/**************************************************************************** ** ** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies). ** Contact: http://www.qt-project.org/ ** ** This file is part of the documentation of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:FDL$ ** GNU Free Documentation License ** Alternatively, this file may be used under the terms of the GNU Free ** Documentation License version 1.3 as published by the Free Software ** Foundation and appearing in the file included in the packaging of ** this file. ** ** Other Usage ** Alternatively, this file may be used in accordance with the terms ** and conditions contained in a signed written agreement between you ** and Nokia. ** ** ** ** ** ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \module QtGui \title The Qt GUI Module \ingroup modules \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, 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. To include the definitions of the module's classes, use the following directive: \snippet code/doc_src_qtgui.pro 0 See the \l {Qt GUI Module Overview} for more details. */ /*! \page qtgui-overview.html \title Qt GUI Module Overview 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. than the enablers found in the Qt GUI module. \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 desktop OpenGL, OpenGL ES 1.1 and OpenGL ES 2.0, 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 and some classes that wrap native OpenGL resources in a simpler Qt API: QOpenGLBuffer, QOpenGLFramebufferObject, and QOpenGLShaderProgram. 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 accellerated 2D graphics, by sacrificing some of the visual quality. \section1 Qt GUI prior to Qt 5.0 Prior to Qt 5.0, the Qt GUI library was the monolithic container for all things relating to graphical user interfaces in Qt, and included the Qt widget set, the item views, the graphics view framework and also printing. Starting Qt 5, these classes have been moved to the QtWidgets library. Printing has been moved to the QtPrintSupport library. Please note that these libraries can be excluded from a Qt installation. QtGui now contains only a small set of enablers, which are generally useful for all graphical applications. */ /* ### DOC-TODO: link under OpenGL to hello-opengl for QWindow in examples/gui/opengl/openglwindow. Idea: QWindow which draws a triangle using GLES 2.0 compatible shaders. Do not care about 1.1 API as almost everyone has 2.0 support these days. */