149 lines
5.6 KiB
Plaintext
149 lines
5.6 KiB
Plaintext
/****************************************************************************
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**
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** Copyright (C) 2019 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the documentation of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:FDL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Free Documentation License Usage
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** Alternatively, this file may be used under the terms of the GNU Free
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** Documentation License version 1.3 as published by the Free Software
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** Foundation and appearing in the file included in the packaging of
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** this file. Please review the following information to ensure
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** the GNU Free Documentation License version 1.3 requirements
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** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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/*!
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\class QSignalSpy
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\inmodule QtTest
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\brief The QSignalSpy class enables introspection of signal emission.
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QSignalSpy can connect to any signal of any object and records its emission.
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QSignalSpy itself is a list of QVariant lists. Each emission of the signal
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will append one item to the list, containing the arguments of the signal.
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The following example records all signal emissions for the \c clicked() signal
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of a QCheckBox:
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\snippet code/doc_src_qsignalspy.cpp 0
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\c{spy.takeFirst()} returns the arguments for the first emitted signal, as a
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list of QVariant objects. The \c clicked() signal has a single bool argument,
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which is stored as the first entry in the list of arguments.
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The example below catches a signal from a custom object:
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\snippet code/doc_src_qsignalspy.cpp 1
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\note Non-standard data types need to be registered, using
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the qRegisterMetaType() function, before you can create a
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QSignalSpy. For example:
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\snippet code/doc_src_qsignalspy.cpp 2
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To retrieve the instance, you can use qvariant_cast:
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\snippet code/doc_src_qsignalspy.cpp 3
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\section1 Verifying Signal Emissions
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The QSignalSpy class provides an elegant mechanism for capturing the list
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of signals emitted by an object. However, you should verify its validity
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after construction. The constructor does a number of sanity checks, such as
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verifying that the signal to be spied upon actually exists. To make the
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diagnosis of test failures easier, the results of these checks should be
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checked by calling \c QVERIFY(spy.isValid()) before proceeding further with
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a test.
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\sa QVERIFY()
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*/
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/*! \fn QSignalSpy::QSignalSpy(const QObject *object, const char *signal)
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Constructs a new QSignalSpy that listens for emissions of the \a signal
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from the QObject \a object. If QSignalSpy is not able to listen for a
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valid signal (for example, because \a object is \nullptr or \a signal does
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not denote a valid signal of \a object), an explanatory warning message
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will be output using qWarning() and subsequent calls to \c isValid() will
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return false.
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Example:
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\snippet code/doc_src_qsignalspy.cpp 4
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*/
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/*! \fn template <typename PointerToMemberFunction> QSignalSpy::QSignalSpy(const QObject *object, PointerToMemberFunction signal)
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\since 5.4
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Constructs a new QSignalSpy that listens for emissions of the \a signal
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from the QObject \a object. If QSignalSpy is not able to listen for a
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valid signal (for example, because \a object is \nullptr or \a signal does
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not denote a valid signal of \a object), an explanatory warning message
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will be output using qWarning() and subsequent calls to \c isValid() will
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return false.
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Example:
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\snippet code/doc_src_qsignalspy.cpp 6
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*/
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/*! \fn QSignalSpy::QSignalSpy(const QObject *obj, const QMetaMethod &signal)
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\since 5.14
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Constructs a new QSignalSpy that listens for emissions of the \a signal
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from the QObject \a obj. If QSignalSpy is not able to listen for a
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valid signal (for example, because \a obj is \nullptr or \a signal does
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not denote a valid signal of \a obj), an explanatory warning message
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will be output using qWarning() and subsequent calls to \c isValid() will
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return false.
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This constructor is convenient to use when Qt's meta-object system is
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heavily used in a test.
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Basic usage example:
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\snippet code/doc_src_qsignalspy.cpp 7
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Imagine we need to check whether all properties of the QWindow class
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that represent minimum and maximum dimensions are properly writable.
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The following example demonstrates one of the approaches:
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\snippet code/doc_src_qsignalspy.cpp 8
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*/
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/*! \fn QSignalSpy::isValid() const
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Returns \c true if the signal spy listens to a valid signal, otherwise false.
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*/
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/*! \fn QSignalSpy::signal() const
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Returns the normalized signal the spy is currently listening to.
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*/
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/*! \fn int QSignalSpy::qt_metacall(QMetaObject::Call call, int id, void **a)
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\internal
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*/
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/*! \fn QSignalSpy::wait(int timeout)
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\since 5.0
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Starts an event loop that runs until the given signal is received.
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Optionally the event loop can return earlier on a \a timeout (in milliseconds).
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Returns \c true if the signal was emitted at least once in \a timeout milliseconds, otherwise returns \c false.
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Example:
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\snippet code/doc_src_qsignalspy.cpp 5
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*/
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