An Exif metadatum, consisting of an ExifKey and a Value and methods to manipulate these. More...

#include <exif.hpp>

Inheritance diagram for Exiv2::Exifdatum:

Public Member Functions
Creators
	Exifdatum (const ExifKey &key, const Value *pValue=nullptr)
	Constructor for new tags created by an application. The Exifdatum is created from a key / value pair. Exifdatum copies (clones) the key and value if one is provided. Alternatively, a program can create an 'empty' Exifdatum with only a key and set the value using setValue(). More...

	Exifdatum (const Exifdatum &rhs)
	Copy constructor.

	~Exifdatum () override=default
	Destructor.

Manipulators
Exifdatum &	operator= (const Exifdatum &rhs)
	Assignment operator.

Exifdatum &	operator= (const uint16_t &value)
	Assign value to the Exifdatum. The type of the new Value is set to UShortValue.

Exifdatum &	operator= (const uint32_t &value)
	Assign value to the Exifdatum. The type of the new Value is set to ULongValue.

Exifdatum &	operator= (const URational &value)
	Assign value to the Exifdatum. The type of the new Value is set to URationalValue.

Exifdatum &	operator= (const int16_t &value)
	Assign value to the Exifdatum. The type of the new Value is set to ShortValue.

Exifdatum &	operator= (const int32_t &value)
	Assign value to the Exifdatum. The type of the new Value is set to LongValue.

Exifdatum &	operator= (const Rational &value)
	Assign value to the Exifdatum. The type of the new Value is set to RationalValue.

Exifdatum &	operator= (const std::string &value)
	Assign value to the Exifdatum. Calls setValue(const std::string&).

Exifdatum &	operator= (const Value &value)
	Assign value to the Exifdatum. Calls setValue(const Value*).

void	setValue (const Value *pValue) override
	Set the value. This method copies (clones) the value pointed to by pValue.

int	setValue (const std::string &value) override
	Set the value to the string value. Uses Value::read(const std::string&). If the Exifdatum does not have a Value yet, then a Value of the correct type for this Exifdatum is created. An AsciiValue is created for unknown tags. Return 0 if the value was read successfully.

int	setDataArea (const byte *buf, size_t len) const
	Set the data area by copying (cloning) the buffer pointed to by buf. More...

Public Member Functions inherited from Exiv2::Metadatum
virtual	~Metadatum ()=default
	Destructor.

std::string	print (const ExifData *pMetadata=nullptr) const
	Write the interpreted value to a string. More...

uint32_t	toUint32 (size_t n=0) const
	Return the n-th component of the value converted to uint32_t.

Friends
template<typename T >
Exifdatum &	setValue (Exifdatum &, const T &)

Accessors
std::string	key () const override
	Return the key of the Exifdatum.

const char *	familyName () const override
	Return the name of the metadata family (which is also the first part of the key)

std::string	groupName () const override
	Return the name of the metadata group (which is also the second part of the key)

std::string	tagName () const override
	Return the name of the tag (which is also the third part of the key)

std::string	tagLabel () const override
	Return a label for the tag.

std::string	tagDesc () const override
	Return a description for the tag.

uint16_t	tag () const override
	Return the tag.

IfdId	ifdId () const
	Return the IFD id as an integer. (Do not use, this is meant for library internal use.)

const char *	ifdName () const
	Return the name of the IFD.

int	idx () const
	Return the index (unique id of this key within the original IFD)

size_t	copy (byte *buf, ByteOrder byteOrder) const override
	Write value to a data buffer and return the number of bytes written. More...

std::ostream &	write (std::ostream &os, const ExifData *pMetadata=nullptr) const override
	Write the interpreted value to an output stream, return the stream. More...

TypeId	typeId () const override
	Return the type id of the value.

const char *	typeName () const override
	Return the name of the type.

size_t	typeSize () const override
	Return the size in bytes of one component of this type.

size_t	count () const override
	Return the number of components in the value.

size_t	size () const override
	Return the size of the value in bytes.

std::string	toString () const override
	Return the value as a string.

std::string	toString (size_t n) const override
	Return the n-th component of the value converted to a string. The behaviour of the method is undefined if there is no n-th component.

int64_t	toInt64 (size_t n=0) const override
	Return the n-th component of the value converted to int64_t. The return value is -1 if the value is not set and the behaviour of the method is undefined if there is no n-th component.

float	toFloat (size_t n=0) const override
	Return the n-th component of the value converted to float. The return value is -1 if the value is not set and the behaviour of the method is undefined if there is no n-th component.

Rational	toRational (size_t n=0) const override
	Return the n-th component of the value converted to Rational. The return value is -1/1 if the value is not set and the behaviour of the method is undefined if there is no n-th component.

Value::UniquePtr	getValue () const override
	Return an auto-pointer to a copy (clone) of the value. The caller owns this copy and the auto-poiner ensures that it will be deleted. More...

const Value &	value () const override
	Return a constant reference to the value. More...

size_t	sizeDataArea () const
	Return the size of the data area.

DataBuf	dataArea () const
	Return a copy of the data area of the value. The caller owns this copy and DataBuf ensures that it will be deleted. More...

Additional Inherited Members
Protected Member Functions inherited from Exiv2::Metadatum
Metadatum &	operator= (const Metadatum &)=default
	Assignment operator. Protected so that it can only be used by subclasses but not directly.

	Metadatum ()=default

	Metadatum (const Metadatum &)=default

Detailed Description

An Exif metadatum, consisting of an ExifKey and a Value and methods to manipulate these.

Examples: addmoddel.cpp.

Constructor & Destructor Documentation

◆ Exifdatum()

Exiv2::Exifdatum::Exifdatum	(	const ExifKey &	key,
		const Value *	pValue = `nullptr`
	)

explicit

Constructor for new tags created by an application. The Exifdatum is created from a key / value pair. Exifdatum copies (clones) the key and value if one is provided. Alternatively, a program can create an 'empty' Exifdatum with only a key and set the value using setValue().

Parameters

key	ExifKey.
pValue	Pointer to an Exifdatum value.

Exceptions

Error if the key cannot be parsed and converted.

Member Function Documentation

◆ copy()

size_t Exiv2::Exifdatum::copy	(	byte *	buf,
		ByteOrder	byteOrder
	)		const

overridevirtual

Write value to a data buffer and return the number of bytes written.

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 characters written.

Implements Exiv2::Metadatum.

◆ dataArea()

DataBuf Exiv2::Exifdatum::dataArea ( ) const

Return a copy of the data area of the value. The caller owns this copy and DataBuf ensures that it will be deleted.

Values may have a data area, which can contain additional information besides the actual value. This method is used to access such a data area.

Returns: A DataBuf containing a copy of the data area or an empty DataBuf if the value does not have a data area assigned or the value is not set.

◆ getValue()

Value::UniquePtr Exiv2::Exifdatum::getValue ( ) const

overridevirtual

Return an auto-pointer to a copy (clone) of the value. The caller owns this copy and the auto-poiner ensures that it will be deleted.

This method is provided for users who need full control over the value. A caller may, e.g., downcast the pointer to the appropriate subclass of Value to make use of the interface of the subclass to set or modify its contents.

Returns: An auto-pointer containing a pointer to a copy (clone) of the value, 0 if the value is not set.

Implements Exiv2::Metadatum.

◆ setDataArea()

int Exiv2::Exifdatum::setDataArea	(	const byte *	buf,
		size_t	len
	)		const

Set the data area by copying (cloning) the buffer pointed to by buf.

Values may have a data area, which can contain additional information besides the actual value. This method is used to set such a data area.

Parameters

buf	Pointer to the source data area
len	Size of the data area

Returns: Return -1 if the Exifdatum does not have a value yet or the value has no data area, else 0.

◆ value()

const Value& Exiv2::Exifdatum::value ( ) const

overridevirtual

Return a constant reference to the value.

This method is provided mostly for convenient and versatile output of the value which can (to some extent) be formatted through standard stream manipulators. Do not attempt to write to the value through this reference. An Error is thrown if the value is not set; as an alternative to catching it, one can use count() to check if there is any data before calling this method.

Returns: A constant reference to the value.

Exceptions

Error if the value is not set.

Implements Exiv2::Metadatum.

Examples: addmoddel.cpp.

◆ write()

std::ostream& Exiv2::Exifdatum::write	(	std::ostream &	os,
		const ExifData *	pMetadata = `nullptr`
	)		const

overridevirtual

Write the interpreted value to an output stream, return the stream.

The method takes an optional pointer to a metadata container. Pretty-print functions may use that to refer to other metadata as it is sometimes not sufficient to know only the value of the metadatum that should be interpreted. Thus, it is advisable to always call this method with a pointer to the metadata container if possible.

This functionality is currently only implemented for Exif tags. The pointer is ignored when used to write IPTC datasets or XMP properties.

Without the optional metadata pointer, you do not usually have to use this function; it is used for the implementation of the output operator for Metadatum, operator<<(std::ostream &os, const Metadatum &md).

See also print(), which prints the interpreted value to a string.

Implements Exiv2::Metadatum.

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

exif.hpp

Public Member Functions

Friends

Accessors

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Exifdatum()

Member Function Documentation

◆ copy()

◆ dataArea()

◆ getValue()

◆ setDataArea()

◆ value()

◆ write()