Region inside a rect or: "Selfmade frame and region-handling for beginners"

[Marc Giesmann]

Hi again!

This doesn't seem to be hard, maybe I'm am too tired to see the quick solution...

I've got a window with a subclassed GRAPHIC CONTROL on it- they've got the same size. So I draw something like a frame on it with the PB GRAPHIC functions, and now I want to make everything transparent, which is IN the frame.

FUNCTION DRAW_TRANSPARENT_BOX(BYVAL hWND AS DWORD, BYVAL lCTRLID AS LONG) AS LONG
   TRY      
      LOCAL lSTRENGHT AS LONG
      lSTRENGHT = 3              'This is how thick the line should be

      LOCAL lWidth, lHeight AS LONG
      CONTROL GET SIZE hWND, lCTRLID TO lWidth,lHeight 'The dimensions are already "pixels" so no conversion needed...!
      
      'Draw everything I want (the "selfmade frame" in this case)
      GRAPHIC ATTACH hWND,lCTRLID
      GRAPHIC CLEAR %WHITE
      GRAPHIC WIDTH lStrenght
      GRAPHIC BOX (0,0)-(lWidth,lHeight),0,%BLACK,%WHITE
      
      'So far so good, now the hard(?) part
      LOCAL QDRRect AS RECT
      GetWindowRect(hWND, QDRRect)
      
      'Now substract the line from my RECT
      QDRRect.nLEFT   = QDRRect.nLEFT     + lSTRENGHT
      QDRRect.nRIGHT  = QDRRect.nRIGHT    - lSTRENGHT
      QDRRect.nTOP    = QDRRect.nTOP      - lSTRENGHT
      QDRRect.nBOTTOM = QDRRect.nBOTTOM   + lSTRENGHT
      
      LOCAL hRGNQDR AS DWORD
      hRGNQDR = CreateRectRgnIndirect(QDRRect)
      
      IF hRGNQDR THEN                           
         SetWindowRgn(hWnd , hRGNQDR, %FALSE)   'Everything IN the frame should be invisible
      ELSE
         MSGBOX STR$(GetLastError())
      END IF
      
    CATCH
      MSGBOX "Error #" + STR$(ERR) + " in " + FUNCNAME$, %MB_OK OR %MB_ICONERROR, "Internal Error ("+FUNCNAME$+")!"
    END TRY

END FUNCTION

Whats wrong here?

Thanks again, best regards from a tired and frustrated
Marc Giesmann