public void DrawBuffer()
{
ESRI.ArcGIS.Display.IScreenDisplay screenDisplay = axMapControl1.ActiveView.ScreenDisplay;
IElement pInptLine = new LineElementClass();
object missing = Type.Missing;
IFillShapeElement pElem = new CircleElementClass();
ISimpleFillSymbol sysm = new SimpleFillSymbol();
sysm.Style = esriSimpleFillStyle.esriSFSDiagonalCross;
sysm.Outline.Width = 20;
//Get the IRGBColor interface
IRgbColor color = new RgbColorClass();
//Set the color properties
color.Red = 255; color.Green = 0; color.Blue = 0;
color.Transparency = 255;
sysm.Color = color; sysm.Outline.Color = color;
pElem.Symbol = sysm;
ESRI.ArcGIS.Display.ISimpleLineSymbol simpleLineSymbol = new ESRI.ArcGIS.Display.SimpleLineSymbolClass();
simpleLineSymbol.Color = color;
ESRI.ArcGIS.Display.ISymbol symbol = simpleLineSymbol as ESRI.ArcGIS.Display.ISymbol; // Dynamic cast.
ESRI.ArcGIS.Display.IRubberBand2 rubberBand = new ESRI.ArcGIS.Display.RubberLineClass();
ESRI.ArcGIS.Geometry.IGeometry geometry = rubberBand.TrackNew(screenDisplay, symbol);
screenDisplay.SetSymbol(symbol);
screenDisplay.DrawPolyline(geometry);
screenDisplay.FinishDrawing();
//Start Buffering
IConstructMultipoint myMultiPoint = new MultipointClass();
myMultiPoint.ConstructDivideLength(geometry as ICurve, 10000);
IGeometryCollection geometryBag = new GeometryBagClass();
IGeometryCollection Rslt = new GeometryBagClass();
IPointCollection pointCollection = myMultiPoint as IPointCollection;
object Missing = Type.Missing;
for(int i = 0; i<pointCollection.PointCount ; i++ )
{
geometryBag.AddGeometry(pointCollection.get_Point(i), ref Missing, ref Missing);
}
IGeometryBag enumGeometry = geometryBag as IGeometryBag;
IBufferConstruction ipBufCon = new BufferConstruction();
IBufferConstructionProperties2 ipBufConProp = (IBufferConstructionProperties2)ipBufCon;
ipBufConProp.UseGeodesicBuffering = true;
ipBufConProp.UnionOverlappingBuffers = true;
ipBufCon.ConstructBuffers((IEnumGeometry)enumGeometry, 500.0 * 1000.0, Rslt);
IPolygon bufrPolygon = Rslt.get_Geometry(0) as IPolygon;
//Fill the BufrPolygon
IElement iElem = pElem as IElement;
iElem.Geometry = bufrPolygon as IGeometry;
IFillShapeElement pElemFillShp = pElem as IFillShapeElement;
//Add the result as an element of the map
pElemFillShp.Symbol = sysm;
axMapControl1.ActiveView.GraphicsContainer.AddElement(pElemFillShp as IElement, 0);
}