Comment example for Delphi

This example does the following:

1.	Loads an image from a TIFF file.
2.	Updates the current comment array by reading comments from the file.
3.	Modifies one of the comments.
4.	Modifies and saves the file.
5.	Reads the comment that was saved, and displays it in a message box.
	This example handles only string comments. For more complex comments, refer to Exif Examples.

procedure TForm1.ReadComment1Click(Sender: TObject);
var
Empty: Variant; { For clearing comments }
MyCommentText: string; { String for CMNT_SZDESC }
NewCommentText: string; { String for CMNT_SZDESC that we read }
FilePath: string; { File to be updated }
i:  Integer; { Counter }
nRet: Integer;
begin
   { Specify the file that we will update. }
   FilePath := 'e:\image1.tif';
   { Specify the Empty variant for clearing comments. }
   VarClear(Empty);
   { Get all of the current comments from the file. }
   { Temporarily disable method errors so that we do not fail when comments are missing. }
   LeadImage1.EnableMethodErrors := False;
   for i := 0 to CMNT_LAST do
   begin
      LeadImage1.Comment[i] := Empty;
      LeadImage1.Comment[i] := LeadImage1.ReadComment(FilePath, 0, i);
   end;
   LeadImage1.EnableMethodErrors := True;
   { Load and modify the image. }
   nRet:= LeadImage1.Load(FilePath, 0, 0, 1);
   if(nRet = SUCCESS)then
   begin
      LeadImage1.Reverse();
      { Update the CMNT_SZDESC comment. }
      MyCommentText := CHR(13) + 'This image has been reversed.';
      LeadImage1.Comment[CMNT_SZDESC] := LeadImage1.Comment[CMNT_SZDESC] + MyCommentText;
      { Save the file and read the comment that we saved. }
      LeadImage1.Save(FilePath, FILE_TIF, LeadImage1.BitmapBits, 0, SAVE_OVERWRITE);
      NewCommentText := LeadImage1.ReadComment(FilePath, 0, CMNT_SZDESC);
      { Display the message. }
      Application.MessageBox(PChar(NewCommentText), 'File Comments', mb_OK);
      { Clear the comments from memory. }
      for i := 0 To CMNT_LAST do
         LeadImage1.Comment[i] := Empty;
   end;
end;