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Xamarin.Forms Map Position and Distance

  • Artikkeli

The Xamarin.Forms.Maps namespace contains a Position struct that's typically used when positioning a map and its pins, and a Distance struct that can optionally be used when positioning a map.

Position

The Position struct encapsulates a position stored as latitude and longitude values. This struct defines two read-only properties:

  • Latitude, of type double, which represents the latitude of the position in decimal degrees.
  • Longitude, of type double, which represents the longitude of the position in decimal degrees.

Position objects are created with the Position constructor, which requires latitude and longitude arguments specified as double values:

Position position = new Position(36.9628066, -122.0194722);

When creating a Position object, the latitude value will be clamped between -90.0 and 90.0, and the longitude value will be clamped between -180.0 and 180.0.

Note

The GeographyUtils class has a ToRadians extension method that converts a double value from degrees to radians, and a ToDegrees extension method that converts a double value from radians to degrees.

Distance

The Distance struct encapsulates a distance stored as a double value, which represents the distance in meters. This struct defines three read-only properties:

  • Kilometers, of type double, which represents the distance in kilometers that's spanned by the Distance.
  • Meters, of type double, which represents the distance in meters that's spanned by the Distance.
  • Miles, of type double, which represents the distance in miles that's spanned by the Distance.

Distance objects can be created with the Distance constructor, which requires a meters argument specified as a double:

Distance distance = new Distance(1450.5);

Alternatively, Distance objects can be created with the FromKilometers, FromMeters, FromMiles, and BetweenPositions factory methods:

Distance distance1 = Distance.FromKilometers(1.45); // argument represents the number of kilometers
Distance distance2 = Distance.FromMeters(1450.5);   // argument represents the number of meters
Distance distance3 = Distance.FromMiles(0.969);     // argument represents the number of miles
Distance distance4 = Distance.BetweenPositions(position1, position2);