1/****************************************************************************
2**
3** Copyright (C) 2016 The Qt Company Ltd.
4** Contact: https://www.qt.io/licensing/
5**
6** This file is part of the QtQml module of the Qt Toolkit.
7**
8** $QT_BEGIN_LICENSE:LGPL$
9** Commercial License Usage
10** Licensees holding valid commercial Qt licenses may use this file in
11** accordance with the commercial license agreement provided with the
12** Software or, alternatively, in accordance with the terms contained in
13** a written agreement between you and The Qt Company. For licensing terms
14** and conditions see https://www.qt.io/terms-conditions. For further
15** information use the contact form at https://www.qt.io/contact-us.
16**
17** GNU Lesser General Public License Usage
18** Alternatively, this file may be used under the terms of the GNU Lesser
19** General Public License version 3 as published by the Free Software
20** Foundation and appearing in the file LICENSE.LGPL3 included in the
21** packaging of this file. Please review the following information to
22** ensure the GNU Lesser General Public License version 3 requirements
23** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
24**
25** GNU General Public License Usage
26** Alternatively, this file may be used under the terms of the GNU
27** General Public License version 2.0 or (at your option) the GNU General
28** Public license version 3 or any later version approved by the KDE Free
29** Qt Foundation. The licenses are as published by the Free Software
30** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
31** included in the packaging of this file. Please review the following
32** information to ensure the GNU General Public License requirements will
33** be met: https://www.gnu.org/licenses/gpl-2.0.html and
34** https://www.gnu.org/licenses/gpl-3.0.html.
35**
36** $QT_END_LICENSE$
37**
38****************************************************************************/
39
40#include "qqmlparserstatus.h"
41
42QT_BEGIN_NAMESPACE
43
44/*!
45 \class QQmlParserStatus
46 \since 5.0
47 \inmodule QtQml
48 \brief The QQmlParserStatus class provides updates on the QML parser state.
49
50 QQmlParserStatus provides a mechanism for classes instantiated by
51 a QQmlEngine to receive notification at key points in their creation.
52
53 This class is often used for optimization purposes, as it allows you to defer an
54 expensive operation until after all the properties have been set on an
55 object. For example, QML's \l {Text} element uses the parser status
56 to defer text layout until all of its properties have been set (we
57 don't want to layout when the \c text is assigned, and then relayout
58 when the \c font is assigned, and relayout again when the \c width is assigned,
59 and so on).
60
61 Be aware that QQmlParserStatus methods are only called when a class is instantiated
62 by a QQmlEngine. If you create the same class directly from C++, these methods will
63 not be called automatically. To avoid this problem, it is recommended that you start
64 deferring operations from classBegin instead of from the initial creation of your class.
65 This will still prevent multiple revaluations during initial binding assignment in QML,
66 but will not defer operations invoked from C++.
67
68 To use QQmlParserStatus, you must inherit both a QObject-derived class
69 and QQmlParserStatus, and use the Q_INTERFACES() macro.
70
71 \code
72 class MyObject : public QObject, public QQmlParserStatus
73 {
74 Q_OBJECT
75 Q_INTERFACES(QQmlParserStatus)
76
77 public:
78 MyObject(QObject *parent = 0);
79 ...
80 void classBegin();
81 void componentComplete();
82 }
83 \endcode
84*/
85
86/*! \internal */
87QQmlParserStatus::QQmlParserStatus()
88: d(nullptr)
89{
90}
91
92/*! \internal */
93QQmlParserStatus::~QQmlParserStatus()
94{
95 if(d)
96 (*d) = nullptr;
97}
98
99/*!
100 \fn void QQmlParserStatus::classBegin()
101
102 Invoked after class creation, but before any properties have been set.
103*/
104
105/*!
106 \fn void QQmlParserStatus::componentComplete()
107
108 Invoked after the root component that caused this instantiation has
109 completed construction. At this point all static values and binding values
110 have been assigned to the class.
111*/
112
113QT_END_NAMESPACE
114