Exiv2::Xmpdatum Class Reference

Information related to an XMP property. An XMP metadatum consists of an XmpKey and a Value and provides methods to manipulate these. More...

#include <xmp.hpp>

Inheritance diagram for Exiv2::Xmpdatum:

Public Member Functions

Creators
 Xmpdatum (const XmpKey &key, const Value *pValue=0)
 Constructor for new tags created by an application. The Xmpdatum is created from a key / value pair. Xmpdatum copies (clones) the value if one is provided. Alternatively, a program can create an 'empty' Xmpdatum with only a key and set the value using setValue(). More...
 
 Xmpdatum (const Xmpdatum &rhs)
 Copy constructor.
 
virtual ~Xmpdatum ()
 Destructor.
 
Manipulators
Xmpdatumoperator= (const Xmpdatum &rhs)
 Assignment operator.
 
Xmpdatumoperator= (const std::string &value)
 Assign std::string value to the Xmpdatum. Calls setValue(const std::string&).
 
Xmpdatumoperator= (const char *value)
 Assign const char* value to the Xmpdatum. Calls operator=(const std::string&).
 
Xmpdatumoperator= (const bool &value)
 Assign a boolean value to the Xmpdatum. Translates the value to a string "true" or "false".
 
template<typename T >
Xmpdatumoperator= (const T &value)
 Assign a value of any type with an output operator to the Xmpdatum. Calls operator=(const std::string&).
 
Xmpdatumoperator= (const Value &value)
 Assign Value value to the Xmpdatum. 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 Xmpdatum does not have a Value yet, then a Value of the correct type for this Xmpdatum is created. If the key is unknown, a XmpTextValue is used as default. Return 0 if the value was read successfully.
 
Accessors
long copy (byte *buf, ByteOrder byteOrder) const
 Not implemented. Calling this method will raise an exception.
 
std::ostream & write (std::ostream &os, const ExifData *pMetadata=0) const
 Write the interpreted value to an output stream, return the stream. More...
 
std::string key () const
 Return the key of the Xmpdatum. The key is of the form 'Xmp.prefix.property'. Note however that the key is not necessarily unique, i.e., an XmpData object may contain multiple metadata with the same key.
 
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 (preferred) schema namespace prefix.
 
std::string tagName () const
 Return the property name.
 
std::string tagLabel () const
 Return a label for the tag.
 
uint16_t tag () const
 Properties don't have a tag number. Return 0.
 
TypeId typeId () const
 Return the type id of the value.
 
const char * typeName () const
 Return the name of the type.
 
long typeSize () const
 The Exif typeSize doesn't make sense here. Return 0.
 
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...
 
- 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...
 

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

Information related to an XMP property. An XMP metadatum consists of an XmpKey and a Value and provides methods to manipulate these.

Constructor & Destructor Documentation

Exiv2::Xmpdatum::Xmpdatum ( const XmpKey key,
const Value pValue = 0 
)
explicit

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

Parameters
keyThe key of the Xmpdatum.
pValuePointer to a Xmpdatum value.
Exceptions
Errorif the key cannot be parsed and converted to a known schema namespace prefix and property name.

Member Function Documentation

Value::AutoPtr Exiv2::Xmpdatum::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.

const Value& Exiv2::Xmpdatum::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.

std::ostream& Exiv2::Xmpdatum::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: