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Qt 6.x
The Qt SDK
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\inmodule QtCore \reentrant More...
#include <qbuffer.h>
Public Member Functions | |
QBuffer (QObject *parent=nullptr) | |
Constructs an empty buffer with the given parent. | |
QBuffer (QByteArray *buf, QObject *parent=nullptr) | |
Constructs a QBuffer that uses the QByteArray pointed to by byteArray as its internal buffer, and with the given parent. | |
~QBuffer () | |
Destroys the buffer. | |
QByteArray & | buffer () |
Returns a reference to the QBuffer's internal buffer. | |
const QByteArray & | buffer () const |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This is the same as data(). | |
void | setBuffer (QByteArray *a) |
Makes QBuffer use the QByteArray pointed to by byteArray as its internal buffer. | |
void | setData (const QByteArray &data) |
Sets the contents of the internal buffer to be data. | |
void | setData (const char *data, qsizetype len) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Sets the contents of the internal buffer to be the first size bytes of data. | |
const QByteArray & | data () const |
Returns the data contained in the buffer. | |
bool | open (OpenMode openMode) override |
\reimp | |
void | close () override |
\reimp | |
qint64 | size () const override |
\reimp | |
qint64 | pos () const override |
\reimp | |
bool | seek (qint64 off) override |
\reimp | |
bool | atEnd () const override |
\reimp | |
bool | canReadLine () const override |
\reimp | |
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QIODevice () | |
Constructs a QIODevice object. | |
QIODevice (QObject *parent) | |
Constructs a QIODevice object with the given parent. | |
virtual | ~QIODevice () |
The destructor is virtual, and QIODevice is an abstract base class. | |
QIODeviceBase::OpenMode | openMode () const |
Returns the mode in which the device has been opened; i.e. | |
void | setTextModeEnabled (bool enabled) |
If enabled is true, this function sets the \l Text flag on the device; otherwise the \l Text flag is removed. | |
bool | isTextModeEnabled () const |
Returns true if the \l Text flag is enabled; otherwise returns false . | |
bool | isOpen () const |
Returns true if the device is open; otherwise returns false . | |
bool | isReadable () const |
Returns true if data can be read from the device; otherwise returns false. | |
bool | isWritable () const |
Returns true if data can be written to the device; otherwise returns false. | |
virtual bool | isSequential () const |
Returns true if this device is sequential; otherwise returns false. | |
int | readChannelCount () const |
int | writeChannelCount () const |
int | currentReadChannel () const |
void | setCurrentReadChannel (int channel) |
int | currentWriteChannel () const |
void | setCurrentWriteChannel (int channel) |
virtual bool | open (QIODeviceBase::OpenMode mode) |
Opens the device and sets its OpenMode to mode. | |
virtual void | close () |
First emits aboutToClose(), then closes the device and sets its OpenMode to NotOpen. | |
virtual qint64 | pos () const |
For random-access devices, this function returns the position that data is written to or read from. | |
virtual qint64 | size () const |
For open random-access devices, this function returns the size of the device. | |
virtual bool | seek (qint64 pos) |
For random-access devices, this function sets the current position to pos, returning true on success, or false if an error occurred. | |
virtual bool | atEnd () const |
Returns true if the current read and write position is at the end of the device (i.e. | |
virtual bool | reset () |
Seeks to the start of input for random-access devices. | |
virtual qint64 | bytesAvailable () const |
Returns the number of bytes that are available for reading. | |
virtual qint64 | bytesToWrite () const |
For buffered devices, this function returns the number of bytes waiting to be written. | |
qint64 | read (char *data, qint64 maxlen) |
Reads at most maxSize bytes from the device into data, and returns the number of bytes read. | |
QByteArray | read (qint64 maxlen) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Reads at most maxSize bytes from the device, and returns the data read as a QByteArray. | |
QByteArray | readAll () |
Reads all remaining data from the device, and returns it as a byte array. | |
qint64 | readLine (char *data, qint64 maxlen) |
This function reads a line of ASCII characters from the device, up to a maximum of maxSize - 1 bytes, stores the characters in data, and returns the number of bytes read. | |
QByteArray | readLine (qint64 maxlen=0) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Reads a line from the device, but no more than maxSize characters, and returns the result as a byte array. | |
virtual bool | canReadLine () const |
Returns true if a complete line of data can be read from the device; otherwise returns false . | |
void | startTransaction () |
void | commitTransaction () |
void | rollbackTransaction () |
bool | isTransactionStarted () const |
qint64 | write (const char *data, qint64 len) |
Writes at most maxSize bytes of data from data to the device. | |
qint64 | write (const char *data) |
qint64 | write (const QByteArray &data) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Writes the content of data to the device. | |
qint64 | peek (char *data, qint64 maxlen) |
QByteArray | peek (qint64 maxlen) |
qint64 | skip (qint64 maxSize) |
virtual bool | waitForReadyRead (int msecs) |
Blocks until new data is available for reading and the readyRead() signal has been emitted, or until msecs milliseconds have passed. | |
virtual bool | waitForBytesWritten (int msecs) |
For buffered devices, this function waits until a payload of buffered written data has been written to the device and the bytesWritten() signal has been emitted, or until msecs milliseconds have passed. | |
void | ungetChar (char c) |
Puts the character c back into the device, and decrements the current position unless the position is 0. | |
bool | putChar (char c) |
Writes the character c to the device. | |
bool | getChar (char *c) |
Reads one character from the device and stores it in c. | |
QString | errorString () const |
Returns a human-readable description of the last device error that occurred. | |
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Q_INVOKABLE | QObject (QObject *parent=nullptr) |
Constructs an object with parent object parent. | |
virtual | ~QObject () |
Destroys the object, deleting all its child objects. | |
virtual bool | event (QEvent *event) |
This virtual function receives events to an object and should return true if the event e was recognized and processed. | |
virtual bool | eventFilter (QObject *watched, QEvent *event) |
Filters events if this object has been installed as an event filter for the watched object. | |
QString | objectName () const |
Q_WEAK_OVERLOAD void | setObjectName (const QString &name) |
Sets the object's name to name. | |
void | setObjectName (QAnyStringView name) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. | |
QBindable< QString > | bindableObjectName () |
bool | isWidgetType () const |
Returns true if the object is a widget; otherwise returns false . | |
bool | isWindowType () const |
Returns true if the object is a window; otherwise returns false . | |
bool | isQuickItemType () const |
Returns true if the object is a QQuickItem; otherwise returns false . | |
bool | signalsBlocked () const noexcept |
Returns true if signals are blocked; otherwise returns false . | |
bool | blockSignals (bool b) noexcept |
If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it). | |
QThread * | thread () const |
Returns the thread in which the object lives. | |
void | moveToThread (QThread *thread) |
Changes the thread affinity for this object and its children. | |
int | startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer) |
This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds. | |
int | startTimer (std::chrono::milliseconds time, Qt::TimerType timerType=Qt::CoarseTimer) |
void | killTimer (int id) |
Kills the timer with timer identifier, id. | |
template<typename T > | |
T | findChild (const QString &aName=QString(), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const |
Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object. | |
template<typename T > | |
QList< T > | findChildren (const QString &aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const |
Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects. | |
template<typename T > | |
QList< T > | findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. | |
const QObjectList & | children () const |
Returns a list of child objects. | |
void | setParent (QObject *parent) |
Makes the object a child of parent. | |
void | installEventFilter (QObject *filterObj) |
Installs an event filter filterObj on this object. | |
void | removeEventFilter (QObject *obj) |
Removes an event filter object obj from this object. | |
QMetaObject::Connection | connect (const QObject *sender, const char *signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const |
bool | disconnect (const char *signal=nullptr, const QObject *receiver=nullptr, const char *member=nullptr) const |
bool | disconnect (const QObject *receiver, const char *member=nullptr) const |
void | dumpObjectTree () const |
Dumps a tree of children to the debug output. | |
void | dumpObjectInfo () const |
Dumps information about signal connections, etc. | |
bool | setProperty (const char *name, const QVariant &value) |
Sets the value of the object's name property to value. | |
bool | setProperty (const char *name, QVariant &&value) |
QVariant | property (const char *name) const |
Returns the value of the object's name property. | |
QList< QByteArray > | dynamicPropertyNames () const |
QBindingStorage * | bindingStorage () |
const QBindingStorage * | bindingStorage () const |
QObject * | parent () const |
Returns a pointer to the parent object. | |
bool | inherits (const char *classname) const |
Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false . | |
Protected Member Functions | |
void | connectNotify (const QMetaMethod &) override |
\reimp | |
void | disconnectNotify (const QMetaMethod &) override |
\reimp | |
qint64 | readData (char *data, qint64 maxlen) override |
\reimp | |
qint64 | writeData (const char *data, qint64 len) override |
\reimp | |
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QIODevice (QIODevicePrivate &dd, QObject *parent=nullptr) | |
virtual qint64 | readData (char *data, qint64 maxlen)=0 |
Reads up to maxSize bytes from the device into data, and returns the number of bytes read or -1 if an error occurred. | |
virtual qint64 | readLineData (char *data, qint64 maxlen) |
Reads up to maxSize characters into data and returns the number of characters read. | |
virtual qint64 | skipData (qint64 maxSize) |
virtual qint64 | writeData (const char *data, qint64 len)=0 |
Writes up to maxSize bytes from data to the device. | |
void | setOpenMode (QIODeviceBase::OpenMode openMode) |
Sets the OpenMode of the device to openMode. | |
void | setErrorString (const QString &errorString) |
Sets the human readable description of the last device error that occurred to str. | |
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QObject * | sender () const |
Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr. | |
int | senderSignalIndex () const |
int | receivers (const char *signal) const |
Returns the number of receivers connected to the signal. | |
bool | isSignalConnected (const QMetaMethod &signal) const |
virtual void | timerEvent (QTimerEvent *event) |
This event handler can be reimplemented in a subclass to receive timer events for the object. | |
virtual void | childEvent (QChildEvent *event) |
This event handler can be reimplemented in a subclass to receive child events. | |
virtual void | customEvent (QEvent *event) |
This event handler can be reimplemented in a subclass to receive custom events. | |
virtual void | connectNotify (const QMetaMethod &signal) |
virtual void | disconnectNotify (const QMetaMethod &signal) |
QObject (QObjectPrivate &dd, QObject *parent=nullptr) | |
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~QIODeviceBase ()=default | |
Additional Inherited Members | |
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enum | OpenModeFlag { NotOpen = 0x0000 , ReadOnly = 0x0001 , WriteOnly = 0x0002 , ReadWrite = ReadOnly | WriteOnly , Append = 0x0004 , Truncate = 0x0008 , Text = 0x0010 , Unbuffered = 0x0020 , NewOnly = 0x0040 , ExistingOnly = 0x0080 } |
This enum is used with QIODevice::open() to describe the mode in which a device is opened. More... | |
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void | deleteLater () |
\threadsafe | |
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void | readyRead () |
This signal is emitted once every time new data is available for reading from the device's current read channel. | |
void | channelReadyRead (int channel) |
void | bytesWritten (qint64 bytes) |
This signal is emitted every time a payload of data has been written to the device's current write channel. | |
void | channelBytesWritten (int channel, qint64 bytes) |
void | aboutToClose () |
This signal is emitted when the device is about to close. | |
void | readChannelFinished () |
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void | destroyed (QObject *=nullptr) |
This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked. | |
void | objectNameChanged (const QString &objectName, QPrivateSignal) |
This signal is emitted after the object's name has been changed. | |
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static QMetaObject::Connection | connect (const QObject *sender, const char *signal, const QObject *receiver, const char *member, Qt::ConnectionType=Qt::AutoConnection) |
\threadsafe | |
static QMetaObject::Connection | connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection) |
template<typename Func1 , typename Func2 > | |
static QMetaObject::Connection | connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType *context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection) |
template<typename Func1 , typename Func2 > | |
static QMetaObject::Connection | connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot) |
static bool | disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *member) |
\threadsafe | |
static bool | disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &member) |
static bool | disconnect (const QMetaObject::Connection &) |
Disconnect a connection. | |
template<typename Func1 , typename Func2 > | |
static bool | disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object *receiver, Func2 slot) |
template<typename Func1 > | |
static bool | disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const QObject *receiver, void **zero) |
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QScopedPointer< QObjectData > | d_ptr |
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QString | objectName |
the name of this object | |
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template< class T > T | qobject_cast (const QObject *object) |
Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr. | |
template< typename T > T | qFindChildqFindChildren (const QObject *obj, const QString &name)() |
template< typename T > QList< T > | qFindChildrenqFindChildren (const QObject *obj, const QString &name)() |
QObjectList | |
\macro Q_CLASSINFO(Name, Value) | |
\inmodule QtCore \reentrant
The QBuffer class provides a QIODevice interface for a QByteArray.
QBuffer allows you to access a QByteArray using the QIODevice interface. The QByteArray is treated just as a standard random-accessed file. Example:
By default, an internal QByteArray buffer is created for you when you create a QBuffer. You can access this buffer directly by calling buffer(). You can also use QBuffer with an existing QByteArray by calling setBuffer(), or by passing your array to QBuffer's constructor.
Call open() to open the buffer. Then call write() or putChar() to write to the buffer, and read(), readLine(), readAll(), or getChar() to read from it. size() returns the current size of the buffer, and you can seek to arbitrary positions in the buffer by calling seek(). When you are done with accessing the buffer, call close().
The following code snippet shows how to write data to a QByteArray using QDataStream and QBuffer:
Effectively, we convert the application's QPalette into a byte array. Here's how to read the data from the QByteArray:
QTextStream and QDataStream also provide convenience constructors that take a QByteArray and that create a QBuffer behind the scenes.
QBuffer emits readyRead() when new data has arrived in the buffer. By connecting to this signal, you can use QBuffer to store temporary data before processing it. QBuffer also emits bytesWritten() every time new data has been written to the buffer.
QBuffer::QBuffer | ( | QByteArray * | byteArray, |
QObject * | parent = nullptr |
||
) |
Constructs a QBuffer that uses the QByteArray pointed to by byteArray as its internal buffer, and with the given parent.
The caller is responsible for ensuring that byteArray remains valid until the QBuffer is destroyed, or until setBuffer() is called to change the buffer. QBuffer doesn't take ownership of the QByteArray.
If you open the buffer in write-only mode or read-write mode and write something into the QBuffer, byteArray will be modified.
Example:
Definition at line 157 of file qbuffer.cpp.
References d.
QBuffer::~QBuffer | ( | ) |
Destroys the buffer.
Definition at line 170 of file qbuffer.cpp.
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overridevirtual |
\reimp
Reimplemented from QIODevice.
Definition at line 365 of file qbuffer.cpp.
References QIODevice::atEnd().
QByteArray & QBuffer::buffer | ( | ) |
Returns a reference to the QBuffer's internal buffer.
You can use it to modify the QByteArray behind the QBuffer's back.
Definition at line 218 of file qbuffer.cpp.
References d.
Referenced by QPicturePrivate::checkFormat(), and QQmlPreviewFileEngine::setSize().
const QByteArray & QBuffer::buffer | ( | ) | const |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This is the same as data().
Definition at line 230 of file qbuffer.cpp.
References d.
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overridevirtual |
\reimp
Reimplemented from QIODevice.
Definition at line 373 of file qbuffer.cpp.
References QIODevice::canReadLine(), d, QIODevice::isOpen(), and pos().
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overridevirtual |
\reimp
Reimplemented from QIODevice.
Definition at line 316 of file qbuffer.cpp.
References QIODevice::close().
Referenced by QZipStreamStrategy::~QZipStreamStrategy(), QPicturePrivate::checkFormat(), QPdfDocumentPrivate::clear(), QQmlPreviewFileEngine::close(), QQmlPreviewFileEngine::setFileName(), QAndroidAudioSource::start(), and QAndroidAudioSource::start().
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overrideprotectedvirtual |
\reimp
Reimplemented from QObject.
Definition at line 438 of file qbuffer.cpp.
References is_tracked_signal(), and signal.
const QByteArray & QBuffer::data | ( | ) | const |
Returns the data contained in the buffer.
This is the same as buffer().
Definition at line 245 of file qbuffer.cpp.
References d.
Referenced by QTextOdfWriter::writeInlineCharacter().
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overrideprotectedvirtual |
\reimp
Reimplemented from QObject.
Definition at line 448 of file qbuffer.cpp.
References is_tracked_signal(), and signal.
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override |
\reimp
Unlike QFile, opening a QBuffer QIODevice::WriteOnly does not truncate it. However, pos() is set to 0. Use QIODevice::Append or QIODevice::Truncate to change either behavior.
Definition at line 296 of file qbuffer.cpp.
References QIODeviceBase::Append, d, QIODevice::open(), qWarning, QIODeviceBase::ReadOnly, QIODeviceBase::Truncate, QIODeviceBase::Unbuffered, and QIODeviceBase::WriteOnly.
Referenced by QPdfDocumentPrivate::QPdfDocumentPrivate(), QPicturePrivate::QPicturePrivate(), QZipStreamStrategy::QZipStreamStrategy(), QPicturePrivate::checkFormat(), QPdfDocumentPrivate::clear(), FinalWidget::mouseMoveEvent(), QQmlPreviewFileEngine::open(), and QAndroidAudioSource::start().
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overridevirtual |
\reimp
Reimplemented from QIODevice.
Definition at line 324 of file qbuffer.cpp.
References QIODevice::pos().
Referenced by canReadLine(), QQmlPreviewFileEngine::pos(), readData(), seek(), and writeData().
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overridevirtual |
\reimp
Reimplemented from QIODevice.
Definition at line 341 of file qbuffer.cpp.
References d, QIODevice::isWritable(), pos(), QT_CATCH, QT_TRY, qWarning, and QIODevice::seek().
Referenced by QPicturePrivate::QPicturePrivate(), QPdfDocumentPrivate::_q_copyFromSequentialSourceDevice(), and QQmlPreviewFileEngine::seek().
void QBuffer::setBuffer | ( | QByteArray * | byteArray | ) |
Makes QBuffer use the QByteArray pointed to by byteArray as its internal buffer.
The caller is responsible for ensuring that byteArray remains valid until the QBuffer is destroyed, or until setBuffer() is called to change the buffer. QBuffer doesn't take ownership of the QByteArray.
Does nothing if isOpen() is true.
If you open the buffer in write-only mode or read-write mode and write something into the QBuffer, byteArray will be modified.
Example:
If byteArray is \nullptr, the buffer creates its own internal QByteArray to work on. This byte array is initially empty.
Definition at line 196 of file qbuffer.cpp.
References d, QIODevice::isOpen(), and qWarning.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Sets the contents of the internal buffer to be the first size bytes of data.
{int} parameter, potentially truncating sizes. Definition at line 278 of file qbuffer.cpp.
References d, QIODevice::isOpen(), and qWarning.
void QBuffer::setData | ( | const QByteArray & | data | ) |
Sets the contents of the internal buffer to be data.
This is the same as assigning data to buffer().
Does nothing if isOpen() is true.
Definition at line 259 of file qbuffer.cpp.
References d, QIODevice::isOpen(), and qWarning.
Referenced by QPdfDocumentPrivate::QPdfDocumentPrivate(), QPicturePrivate::QPicturePrivate(), QPdfDocumentPrivate::clear(), QNetworkAccessManager::post(), QNetworkAccessManager::put(), QNetworkAccessManager::sendCustomRequest(), and QQmlPreviewFileEngine::setFileName().
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overridevirtual |
\reimp
Reimplemented from QIODevice.
Definition at line 332 of file qbuffer.cpp.
References d.
Referenced by QPdfDocumentPrivate::_q_copyFromSequentialSourceDevice(), QPicturePrivate::checkFormat(), and QQmlPreviewFileEngine::size().
\reimp
Implements QIODevice.
Definition at line 397 of file qbuffer.cpp.
References d, QMetaObject::invokeMethod(), pos(), Qt::QueuedConnection, qWarning, and QObject::signalsBlocked().