我试图编写一个只在地图上绘制圆圈的功能。我基本上遵循here给出的代码。这是我的实际代码：
using attempt2.Common;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Device.Location;
using System.Windows;
using Windows.Foundation;
using Windows.UI.Xaml.Controls.Maps;
using Windows.Devices.Geolocation;
using Windows.Services.Maps;
using Windows.Storage.Streams;
using Windows.UI.Xaml.Shapes;
using System.Device.Location;
namespace attempt2
{
class MapsClass
{
//computes a point on the perimeter given an arbitrary point and distance
public GeoCoordinate getDistanceBearing(this GeoCoordinate point, double distance, double bearing = 180)
{
double radius = Convert.ToDouble(this.Set.container.Values["Radius"]);
const double degreestoRadian = Math.PI / 180;
const double radiantoDegrees = 180 / Math.PI;
const double earthRadius = 6378137.0;
var latA = point.Latitude * degreestoRadian;
var longA = point.Longitude * degreestoRadian;
var angularDistance = distance / earthRadius;
var trueCourse = bearing * degreestoRadian;
var lat = Math.Asin(Math.Sin(latA) * Math.Cos(angularDistance) + Math.Cos(latA) * Math.Sin(angularDistance) * Math.Cos(trueCourse));
var dlon = Math.Atan2(Math.Sin(trueCourse) * Math.Sin(angularDistance) * Math.Cos(latA),
Math.Cos(angularDistance) - Math.Sin(latA) * Math.Sin(lat));
var lon = ((longA + dlon + Math.PI) % (Math.PI * 2)) - Math.PI;
var result = new GeoCoordinate(lat * radiantoDegrees, lon * radiantoDegrees);
return result;
}
//adds up a series of those points to create a circle
public static IList<GeoCoordinate> GetCirclePoints(this GeoCoordinate center,
double radius, int nrOfPoints = 50)
{
var angle = 360.0 / nrOfPoints;
var locations = new List<GeoCoordinate>();
for (var i = 0; i <= nrOfPoints; i++)
{
locations.Add(center.getDistanceBearing(radius, angle * i));
}
return locations;
}
//draws the circle on the map
private void MainPageLoaded()
{
if (this.Data.CurrentOrNot == false) //searched location
{
var location = this.Data.SearchedLocation;
Map.Center = location;
Map.ZoomLevel = 16;
var fill = Windows.UI.Color.FromArgb(50, 100, 0, 100);
var stroke = Windows.UI.Color.FromArgb(150, 250, 0, 0);
fill.A = 80;
stroke.A = 80;
var circle = new MapPolygon
{
StrokeThickness = 2,
FillColor = fill,
StrokeColor = stroke,
StrokeDashed = false,
};
foreach (var p in location.GetCirclePoints(150))
{
circle.Path.Add(p);
}
Map.MapElements.Add(circle);
} else
{
var location = this.Data.CurrentLocation;
Map.Center = location;
Map.ZoomLevel = 16;
var fill = Windows.UI.Color.FromArgb(50, 100, 0, 100);
var stroke = Windows.UI.Color.FromArgb(150, 250, 0, 0);
fill.A = 80;
stroke.A = 80;
var circle = new MapPolygon
{
StrokeThickness = 2,
FillColor = fill,
StrokeColor = stroke,
StrokeDashed = false,
};
foreach (var p in location.GetCirclePoints(150))
{
circle.Path.Add(p);
}
Map.MapElements.Add(circle);
}
}
当我调用其中一种方法时，我所遇到的唯一错误就在于这一行，特别是行locations.Add(center.getDistanceBearing(radius, angle * i));以及foreach (var p in location.GetCirclePoints(150))的两个实例。 Visual Studio给了我错误
＆＃39; System.Device.Location.GeoCoordinate＆＃39;不包含＆＃39; getDistanceBearing＆＃39;的定义并且没有延伸方法＆＃39; getDistanceBearing＆＃39;接受类型为＃System; Device.Location.GeoCoordinate＆＃39;的第一个参数。可以找到（你错过了使用指令或程序集引用吗？）
和我引用GetCirclePoints时完全相同类型的错误。但是，当我已经定义了方法时，为什么它会给我这些错误？为什么基本上相同的代码显然适用于我提供的示例？
答案 0 :(得分：0)
扩展方法应该是static类
static方法
MapsClass和getDistanceBearing不是静态的
您可以将您的方法用作常用方法
答案 1 :(得分：0)
您没有遵循扩展方法的规则。 这些类和方法也必须标记为静态。 一个简单的例子：
public static class Extension
{
const string _DefaultBasePath = @"C:\Users\stuyckp\Documents\Visual Studio 2013\Projects\WPF\Interstone";
private static string _BasePath = null;
public static string getFullPath(this string relativePath)
{
if (relativePath == null) return null;
string path = BasePath;
if (!path.EndsWith("\\") && !relativePath.StartsWith("\\")) path += "\\";
return path + relativePath;
}
static private string BasePath
{
get
{
if (_BasePath != null) return _BasePath;
try
{
Configuration cs = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
ConfigurationSectionGroup g = cs.SectionGroups["applicationSettings"];
ClientSettingsSection s
= (from ConfigurationSection section in g.Sections
where section is ClientSettingsSection
select section).FirstOrDefault() as ClientSettingsSection;
_BasePath = s.Settings.Get("BasePath").Value.ValueXml.InnerText;
}
catch
{
_BasePath = _DefaultBasePath;
}
return _BasePath;
}
}
}
不要将任何内容组合在一起，只能将这些静态类用于扩展方法本身所需的代码。这有效地使类中的所有内容成为静态：私有变量，辅助方法，......
所以你需要这样的东西：
public static class MapsClass{
//computes a point on the perimeter given an arbitrary point and distance
public static GeoCoordinate getDistanceBearing(this GeoCoordinate point, double distance, double bearing = 180)
{
double radius = Convert.ToDouble(this.Set.container.Values["Radius"]);
const double degreestoRadian = Math.PI / 180;
const double radiantoDegrees = 180 / Math.PI;
const double earthRadius = 6378137.0;
var latA = point.Latitude * degreestoRadian;
var longA = point.Longitude * degreestoRadian;
var angularDistance = distance / earthRadius;
var trueCourse = bearing * degreestoRadian;
var lat = Math.Asin(Math.Sin(latA) * Math.Cos(angularDistance) + Math.Cos(latA) * Math.Sin(angularDistance) * Math.Cos(trueCourse));
var dlon = Math.Atan2(Math.Sin(trueCourse) * Math.Sin(angularDistance) * Math.Cos(latA),
Math.Cos(angularDistance) - Math.Sin(latA) * Math.Sin(lat));
var lon = ((longA + dlon + Math.PI) % (Math.PI * 2)) - Math.PI;
var result = new GeoCoordinate(lat * radiantoDegrees, lon * radiantoDegrees);
return result;
}
//adds up a series of those points to create a circle
public static IList<GeoCoordinate> GetCirclePoints(this GeoCoordinate center,
double radius, int nrOfPoints = 50)
{
var angle = 360.0 / nrOfPoints;
var locations = new List<GeoCoordinate>();
for (var i = 0; i <= nrOfPoints; i++)
{
locations.Add(center.getDistanceBearing(radius, angle * i));
}
return locations;
}