I have TDBEdit how I forced the user to write in Arabic only
How To Detect Arabic Input in (TDBEdit) in Delphi ?
Using the article Tom mentioned you can achieve what you want:
The article: Arabic blocks in Unicode.
Check for the following inputs
procedure TForm8.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
Caption := 'arabic';
case integer(key) of
1536..1791,1872..1919,2208..2303,-1200..-513,-400..-257,8,32,48..57:
begin
end;
else
// intervene here by setting key = #0
Caption :=key+ ': is not an arabic character';
end;
The numbers above are the decimal representation of the HEX values in the article.