Exiv2::Entry Class Reference

Data structure for one IFD directory entry. See the description of class Ifd for an explanation of the supported modes for memory allocation. More...

#include <ifd.hpp>

Collaboration diagram for Exiv2::Entry:

[legend]List of all members.

Public Member Functions
Creators
	Entry (bool alloc=true)
	Default constructor. The entry allocates memory for its data if alloc is true (the default), otherwise it remembers just the pointers into a read and writeable data buffer which it doesn't allocate or delete.
	~Entry ()
	Destructor.
	Entry (const Entry &rhs)
	Copy constructor.
Manipulators
Entry &	operator= (const Entry &rhs)
	Assignment operator.
void	setTag (uint16 tag)
	Set the tag.
void	setIfdId (IfdId ifdId)
	Set the IFD id.
void	setIdx (int idx)
	Set the index (unique id of an entry within one IFD).
void	setMakerNote (MakerNote *makerNote)
	Set the pointer to the MakerNote.
void	setOffset (uint32 offset)
	Set the offset. The offset is relative to the start of the IFD.
void	setValue (uint32 data, ByteOrder byteOrder)
	Set the value of the entry to a single unsigned long component, i.e., set the type of the entry to unsigned long, number of components to one and the value according to the data provided.
void	setValue (uint16 type, uint32 count, const byte *data, long size)
	Set type, count, the data buffer and its size.
Accessors
uint16	tag () const
	Return the tag.
uint16	type () const
	Return the type id.
const char *	typeName () const
	Return the name of the type.
long	typeSize () const
	Return the size in bytes of one element of this type.
IfdId	ifdId () const
	Return the IFD id.
int	idx () const
	Return the index (unique id >0 of an entry within an IFD, 0 if not set).
MakerNote *	makerNote () const
	Return the pointer to the associated MakerNote.
uint32	count () const
	Return the number of components in the value.
long	size () const
	Return the size of the data buffer in bytes.
uint32	offset () const
	Return the offset from the start of the IFD to the data of the entry.
const byte *	data () const
	Return a pointer to the data area. Do not attempt to write to this pointer.
const byte *	component (uint32 n) const
	Return a pointer to the n-th component, 0 if there is no n-th component. Do not attempt to write to this pointer.
bool	alloc () const
	Get the memory allocation mode.

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Detailed Description

Data structure for one IFD directory entry. See the description of class Ifd for an explanation of the supported modes for memory allocation.

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Member Function Documentation

void Exiv2::Entry::setValue (  uint16  type, uint32  count, const byte *  data, long  size )

Set type, count, the data buffer and its size. Copies the provided buffer when called in memory allocation mode. In non-alloc mode, use this method to initialise the data of a newly created Entry. In this case, only the pointer to the buffer is copied, i.e., the buffer must remain valid throughout the life of the Entry. Subsequent calls in non-alloc mode will overwrite the data pointed to by this pointer with the data provided, i.e., the buffer provided in subsequent calls can be deleted after the call. In either memory allocation mode, the data buffer provided must be large enough to hold count components of type. The size of the buffer will be as indicated in the size argument. I.e., it is possible to allocate (set) a data buffer larger than required to hold count components of the given type. Parameters: type  The type of the data. count  Number of components in the buffer. data  Pointer to the data buffer. size  Size of the desired data buffer in bytes. Exceptions: Error  ("Value too large") if no memory allocation is allowed and the size of the data buffer is larger than the existing data buffer of the entry. Error  ("Size too small") if size is not large enough to hold count components of the given type.

void Exiv2::Entry::setValue (  uint32  data, ByteOrder  byteOrder )

Set the value of the entry to a single unsigned long component, i.e., set the type of the entry to unsigned long, number of components to one and the value according to the data provided. The size of the data buffer is set to at least four bytes, but is left unchanged if it can accomodate the pointer. This method can be used to set the value of a tag which contains a pointer (offset) to a location in the Exif data (like e.g., ExifTag, 0x8769 in IFD0, which contains a pointer to the Exif IFD). This method cannot be used to set the value of a newly created Entry in non-alloc mode.

long Exiv2::Entry::size (   )  const [inline]

Return the size of the data buffer in bytes. Note: There is no minimum size for the data buffer, except that it must be large enough to hold the data.

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

• ifd.hpp
• ifd.cpp

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