// Copyright (C) 2020 The Qt Company Ltd. // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only /*! \page gui-changes-qt6.html \title Changes to Qt GUI \ingroup changes-qt-5-to-6 \brief Kernel, Text, Painting, and Utility classes are modified. Qt 6 is a result of the conscious effort to make the framework more efficient and easy to use. We try to maintain binary and source compatibility for all the public APIs in each release. But some changes were inevitable in an effort to make Qt a better framework. In this topic we summarize those changes in Qt GUI, and provide guidance to handle them. \section1 Kernel classes \section2 The QBitmap class Implicit construction of a QBitmap from a QPixmap is no longer supported. The constructor and assignment operator have been made explicit and marked as deprecated. Use the new static factory function \l{QBitmap::}{fromPixmap} instead. \section2 The QCursor class Implicit construction of a QCursor from a QPixmap is no longer supported, the constructor has been made explicit. \section2 The QKeyCombination class QKeyCombination is a new class for storing a combination of a key with an optional modifier. It should be used as a replacement for combining values from the Qt::Key enum with a modifier in a type-safe way. We recommend migrating code that currently uses operator+() to combine a key and modifiers, as future C++ standards are likely to declare arithmetic operations between unrelated enumeration types as illegal. Use operator|(), and change APIs that expect an \c int to expect a QKeyCombination instead. Existing APIs that expect an \c int for a key combination can be called using QKeyCombination::toCombined(). \section1 Text classes \section2 The QFontDatabase class The QFontDatabase class has now only static member functions. The constructor has been deprecated. Instead of e.g. \code const QStringList fontFamilies = QFontDatabase().families(); \endcode use \code const QStringList fontFamilies = QFontDatabase::families(); \endcode \section2 The QFont class The numerical values of the QFont::Weight enumerator have been changed to be in line with OpenType weight values. QFont::setWeight() expects an enum value instead of an \c int, and code that calls the setter with an integer will fail to compile. To continue to use old integer values, use QFont::setLegacyWeight(). \section1 Painting classes See the porting guide for \l{Changes to Qt Print Support}{Qt Print Support} for information about \l{QPagedPaintDevice} and other printing related classes. \section1 Utility classes \section2 QIntValidator and QDoubleValidator The \l{QIntValidator::}{setRange()} method is no longer marked as virtual. \section1 OpenGL classes With the introduction of Qt RHI as the rendering foundation in Qt, most classes prefixed by \c QOpenGL have been moved into the \l{Qt OpenGL} module. More details can be found in \l{Changes to Qt OpenGL}{the Qt OpenGL porting guide}. One notable exception is the class \l QOpenGLContext, which still resides in Qt GUI. In addition, the class \l QOpenGLWidget has been moved to a new module, named Qt OpenGL Widgets. \section2 The QOpenGLContext class The QOpenGLContext::versionFunctions() function is replaced by QOpenGLVersionFunctionsFactory::get(). QOpenGLVersionFunctionsFactory is a public class now, part of the \l{Qt OpenGL} module. \section2 ANGLE On Windows, ANGLE, a third-party OpenGL ES to Direct 3D translator, is no longer included in Qt. This means Qt::AA_UseOpenGLES and the environment variable \c{QT_OPENGL=angle} no longer have any effect. In \l{Dynamically Loading OpenGL}{dynamic OpenGL builds} there is no automatic fallback to ANGLE in case OpenGL proper fails to initialize. For QWindow or QWidget based applications using OpenGL directly, for example via QOpenGLWidget, this means that OpenGL proper is the only option at run time. However, the alternative of using a pure software OpenGL implementation, such as Mesa llvmpipe that is shipped with the pre-built Qt packages, is still available. For Qt Quick and Qt Quick 3D applications, Qt 6 introduces support for Direct 3D 11, Vulkan, and Metal, in addition to OpenGL. On Windows the default choice is Direct 3D, therefore the removal of ANGLE is alleviated by having support for graphics APIs other than OpenGL as well. \section2 Native clipboard integration Qt 5 provided interfaces for integrating platform specific or custom clipboard formats into Qt through \c QMacPasteboardMime in \c QtMacExtras, and \c QWindowsMime from the Windows QPA API. Since Qt 6.6, the equivalent functionality is provided by the classes QUtiMimeConverter for \macos, and the QWindowsMimeConverter for Windows. Porting from QWindowsMime to QWindowsMimeConverter requires practically no changes, as the virtual interface is identical. However, in Qt 6 it is no longer needed to register a QWindowsMimeConverter implementation; instantiating the type implicitly registers the converter. Porting a QMacPasteboardMime to QUtiMimeConverter requires renaming some of the virtual functions. Note that the \c{QMacPasteboardMime} API used the outdated term \c{flavor} for the native clipboard format on \macos, whereas the platform now uses \c{Uniform Type Identifiers}, i.e. \c{UTI}s, which Qt has adapted for function and parameter names. The \c{mimeFor} and \c{flavorFor} functions are replaced by the \l{QUtiMimeConverter::}{mimeForUti} and \l{QUtiMimeConverter::}{utiForMime} implementations, respectively. Those should return the name of the mime type or \c{UTI} that the converter can convert the input format to, so a port usually just involves renaming existing overrides. The \c{convertToMime}, \c{convertFromMime}, and \c{count} functions in QUtiMimeConverter are identical to their QMacPasteboardMime versions. The \c{canConvert}, \c{converterName} functions are no longer needed, they are implied by implementation of the above functions, so overrides of those functions can be removed. As with the the QWindowsMimeConverter, registration is done by instantiating the type. */