PolygonFence Class

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An irregularly shaped GeoFence connecting an arbitrary number of points.

Inheritance Hierarchy

SystemObject
Telogis.GeoBase.GeoFencePolygonFence

Namespace: Telogis.GeoBase.GeoFence
Assembly: geobase.net (in geobase.net.dll) Version: 4.99.0.0

Syntax

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public class PolygonFence : IMapRenderer, 
	IGeoFence, ICollection<LatLon>, IEnumerable<LatLon>, 
	IEnumerable

Public Class PolygonFence
	Implements IMapRenderer, IGeoFence, ICollection(Of LatLon), 
	IEnumerable(Of LatLon), IEnumerable

The PolygonFence type exposes the following members.

Constructors

	Name	Description
	PolygonFence	Construct a new, empty PolygonFence.

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Properties

	Name	Description
	BoundingBox	Gets the minimum BoundingBox for this GeoFence.
	Count	Gets the number of points that describe this GeoFence.
	IsFixedSize	Gets whether the PolygonFence is a fixed size. Always returns false.
	IsReadOnly	Gets whether the PolygonFence is read-only. Always returns false.
	IsSynchronized	If true, then this array is synchronized (thread-safe).
	Item	Enables the PolygonFence to be treated as an array of LatLons.
	Points	Gets the LatLon points that make up this GeoFence.
	RenderBrush	Brush used to fill the internal area of this GeoFence, use null for no fill.
	RenderPen	Pen used to draw the border around the GeoFence, use null for no border.
	RequiredRendermodes	Gets the RenderMode required by this PolygonFence.
	SyncRoot	Gets the SyncRoot to allow synchronized access to the array of points.

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Methods

	Name	Description
	Add	Add the specified point to this PolygonFence.
	Clear	Clears all points stored in this PolygonFence and clears the BoundingBox.
	Contains	Determine whether the specified point falls inside this PolygonFence.
	CopyTo	Copy the array of points (of which this GeoFence is comprised) to a given array.
	CreateFromStreetLinks	Creates a GeoFence collection containing the street links provided.
	Equals	Determines whether the specified object is equal to the current object. (Inherited from Object.)
	GetEnumerator	Get an enumerator for iteration through the points describing the PolygonFence.
	GetHashCode	Serves as the default hash function. (Inherited from Object.)
	GetObjectData	For serialization of the PolygonFence.
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	IndexOf	Searches the points that make up this GeoFence and returns the index of the point.
	Insert	Inserts a new point to the GeoFence, at the specified index.
	RecalculateBoundingBox	After points have been removed from a PolygonFence, the Bounding Box may be larger than is required to encompass the remaining points. This function recalculates a minimal bounding box that encompasses all the remaining points.
	Remove	Removes a point from the GeoFence.
	RemoveAt	Removes a point from a given index of the GeoFence.
	Render	Renders this PolygonFence on the given IMap.
	SnapToStreets	Create a new PolygonFence that includes only those streets that lie entirely within the area of this fence.
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Remarks

It is not necessary to specify the start and end points to the same co-ordinates to ensure that a closed polygon is drawn. The FillPolygon(Brush, PointF) method will automatically close an open polygon by drawing a line between the start and end points.

Related articles: Geofences Concept.

Examples

The following example creates a large blue PolygonFence. When you create a PolygonFence you will typically set the opacity so that the PolygonFence is translucent (i.e. opacity << 1). This ensures that the map below the PolygonFence is still visible.

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PolygonFence pf = new PolygonFence();

// define the vertices of the polygon
pf.Add(new LatLon(33.1, -117.6));
pf.Add(new LatLon(33.8, -117.8));
pf.Add(new LatLon(33.5, -117.0));

// set the color and opacity of the polygon
pf.Opacity = 0.5;
pf.Fill = new SolidColorBrush(Colors.Blue);

// draw the PolygonFence as an item on a map
myMap.Items.Add(pf);

You can clear all the points from a PolygonFence using the PolygonFence.Clear() method.

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pf.Clear();

If you retain a reference to the PolygonFence you can add and remove it from a map as you wish.

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myMap.Items.Remove(pf); // no longer shown on map
...
myMap.Items.Add(pf); // show it on the map again

The exact same effect can be achieved in XAML code by placing the following code snippet inside a Map object.

XAML

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<GeoFence:PolygonFence 
    x:Name="pf"
    Points="33.581,-117.726 33.588,-117.728 33.585,-117.730"
/>

Note that the points are latitude,longitude coordinates delimited by whitespace.

After you create a PolygonFence you'll often want to add it to a MapCtrl's RendererList so that the PolygonFence will be drawn on the map.

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PolygonFence fence = new PolygonFence();
myMapsRendererList.Add(fence);

This code snippet could be used in conjunction with a MapCtrl's mouse-click event to add a new vertex to the PolygonFence. Note that we redraw the map to reflect the changes made to the geofence.

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private void myMap_MouseClick(object sender, MouseEventArgs e)
{
    if (e.button == MouseButtons.Right)
        fence.Add(myMap.Map.XYtoLatLon(e.X, e.Y));

    myMap.Refresh();
}

The following code snippet could be used in conjunction with a mouse-move event to determine whether the cursor is inside or outside the geofence.

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private void myMap_MouseMove(object sender, MouseEventArgs e)
{
    if (fence.Contains(myMap.Map.XYtoLatLon(e.X, e.Y)) {
        // the mouse cursor is inside the PolygonFence
    }
    else {
        // the mouse cursor is *not* inside the PolygonFence
    }
}

Reference

Telogis.GeoBase.GeoFence Namespace