Question

I’m using the GetTitleBarInfo function in this way

procedure TForm1.Button1Click(Sender: TObject);
var
  TitleInfo       : TTitleBarInfo;
begin
  ZeroMemory(@TitleInfo, SizeOf(TitleInfo));
  GetTitleBarInfo(Handle, TitleInfo);
  ShowMessage(IntToStr(TitleInfo.rcTitleBar.Left));
end;

But none of the GetTitleBarInfo return values (all the values are zero), what I’m missing?

Answer 1

The documentation of the GetTitleBarInfo function states that you must set the cbSize member to
sizeof(TTitleBarInfo) before calling this function, also you must check the boolean result returned by the function.

procedure TForm1.Button1Click(Sender: TObject);
var
  TitleInfo       : TTitleBarInfo;
begin
  ZeroMemory(@TitleInfo, SizeOf(TitleInfo));
  TitleInfo.cbSize:=SizeOf(TitleInfo);
  if GetTitleBarInfo(Handle, TitleInfo) then
   ShowMessage(IntToStr(TitleInfo.rcTitleBar.Left));
end;