Qt Platform Abstraction

The Qt Platform Abstraction (QPA) is the platform abstraction layer for Qt 5 and replaces Qt for Embedded Linux and the platform ports from Qt 4.

QPA plugins are implemented by subclassing various QPlatform* classes. There are several root classes, such as QPlatformIntegration and QPlatformWindow for window system integration and QPlatformTheme for deeper platform theming and integration. QStyle is not a part of QPA.

There are no source or binary compatibility guarantees for the QPA classes, meaning that a platform plugin is only guaranteed to work with the Qt version it was developed against. API changes will however only be made in minor releases. (5.1, 5.2, and so on.)

QPA Minimal Plugins

There is no detailed tutorial documentation for writing QPA plugins at this time. However, there are two minimal plugins shipped with Qt 5 for testing and other special purposes that you can use as examples:

• qtbase/src/plugins/platforms/minimal/
• qtbase/src/plugins/platforms/minimalegl/

The qminimal plugin is used for tools that link against Qt GUI, but do not require window system integration (for example, qmlplugindump). It also has diagnostic support for dumping window contents to image files as determined by environment variables.

Class Overview

• QPlatformIntegration
  • QAbstractEventDispatcher
  • QPlatformAccessibility
  • QPlatformBackingStore
  • QPlatformClipboard
  • QPlatformCursor
  • QPlatformDrag
  • QPlatformFontDatabase
  • QPlatformGraphicsBuffer
  • QPlatformInputContext
  • QPlatformNativeInterface
  • QPlatformOffscreenSurface
  • QPlatformOpenGLContext
  • QPlatformScreen
  • QPlatformServices
  • QPlatformSharedGraphicsCache
  • QPlatformSurface
  • QPlatformWindow
• QPlatformTheme
  • QPlatformDialogHelper
  • QPlatformMenu
  • QPlatformMenuBar
  • QPlatformMenuItem
  • QPlatformSystemTrayIcon
  • platform palettes
  • platform fonts
  • theme hints

qtbase/src/platformsupport contains several helper classes for implementing platform plugins on Unix-like systems.

QPA Plugins

The following table summarizes the platform plugins available for QPA:

Plugin Name	Plugin Class Name	Description
qandroid	QAndroidPlatformIntegration	Android support
qbsdfb	QBsdFbIntegration	BsdFb support
qcocoa	QCocoaIntegrationPlugin	Cocoa support
qdirect2d	QWindowsDirect2DIntegrationPlugin	Similar to the qwindows plugin, but replaces the raster paint engine with a Direct2D-based paint engine for QPixmap and QBackingStore.
qdirectfb	QDirectFbIntegrationPlugin	DirectFB is centered around surfaces, which are the equivalent of a QPaintDevice.
qeglfs	QEglFSIntegrationPlugin	EGLFS support for embedded Linux devices.
qhaiku	QHaikuIntegration	Haiku support
qios	QIOSIntegrationPlugin	iOS support
qlinuxfb	QLinuxFbIntegrationPlugin	LinuxFB support for embedded Linux devices.
qmirclient	QMirClientIntegration	Mir client support
qopenwf	QOpenWFDIntegrationPlugin	OpenWF Display support for managing display control hardware.
qqnx	QQnxIntegrationPlugin	QNX support
qvnc	QVncIntegration	VNC support
qwayland	QWaylandIntegrationPlugin QWaylandBrcmEglPlatformIntegrationPlugin QWaylandEglPlatformIntegrationPlugin QWaylandXCompositeEglPlatformIntegrationPlugin QWaylandXCompositeGlxPlatformIntegrationPlugin	Wayland support
qwindows	QWindowsIntegrationPlugin	Windows support
qwinrt	QWinRTIntegrationPlugin	WinRT and Windows Phone support
qxcb	QXcbIntegrationPlugin	X Window System (X11) support
webgl	QWebGLIntegrationPlugin	WebGL support for Qt Quick applications