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Point QML Type

A specific location, defined by an x,y coordinate pair, and a SpatialReference. More...

Import Statement: import Esri.ArcGISRuntime 100.9
Since: Esri.ArcGISRuntime 100.0
Inherits:

Geometry

Properties

  • m : double
  • x : double
  • y : double
  • z : double

Signals

Detailed Description

Point geometries represent discrete locations or entities, such as a geocoded house address, the location of a water meter in a water utility network, a moving vehicle, and so on. Larger geographic entities (such as cities) are often represented as points on small-scale maps. Points can be used as the geometry of features and graphics, and are often used to construct more complex geometries. They are also used in a Viewpoint to define the center of the display.

Points store a single set of x,y coordinates that define a location (longitude and latitude, for example), and a SpatialReference. Points can optionally have z (altitude) and m (measure) attributes.

For points defined with a geographic spatial reference, the x coordinate is the longitude (east or west), and the y coordinate is the latitude (north or south). When geographic coordinates are represented in strings, points are generally written using the form "(latitude, longitude)", where the y coordinate comes before the x coordinate. Latitude values south of the equator and longitude values west of the prime meridian are expressed as negative numbers.

Use CoordinateFormatter to convert a latitude, longitude-formatted string directly to a Point, and also return a latitude, longitude-formatted string from an existing Point. Other coordinate notations, such as Military Grid Reference System (MGRS) and United States National Grid (USNG) are also supported.

Point is immutable. Instead of changing the properties of an existing Point, you can create new Point instances, or use PointBuilder.

This QML type supports the following default properties. A default property may be declared inside another declared object without being assigned explicitly to a property.

TypeDefault Property
SpatialReferencespatialReference

See also JsonSerializable.

Property Documentation

m : double

An optional coordinate to define a measure value for the point.

M-values are used in linear referencing scenarios and may represent things like mile markers along a highway. Like z-values, every geometry can optionally store m-values with the point coordinates that comprise it. The default m-value is NaN. If an m-value is specified when a geometry is created, the new geometry will have m-values (Geometry::hasM will be true). Note that when you get m-values back from a geometry, the default value of NAN is returned for vertices that do not have m-values. A geometry with m-values is sometimes known as an m-aware geometry.

Geometries can have z-values, indicating values along the z-axis, which is perpendicular to both the x-axis and y-axis. Z-values indicate height above or depth below a surface, or an absolute elevation. For example, z-values are used to draw the locations of geometries in a SceneView. Note that geometries are not considered true 3D shapes and are draped onto surfaces in the view, or in some cases, drawn in a single plane by using z-values. Z-values are stored on Point and Envelope. Because Multipoint, Polyline, and Polygon are created from a collection of Point, all types of geometry can have z-values.

Whether or not a geometry has z-values is determined when the geometry is created; if you use a method that has a z-value parameter, the new geometry will have z-values (Geometry::hasZ will be true). If you create geometries using constructors that take z-value parameters, or if you pass into the constructor points or segments that have z-values, the new geometry will have z-values. A Geometry with z-values is sometimes known as a z-aware geometry.

It may be that not all vertices in your geometry have a z-value defined. NAN is a valid z-value used to indicate an unknown z-value. However, the default z-value is 0. When you get z-values from a geometry that does not have z-values, the default is 0. Check the Geometry::hasZ to determine whether a z-value of 0 means that there are no z-values in the geometry or that the z-value in the geometry's coordinates really is 0.


x : double

The x-coordinate.


y : double

The y-coordinate.


z : double

The z-coordinate.


Signal Documentation

mChanged()

Emitted when the m property changes.

Note: This signal will only be emitted when the property initializes during the instantiation of the component.

Note: The corresponding handler is onMChanged.

This signal was introduced in Esri.ArcGISRuntime 100.4.


xChanged()

Emitted when the x property changes.

Note: This signal will only be emitted when the property initializes during the instantiation of the component.

Note: The corresponding handler is onXChanged.

This signal was introduced in Esri.ArcGISRuntime 100.4.


yChanged()

Emitted when the y property changes.

Note: This signal will only be emitted when the property initializes during the instantiation of the component.

Note: The corresponding handler is onYChanged.

This signal was introduced in Esri.ArcGISRuntime 100.4.


zChanged()

Emitted when the z property changes.

Note: This signal will only be emitted when the property initializes during the instantiation of the component.

Note: The corresponding handler is onZChanged.

This signal was introduced in Esri.ArcGISRuntime 100.4.



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