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TdxMapControlCustomProjection Class

The base class for map projections.

#Declaration

Delphi
TdxMapControlCustomProjection = class(
    TcxInterfacedPersistent
)

#Remarks

Map projections are different ways to map a sphere surface to a plane. However, each map projection distorts the original surface. For example, surface distortion increases as the inspected point moves away from the equator towards the north or south pole in the Spherical Mercator projection. Different map projection types are designed for use in different scenarios.

Refer to the following topic for general information on map projections: https://en.wikipedia.org/wiki/Map_projection.

The TdxMapControlCustomProjection class declares geographic conversion functions common to all map projections. TdxMapControlCustomProjection descendants implement these functions.

#Available Projections

All map layer types support the Spherical Mercator projection (default). Item and Item File layers declare Projection and ProjectionClass properties you can use to switch between the following projections:

Projection Example
Braun Stereographic VCL Map Control: Braun Stereographic
Elliptical Mercator VCL Map Control: Elliptical Mercator
EPSG:4326 (also known as WGS 84 or WGS 1984) VCL Map Control: ESPG:4326
Equal-Area VCL Map Control: Equal-Area
Equirectangular VCL Map Control: Equirectangular
Kavrayskiy VII VCL Map Control: Kavrayskiy VII
Lambert Cylindrical Equal-Area VCL Map Control: Lambert Cylindrical Equal-Area
Miller Cylindrical VCL Map Control: Miller Cylindrical
Sinusoidal VCL Map Control: Sinusoidal
Spherical Mercator VCL Map Control: Spherical Mercator

#Main API Members

The list below outlines key members of the TdxMapControlCustomProjection class. These members allow you to convert map points into specific measurement units according to the actual map projection.

GeoPointToMapUnit
Converts a specified point defined in geographical coordinates to internal map units.
GeoToKilometersSize
This member supports the internal infrastructure and is not intended to be used directly from your code.
KilometersToGeoSize
This member supports the internal infrastructure and is not intended to be used directly from your code.
MapUnitToGeoPoint
Converts a specified point defined in internal map units to geographical coordinates.

#Terminal TdxMapControlCustomProjection Class Descendants

Do not use the TdxMapControlCustomProjection class directly. Use the following descendants instead:

TdxMapControlBraunStereographicProjection
Implements the Braun Stereographic map projection.
TdxMapControlEllipticalMercatorProjection
Implements the Elliptical Mercator Projection.
TdxMapControlEPSG4326Projection
Implements the EPSG:4326 map projection (also known as WGS 84 or WGS 1984).
TdxMapControlEqualAreaProjection
Implements the Equal-Area map projection.
TdxMapControlEquirectangularProjection
Implements the Equirectangular map projection.
TdxMapControlKavrayskiyProjection
Implements the Kavrayskiy VII map projection.
TdxMapControlLambertCylindricalEqualAreaProjection
Implements the Lambert Cylindrical Equal-Area map projection.
TdxMapControlMillerProjection
Implements the Miller map projection.
TdxMapControlSinusoidalProjection
Implements the Sinusoidal map projection.
TdxMapControlSphericalMercatorProjection
Implements the Spherical Mercator map projection.

#Inheritance

See Also