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<td >Qt 5.12</td><td >Qt GUI</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right">Qt 5.12.6 Reference Documentation</td>
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<h3><a name="toc">Contents</a></h3>
<ul>
<li class="level1"><a href="#using-the-module">Using the Module</a></li>
<li class="level2"><a href="#building-with-cmake">Building with CMake</a></li>
<li class="level2"><a href="#building-with-qmake">Building with qmake</a></li>
<li class="level1"><a href="#application-windows">Application Windows</a></li>
<li class="level1"><a href="#2d-graphics">2D Graphics</a></li>
<li class="level1"><a href="#opengl-and-opengl-es-integration">OpenGL and OpenGL ES Integration</a></li>
<li class="level1"><a href="#vulkan-integration">Vulkan Integration</a></li>
<li class="level1"><a href="#drag-and-drop">Drag and Drop</a></li>
<li class="level1"><a href="#licenses-and-attributions">Licenses and Attributions</a></li>
<li class="level1"><a href="#reference">Reference</a></li>
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<h1 class="title">Qt GUI</h1>
<span class="subtitle"></span>
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<div class="descr"> <a name="details"></a>
<p>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.</p>
<p>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.</p>
<a name="using-the-module"></a>
<h2 id="using-the-module">Using the Module</h2>
<p>Using a Qt module requires linking against the module library, either directly or through other dependencies. Several build tools have dedicated support for this, including CMake and <a href="../qmake/qmake-manual.html">qmake</a>.</p>
<a name="building-with-cmake"></a>
<h3 id="building-with-cmake">Building with CMake</h3>
<p>Use the <code>find_package()</code> command to locate the needed module components in the <code>Qt5</code> package:</p>
<pre class="cpp">
find_package(Qt5 COMPONENTS Gui REQUIRED)
target_link_libraries(mytarget Qt5::Gui)
</pre>
<p>See also the <a href="qtgui-index.html#building-with-cmake">Building with CMake</a> overview.</p>
<a name="building-with-qmake"></a>
<h3 id="building-with-qmake">Building with qmake</h3>
<p>If you use <a href="../qmake/qmake-manual.html">qmake</a> to build your projects, Qt GUI is included by default. To disable Qt GUI, add the following line to your <code>.pro</code> file:</p>
<pre class="cpp">
QT -= gui
</pre>
<a name="application-windows"></a>
<h2 id="application-windows">Application Windows</h2>
<p>The most important classes in the Qt GUI module are <a href="qguiapplication.html">QGuiApplication</a> and <a href="qwindow.html">QWindow</a>. A Qt application that wants to show content on screen, will need to make use of these. <a href="qguiapplication.html">QGuiApplication</a> 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.</p>
<p>The <a href="qwindow.html">QWindow</a> class represents a window in the underlying windowing system. It provides a number of virtual functions to handle events (<a href="../qtcore/qevent.html">QEvent</a>) from the windowing system, such as touch-input, exposure, focus, key strokes and geometry changes.</p>
<a name="2d-graphics"></a>
<h2 id="2d-graphics">2D Graphics</h2>
<p>The Qt GUI module contains classes for 2D graphics, imaging, fonts and advanced typography.</p>
<p>A <a href="qwindow.html">QWindow</a> created with the surface type <a href="qsurface.html#SurfaceType-enum">QSurface::RasterSurface</a> can be used in combination with <a href="qbackingstore.html">QBackingStore</a> and <a href="qpainter.html">QPainter</a>, Qt's highly optimized 2D vector graphics API. <a href="qpainter.html">QPainter</a> supports drawing lines, polygons, vector paths, images and text. For more information, see <a href="paintsystem.html">Paint System</a> and <a href="qtgui-rasterwindow-example.html">Raster Window Example</a>.</p>
<p>Qt can load and save images using the <a href="qimage.html">QImage</a> and <a href="qpixmap.html">QPixmap</a> 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 <a href="qimageioplugin.html">QImageIOPlugin</a> class. For more information, see <a href="paintsystem-images.html">Reading and Writing Image Files</a></p>
<p>Typography in Qt is done with <a href="qtextdocument.html">QTextDocument</a> which uses the <a href="qpainter.html">QPainter</a> API in combination with Qt's font classes, primarily <a href="qfont.html">QFont</a>. Applications that prefer more low-level APIs to text and font handling, classes like <a href="qrawfont.html">QRawFont</a> and <a href="qglyphrun.html">QGlyphRun</a> can be used.</p>
<a name="opengl-and-opengl-es-integration"></a>
<h2 id="opengl-and-opengl-es-integration">OpenGL and OpenGL ES Integration</h2>
<p><a href="qwindow.html">QWindow</a> supports rendering using OpenGL and OpenGL ES, depending on what the platform supports. OpenGL rendering is enabled by setting the <a href="qwindow.html">QWindow</a>'s surface type to <a href="qsurface.html#SurfaceType-enum">QSurface::OpenGLSurface</a>, choosing the format attributes with <a href="qsurfaceformat.html">QSurfaceFormat</a>, and then creating a <a href="qopenglcontext.html">QOpenGLContext</a> to manage the native OpenGL context. In addition, Qt has <a href="qopenglpaintdevice.html">QOpenGLPaintDevice</a>, which enables the use of OpenGL accelerated <a href="qpainter.html">QPainter</a> 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 <a href="qopenglfunctions.html">QOpenGLFunctions</a> 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:</p>
<ul>
<li><a href="qopenglbuffer.html">QOpenGLBuffer</a></li>
<li><a href="qopenglframebufferobject.html">QOpenGLFramebufferObject</a></li>
<li><a href="qopenglshaderprogram.html">QOpenGLShaderProgram</a></li>
<li><a href="qopengltexture.html">QOpenGLTexture</a></li>
<li><a href="qopengldebuglogger.html">QOpenGLDebugLogger</a></li>
<li><a href="qopengltimerquery.html">QOpenGLTimerQuery</a></li>
<li><a href="qopenglvertexarrayobject.html">QOpenGLVertexArrayObject</a></li>
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<p>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.</p>
<p>For more information, see the <a href="qtgui-openglwindow-example.html">OpenGL Window Example</a>.</p>
<p>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 <a href="qmatrix4x4.html">QMatrix4x4</a>, <a href="qvector4d.html">QVector4D</a> and <a href="qquaternion.html">QQuaternion</a></p>
<p>A <a href="qwindow.html">QWindow</a> created with the <a href="qsurface.html#SurfaceType-enum">QSurface::OpenGLSurface</a> can be used in combination with <a href="qpainter.html">QPainter</a> and <a href="qopenglpaintdevice.html">QOpenGLPaintDevice</a> to have OpenGL hardware accelerated 2D graphics, by sacrificing some of the visual quality.</p>
<a name="vulkan-integration"></a>
<h2 id="vulkan-integration">Vulkan Integration</h2>
<p>Qt 5.10 added support for <a href="https://www.khronos.org/vulkan/">Vulkan</a>. This requires the presence of the <a href="https://www.lunarg.com/vulkan-sdk/">LunarG Vulkan SDK</a>.</p>
<p>On Windows, the SDK sets the environment variable <code>VULKAN_SDK</code>, which will be detected by the <code>configure</code> script.</p>
<p>On Android, Vulkan headers were added in API level 24 of the NDK.</p>
<p>Relevant classes:</p>
<ul>
<li><a href="qvulkandevicefunctions.html">QVulkanDeviceFunctions</a></li>
<li><a href="qvulkanextension.html">QVulkanExtension</a></li>
<li><a href="qvulkanfunctions.html">QVulkanFunctions</a></li>
<li><a href="qvulkaninfovector.html">QVulkanInfoVector</a></li>
<li><a href="qvulkaninstance.html">QVulkanInstance</a></li>
<li><a href="qvulkanwindow.html">QVulkanWindow</a></li>
<li><a href="qvulkanwindowrenderer.html">QVulkanWindowRenderer</a></li>
</ul>
<p>For more information, see the <a href="qtgui-hellovulkanwidget-example.html">Hello Vulkan Widget Example</a> and the <a href="qtgui-hellovulkanwindow-example.html">Hello Vulkan Window Example</a>.</p>
<a name="drag-and-drop"></a>
<h2 id="drag-and-drop">Drag and Drop</h2>
<p>More info in <a href="dnd.html">Drag and Drop</a></p>
<a name="licenses-and-attributions"></a>
<h2 id="licenses-and-attributions">Licenses and Attributions</h2>
<p>Qt GUI is available under commercial licenses from The Qt Company. In addition, it is available under free software licenses. Since Qt 5.4, these free software licenses are GNU Lesser General Public License, version 3, or the GNU General Public License, version 2. See Qt Licensing for further details.</p>
<p>Furthermore, Qt GUI in Qt 5.12.6 may contain third-party modules under following permissive licenses:</p>
<div class="table"><table class="annotated">
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-angle.html">ANGLE Library, version chromium/3280</a></p></td><td class="tblDescr"><p>BSD 3-clause "New" or "Revised" License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-angle-arrayboundsclamper.html">ANGLE: Array Bounds Clamper for WebKit</a></p></td><td class="tblDescr"><p>BSD 2-clause "Simplified" License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-angle-murmurhash.html">ANGLE: Murmurhash</a></p></td><td class="tblDescr"><p>Public Domain</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-angle-systeminfo.html">ANGLE: Systeminfo</a></p></td><td class="tblDescr"><p>BSD 2-clause "Simplified" License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-angle-trace-event.html">ANGLE: trace_event</a></p></td><td class="tblDescr"><p>BSD 3-clause "New" or "Revised" License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-aglfn.html">Adobe Glyph List For New Fonts, version 1.7</a></p></td><td class="tblDescr"><p>BSD 3-Clause "New" or "Revised" License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-grayraster.html">Anti-aliasing rasterizer from FreeType 2</a></p></td><td class="tblDescr"><p>Freetype Project License or GNU General Public License v2.0 only</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-vera-font.html">Bitstream Vera Font, version 1.10</a></p></td><td class="tblDescr"><p>Bitstream Vera Font License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-cocoa-platform-plugin.html">Cocoa Platform Plugin</a></p></td><td class="tblDescr"><p>BSD 3-clause "New" or "Revised" License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-dejayvu.html">DejaVu Fonts, version 2.37</a></p></td><td class="tblDescr"><p>Bitstream Vera Font License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-freetype-bdf.html">Freetype 2 - Bitmap Distribution Format (BDF) support</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-freetype-pcf.html">Freetype 2 - Portable Compiled Format (PCF) support</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-freetype-zlib.html">Freetype 2 - zlib</a></p></td><td class="tblDescr"><p>zlib License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-freetype.html">Freetype 2, version 2.9.1</a></p></td><td class="tblDescr"><p>Freetype Project License or GNU General Public License v2.0 only</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-harfbuzz.html">HarfBuzz</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-harfbuzz-ng.html">HarfBuzz-NG, version 1.7.4</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-iaccessible2.html">IAccessible2 IDL Specification, version 1.3.0</a></p></td><td class="tblDescr"><p>BSD 3-clause "New" or "Revised" License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-libjpeg.html">LibJPEG-turbo, version 2.0.3</a></p></td><td class="tblDescr"><p>Independent JPEG Group License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-libpng.html">LibPNG, version 1.6.37</a></p></td><td class="tblDescr"><p>libpng License and libpng License 2</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-android-native-style.html">Native Style for Android</a></p></td><td class="tblDescr"><p>Apache License 2.0</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-opengl-es2-headers.html">OpenGL ES 2 Headers, version Revision 27673</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-opengl-headers.html">OpenGL Headers, version Revision 27684</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-pixman.html">Pixman, version 0.17.12</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-smooth-scaling-algorithm.html">Smooth Scaling Algorithm</a></p></td><td class="tblDescr"><p>BSD 2-clause "Simplified" License and Imlib2 License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-vulkan-xml-spec.html">Vulkan API Registry, version 1.0.39</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-webgradients.html">WebGradients</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-wintab.html">Wintab API</a></p></td><td class="tblDescr"><p>Custom License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-xserverhelper.html">X Server helper</a></p></td><td class="tblDescr"><p>X11 License and Historical Permission Notice and Disclaimer</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qtgui-attribution-xcb.html">XCB</a></p></td><td class="tblDescr"><p>MIT License</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qtgui-attribution-icc-srgb-color-profile.html">sRGB color profile icc file</a></p></td><td class="tblDescr"><p>International Color Consortium License</p></td></tr>
</table></div>
<a name="reference"></a>
<h2 id="reference">Reference</h2>
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<li><a href="qtgui-module.html">Qt GUI C++ Classes</a><ul>
<li><a href="../qtcore/events.html">Event Classes</a></li>
<li><a href="painting.html">Painting Classes</a></li>
<li><a href="painting-3d.html">Rendering in 3D</a></li>
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