GetThemeTextExtent

function GetThemeTextExtent(

  hTheme: HTHEME;

  hdc: HDC;

  iPartId: Integer;

  iStateId: Integer;

  pszText: LPCWSTR;

  iCharCount: Integer;

  dwTextFlags: DWORD;

  pBoundingRect: PRect;

  var pExtentRect: RECT

):HRESULT;