BUG: SelectClipRgn() Does Not Update Properly on Printer

• Microsoft Windows Software Development Kit (SDK) for Windows version 3.1

SYMPTOMS

In a Windows 3.1 printing application, calling SelectClipRgn() with the second parameter set to NULL to reset the clipping region to clip output to the printer page does not reset the clipping region. Clipping on the printer device context is still set to the clipping region specified in the previous call to SelectClipRgn().

CAUSE

The HP LaserJet II and HP LaserJet III printer drivers do not handle the call to SelectClipRgn() properly when the hrgn parameter is set to NULL. Instead of setting the clipping region to be the entire printable page (as it should), the call has no effect and the previous clipping region is still the device context's clipping region.

RESOLUTION

Instead of sending NULL as the hrgn parameter to SelectClipRgn(), create a region of the printable area of the page and send that region as the hrgn parameter. This will give the desired effect of calling SelectClipRgn(hPrnDC, NULL). The following is an example of how this workaround could be implemented:

   HRGN hRgn,hPageRgn;
   POINT pt;

   SelectClipRgn(hPrnDC,hRgn=CreateRectRgn(200,200,500,500));
   // .  .  .
   // SelectClipRgn(hPrnDC,NULL);
   // Instead of calling the above function, try this:
   pt.x=GetDeviceCaps(hPrnDC,HORZRES);
   pt.y=GetDeviceCaps(hPrnDC,VERTRES);
   SelectClipRgn(hPrnDC,hPageRgn=CreateRectRgn(0,0,pt.x,pt.y));
   DeleteObject(hRgn);
   DeleteObject(hPageRgn);