C / C++ / MFC

HRESULT GetCaps(
  LPDIRECTDRAW lpDD,
  LPDDCAPS lpDDDriverCaps,
  LPDDCAPS lpDDHELCap
  );

typedef struct _DDCAPS { 
    DWORD    dwSize; 
    DWORD    dwCaps;                  // driver-specific caps 
    DWORD    dwCaps2;                 // more driver-specific caps 
    DWORD    dwCKeyCaps;              // color key caps 
    DWORD    dwFXCaps;                // stretching and effects caps 
    DWORD    dwFXAlphaCaps;           // alpha caps 
    DWORD    dwPalCaps;               // palette caps 
    DWORD    dwSVCaps;                // stereo vision caps 
    DWORD    dwAlphaBltConstBitDepths;       // alpha bit-depth members 
    DWORD    dwAlphaBltPixelBitDepths;       //  .
    DWORD    dwAlphaBltSurfaceBitDepths;     //  .
    DWORD    dwAlphaOverlayConstBitDepths;   //  .
    DWORD    dwAlphaOverlayPixelBitDepths;   //  .
    DWORD    dwAlphaOverlaySurfaceBitDepths; //  .
    DWORD    dwZBufferBitDepths;      // Z-buffer bit depth 
    DWORD    dwVidMemTotal;           // total video memory 
    DWORD    dwVidMemFree;            // total free video memory 
    DWORD    dwMaxVisibleOverlays;    // maximum visible overlays 
    DWORD    dwCurrVisibleOverlays;   // overlays currently visible 
    DWORD    dwNumFourCCCodes;        // number of supported FOURCC codes 
    DWORD    dwAlignBoundarySrc;      // overlay alignment restrictions 
    DWORD    dwAlignSizeSrc;          //  .
    DWORD    dwAlignBoundaryDest;     //  .
    DWORD    dwAlignSizeDest;         //  .
    DWORD    dwAlignStrideAlign;      // stride alignment 
    DWORD    dwRops[DD_ROP_SPACE];    // supported raster ops 
    DWORD    dwReservedCaps;          // reserved
    DWORD    dwMinOverlayStretch;     // overlay stretch factors 
    DWORD    dwMaxOverlayStretch;     //  .
    DWORD    dwMinLiveVideoStretch;   // obsolete
    DWORD    dwMaxLiveVideoStretch;   //  .
    DWORD    dwMinHwCodecStretch;     //  .
    DWORD    dwMaxHwCodecStretch;     //  .
    DWORD    dwReserved1;             // reserved
    DWORD    dwReserved2;             //  .
    DWORD    dwReserved3;             //  .
    DWORD    dwSVBCaps;               // system-to-video blit related caps 
    DWORD    dwSVBCKeyCaps;           //  .
    DWORD    dwSVBFXCaps;             //  .
    DWORD    dwSVBRops[DD_ROP_SPACE]; //  .
    DWORD    dwVSBCaps;               // video-to-system blit related caps 
    DWORD    dwVSBCKeyCaps;           //  .
    DWORD    dwVSBFXCaps;             //  .
    DWORD    dwVSBRops[DD_ROP_SPACE]; //  .
    DWORD    dwSSBCaps;               // system-to-system blit related caps 
    DWORD    dwSSBCKeyCaps;           //  .
    DWORD    dwSSBCFXCaps;            //  .
    DWORD    dwSSBRops[DD_ROP_SPACE]; //  .
    DWORD    dwMaxVideoPorts;         // maximum number of live video ports 
    DWORD    dwCurrVideoPorts;        // current number of live video ports 
    DWORD    dwSVBCaps2;              // additional system-to-video blit caps 
    DWORD    dwNLVBCaps;              // nonlocal-to-local video memory blit caps 
    DWORD    dwNLVBCaps2;             //  .
    DWORD    dwNLVBCKeyCaps;          //  .
    DWORD    dwNLVBFXCaps;            //  .
    DWORD    dwNLVBRops[DD_ROP_SPACE];//  .
    DDSCAPS2 ddsCaps;                 // general surface caps 
} DDCAPS,FAR* LPDDCAPS;  

void CGraphEllipse::zeichne(CDC* pDC)// Draw an ellipse
{ if( m_listAbschnitte.IsEmpty() ) return;
  if( m_a == 0.0 )             return;
  CPen   *pOldPen   = pDC->SelectObject(&m_penStift);// use my pen
  CBrush *pOldBrush = pDC->SelectObject(&m_brPinsel);// use my brush for drawing

  XFORM xfMatrix;//Transformation matrix
  xfMatrix.eM11 = 1.0;//At the beginning there is no transformation
  xfMatrix.eM12 = 0.0;
  xfMatrix.eM21 = 0.0;
  xfMatrix.eM22 = 1.0;
  xfMatrix.eDx  = 0.0;// and no translation
  xfMatrix.eDy  = 0.0;

  double dSinPhi = 0;// no rotation so far
  double dCosPhi = 1;
  double dPhi    = 0;
  // m_a = r1²  m_c = r2² m_b = 0(initially)
  // Circles can't be rotated 
  if( m_c != m_a ) dPhi = atan2(2*m_b,(m_a-m_c))/2.0;

  dSinPhi = sin(dPhi);
  dCosPhi = cos(dPhi);

  xfMatrix.eM11 = dCosPhi; // Now fill in the rotating values
  xfMatrix.eM12 = dSinPhi;
  xfMatrix.eM21 = -dSinPhi;
  xfMatrix.eM22 = dCosPhi;
  xfMatrix.eDx  = m_ptZiehZentrum.x; // Translation component
  xfMatrix.eDy  = m_ptZiehZentrum.y;
  SetGraphicsMode(pDC->m_hDC,GM_ADVANCED);// Tell the DC we want to use path functions
  pDC->BeginPath(); // start path
  SetWorldTransform(pDC->m_hDC,&xfMatrix);// set transforming to do
  pDC->Ellipse(-(int)m_dR1,-(int)m_dR2,(int)m_dR1,(int)m_dR2);// Draw ellipse
  pDC->EndPath();// Path finished
// Now draw the lines and/ or fill pattern
  if( m_bGeschlossen )
    { if( m_bOpaque ) pDC->StrokeAndFillPath();//  with fill pattern
      else            pDC->StrokePath();// without fill pattern
    }
  else				   pDC->StrokePath();
  pDC->SelectObject(pOldPen);
  pDC->SelectObject(pOldBrush);  
  ModifyWorldTransform(pDC->m_hDC,NULL,MWT_IDENTITY);// restore old transformation
  SetGraphicsMode(pDC->m_hDC,GM_COMPATIBLE);// restore old DC mode
}