Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 359
  • Last Modified:

IDirectDrawClipper::SetClipList question

I'm trying to set an IDirectDrawClipper so that it just clips all of a surface.  How do I do this?  I tried using SetClipList, using the following code to create the regiondata:

      HRGN hRgn = CreateRectRgn( 0, 0, Width, Height );
      DWORD dwBufferSize = GetRegionData( hRgn, 0, NULL );
      RGNDATA *rgnData = (RGNDATA *)(new char[dwBufferSize]);
      DWORD dwReturn = GetRegionData( hRgn, dwBufferSize, rgnData );
      if( dwReturn == 0 ) Error( "GetRegionData failed.\n" );
      else if( dwReturn != 1 ) Error( "GetRegionData returned a non-zero value (%d).\n", dwReturn );

But I get the "GetRegionData returned a non-zero value" error.  (dwReturn is 48 bytes, as I expect, because sizeof(RGNDATAHEADER) == 32)

All I wanted was to make a clipper that is Width x Height, for use on an offscreen surface.

Thanks for any help,
0
Bishop051997
Asked:
Bishop051997
  • 2
1 Solution
 
Bishop051997Author Commented:
Adjusted points to 300
0
 
wirusCommented:
There is a bug (or a mistake in documentation).
GetRegionData() returns always number of bytes copied, if buffer size >= required, or 0. However, after checking ReturnValue==dwBufferSize (ReturnValue<=dwBufferSize), you should always check for "1" (because documentation says so...):

ASSERT( ReturnValue<=dwBufferSize && ReturnValue>0 );

I mean your code works, you only have to modify error checking.

Anyway, if you need rectangular regions only, I suggest preparing RGNDATAHEADER youself:

// .......................

RECT theRect = {<rectLeft>, <rectTop>, <rectRight>, <rectBottom>};

// ......................

struct {
RGNDATAHEADER rdh;
RECT rect;
} rectRgnS;
rectRgnS.rdh.dwSize = sizeof(RGNDATAHEADER); // 32
rectRgnS.rdh.iType = RDH_RECTANGLES; // 1
rectRgnS.rdh.nCound = 1;
rectRgnS.rdh.nRgnSize = sizeof(RECT); // 16
memcpy(&rectRgnS.rdh.rcBound, &theRect, sizeof(RECT));
memcpy(&rectRgnS.rect, &theRect, sizeof(RECT));
// ready to use

// ...............................................

\Virus

0
 
Bishop051997Author Commented:
Goddamnit!!  I hate when the documentation is wrong :)

It works now, anyway - thanks.
0

Featured Post

Hire Technology Freelancers with Gigs

Work with freelancers specializing in everything from database administration to programming, who have proven themselves as experts in their field. Hire the best, collaborate easily, pay securely, and get projects done right.

  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now