covutils/lib/referencing.js

Utilities for creating, transforming, and handling Coverage Data objects.

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _slicedToArray = function () { function sliceIterator(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"]) _i["return"](); } finally { if (_d) throw _e; } } return _arr; } return function (arr, i) { if (Array.isArray(arr)) { return arr; } else if (Symbol.iterator in Object(arr)) { return sliceIterator(arr, i); } else { throw new TypeError("Invalid attempt to destructure non-iterable instance"); } }; }();

var _LongitudeAxisIndex;

exports.getHorizontalCRSReferenceObject = getHorizontalCRSReferenceObject;
exports.isEllipsoidalCRS = isEllipsoidalCRS;
exports.getProjection = getProjection;
exports.reproject = reproject;
exports.getLongitudeWrapper = getLongitudeWrapper;
exports.isLongitudeAxis = isLongitudeAxis;
exports.isISODateAxis = isISODateAxis;
exports.asTime = asTime;

var _constants = require('./constants.js');

function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) { arr2[i] = arr[i]; } return arr2; } else { return Array.from(arr); } }

function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }

var OPENGIS_CRS_PREFIX = 'http://www.opengis.net/def/crs/';

/** 3D WGS84 in lat-lon-height order */
var EPSG4979 = OPENGIS_CRS_PREFIX + 'EPSG/0/4979';

/** 2D WGS84 in lat-lon order */
var EPSG4326 = OPENGIS_CRS_PREFIX + 'EPSG/0/4326';

/** 2D WGS84 in lon-lat order */
var CRS84 = OPENGIS_CRS_PREFIX + 'OGC/1.3/CRS84';

/** CRSs in which position is specified by geodetic latitude and longitude */
var EllipsoidalCRSs = [EPSG4979, EPSG4326, CRS84];

/** Position of longitude axis */
var LongitudeAxisIndex = (_LongitudeAxisIndex = {}, _defineProperty(_LongitudeAxisIndex, EPSG4979, 1), _defineProperty(_LongitudeAxisIndex, EPSG4326, 1), _defineProperty(_LongitudeAxisIndex, CRS84, 0), _LongitudeAxisIndex);

/**
 * Return the reference system connection object for the given domain component,
 * or undefined if none exists.
 */
function getReferenceObject(domain, component) {
  var ref = domain.referencing.find(function (ref) {
    return ref.components.indexOf(component) !== -1;
  });
  return ref;
}

/**
 * Return the reference system connection object of the horizontal CRS of the domain,
 * or ``undefined`` if none found.
 * A horizontal CRS is either geodetic (typically ellipsoidal, meaning lat/lon)
 * or projected and has exactly two axes.
 */
function getHorizontalCRSReferenceObject(domain) {
  var isHorizontal = function isHorizontal(ref) {
    return ['GeodeticCRS', 'ProjectedCRS'].indexOf(ref.system.type) !== -1 && ref.components.length === 2;
  };
  var ref = domain.referencing.find(isHorizontal);
  return ref;
}

/**
 * Return whether the reference system is a CRS in which
 * horizontal position is specified by geodetic latitude and longitude.
 */
function isEllipsoidalCRS(rs) {
  // TODO should support unknown CRSs with embedded axis information
  // this also covers the case when there is no ID property
  return EllipsoidalCRSs.indexOf(rs.id) !== -1;
}

/**
 * Return a projection object based on the CRS found in the coverage domain.
 * If no CRS is found or it is unsupported, then ``undefined`` is returned.
 * 
 * A projection converts between geodetic lat/lon and projected x/y values.
 * 
 * For lat/lon CRSs the projection is defined such that an input lat/lon
 * position gets projected/wrapped to the longitude range used in the domain, for example
 * [0,360]. The purpose of this is to make intercomparison between different coverages easier.
 * 
 * The following limitations currently apply:
 * - only ellipsoidal CRSs are supported (lat/lon)
 * - only primitive axes and Tuple/Polygon composite axes are supported 
 * 
 * @param {Domain} domain A coverage domain object.
 * @return {IProjection} A stripped-down leaflet IProjection object.
 */
function getProjection(domain) {
  var ref = domain.referencing.find(function (ref) {
    return isEllipsoidalCRS(ref.system);
  });
  if (!ref) {
    // either no CRS found or not ellipsoidal
    return;
  }

  var lonIdx = LongitudeAxisIndex[ref.system.id];
  if (lonIdx > 1) {
    // this should never happen as longitude is always the first or second axis
    throw new Error();
  }

  var lonComponent = ref.components[lonIdx];

  // we find the min and max longitude occuring in the domain by inspecting the axis values
  // Note: this is inefficient for big composite axes.
  //       In that case, something like a domain extent might help which has the min/max values for each component.
  // TODO handle bounds
  var lonMin = void 0,
      lonMax = void 0;
  if (domain.axes.has(lonComponent)) {
    // longitude is a grid axis
    var lonAxisName = lonComponent;
    var lonAxisVals = domain.axes.get(lonAxisName).values;
    lonMin = lonAxisVals[0];
    lonMax = lonAxisVals[lonAxisVals.length - 1];
    if (lonMin > lonMax) {
      var _ref = [lonMax, lonMin];
      lonMin = _ref[0];
      lonMax = _ref[1];
    }
  } else {
    // TODO there should be no dependency to CovJSON

    // longitude is not a primitive grid axis but a component of a composite axis

    // find the composite axis containing the longitude component
    var axes = [].concat(_toConsumableArray(domain.axes.values()));
    var axis = axes.find(function (axis) {
      return axis.components.indexOf(lonComponent) !== -1;
    });
    var lonCompIdx = axis.components.indexOf(lonComponent);

    // scan the composite axis for min/max longitude values
    lonMin = Infinity;
    lonMax = -Infinity;
    if (axis.dataType === _constants.COVJSON_DATATYPE_TUPLE) {
      var _iteratorNormalCompletion = true;
      var _didIteratorError = false;
      var _iteratorError = undefined;

      try {
        for (var _iterator = axis.values[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
          var tuple = _step.value;

          var lon = tuple[lonCompIdx];
          lonMin = Math.min(lon, lonMin);
          lonMax = Math.max(lon, lonMax);
        }
      } catch (err) {
        _didIteratorError = true;
        _iteratorError = err;
      } finally {
        try {
          if (!_iteratorNormalCompletion && _iterator.return) {
            _iterator.return();
          }
        } finally {
          if (_didIteratorError) {
            throw _iteratorError;
          }
        }
      }
    } else if (axis.dataType === _constants.COVJSON_DATATYPE_POLYGON) {
      var _iteratorNormalCompletion2 = true;
      var _didIteratorError2 = false;
      var _iteratorError2 = undefined;

      try {
        for (var _iterator2 = axis.values[Symbol.iterator](), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
          var poly = _step2.value;
          var _iteratorNormalCompletion3 = true;
          var _didIteratorError3 = false;
          var _iteratorError3 = undefined;

          try {
            for (var _iterator3 = poly[Symbol.iterator](), _step3; !(_iteratorNormalCompletion3 = (_step3 = _iterator3.next()).done); _iteratorNormalCompletion3 = true) {
              var ring = _step3.value;
              var _iteratorNormalCompletion4 = true;
              var _didIteratorError4 = false;
              var _iteratorError4 = undefined;

              try {
                for (var _iterator4 = ring[Symbol.iterator](), _step4; !(_iteratorNormalCompletion4 = (_step4 = _iterator4.next()).done); _iteratorNormalCompletion4 = true) {
                  var point = _step4.value;

                  var _lon = point[lonCompIdx];
                  lonMin = Math.min(_lon, lonMin);
                  lonMax = Math.max(_lon, lonMax);
                }
              } catch (err) {
                _didIteratorError4 = true;
                _iteratorError4 = err;
              } finally {
                try {
                  if (!_iteratorNormalCompletion4 && _iterator4.return) {
                    _iterator4.return();
                  }
                } finally {
                  if (_didIteratorError4) {
                    throw _iteratorError4;
                  }
                }
              }
            }
          } catch (err) {
            _didIteratorError3 = true;
            _iteratorError3 = err;
          } finally {
            try {
              if (!_iteratorNormalCompletion3 && _iterator3.return) {
                _iterator3.return();
              }
            } finally {
              if (_didIteratorError3) {
                throw _iteratorError3;
              }
            }
          }
        }
      } catch (err) {
        _didIteratorError2 = true;
        _iteratorError2 = err;
      } finally {
        try {
          if (!_iteratorNormalCompletion2 && _iterator2.return) {
            _iterator2.return();
          }
        } finally {
          if (_didIteratorError2) {
            throw _iteratorError2;
          }
        }
      }
    } else {
      throw new Error('Unsupported data type: ' + axis.dataType);
    }
  }

  var lonMid = (lonMax + lonMin) / 2;
  var lonMinExtended = lonMid - 180;
  var lonMaxExtended = lonMid + 180;

  return {
    project: function project(_ref2) {
      var lon = _ref2.lon;
      var lat = _ref2.lat;

      var lonProjected = void 0;
      if (lonMinExtended <= lon && lon <= lonMaxExtended) {
        // use unchanged to avoid introducing rounding errors
        lonProjected = lon;
      } else {
        lonProjected = ((lon - lonMinExtended) % 360 + 360) % 360 + lonMinExtended;
      }

      var _ref3 = lonIdx === 0 ? [lonProjected, lat] : [lat, lonProjected];

      var _ref4 = _slicedToArray(_ref3, 2);

      var x = _ref4[0];
      var y = _ref4[1];

      return { x: x, y: y };
    },
    unproject: function unproject(_ref5) {
      var x = _ref5.x;
      var y = _ref5.y;

      var _ref6 = lonIdx === 0 ? [x, y] : [y, x];

      var _ref7 = _slicedToArray(_ref6, 2);

      var lon = _ref7[0];
      var lat = _ref7[1];

      return { lon: lon, lat: lat };
    }
  };
}

/**
 * Reprojects coordinates from one projection to another.
 */
function reproject(pos, fromProjection, toProjection) {
  return toProjection.project(fromProjection.unproject(pos));
}

/**
 * Returns a function which converts an arbitrary longitude to the
 * longitude extent used in the coverage domain.
 * This only supports primitive axes since this is what subsetByValue supports.
 * The longitude extent is extended to 360 degrees if the actual extent is smaller.
 * The extension is done equally on both sides of the extent. 
 * 
 * For example, the domain may have longitudes within [0,360].
 * An input longitude of -70 is converted to 290.
 * All longitudes within [0,360] are returned unchanged.
 * 
 * If the domain has longitudes within [10,50] then the
 * extended longitude range is [-150,210] (-+180 from the middle point).
 * An input longitude of -170 is converted to 190.
 * All longitudes within [-150,210] are returned unchanged.
 * 
 * @ignore
 */
function getLongitudeWrapper(domain, axisName) {
  // TODO deprecate this in favour of getProjection, check leaflet-coverage

  // for primitive axes, the axis identifier = component identifier
  if (!isLongitudeAxis(domain, axisName)) {
    throw new Error('\'' + axisName + '\' is not a longitude axis');
  }

  var vals = domain.axes.get(axisName).values;
  var lon_min = vals[0];
  var lon_max = vals[vals.length - 1];
  if (lon_min > lon_max) {
    var _ref8 = [lon_max, lon_min];
    lon_min = _ref8[0];
    lon_max = _ref8[1];
  }

  var x_mid = (lon_max + lon_min) / 2;
  var x_min = x_mid - 180;
  var x_max = x_mid + 180;

  return function (lon) {
    if (x_min <= lon && lon <= x_max) {
      // directly return to avoid introducing rounding errors
      return lon;
    } else {
      return ((lon - x_min) % 360 + 360) % 360 + x_min;
    }
  };
}

/**
 * Return whether the given domain axis represents longitudes.
 * 
 * @ignore
 */
function isLongitudeAxis(domain, axisName) {
  var ref = getReferenceObject(domain, axisName);
  if (!ref) {
    return false;
  }

  var crsId = ref.system.id;
  // TODO should support unknown CRSs with embedded axis information
  if (EllipsoidalCRSs.indexOf(crsId) === -1) {
    // this also covers the case when there is no ID property
    return false;
  }

  var compIdx = ref.components.indexOf(axisName);
  var isLongitude = LongitudeAxisIndex[crsId] === compIdx;
  return isLongitude;
}

/**
 * Returns true if the given axis has ISO8601 date strings
 * as axis values.
 */
function isISODateAxis(domain, axisName) {
  var val = domain.axes.get(axisName).values[0];
  if (typeof val !== 'string') {
    return false;
  }
  return !isNaN(new Date(val).getTime());
}

function asTime(inp) {
  var res = void 0;
  var err = false;
  if (typeof inp === 'string') {
    res = new Date(inp).getTime();
  } else if (inp instanceof Date) {
    res = inp.getTime();
  } else {
    err = true;
  }
  if (isNaN(res)) {
    err = true;
  }
  if (err) {
    throw new Error('Invalid date: ' + inp);
  }
  return res;
}