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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