org.apache.sis.referencing.operation

## Class DefaultOperationMethod

- Object
- - FormattableObject
  - - AbstractIdentifiedObject
    - - DefaultOperationMethod

- All Implemented Interfaces:
    Serializable, Deprecable, LenientComparable, IdentifiedObject, OperationMethod

      public class DefaultOperationMethod
      extends AbstractIdentifiedObject
      implements OperationMethod

  Describes the algorithm and parameters used to perform a coordinate operation. An `OperationMethod` is a kind of metadata: it does not perform any coordinate operation (e.g. map projection) by itself, but tells us what is needed in order to perform such operation.

  The most important parts of an `OperationMethod` are its name and its group of parameter descriptors. The parameter descriptors do not contain any value, but tell us what are the expected parameters, together with their units of measurement.

  Example: An operation method named “Mercator (variant A)” (EPSG:9804) expects the following parameters:
  - “Latitude of natural origin” in degrees. Default value is 0°.
  - “Longitude of natural origin” in degrees. Default value is 0°.
  - “Scale factor at natural origin” as a dimensionless number. Default value is 1.
  - “False easting” in metres. Default value is 0 m.
  - “False northing” in metres. Default value is 0 m.
  In Apache SIS implementation, the name is the only mandatory property. However it is recommended to provide also identifiers (e.g. “EPSG:9804” in the above example) since names can sometime be ambiguous or be spelled in different ways.
  Departure from the ISO 19111 standard
  The following properties are mandatory according ISO 19111, but may be missing under some conditions in Apache SIS:
  - The formula if it has not been provided to the constructor, or if it can not be inferred from the given math transform.
  - The parameters if the `DefaultOperationMethod(MathTransform)` constructor can not infer them.
  Relationship with other classes or interfaces
  `OperationMethod` describes parameters without providing any value (except sometime default values). When values have been assigned to parameters, the result is a `SingleOperation`. Note that there is different kinds of `SingleOperation` depending on the nature and accuracy of the coordinate operation. See `getOperationType()` for more information.

  The interface performing the actual work of taking coordinates in the source CRS and calculating the new coordinates in the target CRS is `MathTransform`. In order to allow Apache SIS to instantiate those `MathTransform`s from given parameter values, `DefaultOperationMethod` subclasses should implement the `MathTransformProvider` interface.

  Immutability and thread safety
  This class is immutable and thread-safe if all properties given to the constructor are also immutable and thread-safe. It is strongly recommended for all subclasses to be thread-safe, especially the `MathTransformProvider` implementations to be used with `DefaultMathTransformFactory`.
  Since:
    0.5
  See Also:
    `DefaultConversion`, `DefaultTransformation`, `MathTransformProvider`, Serialized Form

  Defined in the `sis-referencing` module

- - ### Field Summary

    - ### Fields inherited from class AbstractIdentifiedObject

      `DEPRECATED_KEY, LOCALE_KEY`

    - ### Fields inherited from interface OperationMethod

      `FORMULA_KEY`

    - ### Fields inherited from interface IdentifiedObject

      `ALIAS_KEY, IDENTIFIERS_KEY, NAME_KEY, REMARKS_KEY`

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `` | `DefaultOperationMethod(Map<String,?> properties, Integer sourceDimensions, Integer targetDimensions, ParameterDescriptorGroup parameters)` Constructs an operation method from a set of properties and a descriptor group.
    `` | `DefaultOperationMethod(MathTransform transform)` Convenience constructor that creates an operation method from a math transform.
    `protected` | `DefaultOperationMethod(OperationMethod method)` Creates a new operation method with the same values than the specified one.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static DefaultOperationMethod` | `castOrCopy(OperationMethod object)` Returns a SIS operation method implementation with the same values than the given arbitrary implementation.
    `protected long` | `computeHashCode()` Invoked by `hashCode()` for computing the hash code when first needed.
    `boolean` | `equals(Object object, ComparisonMode mode)` Compares this operation method with the specified object for equality.
    `protected String` | `formatTo(Formatter formatter)` Formats this operation as a Well Known Text `Method[…]` element.
    `Formula` | `getFormula()` Formula(s) or procedure used by this operation method.
    `Class<? extends OperationMethod>` | `getInterface()` Returns the GeoAPI interface implemented by this class.
    `Class<? extends SingleOperation>` | `getOperationType()` Returns the base interface of the `CoordinateOperation` instances that use this method.
    `ParameterDescriptorGroup` | `getParameters()` Returns the set of parameters.
    `Integer` | `getSourceDimensions()` Number of dimensions in the source CRS of this operation method.
    `Integer` | `getTargetDimensions()` Number of dimensions in the target CRS of this operation method.
    `OperationMethod` | `redimension(int sourceDimensions, int targetDimensions)` Returns this operation method with different dimensions, if we are allowed to change dimensionality.
    `static OperationMethod` | `redimension(OperationMethod method, int sourceDimensions, int targetDimensions)` Returns an operation method with different dimensions, if we are allowed to change dimensionality.

    - ### Methods inherited from class AbstractIdentifiedObject

      `castOrCopy, equals, getAlias, getDescription, getIdentifiers, getName, getRemarks, hashCode, isDeprecated, isHeuristicMatchForName`

    - ### Methods inherited from class FormattableObject

      `print, toString, toString, toWKT`

    - ### Methods inherited from class Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

    - ### Methods inherited from interface IdentifiedObject

      `getAlias, getIdentifiers, getName, getRemarks, toWKT`

- - ### Constructor Detail

    - #### DefaultOperationMethod

          public DefaultOperationMethod(Map<String,?> properties,
                                        Integer sourceDimensions,
                                        Integer targetDimensions,
                                        ParameterDescriptorGroup parameters)

      Constructs an operation method from a set of properties and a descriptor group. The properties map is given unchanged to the super-class constructor. In addition to the properties documented in the parent constructor, the following properties are understood by this constructor:

      Recognized properties (non exhaustive list)
      Property name | Value type | Returned by
      --- | --- | ---
      "formula" | `Formula`, `Citation` or `CharSequence` | `getFormula()`
      Defined in parent classes (reminder)
      "name" | `Identifier` or `String` | `AbstractIdentifiedObject.getName()`
      "alias" | `GenericName` or `CharSequence` (optionally as array) | `AbstractIdentifiedObject.getAlias()`
      "identifiers" | `Identifier` (optionally as array) | `AbstractIdentifiedObject.getIdentifiers()`
      "remarks" | `InternationalString` or `String` | `AbstractIdentifiedObject.getRemarks()`

      The source and target dimensions may be `null` if this method can work with any number of dimensions (e.g. Affine Transform).
      Parameters:
        `properties` - set of properties. Shall contain at least `"name"`.
        `sourceDimensions` - number of dimensions in the source CRS of this operation method, or `null`.
        `targetDimensions` - number of dimensions in the target CRS of this operation method, or `null`.
        `parameters` - description of parameters expected by this operation.

    - #### DefaultOperationMethod

          public DefaultOperationMethod(MathTransform transform)

      Convenience constructor that creates an operation method from a math transform. The information provided in the newly created object are approximative, and usually acceptable only as a fallback when no other information are available.
      Parameters:
        `transform` - the math transform to describe.

    - #### DefaultOperationMethod

          protected DefaultOperationMethod(OperationMethod method)

      Creates a new operation method with the same values than the specified one. This copy constructor provides a way to convert an arbitrary implementation into a SIS one or a user-defined one (as a subclass), usually in order to leverage some implementation-specific API.

      This constructor performs a shallow copy, i.e. the properties are not cloned.

      Parameters:
        `method` - the operation method to copy.
      See Also:
        `castOrCopy(OperationMethod)`

  - ### Method Detail

    - #### castOrCopy

          public static DefaultOperationMethod castOrCopy(OperationMethod object)

      Returns a SIS operation method implementation with the same values than the given arbitrary implementation. If the given object is `null`, then `null` is returned. Otherwise if the given object is already a SIS implementation, then the given object is returned unchanged. Otherwise a new SIS implementation is created and initialized to the attribute values of the given object.
      Parameters:
        `object` - the object to get as a SIS implementation, or `null` if none.
      Returns:
        a SIS implementation containing the values of the given object (may be the given object itself), or `null` if the argument was null.

    - #### redimension

          public static OperationMethod redimension(OperationMethod method,
                                                    int sourceDimensions,
                                                    int targetDimensions)

      Returns an operation method with different dimensions, if we are allowed to change dimensionality. The need to change an `OperationMethod` dimensionality may occur in two contexts:
      - When the original method can work with any number of dimensions. Those methods do not know in advance the number of dimensions, which is fixed only after the actual `MathTransform` instance has been created. Example: Affine conversion.
      - When a three-dimensional method can also be used in the two-dimensional case, typically by assuming that the ellipsoidal height is zero everywhere. Example: Molodensky transform.
      This `redimension(…)` implementation performs the following choice:
      - If the given method is an instance of `DefaultOperationMethod`, then delegate to `redimension(int, int)` in order to allow subclasses to defines their own policy. For example the Molodensky method needs to override.
      - Otherwise for each dimension (source and target):
        - If the corresponding dimension of the given method is `null`, then set that dimension to the given value in a new `OperationMethod`.
        - Otherwise if the given value is not equal to the corresponding dimension in the given method, throw an `IllegalArgumentException`.
      Parameters:
        `method` - the operation method to redimension, or `null`.
        `sourceDimensions` - the desired number of input dimensions.
        `targetDimensions` - the desired number of output dimensions.
      Returns:
        the redimensioned operation method, or `null` if the given method was null, or `method` if no change is needed.
      Throws:
        `IllegalArgumentException` - if the given dimensions are illegal for the given operation method.

    - #### redimension

          public OperationMethod redimension(int sourceDimensions,
                                             int targetDimensions)

      Returns this operation method with different dimensions, if we are allowed to change dimensionality. See `redimension(OperationMethod, int, int)` for more information.

      The default implementation performs the following choice: for each dimension (source and target):

      - If the corresponding dimension of the given method is `null`, then set that dimension to the given value in a new `OperationMethod`.
      - Otherwise if the given value is not equal to the corresponding dimension in the given method, throw an `IllegalArgumentException`.
      Subclasses should override this method if they can work with different number of dimensions. For example a Molodensky transform usually works in a three-dimensional space, but can also work in a two-dimensional space by assuming that the ellipsoidal height is zero everywhere.
      Parameters:
        `sourceDimensions` - the desired number of input dimensions.
        `targetDimensions` - the desired number of output dimensions.
      Returns:
        the redimensioned operation method, or `this` if no change is needed.
      Throws:
        `IllegalArgumentException` - if the given dimensions are illegal for this operation method.
      Since:
        0.6

    - #### getInterface

          public Class<? extends OperationMethod> getInterface()

      Returns the GeoAPI interface implemented by this class. The SIS implementation returns `OperationMethod​.class`.
      Note for implementors: Subclasses usually do not need to override this information since GeoAPI does not define `OperationMethod` sub-interface. Overriding possibility is left mostly for implementors who wish to extend GeoAPI with their own set of interfaces.
      Overrides:
        `getInterface` in class `AbstractIdentifiedObject`
      Returns:
        `OperationMethod​.class` or a user-defined sub-interface.

    - #### getOperationType

          public Class<? extends SingleOperation> getOperationType()

      Returns the base interface of the `CoordinateOperation` instances that use this method. The base `CoordinateOperation` interface is usually one of the following subtypes:
      - `Transformation` if the coordinate operation has some errors (typically of a few metres) because of the empirical process by which the operation parameters were determined. Those errors do not depend on the floating point precision or the accuracy of the implementation algorithm.
      - `Conversion` if the coordinate operation is theoretically of infinite precision, ignoring the limitations of floating point arithmetic (including rounding errors) and the approximations implied by finite series expansions.
      - `Projection` if the coordinate operation is a conversion (as defined above) converting geodetic latitudes and longitudes to plane (map) coordinates. This type can optionally be refined with one of the `CylindricalProjection`, `ConicProjection` or `PlanarProjection` subtypes.
      In case of doubt, `getOperationType()` can conservatively return the base type. The default implementation returns `SingleOperation​.class`, which is the most conservative return value.
      Returns:
        interface implemented by all coordinate operations that use this method.
      See Also:
        `DefaultMathTransformFactory​.getAvailableMethods(Class)`

    - #### getFormula

          public Formula getFormula()

      Formula(s) or procedure used by this operation method. This may be a reference to a publication. Note that the operation method may not be analytic, in which case this attribute references or contains the procedure, not an analytic formula.
      Departure from the ISO 19111 standard: this property is mandatory according ISO 19111, but optional in Apache SIS.
      Specified by:
        `getFormula` in interface `OperationMethod`
      Returns:
        the formula used by this method, or `null` if unknown.
      See Also:
        `DefaultFormula`, `MathTransformProvider`

    - #### getSourceDimensions

          public Integer getSourceDimensions()

      Number of dimensions in the source CRS of this operation method. May be null if unknown, as in an Affine Transform.
      Specified by:
        `getSourceDimensions` in interface `OperationMethod`
      Returns:
        the dimension of source CRS, or `null` if unknown.
      See Also:
        `AbstractMathTransform​.getSourceDimensions()`

    - #### getTargetDimensions

          public Integer getTargetDimensions()

      Number of dimensions in the target CRS of this operation method. May be null if unknown, as in an Affine Transform.
      Specified by:
        `getTargetDimensions` in interface `OperationMethod`
      Returns:
        the dimension of target CRS, or `null` if unknown.
      See Also:
        `AbstractMathTransform​.getTargetDimensions()`

    - #### getParameters

          public ParameterDescriptorGroup getParameters()

      Returns the set of parameters.
      Departure from the ISO 19111 standard: this property is mandatory according ISO 19111, but may be null in Apache SIS if the `DefaultOperationMethod(MathTransform)` constructor has been unable to infer it or if this `OperationMethod` has been read from an incomplete GML document.
      Specified by:
        `getParameters` in interface `OperationMethod`
      Returns:
        the parameters, or `null` if unknown.
      See Also:
        `AbstractSingleOperation​.getParameterDescriptors()`, `AbstractSingleOperation​.getParameterValues()`

    - #### equals

          public boolean equals(Object object,
                                ComparisonMode mode)

      Compares this operation method with the specified object for equality. If the `mode` argument value is `STRICT` or `BY_CONTRACT`, then all available properties are compared including the formula.
      Specified by:
        `equals` in interface `LenientComparable`
      Overrides:
        `equals` in class `AbstractIdentifiedObject`
      Parameters:
        `object` - the object to compare to `this`.
        `mode` - `STRICT` for performing a strict comparison, or `IGNORE_METADATA` for comparing only properties relevant to transformations.
      Returns:
        `true` if both objects are equal.
      See Also:
        `AbstractIdentifiedObject​.computeHashCode()`, `Utilities​.deepEquals(Object, Object, ComparisonMode)`

    - #### computeHashCode

          protected long computeHashCode()

      Invoked by `hashCode()` for computing the hash code when first needed. See `AbstractIdentifiedObject​.computeHashCode()` for more information.
      Overrides:
        `computeHashCode` in class `AbstractIdentifiedObject`
      Returns:
        the hash code value. This value may change in any future Apache SIS version.

    - #### formatTo

          protected String formatTo(Formatter formatter)

      Formats this operation as a Well Known Text `Method[…]` element.
      Overrides:
        `formatTo` in class `AbstractIdentifiedObject`
      Parameters:
        `formatter` - the formatter where to format the inner content of this WKT element.
      Returns:
        `"Method"` (WKT 2) or `"Projection"` (WKT 1).
      See Also:
        WKT 2 specification §17.2.3

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