qqmlitemmodels.qdoc

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// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
 
/*!
    \page qmodelindex-and-related-classes-in-qml.html
    \title QModelIndex and related Classes in QML
 
    Since Qt 5.5, QModelIndex and QPersistentModelIndex are exposed in QML as
    value-based types. Also exposed in a similar fashion are QModelIndexList,
    QItemSelectionRange and QItemSelection. All objects from these types can
    be passed back and forth between QML and C++ as \c var properties or plain
    JavaScript variables.
 
    Below you will find an overview of the API exposed to QML for these classes.
    For more information, refer to their C++ documentation.
 
    \note Since all these types are exposed as \l{Q_GADGET}{gadgets}, there are no property
    change notification signals emitted. Therefore binding to their properties
    may not give the expected results. This is especially true for QPersistentModelIndex.
 
    \section1 QModelIndex and QPersistentModelIndex Types
 
    \list
    \li \b row : int
    \li \b column : int
    \li \b parent : QModelIndex
    \li \b valid : bool
    \li \b model : QAbstractItemModel
    \li \b internalId : quint64
    \endlist
 
    All these properties are read-only, as are their C++ counterparts.
 
    \note The usual caveats apply to QModelIndex in QML. If the underlying model changes
    or gets deleted, it may become dangerous to access its properties. Therefore, you
    should not store any QModelIndex objects. You can, however, store QPersistentModelIndexe
    objects in a safe way.
 
    \section1 QModelIndexList Type
 
    QModelIndexList is exposed in QML as a JavaScript array. Conversions are
    automatically made from and to C++. In fact, any JavaScript array can be
    converted back to QModelIndexList, with non-QModelIndex objects replaced by
    invalid \l{QModelIndex}es.
 
    \note QModelIndex to QPersistentModelIndex conversion happens when accessing
    the array elements because any QModelIndexList property retains reference
    semantics when exposed this way.
 
    \section1 \l QItemSelectionRange Type
 
    \list
    \li \b top : int
    \li \b left : int
    \li \b bottom : int
    \li \b right : int
    \li \b width : int
    \li \b height : int
    \li \b topLeft : QPersistentModelIndex
    \li \b bottomRight : QPersistentModelIndex
    \li \b parent : QModelIndex
    \li \b valid : bool
    \li \b empty : bool
    \li \b model : QAbstractItemModel
    \endlist
 
    All these properties are read-only, as are their C++ counterparts. In addition,
    we also expose the following functions:
 
    \list
    \li bool \b{contains}(QModelIndex \e index)
    \li bool \b{contains}(int \e row, int \e column, QModelIndex \e parentIndex)
    \li bool \b{intersects}(QItemSelectionRange \e other)
    \li QItemSelectionRange \b{intersected}(QItemSelectionRange \e other)
    \endlist
 
    \section1 QItemSelection Type
 
    Similarly to QModelIndexList, \l QItemSelection is exposed in QML as a JavaScript
    array of QItemSelectionRange objects. Conversions are automatically made from and to C++.
    In fact, any JavaScript array can be converted back to QItemSelection, with
    non-QItemSelectionRange objects replaced by empty \l {QItemSelectionRange}s.
 
 
    \sa ItemSelectionModel
*/