.
As an example this might return QRect(0, 0, 1280, 1024), or in a virtual desktop setting QRect(1280, 0, 1280, 1024).
Access functions:
| QRect | geometry() const |
Notifier signal:
| void | geometryChanged(const QRect & geometry) |
logicalDotsPerInch : const qreal
This property holds the number of logical dots or pixels per inch.
This value can be used to convert font point sizes to pixel sizes.
This is a convenience property that's simply the average of the logicalDotsPerInchX and logicalDotsPerInchY properties.
Access functions:
| qreal | logicalDotsPerInch() const |
Notifier signal:
| void | logicalDotsPerInchChanged(qreal dpi) |
See also logicalDotsPerInchX() and logicalDotsPerInchY().
logicalDotsPerInchX : const qreal
This property holds the number of logical dots or pixels per inch in the horizontal direction.
This value is used to convert font point sizes to pixel sizes.
Access functions:
| qreal | logicalDotsPerInchX() const |
Notifier signal:
| void | logicalDotsPerInchXChanged(qreal dpi) |
See also logicalDotsPerInchY().
logicalDotsPerInchY : const qreal
This property holds the number of logical dots or pixels per inch in the vertical direction.
This value is used to convert font point sizes to pixel sizes.
Access functions:
| qreal | logicalDotsPerInchY() const |
Notifier signal:
| void | logicalDotsPerInchYChanged(qreal dpi) |
See also logicalDotsPerInchX().
name : const QString
This property holds a user presentable string representing the screen.
For example, on X11 these correspond to the XRandr screen names, typically "VGA1", "HDMI1", etc.
Access functions:
| QString | name() const |
orientation : const Qt::ScreenOrientation
This property holds the screen orientation.
The screen orientation represents the physical orientation of the display. For example, the screen orientation of a mobile device will change based on the device is being held, and a desktop display might be rotated so that it's in portrait mode.
Qt::PrimaryOrientation is never returned.
Access functions:
| Qt::ScreenOrientation | orientation() const |
Notifier signal:
| void | orientationChanged(Qt::ScreenOrientation orientation) |
See also primaryOrientation() and orientationChanged().
physicalDotsPerInch : const qreal
This property holds the number of physical dots or pixels per inch.
This value represents the pixel density on the screen's display. Depending on what information the underlying system provides the value might not be entirely accurate.
This is a convenience property that's simply the average of the physicalDotsPerInchX and physicalDotsPerInchY properties.
Access functions:
| qreal | physicalDotsPerInch() const |
Notifier signal:
| void | physicalDotsPerInchChanged(qreal dpi) |
See also physicalDotsPerInchX() and physicalDotsPerInchY().
physicalDotsPerInchX : const qreal
This property holds the number of physical dots or pixels per inch in the horizontal direction.
This value represents the actual horizontal pixel density on the screen's display. Depending on what information the underlying system provides the value might not be entirely accurate.
Access functions:
| qreal | physicalDotsPerInchX() const |
Notifier signal:
| void | physicalDotsPerInchXChanged(qreal dpi) |
See also physicalDotsPerInchY().
physicalDotsPerInchY : const qreal
This property holds the number of physical dots or pixels per inch in the vertical direction.
This value represents the actual vertical pixel density on the screen's display. Depending on what information the underlying system provides the value might not be entirely accurate.
Access functions:
| qreal | physicalDotsPerInchY() const |
Notifier signal:
| void | physicalDotsPerInchYChanged(qreal dpi) |
See also physicalDotsPerInchX().
physicalSize : const QSizeF
This property holds the screen's physical size (in millimeters).
The physical size represents the actual physical dimensions of the screen's display.
Depending on what information the underlying system provides the value might not be entirely accurate.
Access functions:
| QSizeF | physicalSize() const |
primaryOrientation : const Qt::ScreenOrientation
This property holds the primary screen orientation.
The primary screen orientation is Qt::LandscapeOrientation if the screen geometry's width is greater than or equal to its height, or Qt::PortraitOrientation otherwise.
Access functions:
| Qt::ScreenOrientation | orientation() const |
Notifier signal:
| void | primaryOrientationChanged(Qt::ScreenOrientation orientation) |
See also primaryOrientationChanged().
refreshRate : const qreal
This property holds the approximate vertical refresh rate of the screen in Hz.
Access functions:
| qreal | refreshRate() const |
Notifier signal:
| void | refreshRateChanged(qreal refreshRate) |
size : const QSize
This property holds the pixel resolution of the screen.
Access functions:
| QSize | size() const |
Notifier signal:
| void | sizeChanged(const QSize & size) |
Member Function Documentation
int QScreen::angleBetween(Qt::ScreenOrientation a, Qt::ScreenOrientation b) const
Convenience function to compute the angle of rotation to get from rotation a to rotation b.
The result will be 0, 90, 180, or 270.
Qt::PrimaryOrientation is interpreted as the screen's primaryOrientation().
QRect QScreen::availableVirtualGeometry() const
QSize QScreen::availableVirtualSize() const
QPixmap QScreen::grabWindow(WId window, int x, int y, int w, int h)
Creates and returns a pixmap constructed by grabbing the contents of the given window restricted by QRect(x, y, width, height).
The arguments (x, y) specify the offset in the window, whereas (width, height) specify the area to be copied. If width is negative, the function copies everything to the right border of the window. If height is negative, the function copies everything to the bottom of the window.
The window system identifier (WId) can be retrieved using the QWidget::winId() function. The rationale for using a window identifier and not a QWidget, is to enable grabbing of windows that are not part of the application, window system frames, and so on.
The grabWindow() function grabs pixels from the screen, not from the window, i.e. if there is another window partially or entirely over the one you grab, you get pixels from the overlying window, too. The mouse cursor is generally not grabbed.
Note on X11 that if the given window doesn't have the same depth as the root window, and another window partially or entirely obscures the one you grab, you will not get pixels from the overlying window. The contents of the obscured areas in the pixmap will be undefined and uninitialized.
On Windows Vista and above grabbing a layered window, which is created by setting the Qt::WA_TranslucentBackground attribute, will not work. Instead grabbing the desktop widget should work.
Warning: In general, grabbing an area outside the screen is not safe. This depends on the underlying window system.
QPlatformScreen * QScreen::handle() const
Get the platform screen handle.
bool QScreen::isLandscape(Qt::ScreenOrientation o) const
Convenience function to check if a screen orientation is either landscape or inverted landscape.
Qt::PrimaryOrientation is interpreted as the screen's primaryOrientation().
bool QScreen::isPortrait(Qt::ScreenOrientation o) const
Convenience function to check if a screen orientation is either portrait or inverted portrait.
Qt::PrimaryOrientation is interpreted as the screen's primaryOrientation().
QRect QScreen::mapBetween(Qt::ScreenOrientation a, Qt::ScreenOrientation b, const QRect & rect) const
Maps the rect between two screen orientations.
This will flip the x and y dimensions of the rectangle if orientation is Qt::PortraitOrientation or Qt::InvertedPortraitOrientation and orientation is Qt::LandscapeOrientation or Qt::InvertedLandscapeOrientation, or vice versa.
Qt::PrimaryOrientation is interpreted as the screen's primaryOrientation().
Qt::ScreenOrientation QScreen::primaryOrientation() const
QTransform QScreen::transformBetween(Qt::ScreenOrientation a, Qt::ScreenOrientation b, const QRect & target) const
Convenience function to compute a transform that maps from the coordinate system defined by orientation a into the coordinate system defined by orientation b and target dimensions target.
Example, a is Qt::Landscape, b is Qt::Portrait, and target is QRect(0, 0, w, h) the resulting transform will be such that the point QPoint(0, 0) is mapped to QPoint(0, w), and QPoint(h, w) is mapped to QPoint(0, h). Thus, the landscape coordinate system QRect(0, 0, h, w) is mapped (with a 90 degree rotation) into the portrait coordinate system QRect(0, 0, w, h).
Qt::PrimaryOrientation is interpreted as the screen's primaryOrientation().
QRect QScreen::virtualGeometry() const
QList<QScreen *> QScreen::virtualSiblings() const
Get the screen's virtual siblings.
The virtual siblings are the screen instances sharing the same virtual desktop. They share a common coordinate system, and windows can freely be moved or positioned across them without having to be re-created.