// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
    \page widgets-changes-qt6.html
    \title Changes to Qt Widgets
    \ingroup changes-qt-5-to-6
    \brief Migrate Qt Widgets to Qt 6.

    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 Widgets, and provide
    guidance to handle them.

    \section1 Kernel classes

    \section2 The QWidget class

    The virtual QWidget::enterEvent() handler now receives a QEnterEvent*
    parameter which has information about the pointer position, rather than
    a plain QEvent*.

    \section2 QDesktopWidget and QApplication::desktop()

    QDesktopWidget was already deprecated in Qt 5, and has been removed in
    Qt 6, together with QApplication::desktop().

    QScreen provides equivalent functionality to query for information about
    available screens, screen that form a virtual desktop, and screen
    geometries.

    Use QWidget::setScreen() to create a QWidget on a specific display;
    note that this does not move a widget to a screen in a virtual desktop
    setup.

    \section2 QAction, QActionGroup

    These classes have been moved into the QtGui module. Member functions that
    depend on types defined in QtWidgets (such as QAction::menu() and
    QAction::setMenu()) are implemented as templates that will be instantiated
    only when called.

    \section1 Widgets

    \section2 The QAbstractButton class

    The default timeout parameter for QAbstractButton::animateClick() is
    removed to allow modern connection syntax without the need for qOverload.

    \section2 The QComboBox class

    The QComboBox::setModel() function is now virtual.

    \section2 The QDateTimeEdit class

    When QDateTimeEdit::setDateTime() is called with a date-time whose
    time-spec doesn't match that of the QDateTimeEdit instance, the
    date-time is converted to the time-spec of the QDateTimeEdit. This
    gives a date-time that describes the same instant in time, but
    does so in the same terms as the QDateTimeEdit uses. Previously,
    the date and time from the passed date-time were combined with the
    time-spec of the widget, ignoring the time-spec of the date-time;
    this could describe a different point in time than the one
    described by the date-time passed.

    \section1 ItemViews

    \section2 The QAbstractItemView class

    The virtual viewOptions() method that previously returned a QStyleOptionViewItem
    object has been renamed to initViewItemOption, and initializes a
    QStyleOptionViewItem object that's passed in through a pointer.

    \section1 Styling Classes and related APIs

    All versioned QStyleOption subclasses are consolidated, and the version
    numbers are reset to 1.

    The various initStyleOption() methods in widget classes are now virtual.

    \section2 Style sheet changes

    Styling a widget by its property in Qt 5 vs Qt 6 is different, especially if the
    property is an enum. In Qt 5, the selector value for such a property is the integer
    equivalent of the enum value, while in Qt 6 the string value is used. The following
    example demonstrates this difference:

    \code
    // Qt 5 style sheet
    QToolButton[popupMode="1"] {
        padding-right: 20px;
    }
    \endcode

    \code
    // Qt 6 style sheet
    QToolButton[popupMode=MenuButtonPopup] {
        padding-right: 20px;
    }
    \endcode

    \section1 Utility Classes

    \section2 QUndoCommand, QUndoStack, and QUndoGroup

    The widget independent classes of the Undo/Redo framework have been moved
    into the QtGui module.
*/
