QDataStream

The QDataStream class provides serialization of binary data to a QIODevice . More

Inheritance diagram of PySide2.QtCore.QDataStream

Synopsis

Functions

Detailed Description

A data stream is a binary stream of encoded information which is 100% independent of the host computer’s operating system, CPU or byte order. For example, a data stream that is written by a PC under Windows can be read by a Sun SPARC running Solaris.

You can also use a data stream to read/write raw unencoded binary data . If you want a “parsing” input stream, see QTextStream .

The QDataStream class implements the serialization of C++’s basic data types, like char , short , int , char * , etc. Serialization of more complex data is accomplished by breaking up the data into primitive units.

A data stream cooperates closely with a QIODevice . A QIODevice represents an input/output medium one can read data from and write data to. The QFile class is an example of an I/O device.

Example (write binary data to a stream):

file_ = QFile("file.dat")
file_.open(QIODevice.WriteOnly)
# we will serialize the data into the file
out = QDataStream(file_)
# serialize a string
out.writeQString("the answer is")
# serialize an integer
out.writeInt32(42)

Example (read binary data from a stream):

file_ = QFile("file.dat")
file_.open(QIODevice.ReadOnly)
# read the data serialized from the file
i = QDataStream(file_)
string = ''
a = 0
# extract "the answer is" and 42
string = i.readQString()
a = i.readInt32()

Each item written to the stream is written in a predefined binary format that varies depending on the item’s type. Supported Qt types include QBrush , QColor , QDateTime , QFont , QPixmap , QString , QVariant and many others. For the complete list of all Qt types supporting data streaming see Serializing Qt Data Types .

For integers it is best to always cast to a Qt integer type for writing, and to read back into the same Qt integer type. This ensures that you get integers of the size you want and insulates you from compiler and platform differences.

To take one example, a char * string is written as a 32-bit integer equal to the length of the string including the ‘\0’ byte, followed by all the characters of the string including the ‘\0’ byte. When reading a char * string, 4 bytes are read to create the 32-bit length value, then that many characters for the char * string including the ‘\0’ terminator are read.

The initial I/O device is usually set in the constructor, but can be changed with setDevice() . If you’ve reached the end of the data (or if there is no I/O device set) atEnd() will return true.

Versioning

QDataStream ‘s binary format has evolved since Qt 1.0, and is likely to continue evolving to reflect changes done in Qt. When inputting or outputting complex types, it’s very important to make sure that the same version of the stream ( version() ) is used for reading and writing. If you need both forward and backward compatibility, you can hardcode the version number in the application:

stream.setVersion(QDataStream.Qt_4_0)

If you are producing a new binary data format, such as a file format for documents created by your application, you could use a QDataStream to write the data in a portable format. Typically, you would write a brief header containing a magic string and a version number to give yourself room for future expansion. For example:

file_ = QFile("file.xxx")
file_.open(QIODevice.WriteOnly)
out = QDataStream(file_)

# Write a header with a "magic number" and a version
out.writeInt32(0xA0B0C0D0)
out.writeInt32(123)

out.setVersion(QDataStream.Qt_4_0)

// Write the data
out << lots_of_interesting_data

Then read it in with:

file_ = QFile("file.xxx")
file_.open(QIODevice.ReadOnly)
i = QDataStream(file_)

// Read and check the header
magic = i.readInt32()
if magic != 0xA0B0C0D0:
    return XXX_BAD_FILE_FORMAT

// Read the version
version = i.readInt32()
if version < 100:
    return XXX_BAD_FILE_TOO_OLD
if version > 123:
    return XXX_BAD_FILE_TOO_NEW

if version <= 110:
    in_.setVersion(QDataStream.Qt_3_2)
else:
    in_.setVersion(QDataStream.Qt_4_0)

// Read the data
in_ >> lots_of_interesting_data
if version >= 120:
    in_ >> data_new_in_XXX_version_1_2
in_ >> other_interesting_data

You can select which byte order to use when serializing data. The default setting is big endian (MSB first). Changing it to little endian breaks the portability (unless the reader also changes to little endian). We recommend keeping this setting unless you have special requirements.

Reading and Writing Raw Binary Data

You may wish to read/write your own raw binary data to/from the data stream directly. Data may be read from the stream into a preallocated char * using readRawData() . Similarly data can be written to the stream using writeRawData() . Note that any encoding/decoding of the data must be done by you.

A similar pair of functions is readBytes() and writeBytes() . These differ from their raw counterparts as follows: readBytes() reads a quint32 which is taken to be the length of the data to be read, then that number of bytes is read into the preallocated char * ; writeBytes() writes a quint32 containing the length of the data, followed by the data. Note that any encoding/decoding of the data (apart from the length quint32) must be done by you.

Reading and Writing Qt Collection Classes

The Qt container classes can also be serialized to a QDataStream . These include QList , QLinkedList , QVector , QSet , QHash , and QMap . The stream operators are declared as non-members of the classes.

Reading and Writing Other Qt Classes

In addition to the overloaded stream operators documented here, any Qt classes that you might want to serialize to a QDataStream will have appropriate stream operators declared as non-member of the class:

QDataStream &operator<<(QDataStream &, const QXxx &);
QDataStream &operator>>(QDataStream &, QXxx &);

For example, here are the stream operators declared as non-members of the QImage class:

QDataStream & operator<< (QDataStream& stream, const QImage& image);
QDataStream & operator>> (QDataStream& stream, QImage& image);

To see if your favorite Qt class has similar stream operators defined, check the Related Non-Members section of the class’s documentation page.

Using Read Transactions

When a data stream operates on an asynchronous device, the chunks of data can arrive at arbitrary points in time. The QDataStream class implements a transaction mechanism that provides the ability to read the data atomically with a series of stream operators. As an example, you can handle incomplete reads from a socket by using a transaction in a slot connected to the readyRead() signal:

in.startTransaction();
QString str;
qint32 a;
in >> str >> a; // try to read packet atomically

if (!in.commitTransaction())
    return;     // wait for more data

If no full packet is received, this code restores the stream to the initial position, after which you need to wait for more data to arrive.

See also

QTextStream QVariant

class QDataStream

QDataStream(arg__1, flags)

QDataStream(arg__1)

QDataStream(arg__1)

param flags

OpenMode

param arg__1

QByteArray

Constructs a data stream that has no I/O device.

See also

setDevice()

Constructs a data stream that operates on a byte array, a . The mode describes how the device is to be used.

Alternatively, you can use QDataStream (const QByteArray &) if you just want to read from a byte array.

Since QByteArray is not a QIODevice subclass, internally a QBuffer is created to wrap the byte array.

Constructs a data stream that uses the I/O device d .

PySide2.QtCore.QDataStream.Version

This enum provides symbolic synonyms for the data serialization format version numbers.

Constant

Description

QDataStream.Qt_1_0

Version 1 (Qt 1.x)

QDataStream.Qt_2_0

Version 2 (Qt 2.0)

QDataStream.Qt_2_1

Version 3 (Qt 2.1, 2.2, 2.3)

QDataStream.Qt_3_0

Version 4 (Qt 3.0)

QDataStream.Qt_3_1

Version 5 (Qt 3.1, 3.2)

QDataStream.Qt_3_3

Version 6 (Qt 3.3)

QDataStream.Qt_4_0

Version 7 (Qt 4.0, Qt 4.1)

QDataStream.Qt_4_1

Version 7 (Qt 4.0, Qt 4.1)

QDataStream.Qt_4_2

Version 8 (Qt 4.2)

QDataStream.Qt_4_3

Version 9 (Qt 4.3)

QDataStream.Qt_4_4

Version 10 (Qt 4.4)

QDataStream.Qt_4_5

Version 11 (Qt 4.5)

QDataStream.Qt_4_6

Version 12 (Qt 4.6, Qt 4.7, Qt 4.8)

QDataStream.Qt_4_7

Same as .

QDataStream.Qt_4_8

Same as .

QDataStream.Qt_4_9

Same as .

QDataStream.Qt_5_0

Version 13 (Qt 5.0)

QDataStream.Qt_5_1

Version 14 (Qt 5.1)

QDataStream.Qt_5_2

Version 15 (Qt 5.2)

QDataStream.Qt_5_3

Same as

QDataStream.Qt_5_4

Version 16 (Qt 5.4)

QDataStream.Qt_5_5

Same as

QDataStream.Qt_5_6

Version 17 (Qt 5.6)

QDataStream.Qt_5_7

Same as

QDataStream.Qt_5_8

Same as

QDataStream.Qt_5_9

Same as

QDataStream.Qt_5_10

Same as

QDataStream.Qt_5_11

Same as

QDataStream.Qt_5_12

Version 18 (Qt 5.12)

QDataStream.Qt_5_13

Version 19 (Qt 5.13)

PySide2.QtCore.QDataStream.ByteOrder

The byte order used for reading/writing the data.

Constant

Description

QDataStream.BigEndian

Most significant byte first (the default)

QDataStream.LittleEndian

Least significant byte first

PySide2.QtCore.QDataStream.Status

This enum describes the current status of the data stream.

Constant

Description

QDataStream.Ok

The data stream is operating normally.

QDataStream.ReadPastEnd

The data stream has read past the end of the data in the underlying device.

QDataStream.ReadCorruptData

The data stream has read corrupt data.

QDataStream.WriteFailed

The data stream cannot write to the underlying device.

PySide2.QtCore.QDataStream.FloatingPointPrecision

The precision of floating point numbers used for reading/writing the data. This will only have an effect if the version of the data stream is Qt_4_6 or higher.

Warning

The floating point precision must be set to the same value on the object that writes and the object that reads the data stream.

Constant

Description

QDataStream.SinglePrecision

All floating point numbers in the data stream have 32-bit precision.

QDataStream.DoublePrecision

All floating point numbers in the data stream have 64-bit precision.

New in version 4.6.

PySide2.QtCore.QDataStream.abortTransaction()

Aborts a read transaction.

This function is commonly used to discard the transaction after higher-level protocol errors or loss of stream synchronization.

If called on an inner transaction, aborting is delegated to the outermost transaction, and subsequently started inner transactions are forced to fail.

For the outermost transaction, discards the restoration point and any internally duplicated data of the stream. Will not affect the current read position of the stream.

Sets the status of the data stream to

  • ReadCorruptData

  • .

PySide2.QtCore.QDataStream.atEnd()
Return type

bool

Returns true if the I/O device has reached the end position (end of the stream or file) or if there is no I/O device set; otherwise returns false .

See also

atEnd()

PySide2.QtCore.QDataStream.byteOrder()
Return type

ByteOrder

Returns the current byte order setting – either BigEndian or LittleEndian .

See also

setByteOrder()

PySide2.QtCore.QDataStream.commitTransaction()
Return type

bool

Completes a read transaction. Returns true if no read errors have occurred during the transaction; otherwise returns false .

If called on an inner transaction, committing will be postponed until the outermost , rollbackTransaction() , or abortTransaction() call occurs.

Otherwise, if the stream status indicates reading past the end of the data, this function restores the stream data to the point of the startTransaction() call. When this situation occurs, you need to wait for more data to arrive, after which you start a new transaction. If the data stream has read corrupt data or any of the inner transactions was aborted, this function aborts the transaction.

PySide2.QtCore.QDataStream.device()
Return type

QIODevice

Returns the I/O device currently set, or None if no device is currently set.

See also

setDevice()

PySide2.QtCore.QDataStream.floatingPointPrecision()
Return type

FloatingPointPrecision

Returns the floating point precision of the data stream.

See also

FloatingPointPrecision setFloatingPointPrecision()

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QSize

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QSizeF

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QSizePolicy

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(item)
Parameters

itemQStandardItem

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QTextFormat

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QTextLength

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QTime

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(tz)
Parameters

tzQTimeZone

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QPoint

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QTransform

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(re)
Parameters

reQRegularExpression

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QRegion

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(regExp)
Parameters

regExpQRegExp

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QRectF

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QRect

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QQuaternion

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(array)
Parameters

arrayQPolygonF

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(polygon)
Parameters

polygonQPolygon

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QPointF

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(item)
Parameters

itemQTableWidgetItem

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(item)
Parameters

itemQTreeWidgetItem

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(history)
Parameters

historyQWebEngineHistory

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(version)
Parameters

versionQVersionNumber

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QVector4D

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QVector3D

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QVector2D

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QUuid

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QUrl

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(cursor)
Parameters

cursorQCursor

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QHostAddress

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(shape)
Parameters

shapeQGeoShape

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(info)
Parameters

infoQGeoSatelliteInfo

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(info)
Parameters

infoQGeoPositionInfo

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(coordinate)
Parameters

coordinateQGeoCoordinate

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QGeoAreaMonitorInfo

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QFont

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QEasingCurve

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QDateTime

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QDate

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QPicture

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QColor

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QCborValue

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QCborMap

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QCborArray

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QByteArray

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QBrush

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QBitArray

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__1)
Parameters

arg__1 – unicode

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QImage

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QPixmap

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QPen

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(p)
Parameters

pQPalette

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QPainterPath

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QNetworkCacheMetaData

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QMatrix4x4

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QMatrix

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QMarginsF

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QMargins

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(item)
Parameters

itemQListWidgetItem

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QLocale

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QJsonArray

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QJsonDocument

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QJsonValue

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QIcon

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(ks)
Parameters

ksQKeySequence

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QLine

Return type

QDataStream

PySide2.QtCore.QDataStream.__lshift__(arg__2)
Parameters

arg__2QLineF

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(polygon)
Parameters

polygonQPolygon

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(item)
Parameters

itemQTreeWidgetItem

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QTransform

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(tz)
Parameters

tzQTimeZone

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QTime

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QTextLength

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QTextFormat

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(item)
Parameters

itemQTableWidgetItem

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(item)
Parameters

itemQStandardItem

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QSizePolicy

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QSizeF

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QSize

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(re)
Parameters

reQRegularExpression

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QRegion

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(regExp)
Parameters

regExpQRegExp

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QRectF

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QRect

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QQuaternion

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(array)
Parameters

arrayQPolygonF

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QImage

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QUrl

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(history)
Parameters

historyQWebEngineHistory

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(version)
Parameters

versionQVersionNumber

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QVector4D

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QVector3D

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QVector2D

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QUuid

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QDate

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QIcon

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QHostAddress

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(info)
Parameters

infoQGeoSatelliteInfo

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(info)
Parameters

infoQGeoPositionInfo

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(coordinate)
Parameters

coordinateQGeoCoordinate

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QGeoAreaMonitorInfo

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QFont

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QEasingCurve

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QDateTime

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(shape)
Parameters

shapeQGeoShape

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(cursor)
Parameters

cursorQCursor

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QColor

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QCborValue

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QCborMap

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QCborArray

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QByteArray

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QBrush

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QBitArray

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QPointF

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QMatrix4x4

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QPoint

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QPixmap

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QPicture

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QPen

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(p)
Parameters

pQPalette

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QPainterPath

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QNetworkCacheMetaData

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QJsonArray

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QMatrix

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QMarginsF

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QMargins

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QLocale

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(item)
Parameters

itemQListWidgetItem

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QLineF

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QLine

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(ks)
Parameters

ksQKeySequence

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QJsonValue

Return type

QDataStream

PySide2.QtCore.QDataStream.__rshift__(arg__2)
Parameters

arg__2QJsonDocument

Return type

QDataStream

PySide2.QtCore.QDataStream.readBool()
Return type

bool

PySide2.QtCore.QDataStream.readDouble()
Return type

qreal

PySide2.QtCore.QDataStream.readFloat()
Return type

float

PySide2.QtCore.QDataStream.readInt16()
Return type

qint16

PySide2.QtCore.QDataStream.readInt32()
Return type

qint32

PySide2.QtCore.QDataStream.readInt64()
Return type

qint64

PySide2.QtCore.QDataStream.readInt8()
Return type

qint8

PySide2.QtCore.QDataStream.readQChar()
Return type

QChar

PySide2.QtCore.QDataStream.readQString()
Return type

unicode

PySide2.QtCore.QDataStream.readQStringList()
Return type

list of strings

PySide2.QtCore.QDataStream.readQVariant()
Return type

object

PySide2.QtCore.QDataStream.readRawData(len)
Parameters

lenint

Return type

int

Reads at most len bytes from the stream into s and returns the number of bytes read. If an error occurs, this function returns -1.

The buffer s must be preallocated. The data is not decoded.

See also

readBytes() read() writeRawData()

PySide2.QtCore.QDataStream.readString()
Return type

unicode

PySide2.QtCore.QDataStream.readUInt16()
Return type

quint16

PySide2.QtCore.QDataStream.readUInt32()
Return type

quint32

PySide2.QtCore.QDataStream.readUInt64()
Return type

quint64

PySide2.QtCore.QDataStream.readUInt8()
Return type

quint8

PySide2.QtCore.QDataStream.resetStatus()

Resets the status of the data stream.

See also

Status status() setStatus()

PySide2.QtCore.QDataStream.rollbackTransaction()

Reverts a read transaction.

This function is commonly used to rollback the transaction when an incomplete read was detected prior to committing the transaction.

If called on an inner transaction, reverting is delegated to the outermost transaction, and subsequently started inner transactions are forced to fail.

For the outermost transaction, restores the stream data to the point of the startTransaction() call. If the data stream has read corrupt data or any of the inner transactions was aborted, this function aborts the transaction.

If the preceding stream operations were successful, sets the status of the data stream to

  • ReadPastEnd

  • .

PySide2.QtCore.QDataStream.setByteOrder(arg__1)
Parameters

arg__1ByteOrder

Sets the serialization byte order to bo .

The bo parameter can be BigEndian or LittleEndian .

The default setting is big endian. We recommend leaving this setting unless you have special requirements.

See also

byteOrder()

PySide2.QtCore.QDataStream.setDevice(arg__1)
Parameters

arg__1QIODevice

void ( QIODevice *d)

Sets the I/O device to d , which can be None to unset to current I/O device.

See also

device()

PySide2.QtCore.QDataStream.setFloatingPointPrecision(precision)
Parameters

precisionFloatingPointPrecision

Sets the floating point precision of the data stream to precision . If the floating point precision is DoublePrecision and the version of the data stream is Qt_4_6 or higher, all floating point numbers will be written and read with 64-bit precision. If the floating point precision is SinglePrecision and the version is Qt_4_6 or higher, all floating point numbers will be written and read with 32-bit precision.

For versions prior to Qt_4_6 , the precision of floating point numbers in the data stream depends on the stream operator called.

The default is DoublePrecision .

Note that this property does not affect the serialization or deserialization of qfloat16 instances.

Warning

This property must be set to the same value on the object that writes and the object that reads the data stream.

PySide2.QtCore.QDataStream.setStatus(status)
Parameters

statusStatus

Sets the status of the data stream to the status given.

Subsequent calls to are ignored until resetStatus() is called.

See also

Status status() resetStatus()

PySide2.QtCore.QDataStream.setVersion(arg__1)
Parameters

arg__1int

Sets the version number of the data serialization format to v , a value of the Version enum.

You don’t have to set a version if you are using the current version of Qt, but for your own custom binary formats we recommend that you do; see Versioning in the Detailed Description.

To accommodate new functionality, the datastream serialization format of some Qt classes has changed in some versions of Qt. If you want to read data that was created by an earlier version of Qt, or write data that can be read by a program that was compiled with an earlier version of Qt, use this function to modify the serialization format used by QDataStream .

The Version enum provides symbolic constants for the different versions of Qt. For example:

out = QDataStream(file_)
out.setVersion(QDataStream.Qt_4_0)

See also

version() Version

PySide2.QtCore.QDataStream.skipRawData(len)
Parameters

lenint

Return type

int

Skips len bytes from the device. Returns the number of bytes actually skipped, or -1 on error.

This is equivalent to calling readRawData() on a buffer of length len and ignoring the buffer.

See also

seek()

PySide2.QtCore.QDataStream.startTransaction()

Starts a new read transaction on the stream.

Defines a restorable point within the sequence of read operations. For sequential devices, read data will be duplicated internally to allow recovery in case of incomplete reads. For random-access devices, this function saves the current position of the stream. Call commitTransaction() , rollbackTransaction() , or abortTransaction() to finish the current transaction.

Once a transaction is started, subsequent calls to this function will make the transaction recursive. Inner transactions act as agents of the outermost transaction (i.e., report the status of read operations to the outermost transaction, which can restore the position of the stream).

Note

Restoring to the point of the nested call is not supported.

When an error occurs during a transaction (including an inner transaction failing), reading from the data stream is suspended (all subsequent read operations return empty/zero values) and subsequent inner transactions are forced to fail. Starting a new outermost transaction recovers from this state. This behavior makes it unnecessary to error-check every read operation separately.

PySide2.QtCore.QDataStream.status()
Return type

Status

Returns the status of the data stream.

See also

Status setStatus() resetStatus()

PySide2.QtCore.QDataStream.unsetDevice()

Note

This function is deprecated.

Unsets the I/O device. Use setDevice (nullptr) instead.

PySide2.QtCore.QDataStream.version()
Return type

int

Returns the version number of the data serialization format.

See also

setVersion() Version

PySide2.QtCore.QDataStream.writeBool(arg__1)
Parameters

arg__1bool

PySide2.QtCore.QDataStream.writeDouble(arg__1)
Parameters

arg__1qreal

PySide2.QtCore.QDataStream.writeFloat(arg__1)
Parameters

arg__1float

PySide2.QtCore.QDataStream.writeInt16(arg__1)
Parameters

arg__1qint16

PySide2.QtCore.QDataStream.writeInt32(arg__1)
Parameters

arg__1qint32

PySide2.QtCore.QDataStream.writeInt64(arg__1)
Parameters

arg__1qint64

PySide2.QtCore.QDataStream.writeInt8(arg__1)
Parameters

arg__1qint8

PySide2.QtCore.QDataStream.writeQChar(arg__1)
Parameters

arg__1QChar

PySide2.QtCore.QDataStream.writeQString(arg__1)
Parameters

arg__1 – unicode

PySide2.QtCore.QDataStream.writeQStringList(arg__1)
Parameters

arg__1 – list of strings

PySide2.QtCore.QDataStream.writeQVariant(arg__1)
Parameters

arg__1 – object

PySide2.QtCore.QDataStream.writeRawData(arg__1)
Parameters

arg__1 – str

Return type

int

Writes len bytes from s to the stream. Returns the number of bytes actually written, or -1 on error. The data is not encoded.

See also

writeBytes() write() readRawData()

PySide2.QtCore.QDataStream.writeString(arg__1)
Parameters

arg__1 – unicode

PySide2.QtCore.QDataStream.writeUInt16(arg__1)
Parameters

arg__1quint16

PySide2.QtCore.QDataStream.writeUInt32(arg__1)
Parameters

arg__1quint32

PySide2.QtCore.QDataStream.writeUInt64(arg__1)
Parameters

arg__1quint64

PySide2.QtCore.QDataStream.writeUInt8(arg__1)
Parameters

arg__1quint8