在使用ArcGIS的过程中，我们会发现在右上角有个长度量算的工具，对于随意在地图上选择的两点进行量算并给出实际距离。那么到底是怎么实现的呢，本文附上实现的源代码，有错误或者更好地优化的方案请进行纠正，努力才会让目标离我们更近些。
//长度量算工具代码 private IHookHelper m_hookHelper; private IGraphicsContainer pGraphicContainer; private IMap pMap; private IActiveView pActiveView; private IDisplayFeedback pDisplayFeedback; private IScreenDisplay pScreenDisplay = null; IPoint pPointStd; IPoint pPoint; IPoint pPointLast; IProximityOperator pProximity; public double measureDistance = 0; public double DistanceSegment = 0; INewLineFeedback pNewLineFeedback = null; public DistancePointsTool() { base.m_category="SpatailAnalyst"; base.m_caption="长度量算"; base.m_message="长度量算"; base.m_toolTip="长度量算"; base.m_name="长度量算"; } public override void OnCreate(object hook) { if (m_hookHelper==null) m_hookHelper=new HookHelperClass(); m_hookHelper.Hook=hook; pActiveView=m_hookHelper.ActiveView; pMap=pActiveView.FocusMap; pGraphicContainer=pMap as IGraphicsContainer; pDisplayFeedback=null; pScreenDisplay=pActiveView.ScreenDisplay; } //重载鼠标点击事件 protected override void OnMouseDown(int Button,int shift,int X,int Y) { //产生一个当前点击的点对象 if (Button==1) { //判断该点是否为第一个点 if (pDisplayFeedback==null) { pPointStd=new PointClass(); pPointStd.SpatialReference=pMap.SpatialReference; pPointStd=pActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(X,Y); pDisplayFeedback=new NewLineFeedbackClass(); pDisplayFeedback.Display=pScreenDisplay; pNewLineFeedback=pDisplayFeedback as INewLineFeedback; pNewLineFeedback.Start(pPointStd); pPointLast=pPointStd; pProximity=pPointStd as IProximityOperator; } else{ pNewLineFeedback=pDisplayFeedback as INewLineFeedback; pNewLineFeedback.AddPoint(pPoint); IProximityOperator pProximity=pPointLast as IProximityOperator; DistanceSegment=pProximity.ReturnDistance(pPoint); measureDistance+=pProximity.ReturnDistance(pPoint); pPointLast =pPoint; } } } //重载鼠标移动事件 public override void OnMouseMove(int Button,int shift,int X,int Y) { pPoint =new PointClass(); pPoint.SpatialReference=pMap.SpatialReference; pPoint=pActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(X,Y); if(pNewLineFeedback!=null) { pNewLineFeedback.MoveTo(pPoint); } } //重载鼠标双击事件，距离量测结束 public override void onDblClick() { base.onDblClick(); IGeometry pGeometry=null; string LengthUnits=null; if (pNewLineFeedback!=null) { pGeometry=pNewLineFeedback.Stop(); pNewLineFeedback=null; IElement pElement=null; ISimpleLineSymbol pSimpleLineSymbol=new SimpleLineSymbolClass(); pSimpleLineSymbol.Width=2; pSimpleLineSymbol.Style=esriSimpleLineStyle.esriSLSSolid; ISimpleFillSymbol pSimpleFillSymbol=new SimpleFillSymbolClass(); pSimpleFillSymbol.Style=esriSimpleFillStyle.esriSFSSolid; pSimpleFillSymbol.Outline= pSimpleLineSymbol; ILineElement pLineElement=new LineElementClass(); pLineElement.Symbol=pSimpleLineSymbol; pElement=pLineElement as IElement; pElement=pLineElement as IElement; pElement.Geometry=pGeometry; IGraphicsContainer pGraphicsContainer=pActiveView.FocusMap as IGraphicsContainer; pGraphicsContainer.AddElement(pElement,0); pActiveView.PartialRefresh(esriViewDrawPhase.esriViewGraphics,null,null); pGraphicsContainer.DeleteElement(pElement); MessageBox.Show("\n线段长度："+DistanceSegment.ToString()+"\n总长度："+measureDistance.ToString()+"\n地图单位："+LengthUnits,"长度量算"); measureDistance=0; DistanceSegment=0; pNewLineFeedback=null; pDisplayFeedback=null; } }