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CDC::BeginPath 

Opens a path bracket in the device context.

BOOL BeginPath( );
Return Value

Nonzero if the function is successful; otherwise 0.

Remarks

After a path bracket is open, an application can begin calling GDI drawing functions to define the points that lie in the path. An application can close an open path bracket by calling the EndPath member function. When an application calls BeginPath, any previous paths are discarded.

See BeginPath in the Platform SDK for a list of the drawing functions that define points in a path for Windows NT and Windows 95/98.

Example Source Code

// This OnDraw() implementation uses GDI paths to draw the outline of
// some text in a TrueType font. The path is used to record the way
// the TrueType font would be drawn. Then, the function uses the data
// returned from CDC::GetPath() to draw the font--without filling it.

void COutlineView::OnDraw(CDC* pDC)
{
   // Describe a 24-point truetype font of normal weight
   LOGFONT lf;
   memset(&lf, 0, sizeof(lf));
   lf.lfHeight = -MulDiv(24, pDC->GetDeviceCaps(LOGPIXELSY), 72);
   lf.lfWeight = FW_NORMAL;
   lf.lfOutPrecision = OUT_TT_ONLY_PRECIS;

   // create and select it
   CFont newFont;
   if (!newFont.CreateFontIndirect(&lf))
      return;
   CFont* pOldFont = pDC->SelectObject(&newFont);

   // use a path to record how the text was drawn
   pDC->BeginPath();
   pDC->TextOut(10, 10, _T("Hockey is Best!"));
   pDC->EndPath();

   // Find out how many points are in the path. Note that
   // for long strings or complex fonts, this number might be
   // gigantic!
   int nNumPts = pDC->GetPath(NULL, NULL, 0);
   if (nNumPts == 0)
      return;

   // Allocate memory to hold points and stroke types from
   // the path.
   LPPOINT lpPoints = new POINT[nNumPts];
   if (lpPoints == NULL)
      return;
   LPBYTE lpTypes = new BYTE[nNumPts];
   if (lpTypes == NULL)
   {
      delete [] lpPoints;
      return;
   }

   // Now that we have the memory, really get the path data.
   nNumPts = pDC->GetPath(lpPoints, lpTypes, nNumPts);

   // If it worked, draw the lines. Win95 and Win98 don't support
   // the PolyDraw API, so we use our own member function to do
   // similar work. If you're targeting only Windows NT, you can
   // use the PolyDraw() API and avoid the COutlineView::PolyDraw()
   // member function.

   if (nNumPts != -1)
      PolyDraw(pDC, lpPoints, lpTypes, nNumPts);

   // Release the memory we used
   delete [] lpPoints;
   delete [] lpTypes;

   // Put back the old font
   pDC->SelectObject(pOldFont);

   return;
}

void COutlineView::PolyDraw(CDC* pDC, CONST LPPOINT lppt, CONST LPBYTE lpbTypes,
   int cCount)
{
   int nIndex;
   LPPOINT pptLastMoveTo = NULL;

   // for each of the points we have...
   for (nIndex = 0; nIndex < cCount; nIndex++)
   {
      switch(lpbTypes[nIndex])
      {
      // React to information from the path by drawing the data
      // we received. For each of the points, record our own
      // "last active point" so we can close figures, lines, and
      // Beziers.

      case PT_MOVETO:
         if (pptLastMoveTo != NULL && nIndex > 0)
            pDC->LineTo(pptLastMoveTo->x, pptLastMoveTo->y);
         pDC->MoveTo(lppt[nIndex].x, lppt[nIndex].y);
         pptLastMoveTo = &lppt[nIndex];
         break;

      case PT_LINETO | PT_CLOSEFIGURE:
         pDC->LineTo(lppt[nIndex].x, lppt[nIndex].y);
         if (pptLastMoveTo != NULL)
            pDC->LineTo(pptLastMoveTo->x, pptLastMoveTo->y);
         pptLastMoveTo = NULL;
         break;

      case PT_LINETO:
         pDC->LineTo(lppt[nIndex].x, lppt[nIndex].y);
         break;

      case PT_BEZIERTO | PT_CLOSEFIGURE:
         ASSERT(nIndex + 2 <= cCount);
         pDC->PolyBezierTo(&lppt[nIndex], 3);
         nIndex += 2;
         if (pptLastMoveTo != NULL)
            pDC->LineTo(pptLastMoveTo->x, pptLastMoveTo->y);
         pptLastMoveTo = NULL;
         break;

      case PT_BEZIERTO:
         ASSERT(nIndex + 2 <= cCount);
         pDC->PolyBezierTo(&lppt[nIndex], 3);
         nIndex += 2;
         break;
      }
   }

   // If the figure was never closed and should be,
   // close it now.
   if (pptLastMoveTo != NULL && nIndex > 1)
      pDC->LineTo(pptLastMoveTo->x, pptLastMoveTo->y);
}