Module java.desktop
Package javax.imageio.plugins.tiff

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 int MAX_DATATYPE
    The numerically largest constant representing a TIFF data type.
    static int MIN_DATATYPE
    The numerically smallest constant representing a TIFF data type.
    static int TIFF_ASCII
    Flag for null-terminated ASCII strings.
    static int TIFF_BYTE
    Flag for 8 bit unsigned integers.
    static int TIFF_DOUBLE
    Flag for 64 bit IEEE doubles.
    static int TIFF_FLOAT
    Flag for 32 bit IEEE floats.
    static int TIFF_IFD_POINTER
    Flag for IFD pointer defined in TIFF Tech Note 1 in TIFF Specification Supplement 1.
    static int TIFF_LONG
    Flag for 32 bit unsigned integers.
    static int TIFF_RATIONAL
    Flag for pairs of 32 bit unsigned integers.
    static int TIFF_SBYTE
    Flag for 8 bit signed integers.
    static int TIFF_SHORT
    Flag for 16 bit unsigned integers.
    static int TIFF_SLONG
    Flag for 32 bit signed integers.
    static int TIFF_SRATIONAL
    Flag for pairs of 32 bit signed integers.
    static int TIFF_SSHORT
    Flag for 16 bit signed integers.
    static int TIFF_UNDEFINED
    Flag for 8 bit uninterpreted bytes.
    static 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

  • 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 TIFFTags 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.