如何在C#中使用GMAP.NET在地图上绘制圆
如何在C#中使用GMAP.NET在地图上绘制圆
提问于 2012-02-16 17:32:54
我在c#中使用GMAP.NET。我可以在窗体上显示地图，现在我正在尝试通过单击某个确定点，保持鼠标左键并将鼠标拖到特定位置来绘制一个圆形鼠标。一旦画出了圆，我想要得到圆心的半径，我相信GMAP能够做到这一点。我使用的是开放街道地图。
我只是不能实现这个功能，任何人谁玩过的GMAP控件亲切地分享你的经验与一些代码，将工作。
谢谢
回答 9
Stack Overflow用户
发布于 2012-03-20 21:00:37
据我所知，能够达到这样的结果的唯一方法是创建一个带有PointLatLng点的列表，并将它们绘制为多边形。下面是一个示例：
private void CreateCircle(PointF point, double radius, int segments)
{
List<PointLatLng> gpollist = new List<PointLatLng>();
double seg = Math.PI * 2 / segments;
for (int i = 0; i < segments; i++)
{
double theta = seg * i;
double a = point.X + Math.Cos(theta) * radius;
double b = point.Y + Math.Sin(theta) * radius;
PointLatLng gpoi = new PointLatLng(a,b);
gpollist.Add(gpoi);
}
GMapPolygon gpol = new GMapPolygon(gpollist, "pol");
overlayOne.Polygons.Add(gpol);
}Stack Overflow用户
发布于 2015-12-09 02:52:50
如果你想使用与绘图类相关的典型的GDI特性，你可以简单的继承GMapMarker类。这使您可以绘制简单的形状，如圆，并创建自定义属性(例如，将计算以英里为单位的形状半径的属性)：
public class GMapPoint : GMap.NET.WindowsForms.GMapMarker
{
private PointLatLng point_;
private float size_;
public PointLatLng Point
{
get
{
return point_;
}
set
{
point_ = value;
}
}
public GMapPoint(PointLatLng p, int size)
: base(p)
{
point_ = p;
size_ = size;
}
public override void OnRender(Graphics g)
{
g.FillRectangle(Brushes.Black, LocalPosition.X, LocalPosition.Y, size_, size_);
//OR
g.DrawEllipse(Pens.Black, LocalPosition.X, LocalPosition.Y, size_, size_);
//OR whatever you need
}
}要在地图上绘制点，请执行以下操作：
GMapOverlay points_ = new GMapOverlay("pointCollection");
points_.Markers.Add(new GMapPoint(new PointLatLng(35.06, -106.36), 10));
gMapControl1.Overlays.Add(points_);(因为我对此有一些疑问)因为我们继承了markers类，所以我们仍然可以利用tooltiptext功能：
GMapPoint pnt = new GMapPoint(new PointLatLng(35.06, -106.36), 10);
pnt.Size = new Size(10,10);
pnt.ToolTipText = "Text Here";
pnt.ToolTipMode = MarkerTooltipMode.Always;
points_.AddMarker(pnt);Stack Overflow用户
发布于 2017-11-21 12:16:51
private void CreateCircle(Double lat, Double lon, double radius, int ColorIndex)
{
PointLatLng point = new PointLatLng(lat, lon);
int segments = 1080;
List<PointLatLng> gpollist = new List<PointLatLng>();
for (int i = 0; i < segments; i++)
{
gpollist.Add(FindPointAtDistanceFrom(point, i*(Math.PI/180), radius / 1000));
}
GMapPolygon polygon = new GMapPolygon(gpollist, "Circle");
switch (ColorIndex) {
case 1:
polygon.Fill = new SolidBrush(Color.FromArgb(80, Color.Red));
break;
case 2:
polygon.Fill = new SolidBrush(Color.FromArgb(80, Color.Orange));
break;
case 3:
polygon.Fill = new SolidBrush(Color.FromArgb(20, Color.Aqua));
break;
default:
MessageBox.Show("No search zone found!");
break;
}
polygon.Stroke = new Pen(Color.Red, 1);
markers.Polygons.Add(polygon);
gMapCtl.Overlays.Add(markers);
}
public static GMap.NET.PointLatLng FindPointAtDistanceFrom(GMap.NET.PointLatLng startPoint, double initialBearingRadians, double distanceKilometres)
{
const double radiusEarthKilometres = 6371.01;
var distRatio = distanceKilometres / radiusEarthKilometres;
var distRatioSine = Math.Sin(distRatio);
var distRatioCosine = Math.Cos(distRatio);
var startLatRad = DegreesToRadians(startPoint.Lat);
var startLonRad = DegreesToRadians(startPoint.Lng);
var startLatCos = Math.Cos(startLatRad);
var startLatSin = Math.Sin(startLatRad);
var endLatRads = Math.Asin((startLatSin * distRatioCosine) + (startLatCos * distRatioSine * Math.Cos(initialBearingRadians)));
var endLonRads = startLonRad + Math.Atan2(Math.Sin(initialBearingRadians) * distRatioSine * startLatCos,distRatioCosine - startLatSin * Math.Sin(endLatRads));
return new GMap.NET.PointLatLng(RadiansToDegrees(endLatRads), RadiansToDegrees(endLonRads));
}
public static double DegreesToRadians(double degrees)
{
const double degToRadFactor = Math.PI/180;
return degrees * degToRadFactor;
}
public static double RadiansToDegrees(double radians)
{
const double radToDegFactor = 180/Math.PI;
return radians * radToDegFactor;
}
public static double DistanceTwoPoint(double startLat, double startLong, double endLat, double endLong) {
var startPoint = new GeoCoordinate(startLat, startLong);
var endPoint = new GeoCoordinate(endLat, endLong);
return startPoint.GetDistanceTo(endPoint);
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/9308673
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