- class QDataStream¶
The
QDataStream
class provides serialization of binary data to aQIODevice
. More…Synopsis¶
Methods¶
def
__init__()
def
atEnd()
def
byteOrder()
def
device()
def
__lshift__()
def
__rshift__()
def
readBool()
def
readBytes()
def
readDouble()
def
readFloat()
def
readInt16()
def
readInt32()
def
readInt64()
def
readInt8()
def
readQChar()
def
readQString()
def
readQVariant()
def
readRawData()
def
readString()
def
readUInt16()
def
readUInt32()
def
readUInt64()
def
readUInt8()
def
resetStatus()
def
setByteOrder()
def
setDevice()
def
setStatus()
def
setVersion()
def
skipRawData()
def
status()
def
version()
def
writeBool()
def
writeBytes()
def
writeDouble()
def
writeFloat()
def
writeInt16()
def
writeInt32()
def
writeInt64()
def
writeInt8()
def
writeQChar()
def
writeQString()
def
writeQVariant()
def
writeRawData()
def
writeString()
def
writeUInt16()
def
writeUInt32()
def
writeUInt64()
def
writeUInt8()
Note
This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE
Detailed Description¶
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
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, seeQTextStream
.The
QDataStream
class implements the serialization of C++’s basic data types, likechar
,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
. AQIODevice
represents an input/output medium one can read data from and write data to. TheQFile
class is an example of an I/O device.Example (write binary data to a stream):
file = QFile("file.dat") file.open(QIODevice.WriteOnly) QDataStream out(file) # we will serialize the data into the file out << QString("the answer is") # serialize a string out << (qint32)42 # serialize an integer
Example (read binary data from a stream):
file = QFile("file.dat") file.open(QIODevice.ReadOnly) QDataStream in(file) # read the data serialized from the file str = QString() a = qint32() in >> str >> a # extract "the answer is" and 42
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.
Enumerations can be serialized through
QDataStream
without the need of manually defining streaming operators. Enum classes are serialized using the declared size.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.Serializing containers and strings¶
The serialization format is a length specifier first, then
l
bytes of data. The length specifier is one quint32 if the version is less than 6.7 or if the number of elements is less than 0xfffffffe (2^32 -2). Otherwise there is an extend value 0xfffffffe followed by one quint64 with the actual value. In addition for containers that support isNull(), it is encoded as a single quint32 with all bits set and no data.To take one example, if the string size fits into 32 bits, 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. If the string size is greater, the value 0xffffffffe is written as a marker of an extended size, followed by 64 bits of the actual size. When reading achar *
string, 4 bytes are read first. If the value is not equal to 0xffffffffe (the marker of extended size), then these 4 bytes are treated as the 32 bit size of the string. Otherwise, the next 8 bytes are read and treated as a 64 bit size of the string. Then, all the characters for thechar *
string, including the ‘\0’ terminator, are read.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 << (quint32)0xA0B0C0D0 out << (qint32)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) in = QDataStream(file) # Read and check the header magic = quint32() in >> magic if magic != 0xA0B0C0D0: return XXX_BAD_FILE_FORMAT # Read the version version = qint32() in >> version 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 *
usingreadRawData()
. Similarly data can be written to the stream usingwriteRawData()
. Note that any encoding/decoding of the data must be done by you.A similar pair of functions is
readBytes()
andwriteBytes()
. 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 preallocatedchar *
;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 includeQList
,QSet
,QHash
, andQMap
. 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:operator<< = QDataStream(QDataStream , QXxx ) operator>> = QDataStream(QDataStream , QXxx )
For example, here are the stream operators declared as non-members of the QImage class:
operator<< = QDataStream(QDataStream stream, QImage image) operator>> = QDataStream(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() str = QString() a = qint32() in >> str >> a # try to read packet atomically if not 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.
Corruption and Security¶
QDataStream
is not resilient against corrupted data inputs and should therefore not be used for security-sensitive situations, even when using transactions. Transactions will help determine if a valid input can currently be decoded with the data currently available on an asynchronous device, but will assume that the data that is available is correctly formed.Additionally, many
QDataStream
demarshalling operators will allocate memory based on information found in the stream. Those operators perform no verification on whether the requested amount of memory is reasonable or if it is compatible with the amount of data available in the stream (example: demarshalling aQByteArray
orQString
may see the request for allocation of several gigabytes of data).QDataStream
should not be used on content whose provenance cannot be trusted. Applications should be designed to attempt to decode only streams whose provenance is at least as trustworthy as that of the application itself or its plugins.See also
QTextStream
QVariant
- class Version¶
(inherits
enum.IntEnum
) 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 Qt_4_6.
QDataStream.Qt_4_8
Same as Qt_4_6.
QDataStream.Qt_4_9
Same as Qt_4_6.
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 Qt_5_2
QDataStream.Qt_5_4
Version 16 (Qt 5.4)
QDataStream.Qt_5_5
Same as Qt_5_4
QDataStream.Qt_5_6
Version 17 (Qt 5.6)
QDataStream.Qt_5_7
Same as Qt_5_6
QDataStream.Qt_5_8
Same as Qt_5_6
QDataStream.Qt_5_9
Same as Qt_5_6
QDataStream.Qt_5_10
Same as Qt_5_6
QDataStream.Qt_5_11
Same as Qt_5_6
QDataStream.Qt_5_12
Version 18 (Qt 5.12)
QDataStream.Qt_5_13
Version 19 (Qt 5.13)
QDataStream.Qt_5_14
Same as Qt_5_13
QDataStream.Qt_5_15
Same as Qt_5_13
QDataStream.Qt_6_0
Version 20 (Qt 6.0)
QDataStream.Qt_6_1
Same as Qt_6_0
QDataStream.Qt_6_2
Same as Qt_6_0
QDataStream.Qt_6_3
Same as Qt_6_0
QDataStream.Qt_6_4
Same as Qt_6_0
QDataStream.Qt_6_5
Same as Qt_6_0
QDataStream.Qt_6_6
Version 21 (Qt 6.6)
QDataStream.Qt_6_7
Version 22 (Qt 6.7)
QDataStream.Qt_6_8
Same as Qt_6_7
See also
- class 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
- class 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.
QDataStream.SizeLimitExceeded
The data stream cannot read or write the data because its size is larger than supported by the current platform. This can happen, for example, when trying to read more that 2 GiB of data on a 32-bit platform.
- class 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.
Added in version 4.6.
- __init__()¶
Constructs a data stream that has no I/O device.
See also
- __init__(arg__1)
- Parameters:
arg__1 –
QIODevice
Constructs a data stream that uses the I/O device
d
.See also
- __init__(arg__1)
- Parameters:
arg__1 –
QByteArray
Constructs a read-only data stream that operates on byte array
a
. UseQDataStream
(QByteArray
*, int) if you want to write to a byte array.Since
QByteArray
is not aQIODevice
subclass, internally aQBuffer
is created to wrap the byte array.- __init__(arg__1, flags)
- Parameters:
arg__1 –
QByteArray
flags – Combination of
OpenModeFlag
Constructs a data stream that operates on a byte array,
a
. Themode
describes how the device is to be used.Alternatively, you can use
QDataStream
(constQByteArray
&) if you just want to read from a byte array.Since
QByteArray
is not aQIODevice
subclass, internally aQBuffer
is created to wrap the byte array.- 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
.
- 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 returnsfalse
.See also
Returns the current byte order setting – either
BigEndian
orLittleEndian
.See also
- commitTransaction()¶
- Return type:
bool
Completes a read transaction. Returns
true
if no read errors have occurred during the transaction; otherwise returnsfalse
.If called on an inner transaction, committing will be postponed until the outermost commitTransaction(),
rollbackTransaction()
, orabortTransaction()
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.Returns the I/O device currently set, or
None
if no device is currently set.See also
- floatingPointPrecision()¶
- Return type:
Returns the floating point precision of the data stream.
- isDeviceTransactionStarted()¶
- Return type:
bool
- __lshift__(st)¶
- Parameters:
st –
QCborSimpleType
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QChar
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QDate
- Return type:
- __lshift__(attr)
- Parameters:
attr –
Attribute
- Return type:
- __lshift__(combination)
- Parameters:
combination –
QKeyCombination
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QTime
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QVector2D
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QVector3D
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QVector4D
- Return type:
- __lshift__(i)
- Parameters:
i – int
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QBitArray
- Return type:
- __lshift__(uuid)
- Parameters:
uuid –
QBluetoothUuid
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QBrush
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QByteArray
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QCanBusFrame
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QCborArray
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QCborMap
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QCborValue
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QColor
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QColorSpace
- Return type:
- __lshift__(cursor)
- Parameters:
cursor –
QCursor
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QDateTime
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QEasingCurve
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QFont
- Return type:
- __lshift__(monitor)
- Parameters:
monitor –
QGeoAreaMonitorInfo
- Return type:
- __lshift__(circle)
- Parameters:
circle –
QGeoCircle
- Return type:
- __lshift__(coordinate)
- Parameters:
coordinate –
QGeoCoordinate
- Return type:
- __lshift__(path)
- Parameters:
path –
QGeoPath
- Return type:
- __lshift__(polygon)
- Parameters:
polygon –
QGeoPolygon
- Return type:
- __lshift__(info)
- Parameters:
info –
QGeoPositionInfo
- Return type:
- __lshift__(rectangle)
- Parameters:
rectangle –
QGeoRectangle
- Return type:
- __lshift__(info)
- Parameters:
info –
QGeoSatelliteInfo
- Return type:
- __lshift__(shape)
- Parameters:
shape –
QGeoShape
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QHostAddress
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QIcon
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QImage
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QJSValue
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QJsonArray
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QJsonDocument
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QJsonObject
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QJsonValue
- Return type:
- __lshift__(ks)
- Parameters:
ks –
QKeySequence
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QLine
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QLineF
- Return type:
- __lshift__(item)
- Parameters:
item –
QListWidgetItem
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QLocale
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QMargins
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QMarginsF
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QMatrix4x4
- Return type:
- __lshift__(pdu)
- Parameters:
pdu –
QModbusPdu
- Return type:
- __lshift__(pdu)
- Parameters:
pdu –
QModbusRequest
- Return type:
- __lshift__(pdu)
- Parameters:
pdu –
QModbusResponse
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QMqttTopicFilter
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QMqttTopicName
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QNetworkCacheMetaData
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QPageRanges
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QPainterPath
- Return type:
- __lshift__(p)
- Parameters:
p –
QPalette
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QPen
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QPicture
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QPixmap
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QPoint
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QPointF
- Return type:
- __lshift__(polygon)
- Parameters:
polygon –
QPolygon
- Return type:
- __lshift__(array)
- Parameters:
array –
QPolygonF
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QQuaternion
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QRect
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QRectF
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QRegion
- Return type:
- __lshift__(re)
- Parameters:
re –
QRegularExpression
- Return type:
- __lshift__(info)
- Parameters:
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QSize
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QSizeF
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QSizePolicy
- Return type:
- __lshift__(item)
- Parameters:
item –
QStandardItem
- Return type:
- __lshift__(arg__1)
- Parameters:
arg__1 – str
- __lshift__(arg__2)
- Parameters:
arg__2 – str
- Return type:
- __lshift__(item)
- Parameters:
item –
QTableWidgetItem
- Return type:
- __lshift__(tz)
- Parameters:
tz –
QTimeZone
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QTransform
- Return type:
- __lshift__(item)
- Parameters:
item –
QTreeWidgetItem
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QUrl
- Return type:
- __lshift__(arg__2)
- Parameters:
arg__2 –
QUuid
- Return type:
- __lshift__(p)
- Parameters:
p – object
- Return type:
- __lshift__(version)
- Parameters:
version –
QVersionNumber
- Return type:
- __lshift__(voice)
- Parameters:
voice –
QVoice
- Return type:
- __rshift__(uuid)
- Parameters:
uuid –
QBluetoothUuid
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QBrush
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QByteArray
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QCanBusFrame
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QCborArray
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QCborMap
- Return type:
- __rshift__(st)
- Parameters:
st –
QCborSimpleType
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QCborValue
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QChar
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QColor
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QColorSpace
- Return type:
- __rshift__(cursor)
- Parameters:
cursor –
QCursor
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QDate
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QDateTime
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QEasingCurve
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QFont
- Return type:
- __rshift__(monitor)
- Parameters:
monitor –
QGeoAreaMonitorInfo
- Return type:
- __rshift__(circle)
- Parameters:
circle –
QGeoCircle
- Return type:
- __rshift__(coordinate)
- Parameters:
coordinate –
QGeoCoordinate
- Return type:
- __rshift__(path)
- Parameters:
path –
QGeoPath
- Return type:
- __rshift__(polygon)
- Parameters:
polygon –
QGeoPolygon
- Return type:
- __rshift__(info)
- Parameters:
info –
QGeoPositionInfo
- Return type:
- __rshift__(attr)
- Parameters:
attr –
Attribute
- Return type:
- __rshift__(rectangle)
- Parameters:
rectangle –
QGeoRectangle
- Return type:
- __rshift__(info)
- Parameters:
info –
QGeoSatelliteInfo
- Return type:
- __rshift__(shape)
- Parameters:
shape –
QGeoShape
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QHostAddress
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QIcon
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QImage
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QJSValue
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QJsonArray
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QJsonDocument
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QJsonObject
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QJsonValue
- Return type:
- __rshift__(combination)
- Parameters:
combination –
QKeyCombination
- Return type:
- __rshift__(ks)
- Parameters:
ks –
QKeySequence
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QLine
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QLineF
- Return type:
- __rshift__(item)
- Parameters:
item –
QListWidgetItem
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QLocale
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QMargins
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QMarginsF
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QMatrix4x4
- Return type:
- __rshift__(code)
- Parameters:
code –
FunctionCode
- Return type:
- __rshift__(pdu)
- Parameters:
pdu –
QModbusRequest
- Return type:
- __rshift__(pdu)
- Parameters:
pdu –
QModbusResponse
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QMqttTopicFilter
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QMqttTopicName
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QNetworkCacheMetaData
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QPageRanges
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QPainterPath
- Return type:
- __rshift__(p)
- Parameters:
p –
QPalette
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QPen
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QPicture
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QPixmap
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QPoint
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QPointF
- Return type:
- __rshift__(polygon)
- Parameters:
polygon –
QPolygon
- Return type:
- __rshift__(array)
- Parameters:
array –
QPolygonF
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QQuaternion
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QRect
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QRectF
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QRegion
- Return type:
- __rshift__(re)
- Parameters:
re –
QRegularExpression
- Return type:
- __rshift__(info)
- Parameters:
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QSize
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QSizeF
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QSizePolicy
- Return type:
- __rshift__(item)
- Parameters:
item –
QStandardItem
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 – str
- Return type:
- __rshift__(item)
- Parameters:
item –
QTableWidgetItem
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QTime
- Return type:
- __rshift__(tz)
- Parameters:
tz –
QTimeZone
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QTransform
- Return type:
- __rshift__(item)
- Parameters:
item –
QTreeWidgetItem
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QUrl
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QUuid
- Return type:
- __rshift__(p)
- Parameters:
p – object
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QVector2D
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QVector3D
- Return type:
- __rshift__(arg__2)
- Parameters:
arg__2 –
QVector4D
- Return type:
- __rshift__(version)
- Parameters:
version –
QVersionNumber
- Return type:
- __rshift__(voice)
- Parameters:
voice –
QVoice
- Return type:
- __rshift__(i)
- Parameters:
i – bool
- Return type:
Reads a boolean value from the stream into
i
. Returns a reference to the stream.- __rshift__(i)
- Parameters:
i –
char
- Return type:
- readBool()¶
- Return type:
bool
- readBytes(len)¶
- Parameters:
len –
qint64
- Return type:
PyTuple
Reads the buffer
s
from the stream and returns a reference to the stream.The buffer
s
is allocated usingnew []
. Destroy it with thedelete []
operator.The
l
parameter is set to the length of the buffer. If the string read is empty,l
is set to 0 ands
is set toNone
.The serialization format is a length specifier first, then
l
bytes of data. The length specifier is one quint32 if the version is less than 6.7 or if the number of elements is less than 0xfffffffe (2^32 -2), otherwise there is an extend value 0xfffffffe followed by one quint64 with the actual value. In addition for containers that support isNull(), it is encoded as a single quint32 with all bits set and no data.See also
- readDouble()¶
- Return type:
float
- readFloat()¶
- Return type:
float
- readInt16()¶
- Return type:
int
- readInt32()¶
- Return type:
int
- readInt64()¶
- Return type:
int
- readInt8()¶
- Return type:
int
- readQChar()¶
- Return type:
QChar
- readQString()¶
- Return type:
str
- readQStringList()¶
- Return type:
list of strings
- readQVariant()¶
- Return type:
object
- readRawData(len)¶
- Parameters:
len – int
- Return type:
int
Reads at most
len
bytes from the stream intos
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
- readString()¶
- Return type:
str
- readUInt16()¶
- Return type:
int
- readUInt32()¶
- Return type:
int
- readUInt64()¶
- Return type:
int
- readUInt8()¶
- Return type:
int
- resetStatus()¶
Resets the status of the data stream.
See also
- 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
.
Sets the serialization byte order to
bo
.The
bo
parameter can beBigEndian
orLittleEndian
.The default setting is big-endian. We recommend leaving this setting unless you have special requirements.
See also
void QDataStream::setDevice(
QIODevice
*d)Sets the I/O device to
d
, which can beNone
to unset to current I/O device.See also
- setFloatingPointPrecision(precision)¶
- Parameters:
precision –
FloatingPointPrecision
Sets the floating point precision of the data stream to
precision
. If the floating point precision isDoublePrecision
and the version of the data stream isQt_4_6
or higher, all floating point numbers will be written and read with 64-bit precision. If the floating point precision isSinglePrecision
and the version isQt_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.
See also
Sets the status of the data stream to the
status
given.Subsequent calls to setStatus() are ignored until
resetStatus()
is called.See also
- setVersion(arg__1)¶
- Parameters:
arg__1 – int
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Sets the version number of the data serialization format to
v
, a value of theVersion
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:- skipRawData(len)¶
- Parameters:
len – int
- 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 lengthlen
and ignoring the buffer.See also
- 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()
, orabortTransaction()
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 startTransaction() 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.
Returns the status of the data stream.
See also
- version()¶
- Return type:
int
Returns the version number of the data serialization format.
See also
- writeBool(arg__1)¶
- Parameters:
arg__1 – bool
- writeBytes(arg__1)¶
- Parameters:
arg__1 – str
- Return type:
Writes the length specifier
len
and the buffers
to the stream and returns a reference to the stream.The
len
is serialized as a quint32 and an optional quint64, followed bylen
bytes froms
. Note that the data is not encoded.See also
- writeDouble(arg__1)¶
- Parameters:
arg__1 – float
- writeFloat(arg__1)¶
- Parameters:
arg__1 – float
- writeInt16(arg__1)¶
- Parameters:
arg__1 – int
- writeInt32(arg__1)¶
- Parameters:
arg__1 – int
- writeInt64(arg__1)¶
- Parameters:
arg__1 – int
- writeInt8(arg__1)¶
- Parameters:
arg__1 – int
- writeQChar(arg__1)¶
- Parameters:
arg__1 –
QChar
- writeQString(arg__1)¶
- Parameters:
arg__1 – str
- writeQStringList(arg__1)¶
- Parameters:
arg__1 – list of strings
- writeQVariant(arg__1)¶
- Parameters:
arg__1 – object
- writeRawData(arg__1)¶
- Parameters:
arg__1 –
PyBuffer
- writeRawData(arg__1)
- Parameters:
arg__1 – str
- Return type:
int
Writes
len
bytes froms
to the stream. Returns the number of bytes actually written, or -1 on error. The data is not encoded.See also
- writeString(arg__1)¶
- Parameters:
arg__1 – str
- writeUInt16(arg__1)¶
- Parameters:
arg__1 – int
- writeUInt32(arg__1)¶
- Parameters:
arg__1 – int
- writeUInt64(arg__1)¶
- Parameters:
arg__1 – int
- writeUInt8(arg__1)¶
- Parameters:
arg__1 – int