[This is preliminary documentation and is subject to change.]

Kinds of Exif metadata items as reported by reader events

Namespace: Tools.MetadataT.ExifT
Assembly: Tools.Metadata (in Tools.Metadata.dll) Version: 1.5.3.38916 (1.5.3.38916)

Syntax

C#
public enum ReaderItemKinds

Visual Basic
Public Enumeration ReaderItemKinds

Visual C++
public enum class ReaderItemKinds

F#
type ReaderItemKinds

JScript
public enum ReaderItemKinds

Members

Member name	Value	Description
Unknown	0	Not used by ReadItem, but used by ExifMapGenerator to indicate bytes of unknown purpose in Exif metadata block
Exif	1	Raised only once at the beginning or reading. ItemStream contains whole strem. Sender is ExifReader. ItemObject is null. CanSkip is true. ItemAbsoluteOffset is 0. ItemLength is length of whole stream. Caught by ExifMapGenerator to determine length of stream but not used in map.
Bom	2	Raised when the Byte Order mark (BOM) is read. This is the 2nd event and occures only once. ItemStream is null. Sender is ExifReader. ItemObject is BOM text ("II" or "MM" or any 2-characters long string in case InvalidDataException passed to ReadError will immediatelly follow; you can recover the exception and Little Endian byte order will be used.) CanSkip is false. ItemAbsoluteOffset is 0. ItemLength is 2. Used by ExifMapGenerator
BomTest	3	Raised when the Byte Order mark test is read. This is the 3rd event and occures only once. ItemStream is null. Sender is ExifReader. ItemObject is 0x2A (UInt16) (or any other number when unrecoverable InvalidDataException will be throwm immediatelly.) CanSkip is false. ItemAbsoluteOffset is 2. ItemLength is 2. Used by ExifMapGenerator
Ifd0Offset	4	Raised when offset to 1st IFD (IFD0) is read. This is the 4th event and occures only once. ItemStream is null. Sender is ExifReader. ItemObject is UInt32 offset to 1st IFD (usually 0x8) CanSkip is false. ItemAbsoluteOffset is 4. ItemLength is 4. Used by ExifMapGenerator
IfdNumberOfEntries	5	Raised when number of entries in IFD is read. Occurs for each IFD and SubIFD. ItemStream is null. Sender is ExifIfdReader. ItemObject is UInt16 number of entries CanSkip is false. ItemAbsoluteOffset is position of the number. ItemLength is 2. Used by ExifMapGenerator
Ifd	6	Raised before IFD is read. ItemStream is null. Sender is ExifIfdReader. ItemObject is null CanSkip is true. ItemAbsoluteOffset is position of first entry. ItemLength is 12 * numjber of entries.
TagNumber	7	Raised when tag number is read. ItemStream is null. Sender is ExifIfdReader. ItemObject is UInt16 tag number CanSkip is false. ItemAbsoluteOffset is position of tag number. ItemLength is 2. Used by ExifMapGenerator
TagDataType	8	Raised when tag data type is read. ItemStream is null. Sender is ExifIfdReader. ItemObject is UInt16 tag data type (see ExifDataTypes) CanSkip is false. ItemAbsoluteOffset is position of data type number. ItemLength is 2. Used by ExifMapGenerator
TagComponents	9	Raised when tag number of components is read. ItemStream is null. Sender is ExifIfdReader. ItemObject is UInt32 number of components CanSkip is false. ItemAbsoluteOffset is position of tag number of bcomponents. ItemLength is 4. Used by ExifMapGenerator
TagDataOrOffset	10	Raised when tag data part is read. Note: Tag data part contains either data or pointer to data depending on if data fits into 4 bytes. ItemStream is null. Sender is ExifIfdReader. ItemObject is Byte 4-bytes data part of tag CanSkip is false. ItemAbsoluteOffset is position data part of tag. ItemLength is 4. Used by ExifMapGenerator
TagHeader	11	Raised when whole tag header is read, before tag data are parsed. ItemStream is null. Sender is ExifIfdReader. ItemObject is null CanSkip is true. ItemAbsoluteOffset is position of tag number. ItemLength is 12. This event carrys no information about tag being red. All necessary informations can be collected from events TagNumber, TagDataType, TagComponents and TagDataOrOffset which always preceed this event in given order.
ExternalTagData	12	Raised when tag data stored outside of tag are read. Raised ony for tags which has data longer than 4 bytes. ItemStream is null. Sender is DirectoryEntry. ItemObject is Byte array with data. CanSkip is false. ItemAbsoluteOffset is position of data. ItemLength is length of data (if previously the InvalidOperationException was recovered the actual lenght of data is less). Used by ExifMapGenerator
Tag	13	Raised after whole tag if read and parsed ItemStream is null. Sender is ExifIfdReader. ItemObject is DirectoryEntry CanSkip is false. ItemAbsoluteOffset is -1 (not supported). ItemLength is -1 (not supported).
NextIfdOffset	14	Raised when pointer to next IFD is read at the end of each IFD ItemStream is null. Sender is ExifIfdReader. ItemObject is UInt32 pointer to next IFD. CanSkip is false. ItemAbsoluteOffset position of pointer. ItemLength is 4. Used by ExifMapGenerator
Thumbnail	15	Raised before thumbnail is read. ItemStream is null. Sender is IfdMain. ItemObject is null. CanSkip is true. ItemAbsoluteOffset is -1 (not supported). ItemLength is -1 (not supported).
JpegThumbnail	16	Raised when reading JPEG thumbnail data. ItemStream is JPEG thumbnail data stream. Sender is IfdMain. ItemObject is null. CanSkip is false. ItemAbsoluteOffset is offset of thumbnail SOI (where JPEG data starts). ItemLength is length of JPEG data. Used by ExifMapGenerator
TiffThumbnailPart	17	Raised when reading part of TIFF thumbnailo data (TIFF thumbnail can be placed in more than one part). ItemStream is stream to that part of data. Sender is IfdMain. ItemObject is null. CanSkip is false. ItemAbsoluteOffset is offset to start of stream of part. ItemLength is legnth of part. Used by ExifMapGenerator
TiffThumbNail	18	Raised after all TIFF thumbnail sub-streams are detected. ItemStream stream of all TIFF thumbnail data. Sender is IfdMain. ItemObject is null. CanSkip is false. ItemAbsoluteOffset is -1 (not supported). ItemLength is -1 (not supported).
Empty	19	Used neither by ExifMapGenerator nor by ExifReader..::..ExifEventArgs. Indicates that given byte is unused.
SubIfdMask	128	Or mask that applies to IfdNumberOfEntries, Ifd and NextIfdOffset to make SubIfdNumberOfEntries, SubIfd and NextSubIfdOffset respectively. This value itself is never used as event identifier.
SubIfdNumberOfEntries	133	Same meaning as IfdNumberOfEntries but for SubIFD. Used by ExifMapGenerator
SubIfd	134	Same meaning as Ifd but for SubIFD. Used by ExifMapGenerator
NextSubIfdOffset	142	Same meaning as NextIfdOffset but for SubIFD. Used by ExifMapGenerator
WriterMask	64	Or mask applied by ExifWriter to items written by it to distinguish them from original ones. Not used by ExifMapGenerator and ExifReader..::..ExifEventArgs.
IsFlags		Gets value indicating if given value is of enum type which has FlagsAttribute applied
GetName		Gets name of given enumeration value
GetConstant		Gets constant field that represents given enum value
GetValue		Gets value of enum in its unedlying type
IsDefined		Gets value idicating if given value is defined as constant in enumeration

Remarks

This enumeration is also used by ExifMapGenerator, but only some (the most low-level ones) members are valid for it.

Syntax

Members

Remarks

See Also