在GIS中，动态轨迹的实现是非常有用的，可用GPS定位，热点跟踪等。在本例中，先创建一个用于呈现动态轨迹的临时图层，并在图层上添加一个点表示位体的位置。代码如下：
/// <summary>
/// 创建动态轨迹图层 /// Glacier /// 2008年8月7日 /// <param name="trackLayerTableName">图层表名</param> /// <param name="trackLayerName">图层名</param> /// <param name="firstPoint">点初始坐标</param>
/// </summary>
protected void CreateTrackLayer(string trackLayerTableName, string trackLayerName, DPoint firstPoint) {
MapInfo.Mapping.Map myMap = MapInfo.Engine.Session.Current.MapFactory[MapControl1.MapAlias]; //创建临时图层 MapInfo.Data.TableInfoMemTable tblInfoTemp = new MapInfo.Data.TableInfoMemTable(trackLayerTableName); MapInfo.Data.Table tblTemp = MapInfo.Engine.Session.Current.Catalog.GetTable(trackLayerTableName); if (tblTemp != null)
{
MapInfo.Engine.Session.Current.Catalog.CloseTable(trackLayerTableName);
} tblInfoTemp.Columns.Add(MapInfo.Data.ColumnFactory.CreateFeatureGeometryColumn(myMap.GetDisplayCoordSys())); tblInfoTemp.Columns.Add(MapInfo.Data.ColumnFactory.CreateStyleColumn()); tblTemp = MapInfo.Engine.Session.Current.Catalog.CreateTable(tblInfoTemp); FeatureLayer workLayer = new FeatureLayer(tblTemp, AnimationLayerName, AnimationLayerName); myMap.Layers.Add(workLayer); //向临时图层中添加初始点 FeatureGeometry pfg = new MapInfo.Geometry.Point(workLayer.CoordSys, firstPoint.x, firstPoint.y) as FeatureGeometry; MapInfo.Styles.CompositeStyle cstyle = new MapInfo.Styles.CompositeStyle(new MapInfo.Styles.SimpleVectorPointStyle(52, System.Drawing.Color.Blue, 30)); MapInfo.Data.Feature pft = new MapInfo.Data.Feature(tblTemp.TableInfo.Columns); pft.Geometry = pfg; pft.Style = cstyle; workLayer.Table.InsertFeature(pft); }实现动态轨迹的第一种方法是，对原来点的坐标的位置进行偏移，从实现位置的更新。代码如下：
/// <summary> /// 把原来的点偏移到新的位置以实现动态轨迹 /// Glacier /// 2008年8月7日 /// <param name="trackLayerTableName">图层表名</param> /// <param name="newPoint">点的新坐标</param> /// </summary> protected void UpdateTrack(string trackLayerTableName, DPoint newPoint) { MapInfo.Data.Table altb = MapInfo.Engine.Session.Current.Catalog.GetTable(trackLayerTableName); if (altb == null) { return; } //Change the positon of the existed feature. SearchInfo si = MapInfo.Data.SearchInfoFactory.SearchWhere(""); Feature ftr = MapInfo.Engine.Session.Current.Catalog.SearchForFeature(altb, si); if (ftr == null) { return; } DPoint offsetPoint = new DPoint(newPoint.x - ftr.Geometry.Centroid.x, newPoint.y - ftr.Geometry.Centroid.y); ftr.Geometry.GetGeometryEditor().OffsetByXY(offsetPoint.x, offsetPoint.y, DistanceUnit.Degree, DistanceType.Spherical); ftr.Geometry.EditingComplete(); ftr.Update(); }实现动态轨迹的第二种方法是，先删除原有的点，再在新的位置添加一个新点。因为第一种方法求偏移过程中可能会产生误差，并且这种误差是会积累的。而这种方法相对来说会比较精确一点。代码如下：
/// <summary> /// 把删除原有点并向图层中添加新点以实现动态轨迹 /// Glacier /// 2008年8月7日 /// <param name="trackLayerTableName">图层表名</param> /// <param name="newPoint">点的新坐标</param> /// </summary> protected void UpdateTrack(string trackLayerTableName, DPoint newPoint) { MapInfo.Data.Table altb = MapInfo.Engine.Session.Current.Catalog.GetTable(trackLayerTableName); if (altb == null) { return; } //Delete the existed feature and create a new one. SearchInfo si = MapInfo.Data.SearchInfoFactory.SearchWhere(""); Feature dftr = MapInfo.Engine.Session.Current.Catalog.SearchForFeature(altb, si); if (dftr == null) { return; } altb.DeleteFeature(dftr); MapInfo.Mapping.Map myMap = MapInfo.Engine.Session.Current.MapFactory[MapControl1.MapAlias]; FeatureGeometry pfg = new MapInfo.Geometry.Point(myMap.GetDisplayCoordSys(), new DPoint(newPoint.x, newPoint.y)) as FeatureGeometry; MapInfo.Styles.CompositeStyle cstyle = new MapInfo.Styles.CompositeStyle(new MapInfo.Styles.SimpleVectorPointStyle(52, System.Drawing.Color.Blue, 30)); MapInfo.Data.Feature pft = new MapInfo.Data.Feature(altb.TableInfo.Columns); pft.Geometry = pfg; pft.Style = cstyle; altb.InsertFeature(pft); }