The Exif file format supports more complex comments than other formats. For a list of the comments, refer to RasterCommentMetadataType Enumeration.

This example demonstrates how to handle Exif comments that are not stored as strings. (For a simpler example for saving strings, refer to the WriteComment method.)

This example does the following:

Visual Basic

Private Sub WriteCommentsTest()
   RasterCodecs.Startup()
   Dim codecs As 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\Exif.tif"

   Dim tempImage As RasterImage = codecs.Load(srcFileName)

   ' Flip the image.
   Dim flipCmd As New FlipCommand(True)
   flipCmd.Run(tempImage)

   ' Add a user comment to the file and save it in another name.
   Dim comment As New RasterCommentMetadata()
   comment.Type = RasterCommentMetadataType.UserComment
   Dim comments As String = "The image has been flipped"
   Dim data() As Char = comments.ToCharArray(0, comments.Length)
   Dim dataComments(8 + comments.Length - 1) As Byte

   ' when you need to write a user comment the first 8 bytes 
   ' must contain the "Ascii" word.
   dataComments(0) = 41
   dataComments(1) = 53
   dataComments(2) = 43
   dataComments(3) = 49
   dataComments(4) = 49
   dataComments(5) = 0
   dataComments(6) = 0
   dataComments(7) = 0

   For i As Integer = 0 To comments.Length - 1
      dataComments(8 + i) = CType(AscW(data(i)), Byte)
   Next

   ' set the data property in the comment object to the dataComments array.
   comment.FromByte(dataComments)

   ' add the user comment to the comments collection of the image
   tempImage.Comments.Add(comment)
   codecs.Options.Save.Comments = True
   codecs.Save(tempImage, destFileName, RasterImageFormat.Exif, 24)
   tempImage.Dispose()

   ' read the user comments and display it
   comment = codecs.ReadComment(destFileName, 1, RasterCommentMetadataType.UserComment)
   dataComments = comment.GetData()
   Dim msg As String = "User comments = "
   For i As Integer = 0 To dataComments.Length - 7
      msg = msg + dataComments(i + 8).ToString
   Next

   MessageBox.Show(msg, "Notice")

   RasterCodecs.Shutdown()
End Sub

C#

private void WriteCommentsTest()
{
   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\Exif.tif";

   RasterImage tempImage = codecs.Load(srcFileName);

   // Flip the image.
   FlipCommand flipCmd = new FlipCommand(true);
   flipCmd.Run(tempImage);
   
   // Add a user comment to the file and save it in another name.
   RasterCommentMetadata comment = new RasterCommentMetadata();
   comment.Type = RasterCommentMetadataType.UserComment;
   string comments = "The image has been flipped";
   char[] data = comments.ToCharArray(0, comments.Length);
   byte[] dataComments = new byte[8 + comments.Length];

   // when you need to write a user comment the first 8 bytes 
   // must contain the "Ascii" word.
   dataComments[0] = 41;
   dataComments[1] = 53;
   dataComments[2] = 43;
   dataComments[3] = 49;
   dataComments[4] = 49;
   dataComments[5] = 0;
   dataComments[6] = 0;
   dataComments[7] = 0;
   
   for(int i = 0; i < comments.Length; i++)
      dataComments[8 + i] = (byte)data[i];

   // set the data property in the comment object to the dataComments array.
   comment.FromByte(dataComments);

   // add the user comment to the comments collection of the image
   tempImage.Comments.Add(comment);
   codecs.Options.Save.Comments = true;
   codecs.Save(tempImage, destFileName, RasterImageFormat.Exif, 24);
   tempImage.Dispose();
   
   // read the user comments and display it
   comment = codecs.ReadComment(destFileName, 1, RasterCommentMetadataType.UserComment);
   dataComments = comment.GetData();
   string msg =  "User comments = ";
   for(int i = 0; i < (dataComments.Length - 8); i++)
      msg += (char)dataComments[i + 8];

   MessageBox.Show(msg, "Notice");

   RasterCodecs.Shutdown();
}