CDC::BeginPath

Artigo
08/25/2010

Abre um colchete de caminho no contexto de dispositivo.

BOOL BeginPath();

Valor de retorno

Diferente de zero se a função for bem-sucedida; caso contrário, 0.

Comentários

Depois de um colchete de caminho está em aberto, um aplicativo pode começar a chamar GDI desenho funções para definir os pontos que estiverem no caminho.Um aplicativo pode fechar um caminho em aberto colchete chamando o EndPath função de membro. Quando um aplicativo chama BeginPath, todos os caminhos anteriores serão descartados.

See BeginPath in the Windows SDK Para obter uma lista de funções desenho que defina pontos em um caminho.

Exemplo

// This 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 CDCView::DrawPath(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("Outline this!"));
   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 = NULL;
   LPBYTE lpTypes = NULL;
   try
   {
      lpPoints = new POINT[nNumPts];
      lpTypes = new BYTE[nNumPts];
   }
   catch (CException* pe)
   {
      delete [] lpPoints;
      lpPoints = NULL;
      delete [] lpTypes;
      lpTypes = NULL;
      pe->Delete();  
   }
   if (lpPoints == NULL || lpTypes == NULL)
      return;

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

   // If it worked, draw the lines. Windows 98 doesn't support
   // the PolyDraw API, so we use our own member function to do
   // similar work. If you're targeting only later versions of 
   // Windows, you can use the PolyDraw() API and avoid the 
   // COutlineView::PolyDraw() member function.

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

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

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

   return;
}