// Calculates the linear distance between two user-defined geometries
private async void DistanceButton_Click(object sender, RoutedEventArgs e)
{
try
{
txtResults.Visibility = Visibility.Collapsed;
_graphicsLayer.Graphics.Clear();
// wait for user to draw a polyline
var line = await mapView.Editor.RequestShapeAsync(DrawShape.Polyline, _lineSymbol);
_graphicsLayer.Graphics.Add(new Graphic(line, _lineSymbol));
// wait for user to draw a point
var point = await mapView.Editor.RequestPointAsync();
_graphicsLayer.Graphics.Add(new Graphic(point, _pointSymbol));
// Calc distance between between line and point
double distance = GeometryEngine.DistanceFromGeometry(line, point) * METERS_TO_MILES;
txtResults.Text = string.Format("Distance between geometries: {0:0.000} miles", distance);
txtResults.Visibility = Visibility.Visible;
}
catch (Exception ex)
{
var _ = new MessageDialog("Distance Calculation Error: " + ex.Message, "Sample Error").ShowAsync();
txtResults.Visibility = Visibility.Collapsed;
_graphicsLayer.Graphics.Clear();
}
}
// calculates how far down a line a certain point on the line is located as a value from 0..1
private double GetFractionAlongLine(Polyline segment, ProximityResult proximity, MapPoint location)
{
double distance1 = 0;
double distance2 = 0;
int pointIndex = proximity.PointIndex;
int vertexCount = segment.Paths[0].Count;
var vertexPoint = segment.Paths[proximity.PartIndex][pointIndex];
Coordinate previousPoint;
int onSegmentIndex = 0;
//Detect which line segment we currently are on
if (pointIndex == 0) //Snapped to first vertex
{
onSegmentIndex = 0;
}
else if (pointIndex == vertexCount - 1) //Snapped to last vertex
{
onSegmentIndex = segment.Paths[0].Count - 2;
}
else
{
Coordinate nextPoint = segment.Paths[0][pointIndex + 1];
var d1 = GeometryEngine.DistanceFromGeometry(new MapPoint(vertexPoint, segment.SpatialReference), new MapPoint(nextPoint, segment.SpatialReference));
var d2 = GeometryEngine.DistanceFromGeometry(location, new MapPoint(nextPoint, segment.SpatialReference));
if (d1 < d2)
{
onSegmentIndex = pointIndex - 1;
}
else
{
onSegmentIndex = pointIndex;
}
}
previousPoint = segment.Paths[0][0];
for (int j = 1; j < onSegmentIndex + 1; j++)
{
Coordinate point = segment.Paths[0][j];
distance1 += GeometryEngine.DistanceFromGeometry(new MapPoint(previousPoint, segment.SpatialReference), new MapPoint(point, segment.SpatialReference));
previousPoint = point;
}
distance1 += GeometryEngine.DistanceFromGeometry(new MapPoint(previousPoint, segment.SpatialReference), location);
previousPoint = segment.Paths[0][onSegmentIndex + 1];
distance2 = GeometryEngine.DistanceFromGeometry(location, new MapPoint(previousPoint, segment.SpatialReference));
previousPoint = vertexPoint;
for (int j = onSegmentIndex + 2; j < segment.Paths[0].Count; j++)
{
Coordinate point = segment.Paths[0][j];
distance2 += GeometryEngine.DistanceFromGeometry(new MapPoint(previousPoint, segment.SpatialReference), new MapPoint(point, segment.SpatialReference));
previousPoint = point;
}
//var previousPoint = proximity.PointIndex ? segment.GetPoint(proximity.PartIndex + 1, 0) : segment.GetPoint(proximity.PartIndex, proximity.PointIndex + 1);
if (distance1 + distance2 == 0)
{
return(1);
}
return(distance1 / (distance1 + distance2));
}