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DeleteTag Method
See Also  Example
Leadtools.Codecs Namespace > RasterCodecs Class : DeleteTag Method




fileName
A String containing the name of the file from which to delete the tag.
pageNumber
The 1-based index of the page from which the tag will be deleted. Use -1 to delete the tag from the last page. Use 1 to delete the tag from the first page.
id
The ID of the tag in the TIFF file. The tag IDs are between 0 and 65535.
Deletes a tag from a file, if the file supports tags (TIFF or Exif).

Syntax

Visual Basic (Declaration) 
Public Sub DeleteTag( _
   ByVal fileName As String, _
   ByVal pageNumber As Integer, _
   ByVal id As Integer _
)
Visual Basic (Usage)Copy Code
Dim instance As RasterCodecs
Dim fileName As String
Dim pageNumber As Integer
Dim id As Integer
 
instance.DeleteTag(fileName, pageNumber, id)
C# 
public void DeleteTag( 
   string fileName,
   int pageNumber,
   int id
)
Managed Extensions for C++ 
public: void DeleteTag( 
   string* fileName,
   int pageNumber,
   int id
)
C++/CLI 
public:
void DeleteTag( 
   String^ fileName,
   int pageNumber,
   int id
)

Parameters

fileName
A String containing the name of the file from which to delete the tag.
pageNumber
The 1-based index of the page from which the tag will be deleted. Use -1 to delete the tag from the last page. Use 1 to delete the tag from the first page.
id
The ID of the tag in the TIFF file. The tag IDs are between 0 and 65535.

Example

Visual BasicCopy Code
RasterCodecs.Tags
      Public Sub TagExample()
         RasterCodecs.Startup()
         Dim codecs As RasterCodecs = New RasterCodecs()

         Dim srcFileName As String = "C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\Image1.cmp"
         Dim destFileName As String = "C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\Image1_PageNumberTag.tif"

         ' Convert the source file to TIF
         Console.WriteLine("Converting the source file to TIF")
         codecs.Convert(srcFileName, destFileName, RasterImageFormat.Tif, 0, 0, 24, Nothing)

         Const pageNumberTagId As Integer = 297
         Dim pageNumber As Integer = 7

         Dim writeTag As RasterTagMetadata = New RasterTagMetadata()
         writeTag.Id = pageNumberTagId
         writeTag.DataType = RasterTagMetadataDataType.Int32
         writeTag.FromInt32(New Integer() {pageNumber})

         Console.WriteLine("Writing the following tag to the file:")
         Console.WriteLine(" ID: {0}", writeTag.Id)
         Console.WriteLine(" DataType: {0}", writeTag.DataType)
         Console.Write(" Data: ")
         Dim writeTagData As Byte() = writeTag.GetData()
         Dim i As Integer = 0
         Do While i < writeTagData.Length
            Console.Write("{0:X} ", writeTagData(i))
            i += 1
         Loop
         Console.WriteLine()

         ' Add the tag
         Console.WriteLine("Writing the page number tag with data = {0} to the file", pageNumber)
         codecs.WriteTag(destFileName, 1, writeTag)

         ' Read the tag and make sure it is in the file
         Console.WriteLine("Reading the page number tag from the file")
         Dim readTag As RasterTagMetadata = codecs.ReadTag(destFileName, 1, pageNumberTagId)

         Console.WriteLine("Tag read from the file:")
         Console.WriteLine(" ID: {0}", readTag.Id)
         Console.WriteLine(" DataType: {0}", readTag.DataType)
         Console.Write(" Data: ")
         Dim readTagData As Byte() = readTag.GetData()
         i = 0
         Do While i < readTagData.Length
            Console.Write("{0:X} ", readTagData(i))
            i += 1
         Loop
         Console.WriteLine()

         Debug.Assert(writeTag.Id = readTag.Id)
         Debug.Assert(writeTag.DataType = readTag.DataType)
         Debug.Assert(writeTagData.Length = writeTagData.Length)
         i = 0
         Do While i < writeTagData.Length
            Debug.Assert(writeTagData(i) = readTagData(i))
            i += 1
         Loop

         ' Delete the tag from the file
         Console.WriteLine("Deleting the tag from the file")
         codecs.DeleteTag(destFileName, 1, pageNumberTagId)

         ' Make sure the tag is deleted
         Console.WriteLine("Reading the tag from the file again")
         readTag = codecs.ReadTag(destFileName, 1, pageNumberTagId)

         If readTag Is Nothing Then
            Console.WriteLine("Tag was not found")
         Else
            Console.WriteLine("Tag is found, this should not happen")
         End If

         Debug.Assert(readTag Is Nothing)

         ' Clean up
         codecs.Dispose()
         RasterCodecs.Shutdown()
      End Sub
C#Copy Code
RasterCodecs.Tags 
      public void TagExample() 
      { 
         RasterCodecs.Startup(); 
         RasterCodecs codecs = new RasterCodecs(); 
 
         string srcFileName = @"C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\Image1.cmp"; 
         string destFileName = @"C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\Image1_PageNumberTag.tif"; 
 
         // Convert the source file to TIF 
         Console.WriteLine("Converting the source file to TIF"); 
         codecs.Convert(srcFileName, destFileName, RasterImageFormat.Tif, 0, 0, 24, null); 
 
         const int pageNumberTagId = 297; 
         int pageNumber = 7; 
 
         RasterTagMetadata writeTag = new RasterTagMetadata(); 
         writeTag.Id = pageNumberTagId; 
         writeTag.DataType = RasterTagMetadataDataType.Int32; 
         writeTag.FromInt32(new int[] { pageNumber }); 
 
         Console.WriteLine("Writing the following tag to the file:"); 
         Console.WriteLine("  ID: {0}", writeTag.Id); 
         Console.WriteLine("  DataType: {0}", writeTag.DataType); 
         Console.Write("  Data: "); 
         byte[] writeTagData = writeTag.GetData(); 
         for(int i = 0; i < writeTagData.Length; i++) 
            Console.Write("{0:X} ", writeTagData[i]); 
         Console.WriteLine(); 
 
         // Add the tag 
         Console.WriteLine("Writing the page number tag with data = {0} to the file", pageNumber); 
         codecs.WriteTag(destFileName, 1, writeTag); 
 
         // Read the tag and make sure its in the file 
         Console.WriteLine("Reading the page number tag from the file"); 
         RasterTagMetadata readTag = codecs.ReadTag(destFileName, 1, pageNumberTagId); 
 
         Console.WriteLine("Tag read from the file:"); 
         Console.WriteLine("  ID: {0}", readTag.Id); 
         Console.WriteLine("  DataType: {0}", readTag.DataType); 
         Console.Write("  Data: "); 
         byte[] readTagData = readTag.GetData(); 
         for(int i = 0; i < readTagData.Length; i++) 
            Console.Write("{0:X} ", readTagData[i]); 
         Console.WriteLine(); 
 
         Debug.Assert(writeTag.Id == readTag.Id); 
         Debug.Assert(writeTag.DataType == readTag.DataType); 
         Debug.Assert(writeTagData.Length == writeTagData.Length); 
         for(int i = 0; i < writeTagData.Length; i++) 
            Debug.Assert(writeTagData[i] == readTagData[i]); 
 
         // Delete the tag from the file 
         Console.WriteLine("Deleting the tag from the file"); 
         codecs.DeleteTag(destFileName, 1, pageNumberTagId); 
 
         // Make sure the tag is deleted 
         Console.WriteLine("Reading the tag from the file again"); 
         readTag = codecs.ReadTag(destFileName, 1, pageNumberTagId); 
 
         if(readTag == null) 
            Console.WriteLine("Tag was not found"); 
         else 
            Console.WriteLine("Tag is found, this should not happen"); 
 
         Debug.Assert(readTag == null); 
 
         // Clean up 
         codecs.Dispose(); 
         RasterCodecs.Shutdown(); 
      }

Remarks

If you want to delete the tag from a particular IFD in the file, set RasterCodecs.Options.Tiff.Save.UseImageFileDirectoryOffset to true, and set RasterCodecs.Options.Tiff.Save.ImageFileDirectoryOffset to the IFD in question. This method will delete tags only from the main IFDs that make up an image. Some TIFF tags are themselves SubIFDs. You can delete tags from such SubIFDs by using RasterCodecs.Options.Tiff.Save.UseImageFileDirectoryOffset and RasterCodecs.Options.Tiff.Save.ImageFileDirectoryOffset specifying the IFD as above.

Notes:

  • The Leadtools.Codecs.Cmp.dll codec is used to delete the tag from all the TIFF and Exif files.
  • Do not attempt to use this method to delete tags from inside the TagFound event. If you want to delete tags that you enumerate, use the TagFound event to add the tags to a list. Upon returning from EnumTags, you can delete all the tags from the list.
  • You should be careful when you delete non-custom tags (tags below 32768). If you delete the wrong tag, you might corrupt the TIF file!.

When you add or remove tags, the tags array at the end of the file is re-written. When you modify existing tags, the new tag value is added to the file and the IFD is modified as necessary. In all of these cases, there is no image recompression.

Requirements

Target Platforms: Microsoft .NET Framework 2.0, Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also