Specifying a Radius for a MapPoint
Environment
| Product Version | 2019.3.1016 |
| Product | RadMap for WinForms |
Description
An example demonstrating how the MapPoint element can be customized to paint a circle with a predefined radius.
Solution
The MapPoint class accepts a System.Drawing.Size object in its constructor and depending on the specified size the control will paint a circular element. A common requirement is to specify a radius for the map point and have its size adjusted according the radius and the current zoom level of the view port. The solution in this article demonstrates a possible custom implementation introducing a new RadiusInMeters property.
Figure 1: Custom Map Point
Updating Header Implementation
public class CustomMapPoint : MapPoint
{
private int radiusInMeters;
public CustomMapPoint(PointG location) : base(location)
{
}
public CustomMapPoint(PointG location, Size size) : base(location, size)
{
}
public int RadiusInMeters
{
get
{
return this.radiusInMeters;
}
set
{
this.radius = radiusInMeters;
}
}
public override void ViewportChanged(IMapViewport viewport, ViewportChangeAction action)
{
var onePixelInMeters = MapTileSystemHelper.GroundResolution(this.Location.Latitude, viewport.ZoomLevel);
var scale = -1.0F;
scale = this.RadiusInMeters * 2 / (double)onePixelInMeters;
Size newSize = Size.Empty;
if (scale > 1)
newSize = new Size(scale, scale);
this.Size = newSize;
base.ViewportChanged(viewport, action);
}
}
Public Class CustomMapPoint
Inherits MapPoint
Public Sub New(location As PointG)
MyBase.New(location)
End Sub
Public Sub New(location As PointG, size As Size)
MyBase.New(location, size)
End Sub
Private _radius As Integer
Public Property RadiusInMeters() As Integer
Get
Return _radius
End Get
Set(ByVal value As Integer)
_radius = value
End Set
End Property
Public Overrides Sub ViewportChanged(viewport As IMapViewport, action As ViewportChangeAction)
Dim onePixelInMeters = MapTileSystemHelper.GroundResolution(Me.Location.Latitude, viewport.ZoomLevel)
Dim scale = -1.0F
scale = Me.RadiusInMeters * 2 / onePixelInMeters
Dim newSize = Size.Empty
If scale > 1 Then
newSize = New Size(scale, scale)
End If
Me.Size = newSize
MyBase.ViewportChanged(viewport, action)
End Sub
End Class
Initial Setup
public RadForm1()
{
InitializeComponent();
MapLayer pointLayer = new MapLayer("PointG");
this.radMap1.Layers.Add(pointLayer);
CustomMapPoint element = new CustomMapPoint(new PointG(34.04302, -118.26725));
element.RadiusInMeters = 100;
element.BackColor = Color.FromArgb(125, Color.LightBlue);
element.BorderColor = Color.Red;
this.radMap1.Layers("PointG").Add(element);
}
Public Sub New()
InitializeComponent()
Dim pointLayer As MapLayer = New MapLayer("PointG")
Me.radMap1.Layers.Add(pointLayer)
Dim element As CustomMapPoint = New CustomMapPoint(New PointG(34.04302, -118.26725))
element.RadiusInMeters = 100
element.BackColor = Color.FromArgb(125, Color.LightBlue)
element.BorderColor = Color.Red
Me.radMap1.Layers("PointG").Add(element)
End Sub
