GDI+: GdipPathIterNextMarker

[José Roca]

The following example creates a GraphicsPath object and adds five figures to the path. The calls to the GdipSetPathMarker function place two markers in the path. The first marker is at the end of a figure, and the second marker is in the middle of a figure. The code passes the address of the GraphicsPath object to the GdipCreatePathIter function to create an iterator that is associated with the path. Then the code calls the GdipPathIterNextMarker function twice to obtain the starting and ending indices of the second marker-delimited section of the path. Finally, the code draws the data points that belong to the second marker-delimited section of the path.

C++

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VOID NextMarkerExample2(HDC hdc)
{
   Graphics graphics(hdc);

   // Create a graphics path with five figures (subpaths).
   GraphicsPath path;

   path.AddRectangle(Rect(20, 20, 60, 30));

   path.SetMarker();                          // first marker
   path.AddLine(100, 20, 160, 50);
   path.AddArc(180, 20, 60, 30, 0, 180);

   path.AddRectangle(Rect(260, 20, 60, 30));
   path.AddLine(340, 20, 400, 50);
   path.SetMarker();                          // second marker
   path.AddArc(340, 20, 60, 30, 0, 180);
   path.CloseFigure();
 
   path.AddRectangle(Rect(420, 20, 60, 30));

   // Create an iterator, and associate it with the path.
   GraphicsPathIterator iterator(&path);

   // Get the second marker-delimited section by calling NextMarker twice.
   INT start;
   INT end;
   INT count;
   count = iterator.NextMarker(&start, &end);
   count = iterator.NextMarker(&start, &end);

   // Get the data points of the second marker-delimited section.
   PointF* points = new PointF[count];
   BYTE* types = new BYTE[count];
   iterator.CopyData(points, types, start, end);

   // Draw the data points of the second marker-delimited section.
   SolidBrush brush(Color(255, 255, 0, 0));
   for(INT j = 0; j < count; ++j)
      graphics.FillEllipse(
         &brush,
         points[j].X - 3.0f,
         points[j].Y - 3.0f,
         6.0f,
         6.0f);

   delete points;
   delete types;
}


PowerBASIC

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SUB GDIP_PathIterNextMarker (BYVAL hdc AS DWORD)

   LOCAL hStatus AS LONG
   LOCAL pGraphics AS DWORD
   LOCAL pPath AS DWORD
   LOCAL pIterator AS DWORD
   LOCAL pBrush AS DWORD
   LOCAL count AS LONG
   LOCAL resultCount AS LONG
   LOCAL startIndex AS LONG
   LOCAL endIndex AS LONG
   LOCAL i AS LONG
   DIM   pPoints(0) AS POINTF
   DIM   pTypes(0) AS BYTE

   hStatus = GdipCreateFromHDC(hdc, pGraphics)

   ' // Create a graphics path with five figures (subpaths).
   hStatus = GdipCreatePath(%FillModeAlternate, pPath)
   hStatus = GdipAddPathRectangle(pPath, 20, 20, 60, 30)
   hStatus = GdipSetPathMarker(pPath)   ' // first marker
   hStatus = GdipAddPathLine(pPath, 100, 20, 160, 50)
   hStatus = GdipAddPathArc(pPath, 180, 20, 60, 30, 0, 180)
   hStatus = GdipAddPathRectangle(pPath, 260, 20, 60, 30)
   hStatus = GdipAddPathLine(pPath, 340, 20, 400, 50)
   hStatus = GdipSetPathMarker(pPath)   ' // second marker
   hStatus = GdipAddPathArc(pPath, 340, 20, 60, 30, 0, 180)
   hStatus = GdipClosePathFigure(pPath)
   hStatus = GdipAddPathRectangle(pPath, 420, 20, 60, 30)

   ' // Create an iterator, and associate it with the path.
   hStatus = GdipCreatePathIter(pIterator, pPath)

   ' // Get the second marker-delimited section by calling NextMarker twice.
   hStatus = GdipPathIterNextMarker(pIterator, count, startIndex, endIndex)
   hStatus = GdipPathIterNextMarker(pIterator, count, startIndex, endIndex)

   ' // Get the data points of the second marker-delimited section.
   IF count THEN
      REDIM pPoints(count - 1)
      REDIM pTypes(count - 1)
      hStatus = GdipPathIterCopyData(pIterator, resultCount, pPoints(0), pTypes(0), startIndex, endIndex)
      ' // Draw the data points of the second marker-delimited section.
      hStatus = GdipCreateSolidFill(GDIP_ARGB(255, 255, 0, 0), pBrush)
      FOR i = 0 TO count - 1
         hStatus = GdipFillEllipse(pGraphics, pBrush, pPoints(i).x - 3, pPoints(i).y - 3, 6, 6)
      NEXT
   END IF

   ' // Cleanup
   IF pBrush THEN GdipDeleteBrush(pBrush)
   IF pIterator THEN GdipDeletePathIter(pIterator)
   IF pPath THEN GdipDeletePath(pPath)
   IF pGraphics THEN GdipDeleteGraphics(pGraphics)

END SUB