关于ArcGIS常用功能的实现

   关于ArcGIS中常见的一些功能的总结，一般首先在前台中放置地图，代码如下所示：

<esri:Map Grid.Row="0" Grid.Column="0" Grid.RowSpan="5" Grid.ColumnSpan="6"  x:Name="MyMap"  WrapAround="True"  
MouseClick="MyMap_MouseClick" ExtentChanged="MyMap_ExtentChanged" />

　　放置了地图之后我们就可以进行相关的操作

  1  地图的放大与缩小：MyMap.Zoom(double param) 其中参数param>1,表示地图放大，例如param=2，表示放大到原来的两倍，param<1表示地图的缩小。

  2  地图范围发生变化时发生的事件，其中this.MyMap.Layers[0]表示图层 0，加载的是本地缓存地图图层，一般用作底图。

ArcGISLocalTiledLayer tpkLayer = new ArcGISLocalTiledLayer("GqyPgisData\\" +_ConfigInfo.TpkName + ".tpk");
MyMap.Layers.Add(tpkLayer);　　

    当地图范围发生改变时，地图图层执行相应的改变。  

private void MyMap_ExtentChanged(object sender, ExtentEventArgs e)
{
////需要判断是否已经有地图比例尺，有比例尺了表示定位完毕可以换算桌面坐标
if (!_mapIntial)
{
Envelope env = this.MyMap.Layers[0].FullExtent;
double x = (env.XMax + env.XMin) / 2.0;
double y = (env.YMax + env.YMin) / 2.0;
Envelope newEnv = new Envelope(x - env.Width / 16.0, y - env.Height / 16.0, x + env.Width / 16.0, y + env.Width / 16.0);
this.MyMap.Extent = newEnv;
}
}　　

  3   测量折线距离

      下面直接贴出代码，并作出相应的解释。首先GeometryService 就是提供针对几何层级的服务，比如说Project，Simplify ， Buffer，Areas And Lengths ， Lengths 等，这个具体的解释请参考这里的官方的解释。LocalGeometryService表示本地几何层级的服务。

public void MapMeasureDistance()
{
//清除测量图层
ClearMyGraphicsLayerMeasure();

//设置测量信息区域可见
gMapInfo.Visibility = Visibility.Visible;
gMapInfo.lblInfo.Content = "请在地图中点击画折线，计算长度！";

_GeometryServiceMeasure = new GeometryService();
LocalGeometryService lgs = LocalGeometryService.GetService();
_GeometryServiceMeasure.Url = lgs.UrlGeometryService;
_GeometryServiceMeasure.LengthsCompleted += _GeometryServiceMeasure_LengthsCompleted;
_GeometryServiceMeasure.Failed += _GeometryServiceMeasure_Failed;
MyMap.IsEnabled = true;

//实例化一个Draw对象，开始画图操作

_DrawMeasure = new Draw(MyMap)
{
DrawMode = DrawMode.Polyline,
IsEnabled = true,

//这里是前台定义的资源，即画线的样式
LineSymbol = Root.Resources["SelectLineSymbol"] as LineSymbol
};

_DrawMeasure.DrawBegin += _DrawMeasure_Begin;
_DrawMeasure.DrawComplete += _DrawMeasure_MeasureLengthsComplete;
}

/// <summary>
/// 开始画
/// </summary>
void _DrawMeasure_Begin(object sender, EventArgs args)
{
//ClearMyGraphicsLayerMeasure();
}

/// <summary>
/// 完成画长度
/// </summary>
void _DrawMeasure_MeasureLengthsComplete(object sender, DrawEventArgs args)
{
Polyline _Polyline = args.Geometry as Polyline;

if (_Polyline.Paths[0].Count > 1)
{
XmlDocument xmlDoc = GISUDPClient.Instance.CreateXmlDocument("GQYPGIS.Xml.Action.ActionMeasureLine.xml");
XmlNode xmlNode = xmlDoc.SelectSingleNode("Action/MapPoints");

//发送直线测量图形命令（点选）
foreach (MapPoint mp in _Polyline.Paths[0])
{

XmlElement xmlElement = xmlDoc.CreateElement("MapPoint");
XmlAttribute xmlAttr = xmlDoc.CreateAttribute("X");
xmlAttr.Value = mp.X.ToString();
xmlElement.Attributes.Append(xmlAttr);
xmlAttr = xmlDoc.CreateAttribute("Y");
xmlAttr.Value = mp.Y.ToString();
xmlElement.Attributes.Append(xmlAttr);

xmlNode.AppendChild(xmlElement);

}
GISUDPClient.Instance.SendTo(xmlDoc);
}

_Polyline.SpatialReference = MyMap.SpatialReference;

Graphic _Graphic = new Graphic()
{
Symbol = Root.Resources["CompleteLineSymbol"] as Symbol,
Geometry = _Polyline
};

GraphicsLayer _GraphicsLayer = MyMap.Layers["MyGraphicsLayerMeasure"] as GraphicsLayer;
_GraphicsLayer.Graphics.Add(_Graphic);

//开始计算长度
_GeometryServiceMeasure.LengthsAsync(_GraphicsLayer.Graphics, LinearUnit.Kilometer, CalculationType.Geodesic, null);

_DrawMeasure.DrawMode = DrawMode.None;
}　　

    4  完成画线后执行的动作

/// <summary>
/// 完成画长度
/// </summary>
void _DrawMeasure_MeasureLengthsComplete(object sender, DrawEventArgs args)
{
Polyline _Polyline = args.Geometry as Polyline;
if (_Polyline.Paths[0].Count > 1)
{
XmlDocument xmlDoc = GISUDPClient.Instance.CreateXmlDocument("GQYPGIS.Xml.Action.ActionMeasureLine.xml");
XmlNode xmlNode = xmlDoc.SelectSingleNode("Action/MapPoints");

//发送直线测量图形命令（点选）
foreach (MapPoint mp in _Polyline.Paths[0])
{
XmlElement xmlElement = xmlDoc.CreateElement("MapPoint");
XmlAttribute xmlAttr = xmlDoc.CreateAttribute("X");
xmlAttr.Value = mp.X.ToString();
xmlElement.Attributes.Append(xmlAttr);

xmlAttr = xmlDoc.CreateAttribute("Y");
xmlAttr.Value = mp.Y.ToString();
xmlElement.Attributes.Append(xmlAttr);

xmlNode.AppendChild(xmlElement);

}
GISUDPClient.Instance.SendTo(xmlDoc);
}

_Polyline.SpatialReference = MyMap.SpatialReference;

Graphic _Graphic = new Graphic()
{
Symbol = Root.Resources["CompleteLineSymbol"] as Symbol,
Geometry = _Polyline
};

GraphicsLayer _GraphicsLayer = MyMap.Layers["MyGraphicsLayerMeasure"] as GraphicsLayer;
_GraphicsLayer.Graphics.Add(_Graphic);

//开始计算长度
_GeometryServiceMeasure.LengthsAsync(_GraphicsLayer.Graphics, LinearUnit.Kilometer, CalculationType.Geodesic, null);
_DrawMeasure.DrawMode = DrawMode.None;
}        

   5   几何服务长度计算完成      

void _GeometryServiceMeasure_LengthsCompleted(object sender, LengthsEventArgs args)
{
gMapInfo.lblInfo.Content = String.Format("折线的长度：{0} 公里", Math.Round(args.Results[0], 3));
}

/// <summary>
/// 几何服务计算周长面积完成
/// </summary>
void _GeometryServiceMeasure_AreasAndLengthsCompleted(object sender, AreasAndLengthsEventArgs args)
{
double kms = args.Results.Lengths[0] * 0.001;
double sqkm = Math.Abs(args.Results.Areas[0]) * 0.001 * 0.001;
//double kms = args.Results.Lengths[0] * 100;
//double miles = args.Results.Lengths[0] * 0.0006213700922;
//double sqkm = Math.Abs(args.Results.Areas[0]) * 10000;
//double sqmi = Math.Abs(args.Results.Areas[0]) * 0.0000003861003;
gMapInfo.lblInfo.Content = String.Format("多边形周长: {1} 公里\r\n多边形面积: {0} 平方公里", Math.Round(sqkm, 3), Math.Round(kms, 3));
}

///<summary>
/// 几何服务失败
///</summary>
void _GeometryServiceMeasure_Failed(object sender, TaskFailedEventArgs e)
{
//throw new NotImplementedException();
}

　　上面就介绍这么多，都是一些基础的功能，最重要的是要经常不断去反思和总结。