获取选中地物的Geometry对象，及把Geometry对象显示在地图上

下面是Map 3D开发时帮助调试检查用的工具类，也是经常会用的的功能。贴在这里共享备查。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using OSGeo.MapGuide;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.Gis.Map.Platform.Interop;
using Autodesk.Gis.Map.Platform.Utils;

namespace TestSolution
{
    public class MapHelper
    {
        /// <summary>
        /// Get the geometry objects of selected features from map
        /// </summary>
        /// <returns></returns>
        static public IList<MgGeometry> GetSelectedFeatureGeometry()
        {
            IList<MgGeometry> list = new List<MgGeometry>();

            PromptSelectionResult selResult =
                Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument.Editor.GetSelection();

            if (selResult.Status == PromptStatus.OK)
            {
                SelectionSet selSet = selResult.Value;
                //Get all the features in SelectionSet
                MgSelectionBase selectionBase = AcMapFeatureEntityService.GetSelection(selSet);

                foreach (MgLayerBase layer in selectionBase.GetLayers())
                {
                    MgFeatureReader featureReader = selectionBase.GetSelectedFeatures(layer, layer.FeatureClassName, false);

                    //Get the name of Geometry Property
                    string gepPropertyName = layer.GetClassDefinition().DefaultGeometryPropertyName;

                    if (string.IsNullOrEmpty(gepPropertyName))
                    {
                        Util.PrintLn("No geometry property exists in layer " + layer.Name);
                        continue;
                    }

                    while (featureReader.ReadNext())
                    {
                        MgByteReader byteReader = featureReader.GetGeometry(gepPropertyName);
                        MgAgfReaderWriter agfReader = new MgAgfReaderWriter();
                        MgGeometry geomtry = agfReader.Read(byteReader);

                        list.Add(geomtry);
                    }

                    featureReader.Close();

                }

               
                
            }
            return list;

        }


        /// <summary>
        /// Add a gemetry to a layer so that it is displayed on map
        /// </summary>
        /// <param name="layer"></param>
        /// <param name="geometry"></param>
        /// <returns></returns>
        static public bool AddFeature(MgLayerBase layer, MgGeometry geometry)
        {
            if (layer == null )
                return false;

            if (geometry == null)
                return false;

            MgClassDefinition classDef = layer.GetClassDefinition();
            string featClassName = layer.FeatureClassName;

            MgPropertyDefinitionCollection propDefs = classDef.GetProperties();
            MgGeometricPropertyDefinition geoPropDef = propDefs.GetItem(classDef.DefaultGeometryPropertyName)
                                                                    as MgGeometricPropertyDefinition;
            //Default Geometry Type of current layer. 
            int layerGeometryType = geoPropDef.GeometryTypes;
            //Geometry Type converted from acdbEntity.
            int geoType = geometry.GetGeometryType();

            //if (!GeometryTypeValidate(layerGeometryType, geoType))
            //{
            //    Util.PrintLn("Geometry type of the entity is invalid to the targeting layer.");
            //    return false;
            //}

            MgPropertyCollection props = new MgPropertyCollection();
            MgAgfReaderWriter writer = new MgAgfReaderWriter();
            MgByteReader byteReader = writer.Write(geometry);
            props.Add(new MgGeometryProperty(classDef.DefaultGeometryPropertyName,byteReader));

            if (props != null)
            {
                MgInsertFeatures insertFeat = new MgInsertFeatures(featClassName, props);
                MgFeatureCommandCollection featCommands = new MgFeatureCommandCollection();
                featCommands.Add(insertFeat);



                try
                {
                    layer.UpdateFeatures(featCommands);
                }
                catch (System.Exception e)
                {
                    Util.PrintLn("Failed to add a Feature.");
                    Util.PrintLn(e.Message);
                    return false;
                }
                return true;
            }
            else
            {
                Util.PrintLn("Operation cancelled");
                return false;
            }
        }


        /// <summary>
        /// Validate whether the Geometry Type of Layer and MgGeometry to be added in match.
        /// </summary>
        /// <param name="layerGeoType">Geometry Type of Layer</param>
        /// <param name="geoType">Geometry Type of the MgGeometry convert from Entity</param>
        /// <returns>true if match</returns>
        private bool GeometryTypeValidate(int layerGeoType, int geoType)
        {
            bool match = false;
            if (geoType == MgGeometryType.Point || geoType == MgGeometryType.MultiPoint)
            {
                if ((layerGeoType & MgFeatureGeometricType.Point) != 0)
                    match = true;
            }
            else if (geoType == MgGeometryType.LineString || geoType == MgGeometryType.MultiLineString)
            {
                if ((layerGeoType & MgFeatureGeometricType.Curve) != 0)
                    match = true;
            }
            else if (geoType == MgGeometryType.Polygon || geoType == MgGeometryType.CurvePolygon
                    || geoType == MgGeometryType.MultiPolygon)
            {
                if ((layerGeoType & MgFeatureGeometricType.Surface) != 0)
                    match = true;
            }

            return match;
        }


    }
}