org.apache.sis.geometry

## Class GeneralEnvelope

- Object
- - AbstractEnvelope
  - - GeneralEnvelope

- All Implemented Interfaces:
    Serializable, Cloneable, Emptiable, Envelope

      public class GeneralEnvelope
      extends AbstractEnvelope
      implements Cloneable, Serializable

  A mutable `Envelope` (a minimum bounding box or rectangle) of arbitrary dimension. Regardless of dimension, an `Envelope` can be represented without ambiguity as two direct positions (coordinate points). To encode an `Envelope`, it is sufficient to encode these two points.
  Note: `Envelope` uses an arbitrary Coordinate Reference System, which does not need to be geographic. This is different than the `GeographicBoundingBox` class provided in the metadata package, which can be used as a kind of envelope restricted to a Geographic CRS having Greenwich prime meridian.
  This particular implementation of `Envelope` is said "General" because it uses coordinates of an arbitrary number of dimensions. This is in contrast with `Envelope2D`, which can use only two-dimensional coordinates.

  A `GeneralEnvelope` can be created in various ways:

  - From a given number of dimension, with all ordinates initialized to 0.
  - From two coordinate points.
  - From a an other envelope (copy constructor).
  - From a geographic bounding box.
  - From a character sequence representing a `BBOX` or a Well Known Text (WKT) format.
  Spanning the anti-meridian of a Geographic CRS
  The Web Coverage Service (WCS) specification authorizes (with special treatment) cases where upper < lower at least in the longitude case. They are envelopes crossing the anti-meridian, like the red box below (the green box is the usual case). The default implementation of methods listed in the right column can handle such cases.

  | Supported methods: `getMinimum(int)` `getMaximum(int)` `getMedian(int)` `getSpan(int)` `isEmpty()` `toSimpleEnvelopes()` `contains(DirectPosition)` `contains(Envelope)` `intersects(Envelope)` `intersect(Envelope)` `add(Envelope)` `add(DirectPosition)`

  Envelope validation
  If and only if this envelope is associated to a non-null CRS, then constructors and setter methods in this class perform the following checks:
  - The number of CRS dimensions must be equals to `this.getDimension()`.
  - For each dimension i, `getLower(i) > getUpper(i)` is allowed only if the coordinate system axis range meaning is `WRAPAROUND`.
  Note that this class does not require the ordinate values to be between the axis minimum and maximum values. This flexibility exists because out-of-range values happen in practice, while they do not hurt the working of `add(…)`, `intersect(…)`, `contains(…)` and similar methods. This in contrast with the `lower > upper` case, which cause the above-cited methods to behave in an unexpected way if the axis does not have wraparound range meaning.
  Since:
    0.3
  See Also:
    `Envelope2D`, `DefaultGeographicBoundingBox`, Serialized Form

  Defined in the `sis-referencing` module

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `GeneralEnvelope(CharSequence wkt)` Constructs a new envelope initialized to the values parsed from the given string in `BOX` or Well Known Text (WKT) format.
    `GeneralEnvelope(CoordinateReferenceSystem crs)` Constructs an empty envelope with the specified coordinate reference system.
    `GeneralEnvelope(DirectPosition lowerCorner, DirectPosition upperCorner)` Constructs an envelope defined by two corners given as direct positions.
    `GeneralEnvelope(double[] lowerCorner, double[] upperCorner)` Constructs an envelope defined by two corners given as sequences of ordinate values.
    `GeneralEnvelope(Envelope envelope)` Constructs a new envelope with the same data than the specified envelope.
    `GeneralEnvelope(GeographicBoundingBox box)` Constructs a new envelope with the same data than the specified geographic bounding box.
    `GeneralEnvelope(int dimension)` Constructs an empty envelope of the specified dimension.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `add(DirectPosition position)` Adds a point to this envelope.
    `void` | `add(Envelope envelope)` Adds an envelope object to this envelope.
    `static GeneralEnvelope` | `castOrCopy(Envelope envelope)` Returns the given envelope as a `GeneralEnvelope` instance.
    `GeneralEnvelope` | `clone()` Returns a deep copy of this envelope.
    `boolean` | `equals(Object object)` Returns `true` if the specified object is an envelope of the same class with equals coordinates and CRS.
    `CoordinateReferenceSystem` | `getCoordinateReferenceSystem()` Returns the envelope coordinate reference system, or `null` if unknown.
    `int` | `getDimension()` Returns the length of coordinate sequence (the number of entries) in this envelope.
    `double` | `getLower(int dimension)` Returns the limit in the direction of decreasing ordinate values in the specified dimension.
    `double` | `getMaximum(int dimension)` Returns the maximal ordinate value for the specified dimension.
    `double` | `getMedian(int dimension)` Returns the median ordinate along the specified dimension.
    `double` | `getMinimum(int dimension)` Returns the minimal ordinate value for the specified dimension.
    `double` | `getSpan(int dimension)` Returns the envelope span (typically width or height) along the specified dimension.
    `double` | `getUpper(int dimension)` Returns the limit in the direction of increasing ordinate values in the specified dimension.
    `int` | `hashCode()` Returns a hash value for this envelope.
    `void` | `intersect(Envelope envelope)` Sets this envelope to the intersection if this envelope with the specified one.
    `boolean` | `isAllNaN()` Returns `false` if at least one ordinate value is not NaN.
    `boolean` | `isEmpty()` Determines whether or not this envelope is empty.
    `boolean` | `normalize()` Ensures that the envelope is contained in the coordinate system domain.
    `void` | `setCoordinateReferenceSystem(CoordinateReferenceSystem crs)` Sets the coordinate reference system in which the coordinate are given.
    `void` | `setEnvelope(double... corners)` Sets the envelope to the specified values, which must be the lower corner coordinates followed by upper corner coordinates.
    `void` | `setEnvelope(Envelope envelope)` Sets this envelope to the same coordinate values than the specified envelope.
    `void` | `setRange(int dimension, double lower, double upper)` Sets the envelope range along the specified dimension.
    `void` | `setToInfinite()` Sets the lower corner to negative infinity and the upper corner to positive infinity.
    `void` | `setToNaN()` Sets all ordinate values to NaN.
    `boolean` | `simplify()` Ensures that lower <= upper for every dimensions.
    `GeneralEnvelope` | `subEnvelope(int beginIndex, int endIndex)` Returns a view over this envelope that encompass only some dimensions.
    `String` | `toString()` Formats this envelope as a "`BOX`" element.
    `void` | `translate(double... vector)` Translates the envelope by the given vector.

    - ### Methods inherited from class AbstractEnvelope

      `contains, contains, contains, equals, getLowerCorner, getMedian, getSpan, getUpperCorner, intersects, intersects, toSimpleEnvelopes`

    - ### Methods inherited from class Object

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

- - ### Constructor Detail

    - #### GeneralEnvelope

          public GeneralEnvelope(DirectPosition lowerCorner,
                                 DirectPosition upperCorner)
                          throws MismatchedDimensionException,
                                 MismatchedReferenceSystemException

      Constructs an envelope defined by two corners given as direct positions. If at least one corner is associated to a CRS, then the new envelope will also be associated to that CRS.
      Parameters:
        `lowerCorner` - the limits in the direction of decreasing ordinate values for each dimension.
        `upperCorner` - the limits in the direction of increasing ordinate values for each dimension.
      Throws:
        `MismatchedDimensionException` - if the two positions do not have the same dimension.
        `MismatchedReferenceSystemException` - if the CRS of the two position are not equal.

    - #### GeneralEnvelope

          public GeneralEnvelope(double[] lowerCorner,
                                 double[] upperCorner)
                          throws MismatchedDimensionException

      Constructs an envelope defined by two corners given as sequences of ordinate values. The Coordinate Reference System is initially `null`.
      Parameters:
        `lowerCorner` - the limits in the direction of decreasing ordinate values for each dimension.
        `upperCorner` - the limits in the direction of increasing ordinate values for each dimension.
      Throws:
        `MismatchedDimensionException` - if the two sequences do not have the same length.

    - #### GeneralEnvelope

          public GeneralEnvelope(int dimension)

      Constructs an empty envelope of the specified dimension. All ordinates are initialized to 0 and the coordinate reference system is undefined.
      Parameters:
        `dimension` - the envelope dimension.

    - #### GeneralEnvelope

          public GeneralEnvelope(CoordinateReferenceSystem crs)

      Constructs an empty envelope with the specified coordinate reference system. All ordinate values are initialized to 0.
      Parameters:
        `crs` - the coordinate reference system.

    - #### GeneralEnvelope

          public GeneralEnvelope(Envelope envelope)

      Constructs a new envelope with the same data than the specified envelope.
      Parameters:
        `envelope` - the envelope to copy.
      See Also:
        `castOrCopy(Envelope)`

    - #### GeneralEnvelope

          public GeneralEnvelope(GeographicBoundingBox box)

      Constructs a new envelope with the same data than the specified geographic bounding box. The coordinate reference system is set to the default geographic CRS. Axis order is (longitude, latitude).
      Parameters:
        `box` - the bounding box to copy.

    - #### GeneralEnvelope

          public GeneralEnvelope(CharSequence wkt)
                          throws IllegalArgumentException

      Constructs a new envelope initialized to the values parsed from the given string in `BOX` or Well Known Text (WKT) format. The given string is typically a `BOX` element like below:

          BOX(-180 -90, 180 90)

      However this constructor is lenient to other geometry types like `POLYGON`. Actually this constructor ignores the geometry type and just applies the following simple rules:
      - Character sequences complying to the rules of Java identifiers are skipped.
      - Coordinates are separated by a coma (`,`) character.
      - The ordinates in a coordinate are separated by a space.
      - Ordinate numbers are assumed formatted in US locale.
      - The coordinate having the highest dimension determines the dimension of this envelope.
      This constructor does not check the consistency of the provided text. For example it does not check that every points in a `LINESTRING` have the same dimension. However this constructor ensures that the parenthesis are balanced, in order to catch some malformed WKT.
      Example: The following texts can be parsed by this constructor in addition of the usual `BOX` element. This constructor creates the bounding box of those geometries:
      - `POINT(6 10)`
      - `MULTIPOLYGON(((1 1, 5 1, 1 5, 1 1),(2 2, 3 2, 3 3, 2 2)))`
      - `GEOMETRYCOLLECTION(POINT(4 6),LINESTRING(3 8,7 10))`
      Parameters:
        `wkt` - the `BOX`, `POLYGON` or other kind of element to parse.
      Throws:
        `IllegalArgumentException` - if the given string can not be parsed.
      See Also:
        `Envelopes​.fromWKT(CharSequence)`, `Envelopes​.toString(Envelope)`

  - ### Method Detail

    - #### castOrCopy

          public static GeneralEnvelope castOrCopy(Envelope envelope)

      Returns the given envelope as a `GeneralEnvelope` instance. If the given envelope is already an instance of `GeneralEnvelope`, then it is returned unchanged. Otherwise the coordinate values and the CRS of the given envelope are copied in a new `GeneralEnvelope`.
      Parameters:
        `envelope` - the envelope to cast, or `null`.
      Returns:
        the values of the given envelope as a `GeneralEnvelope` instance.
      See Also:
        `AbstractEnvelope​.castOrCopy(Envelope)`, `ImmutableEnvelope​.castOrCopy(Envelope)`

    - #### setCoordinateReferenceSystem

          public void setCoordinateReferenceSystem(CoordinateReferenceSystem crs)
                                            throws MismatchedDimensionException

      Sets the coordinate reference system in which the coordinate are given. This method does not reproject the envelope, and does not check if the envelope is contained in the new domain of validity.

      If the envelope coordinates need to be transformed to the new CRS, consider using `Envelopes​.transform(Envelope, CoordinateReferenceSystem)` instead.

      Parameters:
        `crs` - the new coordinate reference system, or `null`.
      Throws:
        `MismatchedDimensionException` - if the specified CRS doesn't have the expected number of dimensions.
        `IllegalStateException` - if a range of ordinate values in this envelope is compatible with the given CRS. See Envelope validation in class javadoc for more details.

    - #### setRange

          public void setRange(int dimension,
                               double lower,
                               double upper)
                        throws IndexOutOfBoundsException

      Sets the envelope range along the specified dimension.
      Parameters:
        `dimension` - the dimension to set.
        `lower` - the limit in the direction of decreasing ordinate values.
        `upper` - the limit in the direction of increasing ordinate values.
      Throws:
        `IndexOutOfBoundsException` - if the given index is out of bounds.
        `IllegalArgumentException` - if `lower > upper` and the axis range meaning at the given dimension is not "wraparound". See Envelope validation in class javadoc for more details.

    - #### setEnvelope

          public void setEnvelope(double... corners)

      Sets the envelope to the specified values, which must be the lower corner coordinates followed by upper corner coordinates. The number of arguments provided shall be twice this envelope dimension, and minimum shall not be greater than maximum.
      Example: (xmin, ymin, zmin, xmax, ymax, zmax)
      Parameters:
        `corners` - ordinates of the new lower corner followed by the new upper corner.

    - #### setEnvelope

          public void setEnvelope(Envelope envelope)
                           throws MismatchedDimensionException

      Sets this envelope to the same coordinate values than the specified envelope. If the given envelope has a non-null Coordinate Reference System (CRS), then the CRS of this envelope will be set to the CRS of the given envelope.
      Parameters:
        `envelope` - the envelope to copy coordinates from.
      Throws:
        `MismatchedDimensionException` - if the specified envelope doesn't have the expected number of dimensions.

    - #### setToInfinite

          public void setToInfinite()

      Sets the lower corner to negative infinity and the upper corner to positive infinity. The coordinate reference system (if any) stay unchanged.

    - #### setToNaN

          public void setToNaN()

      Sets all ordinate values to NaN. The coordinate reference system (if any) stay unchanged.
      See Also:
        `isAllNaN()`

    - #### translate

          public void translate(double... vector)

      Translates the envelope by the given vector. For every dimension i, the lower and upper values are increased by `vector[i]`.

      This method does not check if the translation result is inside the coordinate system domain (e.g. [-180 … +180]° of longitude). Callers can normalize the envelope when desired by call to the `normalize()` method.

      Parameters:
        `vector` - the translation vector. The length of this array shall be equal to this envelope dimension.
      Since:
        0.5

    - #### add

          public void add(DirectPosition position)
                   throws MismatchedDimensionException

      Adds a point to this envelope. The resulting envelope is the smallest envelope that contains both the original envelope and the specified point.

      After adding a point, a call to `contains(DirectPosition)` with the added point as an argument will return `true`, except if one of the point ordinates was `Double​.NaN` in which case the corresponding ordinate has been ignored.

      Pre-conditions
      This method assumes that the specified point uses the same CRS than this envelope. For performance reasons, it will no be verified unless Java assertions are enabled.
      Spanning the anti-meridian of a Geographic CRS
      This method supports envelopes spanning the anti-meridian. In such cases it is possible to move both envelope borders in order to encompass the given point, as illustrated below (the new point is represented by the `+` symbol):

          ─────┐   + ┌─────
          ─────┘     └─────

      The default implementation moves only the border which is closest to the given point.
      Parameters:
        `position` - the point to add.
      Throws:
        `MismatchedDimensionException` - if the given point does not have the expected number of dimensions.
        `AssertionError` - if assertions are enabled and the envelopes have mismatched CRS.

    - #### add

          public void add(Envelope envelope)
                   throws MismatchedDimensionException

      Adds an envelope object to this envelope. The resulting envelope is the union of the two `Envelope` objects.
      Pre-conditions
      This method assumes that the specified envelope uses the same CRS than this envelope. For performance reasons, it will no be verified unless Java assertions are enabled.
      Spanning the anti-meridian of a Geographic CRS
      This method supports envelopes spanning the anti-meridian. If one or both envelopes span the anti-meridian, then the result of the `add` operation may be an envelope expanding to infinities. In such case, the ordinate range will be either [−∞…∞] or [0…−0] depending on whatever the original range span the anti-meridian or not.
      Parameters:
        `envelope` - the `Envelope` to add to this envelope.
      Throws:
        `MismatchedDimensionException` - if the given envelope does not have the expected number of dimensions.
        `AssertionError` - if assertions are enabled and the envelopes have mismatched CRS.
      See Also:
        `DefaultGeographicBoundingBox​.add(GeographicBoundingBox)`

    - #### intersect

          public void intersect(Envelope envelope)
                         throws MismatchedDimensionException

      Sets this envelope to the intersection if this envelope with the specified one.
      Pre-conditions
      This method assumes that the specified envelope uses the same CRS than this envelope. For performance reasons, it will no be verified unless Java assertions are enabled.
      Spanning the anti-meridian of a Geographic CRS
      This method supports envelopes spanning the anti-meridian.
      Parameters:
        `envelope` - the `Envelope` to intersect to this envelope.
      Throws:
        `MismatchedDimensionException` - if the given envelope does not have the expected number of dimensions.
        `AssertionError` - if assertions are enabled and the envelopes have mismatched CRS.
      See Also:
        `DefaultGeographicBoundingBox​.intersect(GeographicBoundingBox)`

    - #### normalize

          public boolean normalize()

      Ensures that the envelope is contained in the coordinate system domain. For each dimension, this method compares the ordinate values against the limits of the coordinate system axis for that dimension. If some ordinates are out of range, then there is a choice depending on the axis range meaning:
      - If `RangeMeaning​.EXACT` (typically latitudes ordinates), then values greater than the axis maximal value are replaced by the axis maximum, and values smaller than the axis minimal value are replaced by the axis minimum.
      - If `RangeMeaning​.WRAPAROUND` (typically longitudes ordinates), then a multiple of the axis range (e.g. 360° for longitudes) is added or subtracted. Example:
        - the [190 … 200]° longitude range is converted to [-170 … -160]°,
        - the [170 … 200]° longitude range is converted to [+170 … -160]°.
        See Spanning the anti-meridian of a Geographic CRS in the class javadoc for more information about the meaning of such range.
      Spanning the anti-meridian of a Geographic CRS
      If the envelope is spanning the anti-meridian, then some lower ordinate values may become greater than their upper counterpart as a result of this method call. If such effect is undesirable, then this method may be combined with `simplify()` as below:

          if (envelope.normalize()) {
              envelope.simplify();
          }

      Choosing the range of longitude values
      Geographic CRS typically have longitude values in the [-180 … +180]° range, but the [0 … 360]° range is also occasionally used. Callers need to ensure that this envelope CRS is associated to axes having the desired minimum and maximum value.
      Usage
      This method is sometime useful before to compute the union or intersection of envelopes, in order to ensure that both envelopes are defined in the same domain. This method may also be invoked before to project an envelope, since some projections produce `Double​.NaN` numbers when given an ordinate value out of bounds.
      Returns:
        `true` if this envelope has been modified as a result of this method call, or `false` if no change has been done.
      See Also:
        `AbstractDirectPosition​.normalize()`

    - #### simplify

          public boolean simplify()
                           throws IllegalStateException

      Ensures that lower <= upper for every dimensions. If a upper ordinate value is less than a lower ordinate value, then there is a choice:
      - If the axis has `RangeMeaning​.WRAPAROUND`, then:
        - the lower ordinate value is set to the axis minimum value, and
        - the upper ordinate value is set to the axis maximum value.
      - Otherwise an `IllegalStateException` is thrown.
      This method is useful when the envelope needs to be used with libraries that do not support envelopes spanning the anti-meridian.
      Returns:
        `true` if this envelope has been modified as a result of this method call, or `false` if no change has been done.
      Throws:
        `IllegalStateException` - if a upper ordinate value is less than a lower ordinate value on an axis which does not have the `WRAPAROUND` range meaning.
      See Also:
        `AbstractEnvelope​.toSimpleEnvelopes()`

    - #### subEnvelope

          public GeneralEnvelope subEnvelope(int beginIndex,
                                             int endIndex)
                                      throws IndexOutOfBoundsException

      Returns a view over this envelope that encompass only some dimensions. The returned object is "live": changes applied on the original envelope is reflected in the sub-envelope view, and conversely.

      This method is useful for querying and updating only some dimensions. For example in order to expand only the horizontal component of a four dimensional (x,y,z,t) envelope, one can use:

          envelope.subEnvelope(0, 2).add(myPosition2D);

      If the sub-envelope needs to be independent from the original envelope, use the following idiom:

          GeneralEnvelope copy = envelope.subEnvelope(0, 2).clone();

      The sub-envelope is initialized with a `null` CRS. This method does not compute a sub-CRS because it may not be needed, or the sub-CRS may be already known by the caller.
      Parameters:
        `beginIndex` - the index of the first valid ordinate value of the corners.
        `endIndex` - the index after the last valid ordinate value of the corners.
      Returns:
        the sub-envelope of dimension `endIndex - beginIndex`.
      Throws:
        `IndexOutOfBoundsException` - if an index is out of bounds.
      See Also:
        `CRS​.getComponentAt(CoordinateReferenceSystem, int, int)`

    - #### clone

          public GeneralEnvelope clone()

      Returns a deep copy of this envelope.
      Overrides:
        `clone` in class `Object`
      Returns:
        a clone of this envelope.

    - #### getDimension

          public int getDimension()

      Returns the length of coordinate sequence (the number of entries) in this envelope. This information is available even when the coordinate reference system is unknown.
      Specified by:
        `getDimension` in interface `Envelope`
      Returns:
        the dimensionality of this envelope.

    - #### getCoordinateReferenceSystem

          public CoordinateReferenceSystem getCoordinateReferenceSystem()

      Returns the envelope coordinate reference system, or `null` if unknown. If non-null, it shall be the same as lower corner and upper corner CRS.
      Specified by:
        `getCoordinateReferenceSystem` in interface `Envelope`
      Returns:
        the envelope CRS, or `null` if unknown.

    - #### getLower

          public double getLower(int dimension)
                          throws IndexOutOfBoundsException

      Returns the limit in the direction of decreasing ordinate values in the specified dimension. This is usually the algebraic minimum, except if this envelope spans the anti-meridian.
      Specified by:
        `getLower` in class `AbstractEnvelope`
      Parameters:
        `dimension` - the dimension for which to obtain the ordinate value.
      Returns:
        the starting ordinate value at the given dimension.
      Throws:
        `IndexOutOfBoundsException` - if the given index is negative or is equals or greater than the envelope dimension.

    - #### getUpper

          public double getUpper(int dimension)
                          throws IndexOutOfBoundsException

      Returns the limit in the direction of increasing ordinate values in the specified dimension. This is usually the algebraic maximum, except if this envelope spans the anti-meridian.
      Specified by:
        `getUpper` in class `AbstractEnvelope`
      Parameters:
        `dimension` - the dimension for which to obtain the ordinate value.
      Returns:
        the starting ordinate value at the given dimension.
      Throws:
        `IndexOutOfBoundsException` - if the given index is negative or is equals or greater than the envelope dimension.

    - #### getMinimum

          public double getMinimum(int dimension)
                            throws IndexOutOfBoundsException

      Returns the minimal ordinate value for the specified dimension. In the typical case of non-empty envelopes not spanning the anti-meridian, this method returns the `AbstractEnvelope​.getLower(int)` value verbatim. In the case of envelope spanning the anti-meridian, this method returns the axis minimum value. If the range in the given dimension is invalid, then this method returns `NaN`.
      Specified by:
        `getMinimum` in interface `Envelope`
      Overrides:
        `getMinimum` in class `AbstractEnvelope`
      Parameters:
        `dimension` - the dimension for which to obtain the ordinate value.
      Returns:
        the minimal ordinate value at the given dimension.
      Throws:
        `IndexOutOfBoundsException` - if the given index is negative or is equals or greater than the envelope dimension.

    - #### getMaximum

          public double getMaximum(int dimension)
                            throws IndexOutOfBoundsException

      Returns the maximal ordinate value for the specified dimension. In the typical case of non-empty envelopes not spanning the anti-meridian, this method returns the `AbstractEnvelope​.getUpper(int)` value verbatim. In the case of envelope spanning the anti-meridian, this method returns the axis maximum value. If the range in the given dimension is invalid, then this method returns `NaN`.
      Specified by:
        `getMaximum` in interface `Envelope`
      Overrides:
        `getMaximum` in class `AbstractEnvelope`
      Parameters:
        `dimension` - the dimension for which to obtain the ordinate value.
      Returns:
        the maximal ordinate value at the given dimension.
      Throws:
        `IndexOutOfBoundsException` - if the given index is negative or is equals or greater than the envelope dimension.

    - #### getMedian

          public double getMedian(int dimension)
                           throws IndexOutOfBoundsException

      Returns the median ordinate along the specified dimension. In most cases, the result is equals (minus rounding error) to:

          median = (getUpper(dimension) + getLower(dimension)) / 2;

      Spanning the anti-meridian of a Geographic CRS
      If upper < lower and the range meaning for the requested dimension is wraparound, then the median calculated above is actually in the middle of the space outside the envelope. In such cases, this method shifts the median value by half of the periodicity (180° in the longitude case) in order to switch from outer space to inner space. If the axis range meaning is not `WRAPAROUND`, then this method returns `NaN`.
      Specified by:
        `getMedian` in interface `Envelope`
      Overrides:
        `getMedian` in class `AbstractEnvelope`
      Parameters:
        `dimension` - the dimension for which to obtain the ordinate value.
      Returns:
        the median ordinate at the given dimension, or `Double​.NaN`.
      Throws:
        `IndexOutOfBoundsException` - if the given index is negative or is equals or greater than the envelope dimension.

    - #### getSpan

          public double getSpan(int dimension)
                         throws IndexOutOfBoundsException

      Returns the envelope span (typically width or height) along the specified dimension. In most cases, the result is equals (minus rounding error) to:

          span = getUpper(dimension) - getLower(dimension);

      Spanning the anti-meridian of a Geographic CRS
      If upper < lower and the range meaning for the requested dimension is wraparound, then the span calculated above is negative. In such cases, this method adds the periodicity (typically 360° of longitude) to the span. If the result is a positive number, it is returned. Otherwise this method returns `NaN`.
      Specified by:
        `getSpan` in interface `Envelope`
      Overrides:
        `getSpan` in class `AbstractEnvelope`
      Parameters:
        `dimension` - the dimension for which to obtain the span.
      Returns:
        the span (typically width or height) at the given dimension, or `Double​.NaN`.
      Throws:
        `IndexOutOfBoundsException` - if the given index is negative or is equals or greater than the envelope dimension.

    - #### isEmpty

          public boolean isEmpty()

      Determines whether or not this envelope is empty. An envelope is empty if it has zero dimension, or if the span of at least one axis is negative, 0 or `NaN`.
      Note: Strictly speaking, there is an ambiguity if a span is `NaN` or if the envelope contains both 0 and infinite spans (since 0⋅∞ = `NaN`). In such cases, this method arbitrarily ignores the infinite values and returns `true`.
      If `isEmpty()` returns `false`, then `AbstractEnvelope​.isAllNaN()` is guaranteed to also return `false`. However the converse is not always true.
      Specified by:
        `isEmpty` in interface `Emptiable`
      Overrides:
        `isEmpty` in class `AbstractEnvelope`
      Returns:
        `true` if this envelope is empty.
      See Also:
        `DefaultGeographicBoundingBox​.isEmpty()`, `RectangularShape​.isEmpty()`

    - #### isAllNaN

          public boolean isAllNaN()

      Returns `false` if at least one ordinate value is not NaN. This `isAllNaN()` check is different than the `AbstractEnvelope​.isEmpty()` check since it returns `false` for a partially initialized envelope, while `isEmpty()` returns `false` only after all dimensions have been initialized. More specifically, the following rules apply:
      - If `isAllNaN() == true`, then `isEmpty() == true`
      - If `isEmpty() == false`, then `isAllNaN() == false`
      - The converse of the above-cited rules are not always true.
      Note that an all-NaN envelope can still have a non-null coordinate reference system.
      Overrides:
        `isAllNaN` in class `AbstractEnvelope`
      Returns:
        `true` if this envelope has NaN values.
      See Also:
        `setToNaN()`, `DefaultGeographicBoundingBox​.isEmpty()`

    - #### hashCode

          public int hashCode()

      Returns a hash value for this envelope.
      Overrides:
        `hashCode` in class `AbstractEnvelope`

    - #### equals

          public boolean equals(Object object)

      Returns `true` if the specified object is an envelope of the same class with equals coordinates and CRS.
      Implementation note: This implementation requires that the provided `object` argument is of the same class than this envelope. We do not relax this rule since not every implementations in the SIS code base follow the same contract.
      Overrides:
        `equals` in class `AbstractEnvelope`
      Parameters:
        `object` - the object to compare with this envelope.
      Returns:
        `true` if the given object is equal to this envelope.

    - #### toString

          public String toString()

      Formats this envelope as a "`BOX`" element. The output is of the form "`BOX` n `D(`lower corner`,`upper corner`)`" where n is the number of dimensions. The number of dimension is written only if different than 2.
      Example:
      - `BOX(-90 -180, 90 180)`
      - `BOX3D(-90 -180 0, 90 180 1)`
      Note: The `BOX` element is not part of the standard Well Known Text (WKT) format. However it is understood by many software libraries, for example GDAL and PostGIS.
      The string returned by this method can be parsed by the `GeneralEnvelope` constructor.
      Overrides:
        `toString` in class `AbstractEnvelope`
      Returns:
        this envelope as a `BOX` or `BOX3D` (most typical dimensions) element.

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