QScreen

QScreen is a class in the QtGui module of the Qt application framework. It represents a display device in a multi-monitor environment and provides access to a screen’s geometric and perceptual properties. Each screen object exposes information such as its geometry in pixels, available geometry, physical size in millimeters, color depth, refresh rate, and DPI-related metrics, as well as the device pixel ratio used for HiDPI scaling. QScreen is a QObject-derived class and can emit signals when its properties change, enabling responsive UI updates when displays are added, removed, or settings change.

Key properties and methods commonly used with QScreen include geometry(), availableGeometry(), and size() to determine layout bounds; physicalSize() for the physical dimensions; depth() for color depth in bits per pixel; refreshRate() for the display refresh rate; logicalDotsPerInch() and physicalDotsPerInch() for DPI information; devicePixelRatio() and devicePixelRatioF() for HiDPI scaling; device name via name() and other identification details. These facilities support dynamic UI adaptation in applications that run on multiple screens or high-DPI displays.

QScreen is part of modern multi-screen management in Qt. Applications typically obtain screen objects through QGuiApplication::primaryScreen() or QGuiApplication::screens() to enumerate all available displays and adjust windows, pens, fonts, and layouts accordingly. In Qt, QScreen complements or replaces older infrastructure such as QDesktopWidget and is central to handling display properties in Qt's platform abstraction layer.

Example usage commonly includes retrieving the primary screen to query geometry or DPI, e.g., QScreen* screen = QGuiApplication::primaryScreen(); QRect g = screen->geometry(); int dpr = screen->devicePixelRatio();.