function OnReplaceFilenameLeftToRight(const FileName: UnicodeString;
        const isFolder: Boolean):UnicodeString;
var i,keeplen:Integer;
    Dash,NameNoExt,Hash,FileExt:UnicodeString;
begin
  if isFolder or 
     (Length(FileName)<12) or // performance optimization
     (Length(FileName)+Length(CurrentSubPath)+Length(RightBasePath)<=250) or
     (Length(FileName)-Length(ExtractFileExt(FileName))<12)
     then
     Result:=FileName
  else begin
     NameNoExt:=ChangeFileExt(FileName,'');
     Hash:=UnicodeStringCRC32Base64(NameNoExt);
     while (Hash[Length(Hash)]='=') do
       SetLength(Hash,Length(Hash)-1);
     Hash:=StringReplace(Hash,'/','$',false);
     FileExt:=ExtractFileExt(FileName);
     keeplen:=250-Length(CurrentSubPath)-Length(RightBasePath)-Length(FileExt);
     Dash:='-';
     Result:=Copy(NameNoExt,1,keeplen)+Dash+Hash+FileExt;
     end;
  end;