# Class TIFFTag

java.lang.Object
javax.imageio.plugins.tiff.TIFFTag

public class TIFFTag extends Object
A class defining the notion of a TIFF tag. A TIFF tag is a key that may appear in an Image File Directory (IFD). In the IFD each tag has some data associated with it, which may consist of zero or more values of a given data type. The combination of a tag and a value is known as an IFD Entry or TIFF Field.

The actual tag values used in the root IFD of a standard ("baseline") tiff stream are defined in the `BaselineTIFFTagSet` class.

Since:
  9
See Also:
  - `BaselineTIFFTagSet`
  - `TIFFField`
  - `TIFFTagSet`

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final int`
  `MAX_DATATYPE`
  The numerically largest constant representing a TIFF data type.
  `static final int`
  `MIN_DATATYPE`
  The numerically smallest constant representing a TIFF data type.
  `static final int`
  `TIFF_ASCII`
  Flag for null-terminated ASCII strings.
  `static final int`
  `TIFF_BYTE`
  Flag for 8 bit unsigned integers.
  `static final int`
  `TIFF_DOUBLE`
  Flag for 64 bit IEEE doubles.
  `static final int`
  `TIFF_FLOAT`
  Flag for 32 bit IEEE floats.
  `static final int`
  `TIFF_IFD_POINTER`
  Flag for IFD pointer defined in TIFF Tech Note 1 in TIFF Specification Supplement 1.
  `static final int`
  `TIFF_LONG`
  Flag for 32 bit unsigned integers.
  `static final int`
  `TIFF_RATIONAL`
  Flag for pairs of 32 bit unsigned integers.
  `static final int`
  `TIFF_SBYTE`
  Flag for 8 bit signed integers.
  `static final int`
  `TIFF_SHORT`
  Flag for 16 bit unsigned integers.
  `static final int`
  `TIFF_SLONG`
  Flag for 32 bit signed integers.
  `static final int`
  `TIFF_SRATIONAL`
  Flag for pairs of 32 bit signed integers.
  `static final int`
  `TIFF_SSHORT`
  Flag for 16 bit signed integers.
  `static final int`
  `TIFF_UNDEFINED`
  Flag for 8 bit uninterpreted bytes.
  `static final String`
  `UNKNOWN_TAG_NAME`
  The name assigned to a tag with an unknown tag number.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `TIFFTag(String name, int number, int dataTypes)`
  Constructs a `TIFFTag` with a given name, tag number, and set of legal data types.
  `TIFFTag(String name, int number, int dataTypes, int count)`
  Constructs a `TIFFTag` with a given name, tag number, set of legal data types, and value count.
  `TIFFTag(String name, int number, TIFFTagSet tagSet)`
  Constructs a `TIFFTag` with a given name, tag number and `TIFFTagSet` to which it refers.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected void`
  `addValueName(int value, String name)`
  Adds a mnemonic name for a particular value that this tag's data may take on.
  `int`
  `getCount()`
  Returns the value count of this tag.
  `int`
  `getDataTypes()`
  Returns a bit mask indicating the set of data types that may be used to store the data associated with the tag.
  `String`
  `getName()`
  Returns the name of the tag, as it will appear in image metadata.
  `int[]`
  `getNamedValues()`
  Returns an array of values for which mnemonic names are defined.
  `int`
  `getNumber()`
  Returns the integer used to represent the tag.
  `static int`
  `getSizeOfType(int dataType)`
  Returns the number of bytes used to store a value of the given data type.
  `TIFFTagSet`
  `getTagSet()`
  Returns the `TIFFTagSet` of which this tag is a part.
  `String`
  `getValueName(int value)`
  Returns the mnemonic name associated with a particular value that this tag's data may take on, or `null` if no name is present.
  `boolean`
  `hasValueNames()`
  Returns `true` if there are mnemonic names associated with the set of legal values for the data associated with this tag.
  `boolean`
  `isDataTypeOK(int dataType)`
  Returns `true` if the given data type may be used for the data associated with this tag.
  `boolean`
  `isIFDPointer()`
  Returns `true` if this tag is used to point to an IFD structure containing additional tags.

  ### Methods declared in class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### TIFF_BYTE

    public static final int TIFF_BYTE
    Flag for 8 bit unsigned integers.
    See Also:
      - Constant Field Values

  - ### TIFF_ASCII

    public static final int TIFF_ASCII
    Flag for null-terminated ASCII strings.
    See Also:
      - Constant Field Values

  - ### TIFF_SHORT

    public static final int TIFF_SHORT
    Flag for 16 bit unsigned integers.
    See Also:
      - Constant Field Values

  - ### TIFF_LONG

    public static final int TIFF_LONG
    Flag for 32 bit unsigned integers.
    See Also:
      - Constant Field Values

  - ### TIFF_RATIONAL

    public static final int TIFF_RATIONAL
    Flag for pairs of 32 bit unsigned integers.
    See Also:
      - Constant Field Values

  - ### TIFF_SBYTE

    public static final int TIFF_SBYTE
    Flag for 8 bit signed integers.
    See Also:
      - Constant Field Values

  - ### TIFF_UNDEFINED

    public static final int TIFF_UNDEFINED
    Flag for 8 bit uninterpreted bytes.
    See Also:
      - Constant Field Values

  - ### TIFF_SSHORT

    public static final int TIFF_SSHORT
    Flag for 16 bit signed integers.
    See Also:
      - Constant Field Values

  - ### TIFF_SLONG

    public static final int TIFF_SLONG
    Flag for 32 bit signed integers.
    See Also:
      - Constant Field Values

  - ### TIFF_SRATIONAL

    public static final int TIFF_SRATIONAL
    Flag for pairs of 32 bit signed integers.
    See Also:
      - Constant Field Values

  - ### TIFF_FLOAT

    public static final int TIFF_FLOAT
    Flag for 32 bit IEEE floats.
    See Also:
      - Constant Field Values

  - ### TIFF_DOUBLE

    public static final int TIFF_DOUBLE
    Flag for 64 bit IEEE doubles.
    See Also:
      - Constant Field Values

  - ### TIFF_IFD_POINTER

    public static final int TIFF_IFD_POINTER
    Flag for IFD pointer defined in TIFF Tech Note 1 in TIFF Specification Supplement 1.
    See Also:
      - Constant Field Values

  - ### MIN_DATATYPE

    public static final int MIN_DATATYPE
    The numerically smallest constant representing a TIFF data type.
    See Also:
      - Constant Field Values

  - ### MAX_DATATYPE

    public static final int MAX_DATATYPE
    The numerically largest constant representing a TIFF data type.
    See Also:
      - Constant Field Values

  - ### UNKNOWN_TAG_NAME

    public static final String UNKNOWN_TAG_NAME
    The name assigned to a tag with an unknown tag number. Such a tag may be created for example when reading an IFD and a tag number is encountered which is not in any of the `TIFFTagSet`s known to the reader.
    See Also:
      - Constant Field Values

- ## Constructor Details

  - ### TIFFTag

    public TIFFTag(String name, int number, int dataTypes, int count)
    Constructs a `TIFFTag` with a given name, tag number, set of legal data types, and value count. A negative value count signifies that either an arbitrary number of values is legal or the required count is determined by the values of other fields in the IFD. A non-negative count specifies the number of values which an associated field must contain. The tag will have no associated `TIFFTagSet`.

    If there are mnemonic names to be associated with the legal data values for the tag, `addValueName()` should be called on the new instance for each name. Mnemonic names apply only to tags which have integral data type.

    See the documentation for `getDataTypes()` for an explanation of how the set of data types is to be converted into a bit mask.

    Parameters:
      `name` - the name of the tag.
      `number` - the number used to represent the tag.
      `dataTypes` - a bit mask indicating the set of legal data types for this tag.
      `count` - the value count for this tag.
    Throws:
      `NullPointerException` - if name is null.
      `IllegalArgumentException` - if number is negative or dataTypes is negative or specifies an out of range type.

  - ### TIFFTag

    public TIFFTag(String name, int number, TIFFTagSet tagSet)
    Constructs a `TIFFTag` with a given name, tag number and `TIFFTagSet` to which it refers. The legal data types are set to include `TIFF_LONG` and `TIFF_IFD_POINTER` and the value count is unity. The `TIFFTagSet` will represent the set of `TIFFTag`s which appear in the IFD pointed to. A `TIFFTag` represents an IFD pointer if and only if `tagSet` is non-`null` or the data type `TIFF_IFD_POINTER` is legal.
    Parameters:
      `name` - the name of the tag.
      `number` - the number used to represent the tag.
      `tagSet` - the `TIFFTagSet` to which this tag belongs.
    Throws:
      `NullPointerException` - if name or tagSet is null.
      `IllegalArgumentException` - if number is negative.
    See Also:
      - `TIFFTag(String, int, int, int)`

  - ### TIFFTag

    public TIFFTag(String name, int number, int dataTypes)
    Constructs a `TIFFTag` with a given name, tag number, and set of legal data types. The value count of the tag will be undefined and it will have no associated `TIFFTagSet`.
    Parameters:
      `name` - the name of the tag.
      `number` - the number used to represent the tag.
      `dataTypes` - a bit mask indicating the set of legal data types for this tag.
    Throws:
      `NullPointerException` - if name is null.
      `IllegalArgumentException` - if number is negative or dataTypes is negative or specifies an out of range type.
    See Also:
      - `TIFFTag(String, int, int, int)`

- ## Method Details

  - ### getSizeOfType

    public static int getSizeOfType(int dataType)
    Returns the number of bytes used to store a value of the given data type.
    Parameters:
      `dataType` - the data type to be queried.
    Returns:
      the number of bytes used to store the given data type.
    Throws:
      `IllegalArgumentException` - if `datatype` is less than `MIN_DATATYPE` or greater than `MAX_DATATYPE`.

  - ### getName

    public String getName()
    Returns the name of the tag, as it will appear in image metadata.
    Returns:
      the tag name, as a `String`.

  - ### getNumber

    public int getNumber()
    Returns the integer used to represent the tag.
    Returns:
      the tag number, as an `int`.

  - ### getDataTypes

    public int getDataTypes()
    Returns a bit mask indicating the set of data types that may be used to store the data associated with the tag. For example, a tag that can store both SHORT and LONG values would return a value of:

         (1 << TIFFTag.TIFF_SHORT) | (1 << TIFFTag.TIFF_LONG)

    Returns:
      an `int` containing a bitmask encoding the set of valid data types.

  - ### getCount

    public int getCount()
    Returns the value count of this tag. If this value is positive, it represents the required number of values for a `TIFFField` which has this tag. If the value is negative, the count is undefined. In the latter case the count may be derived, e.g., the number of values of the `BitsPerSample` field is `SamplesPerPixel`, or it may be variable as in the case of most `US-ASCII` fields.
    Returns:
      the value count of this tag.

  - ### isDataTypeOK

    public boolean isDataTypeOK(int dataType)
    Returns `true` if the given data type may be used for the data associated with this tag.
    Parameters:
      `dataType` - the data type to be queried, one of `TIFF_BYTE`, `TIFF_SHORT`, etc.
    Returns:
      a `boolean` indicating whether the given data type may be used with this tag.
    Throws:
      `IllegalArgumentException` - if `datatype` is less than `MIN_DATATYPE` or greater than `MAX_DATATYPE`.

  - ### getTagSet

    public TIFFTagSet getTagSet()
    Returns the `TIFFTagSet` of which this tag is a part.
    Returns:
      the containing `TIFFTagSet`.

  - ### isIFDPointer

    public boolean isIFDPointer()
    Returns `true` if this tag is used to point to an IFD structure containing additional tags. A `TIFFTag` represents an IFD pointer if and only if its `TIFFTagSet` is non-`null` or the data type `TIFF_IFD_POINTER` is legal. This condition will be satisfied if and only if either `getTagSet() != null` or `isDataTypeOK(TIFF_IFD_POINTER) == true`.

    Many TIFF extensions use the IFD mechanism in order to limit the number of new tags that may appear in the root IFD.

    Returns:
      `true` if this tag points to an IFD.

  - ### hasValueNames

    public boolean hasValueNames()
    Returns `true` if there are mnemonic names associated with the set of legal values for the data associated with this tag. Mnemonic names apply only to tags which have integral data type.
    Returns:
      `true` if mnemonic value names are available.

  - ### addValueName

    protected void addValueName(int value, String name)
    Adds a mnemonic name for a particular value that this tag's data may take on. Mnemonic names apply only to tags which have integral data type.
    Parameters:
      `value` - the data value.
      `name` - the name to associate with the value.

  - ### getValueName

    public String getValueName(int value)
    Returns the mnemonic name associated with a particular value that this tag's data may take on, or `null` if no name is present. Mnemonic names apply only to tags which have integral data type.
    Parameters:
      `value` - the data value.
    Returns:
      the mnemonic name associated with the value, as a `String`.

  - ### getNamedValues

    public int[] getNamedValues()
    Returns an array of values for which mnemonic names are defined. The method `getValueName()` will return non-`null` only for values contained in the returned array. Mnemonic names apply only to tags which have integral data type.
    Returns:
      the values for which there is a mnemonic name.