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 NamePlugin Class NameDescription
qandroidQAndroidPlatformIntegrationAndroid support
qbsdfbQBsdFbIntegrationBsdFb support
qcocoaQCocoaIntegrationPluginCocoa support
qdirect2dQWindowsDirect2DIntegrationPluginSimilar to the qwindows plugin, but replaces the raster paint engine with a Direct2D-based paint engine for QPixmap and QBackingStore.
qdirectfbQDirectFbIntegrationPluginDirectFB is centered around surfaces, which are the equivalent of a QPaintDevice.
qeglfsQEglFSIntegrationPluginEGLFS support for embedded Linux devices.
qhaikuQHaikuIntegrationHaiku support
qiosQIOSIntegrationPluginiOS support
qlinuxfbQLinuxFbIntegrationPluginLinuxFB support for embedded Linux devices.
qmirclientQMirClientIntegrationMir client support
qopenwfQOpenWFDIntegrationPluginOpenWF Display support for managing display control hardware.
qqnxQQnxIntegrationPluginQNX support
qvncQVncIntegrationVNC support
qwayland
  • QWaylandIntegrationPlugin
  • QWaylandBrcmEglPlatformIntegrationPlugin
  • QWaylandEglPlatformIntegrationPlugin
  • QWaylandXCompositeEglPlatformIntegrationPlugin
  • QWaylandXCompositeGlxPlatformIntegrationPlugin
Wayland support
qwindowsQWindowsIntegrationPluginWindows support
qwinrtQWinRTIntegrationPluginWinRT and Windows Phone support
qxcbQXcbIntegrationPluginX Window System (X11) support

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