GPS点到道路起点距离

 采集的GPS点或者道路存在误差，因此Iidentify用的时候点转换成envelope。

using System;
using System.Collections.Generic;
using System.Text;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using ESRI.ArcGIS.Carto;
using ESRI.ArcGIS.Controls;
using ESRI.ArcGIS.Display;
using ESRI.ArcGIS.Geometry;
using ESRI.ArcGIS.MapControl;
using ESRI.ArcGIS.SystemUI;
using ESRI.ArcGIS.Output;
using ESRI.ArcGIS.esriSystem;

using ESRI.ArcGIS.ToolbarControl;
using ESRI.ArcGIS.Geodatabase;
using ESRI.ArcGIS.DataSourcesGDB;
using ESRI.ArcGIS.AnalysisTools;
using ESRI.ArcGIS.DataSourcesFile;

namespace ClassLibrary1
{
    public class GIS
    {
        public static GIS pGIS = new GIS();
        public IPoint pointNow;//当前点的坐标
        public IPolyline polylineNow;//当前公路  
        ILayer roadLayer;
        /// <summary>
        /// 
        /// </summary>
        /// <param name="x"></param>
        /// <param name="y"></param>
        /// <returns></returns>
        public IPoint producePoint(double x, double y)
        {
            pointNow = new PointClass();
            pointNow.PutCoords(x, y);
            return pointNow;
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="x"></param>
        /// <param name="y"></param>
        /// <returns></returns>
        //public IPoint producePoint()
        //{
        //    //pointNow = new PointClass();
        //    //pointNow.PutCoords(dx,dy);
        //    //return pointNow;
        //}


        public void setEnv(string FilePath)
        {
            string WorkSpacePath = System.IO.Path.GetDirectoryName(FilePath);
            string ShapeFilePath = System.IO.Path.GetFileName(FilePath);
            IWorkspaceFactory pWorkspaceFactory = new ShapefileWorkspaceFactoryClass();
            IWorkspace pWorkspace = pWorkspaceFactory.OpenFromFile(WorkSpacePath, 1);
            IFeatureWorkspace pFeatureWorkspace = pWorkspace as IFeatureWorkspace;
            IFeatureClass pFeatureClass = pFeatureWorkspace.OpenFeatureClass(ShapeFilePath);
            IDataset pDataset = pFeatureClass as IDataset;
            IFeatureLayer pFeatureLayer = new FeatureLayerClass();
            pFeatureLayer.FeatureClass = pFeatureClass;
            pFeatureLayer.Name = pDataset.Name;
            ILayer pLayer = pFeatureLayer as ILayer;
            roadLayer = pLayer;
        }



        /// <summary>
        /// 
        /// </summary>
        /// <param name="dx"></param>
        /// <param name="dy"></param>
        /// <returns></returns>
        public IPolyline getPolyline(IPoint pPoint)
        {
            if (roadLayer == null)
            {
                MessageBox.Show("请输入地图文件路径和名称");
                return null;
            }
            else
            {
                IFeatureLayer roadFeatureLayer = roadLayer as IFeatureLayer;
                IIdentify i = (IIdentify)roadLayer;
                IEnvelope env = new EnvelopeClass() as IEnvelope;
                env.PutCoords(pPoint.X - 0.1, pPoint.Y - 0.1, pPoint.X + 0.1, pPoint.Y + 0.1);
                IArray pIDArray = i.Identify(env);
                IFeatureIdentifyObj pFeatIdObj;
                pFeatIdObj = pIDArray.get_Element(0) as IFeatureIdentifyObj;
                IRowIdentifyObject pRowIdentifyObj = pFeatIdObj as IRowIdentifyObject;
                IFeature pFeature = pRowIdentifyObj.Row as IFeature;
                IPolyline pPolyline = pFeature.Shape as IPolyline;
                return pPolyline;
            }
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="pPoint"></param>
        /// <param name="pPolyline"></param>
        /// <returns></returns>
        public double getDistance(IPoint pPoint, IPolyline pPolyline)
        {
            IPoint outPoint = new PointClass();
            double distanceAlongCurve = 0;//该点在曲线上最近的点距曲线起点的距离
            double distanceFromCurve = 0;//该点到曲线的直线距离
            bool bRightSide = false;
            bool asRatio = false;
            pPolyline.QueryPointAndDistance(esriSegmentExtension.esriNoExtension, pPoint, asRatio, outPoint, ref distanceAlongCurve, ref distanceFromCurve, ref bRightSide);
            return distanceAlongCurve;
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="dValue"></param>
        /// <param name="inUnits"></param>
        /// <param name="outUnits"></param>
        /// <returns></returns>
        public double ConvertUnit(double dValue, esriUnits inUnits, esriUnits outUnits)
        {
            IUnitConverter pUnitConverter = new UnitConverterClass();
            dValue = pUnitConverter.ConvertUnits(dValue, inUnits, outUnits);
            return dValue;
        }
        public string getNo(double x, double y)
        {
            pointNow = producePoint(x, y);
            polylineNow = getPolyline(pointNow);
            double distance = getDistance(pointNow, polylineNow);
            double distanceresult = ConvertUnit(distance, ESRI.ArcGIS.esriSystem.esriUnits.esriDecimalDegrees, ESRI.ArcGIS.esriSystem.esriUnits.esriMeters);
            return distanceresult.ToString();

        }


    }
}