VC+MO中如何进行buffer分析

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<TD  width="100%"><IMG src="http://www.gischina.com/bbs/face/em01.gif" border=0> <B>VC+MO中如何进行buffer分析</B>
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已经通过查询函数取的用户选择的直线line;
CMoRectangle rect;
VARIANT vRect;
rect = line.GetExtent();
vRect.vt = VT_DISPATCH;
vRect.pdispVal = rect;
CMoPolygon* poly = new CMoPolygon(line.Buffer(1000,vRect));
但是poly为空，请问有没有作个缓冲区分析的高手请指点</TD></TR></TABLE>

<P>最近在想做一个类似的东西，看了以后有点启发哦~~~~~~~~</P>
<P>多谢了</P>

<P>我做的！！</P><P>vector<CMoPolygon> CreateBuffer(CMoRecordset; BufferRecords, double; BufferTolerance, int; BufferLayerStyle, string; BufferUnits)
{
 vector<CMoPolygon> TempVectorPoly;
 CComVariant Extent(m_map.GetFullExtent().m_lpDispatch);
 if (BufferUnits == "千米")
  BufferTolerance = 1000 * BufferTolerance;
  
 switch (BufferLayerStyle)
 {
 case 0://点图层
  {
   BufferRecords.MoveFirst();
   while (!BufferRecords.GetEof())
   {
    CMoPoint point(BufferRecords.GetFields().Item(CComVariant("Shape")).GetValue().pdispVal);
    CMoPolygon PolygonBuffer(point.Buffer(BufferTolerance,Extent));
    TempVectorPoly.push_back(PolygonBuffer);
    BufferRecords.MoveNext();
   }
   break;
  }
 case 1://线图层
  {
   BufferRecords.MoveFirst();
   while (!BufferRecords.GetEof())
   {
    CMoLine line(BufferRecords.GetFields().Item(CComVariant("Shape")).GetValue().pdispVal);
    CMoPolygon PolygonBuffer(line.Buffer(BufferTolerance,Extent));
    TempVectorPoly.push_back(PolygonBuffer);
    BufferRecords.MoveNext();  
   }
   break;
  }
 case 2://面图层
  {
   BufferRecords.MoveFirst();
   while (!BufferRecords.GetEof())
   {
    CMoPolygon Polygon(BufferRecords.GetFields().Item(CComVariant("Shape")).GetValue().pdispVal);
    CMoPolygon PolygonBuffer(Polygon.Buffer(BufferTolerance,Extent));
    TempVectorPoly.push_back(PolygonBuffer);
    BufferRecords.MoveNext();  
   }
   break;
  }
 }
 return TempVectorPoly;
}</P>

<P>我还是不太懂，我是这么写的</P><P>CMoSymbol symBuffer;
   symBuffer.CreateDispatch(TEXT("MapObjects2.Symbol"));
   symBuffer.SetSymbolType(moFillSymbol);
   symBuffer.SetStyle(moLightGrayFill);
   symBuffer.SetColor(Color);
   symBuffer.SetOutline(FALSE);</P><P>   CMoPolygon shpBuffer;
   VARIANT va;
   VariantInit(;va);
   va.vt=VT_DISPATCH;</P><P>    va.pdispVal=g_searchLine.GetExtent();     //此时g_searchLine已赋值
    shpBuffer=g_searchLine.Buffer(100,va);</P><P>为什么我执行到最后一句总是出错呢？应该怎么做？
   </P>

建议：rect 取 m_map.GetFullExtent();

<img src="images/post/smile/dvbbs/em04.gif" /><img src="images/post/smile/dvbbs/em04.gif" />

<P>多谢！</P>

<P><a href="http://gisempire.com/bbs/dispbbs.asp?BoardID=39;ID=5491" target="_blank" >http://gisempire.com/bbs/dispbbs.asp?BoardID=39;ID=5491</A></P><P>这是一个vb的例子</P>