Documentation of SFML 2.5.1

sf::Packet Class Reference

Utility class to build blocks of data to transfer over the network. More...

#include <Packet.hpp>

Public Member Functions

 Packet ()
 Default constructor. More...
 
virtual ~Packet ()
 Virtual destructor. More...
 
void append (const void *data, std::size_t sizeInBytes)
 Append data to the end of the packet. More...
 
void clear ()
 Clear the packet. More...
 
const void * getData () const
 Get a pointer to the data contained in the packet. More...
 
std::size_t getDataSize () const
 Get the size of the data contained in the packet. More...
 
bool endOfPacket () const
 Tell if the reading position has reached the end of the packet. More...
 
 operator BoolType () const
 Test the validity of the packet, for reading. More...
 
Packetoperator>> (bool &data)
 Overload of operator >> to read data from the packet. More...
 
Packetoperator>> (Int8 &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (Uint8 &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (Int16 &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (Uint16 &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (Int32 &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (Uint32 &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (Int64 &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (Uint64 &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (float &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (double &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (char *data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (std::string &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (wchar_t *data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (std::wstring &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator>> (String &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (bool data)
 Overload of operator << to write data into the packet. More...
 
Packetoperator<< (Int8 data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (Uint8 data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (Int16 data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (Uint16 data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (Int32 data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (Uint32 data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (Int64 data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (Uint64 data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (float data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (double data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (const char *data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (const std::string &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (const wchar_t *data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (const std::wstring &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 
Packetoperator<< (const String &data)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 

Protected Member Functions

virtual const void * onSend (std::size_t &size)
 Called before the packet is sent over the network. More...
 
virtual void onReceive (const void *data, std::size_t size)
 Called after the packet is received over the network. More...
 

Friends

class TcpSocket
 
class UdpSocket
 

Detailed Description

Utility class to build blocks of data to transfer over the network.

Packets provide a safe and easy way to serialize data, in order to send it over the network using sockets (sf::TcpSocket, sf::UdpSocket).

Packets solve 2 fundamental problems that arise when transferring data over the network:

  • data is interpreted correctly according to the endianness
  • the bounds of the packet are preserved (one send == one receive)

The sf::Packet class provides both input and output modes. It is designed to follow the behavior of standard C++ streams, using operators >> and << to extract and insert data.

It is recommended to use only fixed-size types (like sf::Int32, etc.), to avoid possible differences between the sender and the receiver. Indeed, the native C++ types may have different sizes on two platforms and your data may be corrupted if that happens.

Usage example:

sf::Uint32 x = 24;
std::string s = "hello";
double d = 5.89;
// Group the variables to send into a packet
sf::Packet packet;
packet << x << s << d;
// Send it over the network (socket is a valid sf::TcpSocket)
socket.send(packet);
-----------------------------------------------------------------
// Receive the packet at the other end
sf::Packet packet;
socket.receive(packet);
// Extract the variables contained in the packet
sf::Uint32 x;
std::string s;
double d;
if (packet >> x >> s >> d)
{
// Data extracted successfully...
}

Packets have built-in operator >> and << overloads for standard types:

  • bool
  • fixed-size integer types (sf::Int8/16/32, sf::Uint8/16/32)
  • floating point numbers (float, double)
  • string types (char*, wchar_t*, std::string, std::wstring, sf::String)

Like standard streams, it is also possible to define your own overloads of operators >> and << in order to handle your custom types.

struct MyStruct
{
float number;
sf::Int8 integer;
std::string str;
};
sf::Packet& operator <<(sf::Packet& packet, const MyStruct& m)
{
return packet << m.number << m.integer << m.str;
}
sf::Packet& operator >>(sf::Packet& packet, MyStruct& m)
{
return packet >> m.number >> m.integer >> m.str;
}

Packets also provide an extra feature that allows to apply custom transformations to the data before it is sent, and after it is received. This is typically used to handle automatic compression or encryption of the data. This is achieved by inheriting from sf::Packet, and overriding the onSend and onReceive functions.

Here is an example:

class ZipPacket : public sf::Packet
{
virtual const void* onSend(std::size_t& size)
{
const void* srcData = getData();
std::size_t srcSize = getDataSize();
return MySuperZipFunction(srcData, srcSize, &size);
}
virtual void onReceive(const void* data, std::size_t size)
{
std::size_t dstSize;
const void* dstData = MySuperUnzipFunction(data, size, &dstSize);
append(dstData, dstSize);
}
};
// Use like regular packets:
ZipPacket packet;
packet << x << s << d;
...
See also
sf::TcpSocket, sf::UdpSocket

Definition at line 47 of file Packet.hpp.

Constructor & Destructor Documentation

◆ Packet()

sf::Packet::Packet ( )

Default constructor.

Creates an empty packet.

◆ ~Packet()

virtual sf::Packet::~Packet ( )
virtual

Virtual destructor.

Member Function Documentation

◆ append()

void sf::Packet::append ( const void *  data,
std::size_t  sizeInBytes 
)

Append data to the end of the packet.

Parameters
dataPointer to the sequence of bytes to append
sizeInBytesNumber of bytes to append
See also
clear

◆ clear()

void sf::Packet::clear ( )

Clear the packet.

After calling Clear, the packet is empty.

See also
append

◆ endOfPacket()

bool sf::Packet::endOfPacket ( ) const

Tell if the reading position has reached the end of the packet.

This function is useful to know if there is some data left to be read, without actually reading it.

Returns
True if all data was read, false otherwise
See also
operator bool

◆ getData()

const void* sf::Packet::getData ( ) const

Get a pointer to the data contained in the packet.

Warning: the returned pointer may become invalid after you append data to the packet, therefore it should never be stored. The return pointer is NULL if the packet is empty.

Returns
Pointer to the data
See also
getDataSize

◆ getDataSize()

std::size_t sf::Packet::getDataSize ( ) const

Get the size of the data contained in the packet.

This function returns the number of bytes pointed to by what getData returns.

Returns
Data size, in bytes
See also
getData

◆ onReceive()

virtual void sf::Packet::onReceive ( const void *  data,
std::size_t  size 
)
protectedvirtual

Called after the packet is received over the network.

This function can be defined by derived classes to transform the data after it is received; this can be used for decompression, decryption, etc. The function receives a pointer to the received data, and must fill the packet with the transformed bytes. The default implementation fills the packet directly without transforming the data.

Parameters
dataPointer to the received bytes
sizeNumber of bytes
See also
onSend

◆ onSend()

virtual const void* sf::Packet::onSend ( std::size_t &  size)
protectedvirtual

Called before the packet is sent over the network.

This function can be defined by derived classes to transform the data before it is sent; this can be used for compression, encryption, etc. The function must return a pointer to the modified data, as well as the number of bytes pointed. The default implementation provides the packet's data without transforming it.

Parameters
sizeVariable to fill with the size of data to send
Returns
Pointer to the array of bytes to send
See also
onReceive

◆ operator BoolType()

sf::Packet::operator BoolType ( ) const

Test the validity of the packet, for reading.

This operator allows to test the packet as a boolean variable, to check if a reading operation was successful.

A packet will be in an invalid state if it has no more data to read.

This behavior is the same as standard C++ streams.

Usage example:

float x;
packet >> x;
if (packet)
{
// ok, x was extracted successfully
}
// -- or --
float x;
if (packet >> x)
{
// ok, x was extracted successfully
}

Don't focus on the return type, it's equivalent to bool but it disallows unwanted implicit conversions to integer or pointer types.

Returns
True if last data extraction from packet was successful
See also
endOfPacket

◆ operator<<() [1/16]

Packet& sf::Packet::operator<< ( bool  data)

Overload of operator << to write data into the packet.

◆ operator<<() [2/16]

Packet& sf::Packet::operator<< ( Int8  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [3/16]

Packet& sf::Packet::operator<< ( Uint8  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [4/16]

Packet& sf::Packet::operator<< ( Int16  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [5/16]

Packet& sf::Packet::operator<< ( Uint16  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [6/16]

Packet& sf::Packet::operator<< ( Int32  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [7/16]

Packet& sf::Packet::operator<< ( Uint32  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [8/16]

Packet& sf::Packet::operator<< ( Int64  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [9/16]

Packet& sf::Packet::operator<< ( Uint64  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [10/16]

Packet& sf::Packet::operator<< ( float  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [11/16]

Packet& sf::Packet::operator<< ( double  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [12/16]

Packet& sf::Packet::operator<< ( const char *  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [13/16]

Packet& sf::Packet::operator<< ( const std::string &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [14/16]

Packet& sf::Packet::operator<< ( const wchar_t *  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [15/16]

Packet& sf::Packet::operator<< ( const std::wstring &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator<<() [16/16]

Packet& sf::Packet::operator<< ( const String data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [1/16]

Packet& sf::Packet::operator>> ( bool &  data)

Overload of operator >> to read data from the packet.

◆ operator>>() [2/16]

Packet& sf::Packet::operator>> ( Int8 &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [3/16]

Packet& sf::Packet::operator>> ( Uint8 &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [4/16]

Packet& sf::Packet::operator>> ( Int16 &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [5/16]

Packet& sf::Packet::operator>> ( Uint16 &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [6/16]

Packet& sf::Packet::operator>> ( Int32 &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [7/16]

Packet& sf::Packet::operator>> ( Uint32 &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [8/16]

Packet& sf::Packet::operator>> ( Int64 &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [9/16]

Packet& sf::Packet::operator>> ( Uint64 &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [10/16]

Packet& sf::Packet::operator>> ( float &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [11/16]

Packet& sf::Packet::operator>> ( double &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [12/16]

Packet& sf::Packet::operator>> ( char *  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [13/16]

Packet& sf::Packet::operator>> ( std::string &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [14/16]

Packet& sf::Packet::operator>> ( wchar_t *  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [15/16]

Packet& sf::Packet::operator>> ( std::wstring &  data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ operator>>() [16/16]

Packet& sf::Packet::operator>> ( String data)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.


The documentation for this class was generated from the following file: