cheap-ruler
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A collection of fast approximations to common geographic measurements.
217 lines (216 loc) • 8.59 kB
TypeScript
/**
* A collection of very fast approximations to common geodesic measurements. Useful for performance-sensitive code that measures things on a city scale.
*/
export default class CheapRuler {
/**
* Creates a ruler object from tile coordinates (y and z).
*
* @param {number} y
* @param {number} z
* @param {keyof typeof factors} [units='kilometers']
* @returns {CheapRuler}
* @example
* const ruler = cheapRuler.fromTile(1567, 12);
* //=ruler
*/
static fromTile(y: number, z: number, units?: "kilometers" | "miles" | "nauticalmiles" | "meters" | "metres" | "yards" | "feet" | "inches" | undefined): CheapRuler;
/**
* Multipliers for converting between units.
*
* @example
* // convert 50 meters to yards
* 50 * CheapRuler.units.yards / CheapRuler.units.meters;
*/
static get units(): {
kilometers: number;
miles: number;
nauticalmiles: number;
meters: number;
metres: number;
yards: number;
feet: number;
inches: number;
};
/**
* Creates a ruler instance for very fast approximations to common geodesic measurements around a certain latitude.
*
* @param {number} lat latitude
* @param {keyof typeof factors} [units='kilometers']
* @example
* const ruler = cheapRuler(35.05, 'miles');
* //=ruler
*/
constructor(lat: number, units?: "kilometers" | "miles" | "nauticalmiles" | "meters" | "metres" | "yards" | "feet" | "inches" | undefined);
kx: number;
ky: number;
/**
* Given two points of the form [longitude, latitude], returns the distance.
*
* @param {[number, number]} a point [longitude, latitude]
* @param {[number, number]} b point [longitude, latitude]
* @returns {number} distance
* @example
* const distance = ruler.distance([30.5, 50.5], [30.51, 50.49]);
* //=distance
*/
distance(a: [number, number], b: [number, number]): number;
/**
* Returns the bearing between two points in angles.
*
* @param {[number, number]} a point [longitude, latitude]
* @param {[number, number]} b point [longitude, latitude]
* @returns {number} bearing
* @example
* const bearing = ruler.bearing([30.5, 50.5], [30.51, 50.49]);
* //=bearing
*/
bearing(a: [number, number], b: [number, number]): number;
/**
* Returns a new point given distance and bearing from the starting point.
*
* @param {[number, number]} p point [longitude, latitude]
* @param {number} dist distance
* @param {number} bearing
* @returns {[number, number]} point [longitude, latitude]
* @example
* const point = ruler.destination([30.5, 50.5], 0.1, 90);
* //=point
*/
destination(p: [number, number], dist: number, bearing: number): [number, number];
/**
* Returns a new point given easting and northing offsets (in ruler units) from the starting point.
*
* @param {[number, number]} p point [longitude, latitude]
* @param {number} dx easting
* @param {number} dy northing
* @returns {[number, number]} point [longitude, latitude]
* @example
* const point = ruler.offset([30.5, 50.5], 10, 10);
* //=point
*/
offset(p: [number, number], dx: number, dy: number): [number, number];
/**
* Given a line (an array of points), returns the total line distance.
*
* @param {[number, number][]} points [longitude, latitude]
* @returns {number} total line distance
* @example
* const length = ruler.lineDistance([
* [-67.031, 50.458], [-67.031, 50.534],
* [-66.929, 50.534], [-66.929, 50.458]
* ]);
* //=length
*/
lineDistance(points: [number, number][]): number;
/**
* Given a polygon (an array of rings, where each ring is an array of points), returns the area.
*
* @param {[number, number][][]} polygon
* @returns {number} area value in the specified units (square kilometers by default)
* @example
* const area = ruler.area([[
* [-67.031, 50.458], [-67.031, 50.534], [-66.929, 50.534],
* [-66.929, 50.458], [-67.031, 50.458]
* ]]);
* //=area
*/
area(polygon: [number, number][][]): number;
/**
* Returns the point at a specified distance along the line.
*
* @param {[number, number][]} line
* @param {number} dist distance
* @returns {[number, number]} point [longitude, latitude]
* @example
* const point = ruler.along(line, 2.5);
* //=point
*/
along(line: [number, number][], dist: number): [number, number];
/**
* Returns the distance from a point `p` to a line segment `a` to `b`.
*
* @pointToSegmentDistance
* @param {[number, number]} p point [longitude, latitude]
* @param {[number, number]} a segment point 1 [longitude, latitude]
* @param {[number, number]} b segment point 2 [longitude, latitude]
* @returns {number} distance
* @example
* const distance = ruler.pointToSegmentDistance([-67.04, 50.5], [-67.05, 50.57], [-67.03, 50.54]);
* //=distance
*/
pointToSegmentDistance(p: [number, number], a: [number, number], b: [number, number]): number;
/**
* Returns an object of the form {point, index, t}, where point is closest point on the line
* from the given point, index is the start index of the segment with the closest point,
* and t is a parameter from 0 to 1 that indicates where the closest point is on that segment.
*
* @param {[number, number][]} line
* @param {[number, number]} p point [longitude, latitude]
* @returns {{point: [number, number], index: number, t: number}} {point, index, t}
* @example
* const point = ruler.pointOnLine(line, [-67.04, 50.5]).point;
* //=point
*/
pointOnLine(line: [number, number][], p: [number, number]): {
point: [number, number];
index: number;
t: number;
};
/**
* Returns a part of the given line between the start and the stop points (or their closest points on the line).
*
* @param {[number, number]} start point [longitude, latitude]
* @param {[number, number]} stop point [longitude, latitude]
* @param {[number, number][]} line
* @returns {[number, number][]} line part of a line
* @example
* const line2 = ruler.lineSlice([-67.04, 50.5], [-67.05, 50.56], line1);
* //=line2
*/
lineSlice(start: [number, number], stop: [number, number], line: [number, number][]): [number, number][];
/**
* Returns a part of the given line between the start and the stop points indicated by distance along the line.
*
* @param {number} start start distance
* @param {number} stop stop distance
* @param {[number, number][]} line
* @returns {[number, number][]} part of a line
* @example
* const line2 = ruler.lineSliceAlong(10, 20, line1);
* //=line2
*/
lineSliceAlong(start: number, stop: number, line: [number, number][]): [number, number][];
/**
* Given a point, returns a bounding box object ([w, s, e, n]) created from the given point buffered by a given distance.
*
* @param {[number, number]} p point [longitude, latitude]
* @param {number} buffer
* @returns {[number, number, number, number]} bbox ([w, s, e, n])
* @example
* const bbox = ruler.bufferPoint([30.5, 50.5], 0.01);
* //=bbox
*/
bufferPoint(p: [number, number], buffer: number): [number, number, number, number];
/**
* Given a bounding box, returns the box buffered by a given distance.
*
* @param {[number, number, number, number]} bbox ([w, s, e, n])
* @param {number} buffer
* @returns {[number, number, number, number]} bbox ([w, s, e, n])
* @example
* const bbox = ruler.bufferBBox([30.5, 50.5, 31, 51], 0.2);
* //=bbox
*/
bufferBBox(bbox: [number, number, number, number], buffer: number): [number, number, number, number];
/**
* Returns true if the given point is inside in the given bounding box, otherwise false.
*
* @param {[number, number]} p point [longitude, latitude]
* @param {[number, number, number, number]} bbox ([w, s, e, n])
* @returns {boolean}
* @example
* const inside = ruler.insideBBox([30.5, 50.5], [30, 50, 31, 51]);
* //=inside
*/
insideBBox(p: [number, number], bbox: [number, number, number, number]): boolean;
}