function HTTPEncode(const AStr: string): string;
 const
 NoConversion = ['A'..'Z', 'a'..'z', '*', '@', '.', '_', '-'];
 var
 Sp, Rp: PChar;
 begin
 SetLength(Result, Length(AStr) * 3);
 Sp := PChar(AStr);
 Rp := PChar(Result);
 while Sp^ <> #0 do
 begin
 if Sp^ in NoConversion then
 Rp^ := Sp^
 else if Sp^ = ' ' then
 Rp^ := '+'
 else
 begin
 FormatBuf(Rp^, 3, '%%%.2x', 6, [Ord(Sp^)]);
 Inc(Rp, 2);
 end;
 Inc(Rp);
 Inc(Sp);
 end;
 SetLength(Result, Rp - PChar(Result));
 end;


 procedure TForm1.Button1Click(Sender: TObject);
 begin
 Edit1.Text := HTTPEncode(Edit1.Text);
 end;