DCMTK: DcmSpecificCharacterSet Class Reference

DCMTK Version 3.7.0 OFFIS DICOM Toolkit

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Public Member Functions | Static Public Member Functions | Protected Member Functions | Private Types | Private Attributes | List of all members
DcmSpecificCharacterSet Class Reference

A class for managing and converting between different DICOM character sets. More...

## Public Member Functions
| DcmSpecificCharacterSet ()
| constructor.
virtual | ~DcmSpecificCharacterSet ()
| destructor
virtual void | clear ()
| clear the internal state.
virtual | operator OFBool () const
| query whether selectCharacterSet() has successfully been called for this object, i.e. whether convertString() may be called.
virtual OFBool | operator! () const
| query whether selectCharacterSet() has not been called before, i.e. convertString() would fail.
virtual const OFString & | getSourceCharacterSet () const
| get currently selected source DICOM character set(s).
virtual const OFString & | getDestinationCharacterSet () const
| get currently selected destination DICOM character set.
virtual const OFString & | getDestinationEncoding () const
| get currently selected destination encoding, i.e. the name of the character set as used by the underlying character encoding library for the conversion.
virtual unsigned | getConversionFlags () const
| get flags controlling converter behavior, e.g. specifying how illegal character sequences should be handled during conversion.
virtual OFCondition | setConversionFlags (const unsigned flags)
| set flags controlling converter behavior, e.g. illegal character sequences should be handled during conversion.
virtual OFCondition | selectCharacterSet (const OFString &fromCharset, const OFString &toCharset="ISO_IR 192")
| select DICOM character sets for the input and output string, between which subsequent calls of convertString() convert.
virtual OFCondition | selectCharacterSet (DcmItem &dataset, const OFString &toCharset="ISO_IR 192")
| select DICOM character sets for the input and output string, between which subsequent calls of convertString() convert.
virtual OFCondition | convertString (const OFString &fromString, OFString &toString, const OFString &delimiters="")
| convert the given string from the selected source character set(s) to the selected destination character set.
virtual OFCondition | convertString (const char *fromString, const size_t fromLength, OFString &toString, const OFString &delimiters="")
| convert the given string from the selected source character set(s) to the selected destination character set.

## Static Public Member Functions
static OFBool | isConversionAvailable ()
| check whether the underlying character set conversion library is available.
static size_t | countCharactersInUTF8String (const OFString &utf8String)
| count characters in given UTF-8 string and return the resulting number of so-called "code points".

## Protected Member Functions
virtual OFCondition | determineDestinationEncoding (const OFString &toCharset)
| determine the destination character encoding (as used by the underlying character encoding library) from the given DICOM defined term (specific character set), and set the member variables accordingly.
virtual OFCondition | selectCharacterSetWithoutCodeExtensions ()
| select a particular DICOM character set without code extensions for subsequent conversions.
virtual OFCondition | selectCharacterSetWithCodeExtensions (const unsigned long sourceVM)
| select a particular DICOM character set with code extensions for subsequent conversions.
virtual OFCondition | convertStringWithoutCodeExtensions (const char *fromString, const size_t fromLength, OFString &toString, const OFString &delimiters)
| convert the given string from the selected source character set (without code extensions) to the selected destination character set
virtual OFCondition | convertStringWithCodeExtensions (const char *fromString, const size_t fromLength, OFString &toString, const OFString &delimiters, const OFBool hasEscapeChar)
| convert the given string from the selected source character set(s) to the selected destination character set.
virtual OFBool | checkForEscapeCharacter (const char *strValue, const size_t strLength) const
| check whether the given string contains at least one escape character (ESC), because it is used for code extension techniques like ISO 2022
virtual OFString | convertToLengthLimitedOctalString (const char *strValue, const size_t strLength) const
| convert given string to octal format, i.e. all non-ASCII and control characters are converted to their octal representation.

## Private Types
typedef OFMap< OFString, OFCharacterEncoding > | T_EncodingConvertersMap
| type definition of a map storing the identifier (key) of a character set and the associated character set converter

## Private Attributes
OFString | SourceCharacterSet
| selected source character set(s) based on one or more DICOM defined terms
OFString | DestinationCharacterSet
| selected destination character set based on a single DICOM defined term
OFString | DestinationEncoding
| selected destination encoding based on names supported by the underlying character encoding library
OFCharacterEncoding | DefaultEncodingConverter
| character encoding converter
T_EncodingConvertersMap | EncodingConverters
| map of character set conversion descriptors (only used if multiple character sets are needed)

## Detailed Description

A class for managing and converting between different DICOM character sets.

The conversion relies on the OFCharacterEncoding class, which again relies on an underlying character encoding library (e.g. oficonv or libiconv).

Note
  Please note that a current limitation is that only a single value is allowed for the destination character set (i.e. no code extensions). Of course, for the source character set, also multiple values are supported.

## Constructor & Destructor Documentation

## ◆ DcmSpecificCharacterSet()

DcmSpecificCharacterSet::DcmSpecificCharacterSet | ( |  | ) |

constructor.

Initializes the member variables.

## Member Function Documentation

## ◆ checkForEscapeCharacter()

virtual OFBool DcmSpecificCharacterSet::checkForEscapeCharacter | ( | const char * | strValue,
|  | const size_t | strLength ) const
| protectedvirtual

check whether the given string contains at least one escape character (ESC), because it is used for code extension techniques like ISO 2022

Parameters

  strValue | input string to be checked for any escape character
  strLength | length of the input string

Returns
  OFTrue if an escape character has been found, OFFalse otherwise

## ◆ clear()

virtual void DcmSpecificCharacterSet::clear | ( |  | ) |
| virtual

clear the internal state.

This also forgets about the currently selected character sets, so selectCharacterSet() has to be called again before a string can be converted with convertString().

## ◆ convertString() [1/2]

virtual OFCondition DcmSpecificCharacterSet::convertString | ( | const char * | fromString,
|  | const size_t | fromLength,
|  | OFString & | toString,
|  | const OFString & | delimiters = "" )
| virtual

convert the given string from the selected source character set(s) to the selected destination character set.

That means selectCharacterSet() has to be called prior to this method. Since the length of the input string has to be specified explicitly, the string can contain more than one NULL byte.

Note
  The conversion code does not perform a thorough validation of the string. For example, characters that are permitted in the source character set but forbidden in DICOM (such as byte positions 0x80-0x9F in ISO_IR 100) may be converted without warning or error.

Parameters

  fromString | input string to be converted (using the currently selected character set)
  fromLength | length of the input string (number of bytes without the trailing NULL byte)
  toString | reference to variable where the converted string (using the currently selected destination character set) is stored
  delimiters | optional string of characters that are regarded as delimiters, i.e. when found the character set is switched back to the default. CR, LF, FF and HT are always regarded as delimiters (see DICOM PS 3.5).

Returns
  status, EC_Normal if successful, an error code otherwise

## ◆ convertString() [2/2]

virtual OFCondition DcmSpecificCharacterSet::convertString | ( | const OFString & | fromString,
|  | OFString & | toString,
|  | const OFString & | delimiters = "" )
| virtual

convert the given string from the selected source character set(s) to the selected destination character set.

That means selectCharacterSet() has to be called prior to this method.

Note
  The conversion code does not perform a thorough validation of the string. For example, characters that are permitted in the source character set but forbidden in DICOM (such as byte positions 0x80-0x9F in ISO_IR 100) may be converted without warning or error.

Parameters

  fromString | input string to be converted (using the currently selected source character set)
  toString | reference to variable where the converted string (using the currently selected destination character set) is stored
  delimiters | optional string of characters that are regarded as delimiters, i.e. when found the character set is switched back to the default. CR, LF, FF and HT are always regarded as delimiters (see DICOM PS 3.5).

Returns
  status, EC_Normal if successful, an error code otherwise

## ◆ convertStringWithCodeExtensions()

virtual OFCondition DcmSpecificCharacterSet::convertStringWithCodeExtensions | ( | const char * | fromString,
|  | const size_t | fromLength,
|  | OFString & | toString,
|  | const OFString & | delimiters,
|  | const OFBool | hasEscapeChar )
| protectedvirtual

convert the given string from the selected source character set(s) to the selected destination character set.

This method supports code extension techniques according to ISO 2022 for the input string.

Parameters

  fromString | input string to be converted
  fromLength | length of the input string (in bytes)
  toString | reference to variable where to store the converted string
  delimiters | string of characters regarded as delimiters
  hasEscapeChar | flag indicating wether the input string contains one or more escape characters (ESC)

Returns
  status, EC_Normal if successful, an error code otherwise

## ◆ convertStringWithoutCodeExtensions()

virtual OFCondition DcmSpecificCharacterSet::convertStringWithoutCodeExtensions | ( | const char * | fromString,
|  | const size_t | fromLength,
|  | OFString & | toString,
|  | const OFString & | delimiters )
| protectedvirtual

convert the given string from the selected source character set (without code extensions) to the selected destination character set

Parameters

  fromString | input string to be converted
  fromLength | length of the input string (in bytes)
  toString | reference to variable where to store the converted string
  delimiters | string of characters regarded as delimiters

Returns
  status, EC_Normal if successful, an error code otherwise

## ◆ convertToLengthLimitedOctalString()

virtual OFString DcmSpecificCharacterSet::convertToLengthLimitedOctalString | ( | const char * | strValue,
|  | const size_t | strLength ) const
| protectedvirtual

convert given string to octal format, i.e. all non-ASCII and control characters are converted to their octal representation.

The total length of the string is always limited to a particular maximum (see implementation). If the converted string would be longer, it is cropped and "..." is appended to indicate this cropping.

Parameters

  strValue | input string to be converted and possibly cropped
  strLength | length of the input string

Returns
  resulting string in octal format

## ◆ countCharactersInUTF8String()

size_t DcmSpecificCharacterSet::countCharactersInUTF8String | ( | const OFString & | utf8String | ) |
| static

count characters in given UTF-8 string and return the resulting number of so-called "code points".

Please note that invalid UTF-8 encodings are not handled properly. ASCII strings (7-bit) are also supported, although OFString::length() is probably much faster.

Parameters

  utf8String | valid character string with UTF-8 encoding

Returns
  number of characters (code points) in given UTF-8 string

## ◆ determineDestinationEncoding()

virtual OFCondition DcmSpecificCharacterSet::determineDestinationEncoding | ( | const OFString & | toCharset | ) |
| protectedvirtual

determine the destination character encoding (as used by the underlying character encoding library) from the given DICOM defined term (specific character set), and set the member variables accordingly.

Parameters

  toCharset | name of the destination character set used for the output string

Returns
  status, EC_Normal if successful, an error code otherwise

## ◆ getConversionFlags()

virtual unsigned DcmSpecificCharacterSet::getConversionFlags | ( |  | ) | const
| virtual

get flags controlling converter behavior, e.g. specifying how illegal character sequences should be handled during conversion.

Note
  This method will always return 0 if no encoder was selected using selectEncoding() before calling it.

Returns
  a combination the IllegalSequenceMode constants (bitwise or) that is currently set or 0 if the current mode cannot be determined.

## ◆ getDestinationCharacterSet()

virtual const OFString & DcmSpecificCharacterSet::getDestinationCharacterSet | ( |  | ) | const
| virtual

get currently selected destination DICOM character set.

Please note that the returned string, which contains a defined term, is always normalized, i.e. leading and trailing spaces have been removed.

Returns
  currently selected destination DICOM character set or an empty string if none is selected (identical to ASCII, which is the default)

## ◆ getDestinationEncoding()

virtual const OFString & DcmSpecificCharacterSet::getDestinationEncoding | ( |  | ) | const
| virtual

get currently selected destination encoding, i.e. the name of the character set as used by the underlying character encoding library for the conversion.

If code extension techniques are used to switch between different character encodings, the main/default encoding is returned.

Returns
  currently selected destination encoding or an empty string if none is selected

## ◆ getSourceCharacterSet()

virtual const OFString & DcmSpecificCharacterSet::getSourceCharacterSet | ( |  | ) | const
| virtual

get currently selected source DICOM character set(s).

Please note that the returned string can contain multiple values (defined terms separated by a backslash) if code extension techniques are used. Furthermore, the returned string is always normalized, i.e. leading and trailing spaces have been removed.

Returns
  currently selected source DICOM character set(s) or an empty string if none is selected (identical to ASCII, which is the default)

## ◆ isConversionAvailable()

OFBool DcmSpecificCharacterSet::isConversionAvailable | ( |  | ) |
| static

check whether the underlying character set conversion library is available.

If not, no conversion between different character sets will be possible.

Returns
  OFTrue if the character set conversion is available, OFFalse otherwise

## ◆ operator OFBool()

virtual DcmSpecificCharacterSet::operator OFBool | ( |  | ) | const
| virtual

query whether selectCharacterSet() has successfully been called for this object, i.e. whether convertString() may be called.

Returns
  OFTrue if selectCharacterSet() was successfully called before, OFFalse if not (or clear() has been called in the meantime).

## ◆ operator!()

virtual OFBool DcmSpecificCharacterSet::operator! | ( |  | ) | const
| virtual

query whether selectCharacterSet() has not been called before, i.e. convertString() would fail.

Returns
  OFTrue if selectCharacterSet() must be called before using convertString(), OFFalse if it has already been called.

## ◆ selectCharacterSet() [1/2]

virtual OFCondition DcmSpecificCharacterSet::selectCharacterSet | ( | const OFString & | fromCharset,
|  | const OFString & | toCharset = "ISO_IR 192" )
| virtual

select DICOM character sets for the input and output string, between which subsequent calls of convertString() convert.

The defined terms for a particular character set can be found in the DICOM standard, e.g. "ISO_IR 100" for ISO 8859-1 (Latin 1) or "ISO_IR 192" for Unicode in UTF-8. An empty string denotes the default character repertoire, which is ASCII (7-bit). If multiple values are given for 'fromCharset' (separated by a backslash) code extension techniques are used and escape sequences may be encountered in the source string to switch between the specified character sets.

Parameters

  fromCharset | name of the source character set(s) used for the input string as given in the DICOM attribute Specific Character Set (0008,0005). Leading and trailing spaces are removed automatically (if present).
  toCharset | name of the destination character set used for the output string. Only a single value is permitted (no code extensions). Leading and trailing spaces are removed automatically (if present). The default value is "ISO_IR 192" (Unicode in UTF-8).

Returns
  status, EC_Normal if successful, an error code otherwise

## ◆ selectCharacterSet() [2/2]

virtual OFCondition DcmSpecificCharacterSet::selectCharacterSet | ( | DcmItem & | dataset,
|  | const OFString & | toCharset = "ISO_IR 192" )
| virtual

select DICOM character sets for the input and output string, between which subsequent calls of convertString() convert.

The source character set is determined from the DICOM element Specific Character Set (0008,0005) stored in the given dataset/item. The defined terms for the destination character set can be found in the DICOM standard, e.g. "ISO_IR 100" for ISO 8859-1 (Latin 1) or "ISO_IR 192" for Unicode in UTF-8. An empty string denotes the default character repertoire, which is ASCII (7-bit). If multiple values are found in the Specific Character Set element of the given 'dataset' (separated by a backslash) code extension techniques are used and escape sequences may be encountered in the source string to switch between the specified character sets.

Parameters

  dataset | DICOM dataset or item from which the source character set should be retrieved. If the data element Specific Character Set (0008,0005) is empty or missing, the default character set (i.e. ASCII) is used.
  toCharset | name of the destination character set used for the the output string. Only a single value is permitted (no code extensions). Leading and trailing spaces are removed automatically (if present). The default value is "ISO_IR 192" (Unicode in UTF-8).

Returns
  status, EC_Normal if successful, an error code otherwise

## ◆ selectCharacterSetWithCodeExtensions()

virtual OFCondition DcmSpecificCharacterSet::selectCharacterSetWithCodeExtensions | ( | const unsigned long | sourceVM | ) |
| protectedvirtual

select a particular DICOM character set with code extensions for subsequent conversions.

The corresponding DICOM defined terms for the source character set are determined from the member variable 'SourceCharacterSet'.

Parameters

  sourceVM | value multiplicity of the member variable 'SourceCharacterSet'. Usually, this value has already been determined by the calling method.

Returns
  status, EC_Normal if successful, an error code otherwise

## ◆ selectCharacterSetWithoutCodeExtensions()

virtual OFCondition DcmSpecificCharacterSet::selectCharacterSetWithoutCodeExtensions | ( |  | ) |
| protectedvirtual

select a particular DICOM character set without code extensions for subsequent conversions.

The corresponding DICOM defined term for the source character set is determined from the member variable 'SourceCharacterSet'.

Returns
  status, EC_Normal if successful, an error code otherwise

## ◆ setConversionFlags()

virtual OFCondition DcmSpecificCharacterSet::setConversionFlags | ( | const unsigned | flags | ) |
| virtual

set flags controlling converter behavior, e.g. illegal character sequences should be handled during conversion.

Precondition
  An encoding has been selected by successfully calling OFCharacterEncoding::selectEncoding(), i.e. OFCharacterEncoding::isLibraryAvailable() and *this evaluate to OFTrue.

Parameters

  flags | the conversion flags that shall be used, a combination of the OFCharacterEncoding::ConversionFlags constants, e.g. TransliterateIllegalSequences | DiscardIllegalSequences.

Returns
  EC_Normal if the flags were set, an error code otherwise, i.e. if the flags are not supported by the underlying implementation.

See also
  OFCharacterEncoding::supportsConversionFlags()

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

- dcmdata/include/dcmtk/dcmdata/dcspchrs.h

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