Exiv2::Exifdatum Class Reference

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=0)
 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.
 
virtual ~Exifdatum ()
 Destructor.
 
Manipulators
Exifdatumoperator= (const Exifdatum &rhs)
 Assignment operator.
 
Exifdatumoperator= (const uint16_t &value)
 Assign value to the Exifdatum. The type of the new Value is set to UShortValue.
 
Exifdatumoperator= (const uint32_t &value)
 Assign value to the Exifdatum. The type of the new Value is set to ULongValue.
 
Exifdatumoperator= (const URational &value)
 Assign value to the Exifdatum. The type of the new Value is set to URationalValue.
 
Exifdatumoperator= (const int16_t &value)
 Assign value to the Exifdatum. The type of the new Value is set to ShortValue.
 
Exifdatumoperator= (const int32_t &value)
 Assign value to the Exifdatum. The type of the new Value is set to LongValue.
 
Exifdatumoperator= (const Rational &value)
 Assign value to the Exifdatum. The type of the new Value is set to RationalValue.
 
Exifdatumoperator= (const std::string &value)
 Assign value to the Exifdatum. Calls setValue(const std::string&).
 
Exifdatumoperator= (const Value &value)
 Assign value to the Exifdatum. Calls setValue(const Value*).
 
void setValue (const Value *pValue)
 Set the value. This method copies (clones) the value pointed to by pValue.
 
int setValue (const std::string &value)
 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, long len)
 Set the data area by copying (cloning) the buffer pointed to by buf. More...
 
Accessors
std::string key () const
 Return the key of the Exifdatum.
 
const char * familyName () const
 Return the name of the metadata family (which is also the first part of the key)
 
std::string groupName () const
 Return the name of the metadata group (which is also the second part of the key)
 
std::string tagName () const
 Return the name of the tag (which is also the third part of the key)
 
std::string tagLabel () const
 Return a label for the tag.
 
uint16_t tag () const
 Return the tag.
 
int 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)
 
long copy (byte *buf, ByteOrder byteOrder) const
 Write value to a data buffer and return the number of bytes written. More...
 
std::ostream & write (std::ostream &os, const ExifData *pMetadata=0) const
 Write the interpreted value to an output stream, return the stream. More...
 
TypeId typeId () const
 Return the type id of the value.
 
const char * typeName () const
 Return the name of the type.
 
long typeSize () const
 Return the size in bytes of one component of this type.
 
long count () const
 Return the number of components in the value.
 
long size () const
 Return the size of the value in bytes.
 
std::string toString () const
 Return the value as a string.
 
std::string toString (long n) const
 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.
 
long toLong (long n=0) const
 Return the n-th component of the value converted to long. 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 (long n=0) const
 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 (long n=0) const
 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::AutoPtr getValue () const
 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 Valuevalue () const
 Return a constant reference to the value. More...
 
long 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...
 
- Public Member Functions inherited from Exiv2::Metadatum
 Metadatum ()
 Default Constructor.
 
 Metadatum (const Metadatum &rhs)
 Copy constructor.
 
virtual ~Metadatum ()
 Destructor.
 
std::string print (const ExifData *pMetadata=0) const
 Write the interpreted value to a string. More...
 

Friends

template<typename T >
ExifdatumsetValue (Exifdatum &, const T &)
 

Additional Inherited Members

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

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 = 0 
)
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
keyExifKey.
pValuePointer to an Exifdatum value.
Exceptions
Errorif the key cannot be parsed and converted.

Member Function Documentation

◆ copy()

long Exiv2::Exifdatum::copy ( byte buf,
ByteOrder  byteOrder 
) const
virtual

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
bufData buffer to write to.
byteOrderApplicable 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::AutoPtr Exiv2::Exifdatum::getValue ( ) const
virtual

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,
long  len 
)

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
bufPointer to the source data area
lenSize 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
virtual

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
Errorif the value is not set.

Implements Exiv2::Metadatum.

Examples:
addmoddel.cpp.

◆ write()

std::ostream& Exiv2::Exifdatum::write ( std::ostream &  os,
const ExifData pMetadata = 0 
) const
virtual

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: