TIFFDirectory
Date: 2016-04-28

org.apache.xmlgraphics.image.codec.tiff

## Class TIFFDirectory

- java.lang.Object
- - org.apache.xmlgraphics.image.codec.tiff.TIFFDirectory

- All Implemented Interfaces:
    java.io.Serializable

      public class TIFFDirectory
      extends java.lang.Object
      implements java.io.Serializable

  A class representing an Image File Directory (IFD) from a TIFF 6.0 stream. The TIFF file format is described in more detail in the comments for the TIFFDescriptor class.

  A TIFF IFD consists of a set of TIFFField tags. Methods are provided to query the set of tags and to obtain the raw field array. In addition, convenience methods are provided for acquiring the values of tags that contain a single value that fits into a byte, int, long, float, or double.

  Every TIFF file is made up of one or more public IFDs that are joined in a linked list, rooted in the file header. A file may also contain so-called private IFDs that are referenced from tag data and do not appear in the main list.

  This class is not a committed part of the JAI API. It may be removed or changed in future releases of JAI.

  See Also:
    `TIFFField`, Serialized Form

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `TIFFDirectory(SeekableStream stream, int directory)` Constructs a TIFFDirectory from a SeekableStream.
    `TIFFDirectory(SeekableStream stream, long ifdOffset, int directory)` Constructs a TIFFDirectory by reading a SeekableStream.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `TIFFField` | `getField(int tag)` Returns the value of a given tag as a TIFFField, or null if the tag is not present.
    `byte` | `getFieldAsByte(int tag)` Returns the value of index 0 of a given tag as a byte.
    `byte` | `getFieldAsByte(int tag, int index)` Returns the value of a particular index of a given tag as a byte.
    `double` | `getFieldAsDouble(int tag)` Returns the value of index 0 of a given tag as a double.
    `double` | `getFieldAsDouble(int tag, int index)` Returns the value of a particular index of a given tag as a double.
    `float` | `getFieldAsFloat(int tag)` Returns the value of index 0 of a given tag as a float.
    `float` | `getFieldAsFloat(int tag, int index)` Returns the value of a particular index of a given tag as a float.
    `long` | `getFieldAsLong(int tag)` Returns the value of index 0 of a given tag as a long.
    `long` | `getFieldAsLong(int tag, int index)` Returns the value of a particular index of a given tag as a long.
    `TIFFField[]` | `getFields()` Returns an array of TIFFFields containing all the fields in this directory.
    `long` | `getIFDOffset()` Returns the offset of the IFD corresponding to this `TIFFDirectory`.
    `long` | `getNextIFDOffset()` Returns the offset of the next IFD after the IFD corresponding to this `TIFFDirectory`.
    `static int` | `getNumDirectories(SeekableStream stream)` Returns the number of image directories (subimages) stored in a given TIFF file, represented by a `SeekableStream`.
    `int` | `getNumEntries()` Returns the number of directory entries.
    `int[]` | `getTags()` Returns an ordered array of ints indicating the tag values.
    `boolean` | `isBigEndian()` Returns a boolean indicating whether the byte order used in the the TIFF file is big-endian.
    `boolean` | `isTagPresent(int tag)` Returns true if a tag appears in the directory.

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### TIFFDirectory

          public TIFFDirectory(SeekableStream stream,
                       int directory)
                        throws java.io.IOException

      Constructs a TIFFDirectory from a SeekableStream. The directory parameter specifies which directory to read from the linked list present in the stream; directory 0 is normally read but it is possible to store multiple images in a single TIFF file by maintaing multiple directories.
      Parameters:
        `stream` - a SeekableStream to read from.
        `directory` - the index of the directory to read.
      Throws:
        `java.io.IOException`

    - #### TIFFDirectory

          public TIFFDirectory(SeekableStream stream,
                       long ifdOffset,
                       int directory)
                        throws java.io.IOException

      Constructs a TIFFDirectory by reading a SeekableStream. The ifd_offset parameter specifies the stream offset from which to begin reading; this mechanism is sometimes used to store private IFDs within a TIFF file that are not part of the normal sequence of IFDs.
      Parameters:
        `stream` - a SeekableStream to read from.
        `ifdOffset` - the long byte offset of the directory.
        `directory` - the index of the directory to read beyond the one at the current stream offset; zero indicates the IFD at the current offset.
      Throws:
        `java.io.IOException`

  - ### Method Detail

    - #### getNumEntries

          public int getNumEntries()

      Returns the number of directory entries.

    - #### getField

          public TIFFField getField(int tag)

      Returns the value of a given tag as a TIFFField, or null if the tag is not present.

    - #### isTagPresent

          public boolean isTagPresent(int tag)

      Returns true if a tag appears in the directory.

    - #### getTags

          public int[] getTags()

      Returns an ordered array of ints indicating the tag values.

    - #### getFields

          public TIFFField[] getFields()

      Returns an array of TIFFFields containing all the fields in this directory.

    - #### getFieldAsByte

          public byte getFieldAsByte(int tag,
                            int index)

      Returns the value of a particular index of a given tag as a byte. The caller is responsible for ensuring that the tag is present and has type TIFFField.TIFF_SBYTE, TIFF_BYTE, or TIFF_UNDEFINED.

    - #### getFieldAsByte

          public byte getFieldAsByte(int tag)

      Returns the value of index 0 of a given tag as a byte. The caller is responsible for ensuring that the tag is present and has type TIFFField.TIFF_SBYTE, TIFF_BYTE, or TIFF_UNDEFINED.

    - #### getFieldAsLong

          public long getFieldAsLong(int tag,
                            int index)

      Returns the value of a particular index of a given tag as a long. The caller is responsible for ensuring that the tag is present and has type TIFF_BYTE, TIFF_SBYTE, TIFF_UNDEFINED, TIFF_SHORT, TIFF_SSHORT, TIFF_SLONG or TIFF_LONG.

    - #### getFieldAsLong

          public long getFieldAsLong(int tag)

      Returns the value of index 0 of a given tag as a long. The caller is responsible for ensuring that the tag is present and has type TIFF_BYTE, TIFF_SBYTE, TIFF_UNDEFINED, TIFF_SHORT, TIFF_SSHORT, TIFF_SLONG or TIFF_LONG.

    - #### getFieldAsFloat

          public float getFieldAsFloat(int tag,
                              int index)

      Returns the value of a particular index of a given tag as a float. The caller is responsible for ensuring that the tag is present and has numeric type (all but TIFF_UNDEFINED and TIFF_ASCII).

    - #### getFieldAsFloat

          public float getFieldAsFloat(int tag)

      Returns the value of index 0 of a given tag as a float. The caller is responsible for ensuring that the tag is present and has numeric type (all but TIFF_UNDEFINED and TIFF_ASCII).

    - #### getFieldAsDouble

          public double getFieldAsDouble(int tag,
                                int index)

      Returns the value of a particular index of a given tag as a double. The caller is responsible for ensuring that the tag is present and has numeric type (all but TIFF_UNDEFINED and TIFF_ASCII).

    - #### getFieldAsDouble

          public double getFieldAsDouble(int tag)

      Returns the value of index 0 of a given tag as a double. The caller is responsible for ensuring that the tag is present and has numeric type (all but TIFF_UNDEFINED and TIFF_ASCII).

    - #### getNumDirectories

          public static int getNumDirectories(SeekableStream stream)
                                       throws java.io.IOException

      Returns the number of image directories (subimages) stored in a given TIFF file, represented by a `SeekableStream`.
      Throws:
        `java.io.IOException`

    - #### isBigEndian

          public boolean isBigEndian()

      Returns a boolean indicating whether the byte order used in the the TIFF file is big-endian. That is, whether the byte order is from the most significant to the least significant.

    - #### getIFDOffset

          public long getIFDOffset()

      Returns the offset of the IFD corresponding to this `TIFFDirectory`.

    - #### getNextIFDOffset

          public long getNextIFDOffset()

      Returns the offset of the next IFD after the IFD corresponding to this `TIFFDirectory`.