Calculates the size and location of the specified text when rendered in the visual style font
#include <WinAPITheme.au3>
_WinAPI_GetThemeTextExtent ( $hTheme, $iPartID, $iStateID, $hDC, $sText, $tRECT, $iFlags )
| $hTheme | Handle to a window's specified theme data. |
| $iPartID | The part in which the text will be drawn. |
| $iStateID | The state of the part. |
| $hDC | Handle to the device context to select the font into. |
| $sText | The string that contains the text to draw. |
| $tRECT | $tagRECT structure that contains the rectangle used to control layout of the text. This parameter may be set to 0. |
| $iFlags | The string's formatting flags ($DT_* defined in "APIGdiConstants.au3). |
| Success: | $tagRECT structure that contains, in logical coordinates, the rectangle required to fit the rendered text. |
| Failure: | Sets the @error flag to non-zero, @extended flag may contain the HRESULT error code. |
Search GetThemeTextExtent in MSDN Library.