1
/****************************************************************************
3
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
4
** Contact: http://www.qt-project.org/legal
6
** This file is part of the documentation of the Qt Toolkit.
8
** $QT_BEGIN_LICENSE:BSD$
9
** You may use this file under the terms of the BSD license as follows:
11
** "Redistribution and use in source and binary forms, with or without
12
** modification, are permitted provided that the following conditions are
14
** * Redistributions of source code must retain the above copyright
15
** notice, this list of conditions and the following disclaimer.
16
** * Redistributions in binary form must reproduce the above copyright
17
** notice, this list of conditions and the following disclaimer in
18
** the documentation and/or other materials provided with the
20
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
21
** of its contributors may be used to endorse or promote products derived
22
** from this software without specific prior written permission.
25
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
39
****************************************************************************/
43
QVariant v(123); // The variant now contains an int
44
int x = v.toInt(); // x = 123
45
out << v; // Writes a type tag and an int to out
46
v = QVariant("hello"); // The variant now contains a QByteArray
47
v = QVariant(tr("hello")); // The variant now contains a QString
48
int y = v.toInt(); // y = 0 since v cannot be converted to an int
49
QString s = v.toString(); // s = tr("hello") (see QObject::tr())
50
out << v; // Writes a type tag and a QString to out
52
QDataStream in(...); // (opening the previously written stream)
53
in >> v; // Reads an Int variant
54
int z = v.toInt(); // z = 123
55
qDebug("Type is %s", // prints "Type is int"
57
v = v.toInt() + 100; // The variant now hold the value 223
58
v = QVariant(QStringList());
63
QVariant x, y(QString()), z(QString(""));
64
x.convert(QVariant::Int);
66
// y.isNull() == true, z.isNull() == false
73
QColor color = variant.value<QColor>();
78
QColor color = palette().background().color();
79
QVariant variant = color;
87
int i = v.toInt(); // i is now 5
88
QString s = v.toString() // s is now "5"
95
MyCustomStruct c2 = v.value<MyCustomStruct>();
103
if (v.canConvert<MyCustomStruct>())
104
c = v.value<MyCustomStruct>();
107
int i = v.value<int>(); // same as v.toInt()
108
QString s = v.value<QString>(); // same as v.toString(), s is now "7"
109
MyCustomStruct c2 = v.value<MyCustomStruct>(); // conversion failed, c2 is empty
116
v.canConvert<int>(); // returns true
117
v.canConvert<QString>(); // returns true
122
v.canConvert<int>(); // returns false
123
v.canConvert<MyCustomStruct>(); // returns true
129
return QVariant::fromValue(s);
134
QObject *object = getObjectFromSomewhere();
135
QVariant data = QVariant::fromValue(object);