Value for an Exif comment. More...

#include <value.hpp>

Inheritance diagram for Exiv2::CommentValue:

Classes
class	CharsetInfo
	Charset information lookup functions. Implemented as a static class. More...

struct	CharsetTable
	Information pertaining to the defined character sets. More...

Public Types
enum	CharsetId { ascii , jis , unicode , undefined , invalidCharsetId , lastCharsetId }
	Character set identifiers for the character sets defined by Exif.

using	UniquePtr = std::unique_ptr< CommentValue >
	Shortcut for a CommentValue auto pointer.

Public Types inherited from Exiv2::StringValueBase
using	UniquePtr = std::unique_ptr< StringValueBase >
	Shortcut for a StringValueBase auto pointer.

Public Types inherited from Exiv2::Value
using	UniquePtr = std::unique_ptr< Value >
	Shortcut for a Value auto pointer.

Public Member Functions
Creators
	CommentValue ()
	Default constructor.

	CommentValue (const std::string &comment)
	Constructor, uses read(const std::string& comment)

Manipulators
int	read (const std::string &comment) override
	Read the value from a comment. More...

int	read (const byte *buf, size_t len, ByteOrder byteOrder) override
	Read the value from a character buffer. More...

Public Member Functions inherited from Exiv2::StringValueBase
	StringValueBase (TypeId typeId, const std::string &buf)
	Constructor for subclasses.

UniquePtr	clone () const

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

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

int64_t	toInt64 (size_t n=0) const override
	Convert the n-th component of the value to an int64_t. The behaviour of this method may be undefined if there is no n-th component. More...

uint32_t	toUint32 (size_t n=0) const override
	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. More...

float	toFloat (size_t n=0) const override
	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. More...

Rational	toRational (size_t n=0) const override
	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. More...

Public Member Functions inherited from Exiv2::Value
	Value (TypeId typeId)
	Constructor, taking a type id to initialize the base class with.

virtual	~Value ()=default
	Virtual destructor.

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

TypeId	typeId () const
	Return the type identifier (Exif data format type).

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

std::string	toString () const
	Return the value as a string. Implemented in terms of write(std::ostream& os) const of the concrete class.

virtual std::string	toString (size_t n) const
	Return the n-th component of the value as a string. The default implementation returns toString(). The behaviour of this method may be undefined if there is no n-th component.

virtual size_t	sizeDataArea () const
	Return the size of the data area, 0 if there is none.

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

bool	ok () const
	Check the ok status indicator. After a to<Type> conversion, this indicator shows whether the conversion was successful.

Accessors
ByteOrder	byteOrder_ {littleEndian}
	Byte order of the comment string that was read.

UniquePtr	clone () const

size_t	copy (byte *buf, ByteOrder byteOrder) const override
	Write value to a character data buffer. More...

std::ostream &	write (std::ostream &os) const override
	Write the comment in a format which can be read by read(const std::string& comment).

std::string	comment (const char *encoding=nullptr) const
	Return the comment (without a charset="..." prefix) More...

const char *	detectCharset (std::string &c) const
	Determine the character encoding that was used to encode the UNICODE comment value as an iconv(3) name. More...

CharsetId	charsetId () const
	Return the Exif charset id of the comment.

Additional Inherited Members
Static Public Member Functions inherited from Exiv2::Value
static UniquePtr	create (TypeId typeId)
	A (simple) factory to create a Value type. More...

Public Attributes inherited from Exiv2::StringValueBase
std::string	value_
	Stores the string value.

Protected Member Functions inherited from Exiv2::StringValueBase
Protected Member Functions inherited from Exiv2::Value
	Value (const Value &)=default

Value &	operator= (const Value &)=default
	Assignment operator. Protected so that it can only be used by subclasses but not directly.

Protected Attributes inherited from Exiv2::Value
bool	ok_ {true}
	Indicates the status of the previous to<Type> conversion.

Detailed Description

Value for an Exif comment.

This can be a plain Ascii string or a multiple byte encoded string. The comment is expected to be encoded in the character set indicated (default undefined), but this is not checked. It is left to caller to decode and encode the string to and from readable text if that is required.

Member Function Documentation

◆ comment()

std::string Exiv2::CommentValue::comment ( const char * encoding = nullptr ) const

Return the comment (without a charset="..." prefix)

The comment is decoded to UTF-8. For Exif UNICODE comments, the function makes an attempt to correctly determine the character encoding of the value. Alternatively, the optional encoding parameter can be used to specify it.

Parameters

encoding Optional argument to specify the character encoding that the comment is encoded in, as an iconv(3) name. Only used for Exif UNICODE comments.

Returns: A string containing the comment converted to UTF-8.

◆ copy()

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

overridevirtual

Write value to a character data buffer.

The user must ensure that the buffer has enough memory. Otherwise the call results in undefined behaviour.

Note: The byte order is required by the interface but not used by this method, so just use the default.

Parameters

buf	Data buffer to write to.
byteOrder	Byte order. Not used.

Returns: Number of characters written.

Reimplemented from Exiv2::StringValueBase.

◆ detectCharset()

const char* Exiv2::CommentValue::detectCharset ( std::string & c ) const

Determine the character encoding that was used to encode the UNICODE comment value as an iconv(3) name.

If the comment c starts with a BOM, the BOM is interpreted and removed from the string.

Todo: Implement rules to guess if the comment is UTF-8 encoded.

◆ read() [1/2]

int Exiv2::CommentValue::read	(	const byte *	buf,
		size_t	len,
		ByteOrder	byteOrder
	)

overridevirtual

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).

Returns: 0 if successful.

Reimplemented from Exiv2::StringValueBase.

◆ read() [2/2]

int Exiv2::CommentValue::read ( const std::string & comment )

overridevirtual

Read the value from a comment.

The format of comment is:
[charset=["]Ascii|Jis|Unicode|Undefined["] ]comment
The default charset is Undefined.

Returns: 0 if successful
1 if an invalid character set is encountered

Reimplemented from Exiv2::StringValueBase.

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

value.hpp

Classes

Public Types

Public Member Functions

Accessors

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ comment()

◆ copy()

◆ detectCharset()

◆ read() [1/2]

◆ read() [2/2]