Exiv2::Value Class Reference

Common interface for all types of values used with metadata. More...

#include <value.hpp>

Inheritance diagram for Exiv2::Value:

[legend]List of all members.

Public Member Functions
Creators
	Value (TypeId typeId)
	Constructor, taking a type id to initialize the base class with.
	Value (const Value &rhs)
	Copy constructor.
virtual	~Value ()
	Virtual destructor.
Manipulators
virtual void	read (const byte *buf, long len, ByteOrder byteOrder)=0
	Read the value from a character buffer.
virtual void	read (const std::string &buf)=0
	Set the value from a string buffer. The format of the string corresponds to that of the write() method, i.e., a string obtained through the write() method can be read by this function.
Accessors
TypeId	typeId () const
	Return the type identifier (Exif data format type).
std::string	toString () const
	Return the value as a string. Implemented in terms of write(std::ostream& os) const of the concrete class.
virtual long	copy (byte *buf, ByteOrder byteOrder) const =0
	Write value to a data buffer.
virtual long	count () const =0
	Return the number of components of the value.
virtual long	size () const =0
	Return the size of the value in bytes.
virtual Value *	clone () const =0
	Return a pointer to a copy of itself (deep copy). The caller owns this copy and is responsible to delete it!
virtual std::ostream &	write (std::ostream &os) const =0
	Write the value to an output stream. You do not usually have to use this function; it is used for the implementation of the output operator for Value, operator<<(std::ostream &os, const Value &value).
virtual long	toLong (long n=0) const =0
	Convert the n-th component of the value to a long. The behaviour of this method may be undefined if there is no n-th component.
virtual float	toFloat (long n=0) const =0
	Convert the n-th component of the value to a float. The behaviour of this method may be undefined if there is no n-th component.
virtual Rational	toRational (long n=0) const =0
	Convert the n-th component of the value to a Rational. The behaviour of this method may be undefined if there is no n-th component.
Static Public Member Functions
Value *	create (TypeId typeId)
	A (simple) factory to create a Value type.
Protected Member Functions
Value &	operator= (const Value &rhs)
	Assignment operator. Protected so that it can only be used by subclasses but not directly.

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Detailed Description

Common interface for all types of values used with metadata.

The interface provides a uniform way to access values independent from their actual C++ type for simple tasks like reading the values from a string or data buffer. For other tasks, like modifying values you may need to downcast it to the actual subclass of Value so that you can access the subclass specific interface.

Examples:

addmoddel.cpp.

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Member Function Documentation

virtual long Exiv2::Value::copy (  byte *  buf, ByteOrder  byteOrder )  const [pure virtual]

Write value to a data buffer. The user must ensure that the buffer has enough memory. Otherwise the call results in undefined behaviour. Parameters: buf  Data buffer to write to. byteOrder  Applicable byte order (little or big endian). Returns: Number of bytes written. Implemented in Exiv2::DataValue, Exiv2::StringValueBase, Exiv2::DateValue, Exiv2::TimeValue, and Exiv2::ValueType< T >.

Value * Exiv2::Value::create (  TypeId  typeId  )  [static]

A (simple) factory to create a Value type. The following Value subclasses are created depending on typeId: typeId Value subclass invalidTypeId DataValue(invalidTypeId) unsignedByte DataValue(unsignedByte) asciiString AsciiValue string StringValue unsignedShort ValueType < uint16 > unsignedLong ValueType < uint32 > unsignedRational ValueType < URational > invalid6 DataValue(invalid6) undefined DataValue signedShort ValueType < int16 > signedLong ValueType < int32 > signedRational ValueType < Rational > date DateValue time TimeValue default: DataValue(typeId) Parameters: typeId  Type of the value. Returns: Pointer to the newly created Value. The caller owns this copy and is responsible to delete it! Examples: addmoddel.cpp.

virtual void Exiv2::Value::read (  const std::string &  buf  )  [pure virtual]

Set the value from a string buffer. The format of the string corresponds to that of the write() method, i.e., a string obtained through the write() method can be read by this function. Parameters: buf  The string to read from. Implemented in Exiv2::DataValue, Exiv2::StringValueBase, Exiv2::AsciiValue, Exiv2::DateValue, Exiv2::TimeValue, and Exiv2::ValueType< T >.

virtual void Exiv2::Value::read (  const byte *  buf, long  len, ByteOrder  byteOrder )  [pure virtual]

Read the value from a character buffer. Parameters: buf  Pointer to the data buffer to read from len  Number of bytes in the data buffer byteOrder  Applicable byte order (little or big endian). Implemented in Exiv2::DataValue, Exiv2::StringValueBase, Exiv2::AsciiValue, Exiv2::DateValue, Exiv2::TimeValue, and Exiv2::ValueType< T >. Examples: addmoddel.cpp.

virtual float Exiv2::Value::toFloat (  long  n = 0  )  const [pure virtual]

Convert the n-th component of the value to a float. The behaviour of this method may be undefined if there is no n-th component. Returns: The converted value. Implemented in Exiv2::DataValue, Exiv2::StringValueBase, Exiv2::DateValue, Exiv2::TimeValue, and Exiv2::ValueType< T >.

virtual long Exiv2::Value::toLong (  long  n = 0  )  const [pure virtual]

Convert the n-th component of the value to a long. The behaviour of this method may be undefined if there is no n-th component. Returns: The converted value. Implemented in Exiv2::DataValue, Exiv2::StringValueBase, Exiv2::DateValue, Exiv2::TimeValue, and Exiv2::ValueType< T >.

virtual Rational Exiv2::Value::toRational (  long  n = 0  )  const [pure virtual]

Convert the n-th component of the value to a Rational. The behaviour of this method may be undefined if there is no n-th component. Returns: The converted value. Implemented in Exiv2::DataValue, Exiv2::StringValueBase, Exiv2::DateValue, Exiv2::TimeValue, and Exiv2::ValueType< T >.

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

• value.hpp
• value.cpp

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