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Please review the following information to ensure ** the GNU Free Documentation License version 1.3 requirements ** will be met: https://www.gnu.org/licenses/fdl-1.3.html. ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \module QtGui \title Qt GUI C++ Classes \ingroup modules \qtvariable gui \brief The Qt GUI module provides the basic enablers for graphical applications written with Qt. The Qt GUI module provides classes for windowing system integration, event handling, OpenGL and OpenGL ES integration, Vulkan integration, 2D graphics, imaging, fonts and typography. These classes are used internally by Qt's user interface technologies and can also be used directly, for instance to write applications using low-level OpenGL ES graphics APIs. */ /*! \page qtgui-index.html \title Qt GUI The Qt GUI module provides classes for windowing system integration, event handling, OpenGL and OpenGL ES integration, 2D graphics, basic imaging, fonts and text. These classes are used internally by Qt's user interface technologies and can also be used directly, for instance to write applications using low-level OpenGL ES graphics APIs. For application developers writing user interfaces, Qt provides higher level API's, like Qt Quick, that are much more suitable than the enablers found in the Qt GUI module. \if !defined(qtforpython) \include module-use.qdocinc using qt module \quotefile overview/using-qt-gui.cmake See also the \l[QtDoc]{Build with CMake} overview. \section2 Building with qmake If you use \l qmake to build your projects, Qt GUI is included by default. To disable Qt GUI, add the following line to your \c .pro file: \snippet code/doc_src_qtgui.pro 1 \endif \section1 Application Windows The most important classes in the Qt GUI module are QGuiApplication and QWindow. A Qt application that wants to show content on screen, will need to make use of these. QGuiApplication contains the main event loop, where all events from the window system and other sources are processed and dispatched. It also handles the application's initialization and finalization. The \l QWindow class represents a window in the underlying windowing system. It provides a number of virtual functions to handle events (\l {QEvent}) from the windowing system, such as touch-input, exposure, focus, key strokes and geometry changes. \section1 2D Graphics The Qt GUI module contains classes for 2D graphics, imaging, fonts and advanced typography. A \l QWindow created with the surface type \l {QSurface::RasterSurface} can be used in combination with \l {QBackingStore} and \l {QPainter}, Qt's highly optimized 2D vector graphics API. QPainter supports drawing lines, polygons, vector paths, images and text. For more information, see \l{Paint System} and \l {Raster Window Example}. Qt can load and save images using the \l QImage and \l QPixmap classes. By default, Qt supports the most common image formats including JPEG and PNG among others. Users can add support for additional formats via the \l QImageIOPlugin class. For more information, see \l {Reading and Writing Image Files} Typography in Qt is done with \l QTextDocument which uses the \l QPainter API in combination with Qt's font classes, primarily QFont. Applications that prefer more low-level APIs to text and font handling, classes like QRawFont and QGlyphRun can be used. \section1 OpenGL and OpenGL ES Integration QWindow supports rendering using OpenGL and OpenGL ES, depending on what the platform supports. OpenGL rendering is enabled by setting the QWindow's surface type to QSurface::OpenGLSurface, choosing the format attributes with QSurfaceFormat, and then creating a QOpenGLContext to manage the native OpenGL context. In addition, Qt has QOpenGLPaintDevice, which enables the use of OpenGL accelerated QPainter rendering, as well as convenience classes that simplify the writing of OpenGL code and hides the complexities of extension handling and the differences between OpenGL ES 2 and desktop OpenGL. The convenience classes include QOpenGLFunctions that lets an application use all the OpenGL ES 2 functions on desktop OpenGL without having to manually resolve the OpenGL function pointers, thus allowing cross-platform development of applications targeting mobile or embedded devices, and some classes that wrap native OpenGL functionality in a simpler Qt API: \list \li QOpenGLBuffer \li QOpenGLFramebufferObject \li QOpenGLShaderProgram \li QOpenGLTexture \li QOpenGLDebugLogger \li QOpenGLTimerQuery \li QOpenGLVertexArrayObject \endlist Finally, in order to provide better support for the newer versions (3.0 and higher) of OpenGL, a versioned function wrapper mechanism is also available: The QOpenGLFunction_N_N family of classes expose all the functions in a given OpenGL version and profile, allowing easy development of desktop applications relying on modern, desktop-only OpenGL features. For more information, see the \l {OpenGL Window Example}. The Qt GUI module also contains a few math classes to aid with the most common mathmatical operations related to 3D graphics. These classes include \l {QMatrix4x4}, \l {QVector4D} and \l {QQuaternion} A \l {QWindow} created with the \l {QSurface::OpenGLSurface} can be used in combination with \l QPainter and \l QOpenGLPaintDevice to have OpenGL hardware accelerated 2D graphics, by sacrificing some of the visual quality. \section1 Vulkan Integration Qt 5.10 added support for \l {Vulkan}. This requires the presence of the \l{LunarG Vulkan SDK}. On Windows, the SDK sets the environment variable \c {VULKAN_SDK}, which will be detected by the \c {configure} script. On Android, Vulkan headers were added in API level 24 of the NDK. Relevant classes: \list \li QVulkanDeviceFunctions \li QVulkanExtension \li QVulkanFunctions \li QVulkanInfoVector \li QVulkanInstance \li QVulkanWindow \li QVulkanWindowRenderer \endlist For more information, see the \l{Hello Vulkan Widget Example} and the \l {Hello Vulkan Window Example}. \section1 Drag and Drop More info in \l{Drag and Drop} \section1 Licenses and Attributions Qt GUI is available under commercial licenses from \l{The Qt Company}. In addition, it is available under free software licenses. Since Qt 5.4, these free software licenses are \l{GNU Lesser General Public License, version 3}, or the \l{GNU General Public License, version 2}. See \l{Qt Licensing} for further details. Furthermore, Qt GUI in Qt \QtVersion may contain third-party modules under following permissive licenses: \generatelist{groupsbymodule attributions-qtgui} \section1 Reference \list \li \l{Qt GUI C++ Classes} \list \li \l{Event Classes} \li \l{Painting Classes} \li \l{Rendering in 3D} \endlist \endlist */