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Polyline.js
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Polyline.js
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/**
* @module ol/format/Polyline
*/
import Feature from '../Feature.js';
import LineString from '../geom/LineString.js';
import TextFeature from './TextFeature.js';
import {flipXY} from '../geom/flat/flip.js';
import {get as getProjection} from '../proj.js';
import {getStrideForLayout} from '../geom/SimpleGeometry.js';
import {inflateCoordinates} from '../geom/flat/inflate.js';
import {transformGeometryWithOptions} from './Feature.js';
/**
* @typedef {Object} Options
* @property {number} [factor=1e5] The factor by which the coordinates values will be scaled.
* @property {import("../geom/Geometry.js").GeometryLayout} [geometryLayout='XY'] Layout of the
* feature geometries created by the format reader.
*/
/**
* @classdesc
* Feature format for reading and writing data in the Encoded
* Polyline Algorithm Format.
*
* When reading features, the coordinates are assumed to be in two dimensions
* and in [latitude, longitude] order.
*
* As Polyline sources contain a single feature,
* {@link module:ol/format/Polyline~Polyline#readFeatures} will return the
* feature in an array.
*
* @api
*/
class Polyline extends TextFeature {
/**
* @param {Options} [options] Optional configuration object.
*/
constructor(options) {
super();
options = options ? options : {};
/**
* @type {import("../proj/Projection.js").default}
*/
this.dataProjection = getProjection('EPSG:4326');
/**
* @private
* @type {number}
*/
this.factor_ = options.factor ? options.factor : 1e5;
/**
* @private
* @type {import("../geom/Geometry.js").GeometryLayout}
*/
this.geometryLayout_ = options.geometryLayout
? options.geometryLayout
: 'XY';
}
/**
* @protected
* @param {string} text Text.
* @param {import("./Feature.js").ReadOptions} [options] Read options.
* @return {import("../Feature.js").default} Feature.
*/
readFeatureFromText(text, options) {
const geometry = this.readGeometryFromText(text, options);
return new Feature(geometry);
}
/**
* @param {string} text Text.
* @param {import("./Feature.js").ReadOptions} [options] Read options.
* @protected
* @return {Array<Feature>} Features.
*/
readFeaturesFromText(text, options) {
const feature = this.readFeatureFromText(text, options);
return [feature];
}
/**
* @param {string} text Text.
* @param {import("./Feature.js").ReadOptions} [options] Read options.
* @protected
* @return {import("../geom/Geometry.js").default} Geometry.
*/
readGeometryFromText(text, options) {
const stride = getStrideForLayout(this.geometryLayout_);
const flatCoordinates = decodeDeltas(text, stride, this.factor_);
flipXY(flatCoordinates, 0, flatCoordinates.length, stride, flatCoordinates);
const coordinates = inflateCoordinates(
flatCoordinates,
0,
flatCoordinates.length,
stride,
);
const lineString = new LineString(coordinates, this.geometryLayout_);
return transformGeometryWithOptions(
lineString,
false,
this.adaptOptions(options),
);
}
/**
* @param {import("../Feature.js").default<LineString>} feature Features.
* @param {import("./Feature.js").WriteOptions} [options] Write options.
* @protected
* @return {string} Text.
*/
writeFeatureText(feature, options) {
const geometry = feature.getGeometry();
if (geometry) {
return this.writeGeometryText(geometry, options);
}
throw new Error('Expected `feature` to have a geometry');
}
/**
* @param {Array<import("../Feature.js").default<LineString>>} features Features.
* @param {import("./Feature.js").WriteOptions} [options] Write options.
* @protected
* @return {string} Text.
*/
writeFeaturesText(features, options) {
return this.writeFeatureText(features[0], options);
}
/**
* @param {LineString} geometry Geometry.
* @param {import("./Feature.js").WriteOptions} [options] Write options.
* @protected
* @return {string} Text.
*/
writeGeometryText(geometry, options) {
geometry =
/** @type {LineString} */
(
transformGeometryWithOptions(geometry, true, this.adaptOptions(options))
);
const flatCoordinates = geometry.getFlatCoordinates();
const stride = geometry.getStride();
flipXY(flatCoordinates, 0, flatCoordinates.length, stride, flatCoordinates);
return encodeDeltas(flatCoordinates, stride, this.factor_);
}
}
/**
* Encode a list of n-dimensional points and return an encoded string
*
* Attention: This function will modify the passed array!
*
* @param {Array<number>} numbers A list of n-dimensional points.
* @param {number} stride The number of dimension of the points in the list.
* @param {number} [factor] The factor by which the numbers will be
* multiplied. The remaining decimal places will get rounded away.
* Default is `1e5`.
* @return {string} The encoded string.
* @api
*/
export function encodeDeltas(numbers, stride, factor) {
factor = factor ? factor : 1e5;
let d;
const lastNumbers = new Array(stride);
for (d = 0; d < stride; ++d) {
lastNumbers[d] = 0;
}
for (let i = 0, ii = numbers.length; i < ii; ) {
for (d = 0; d < stride; ++d, ++i) {
const num = numbers[i];
const delta = num - lastNumbers[d];
lastNumbers[d] = num;
numbers[i] = delta;
}
}
return encodeFloats(numbers, factor);
}
/**
* Decode a list of n-dimensional points from an encoded string
*
* @param {string} encoded An encoded string.
* @param {number} stride The number of dimension of the points in the
* encoded string.
* @param {number} [factor] The factor by which the resulting numbers will
* be divided. Default is `1e5`.
* @return {Array<number>} A list of n-dimensional points.
* @api
*/
export function decodeDeltas(encoded, stride, factor) {
factor = factor ? factor : 1e5;
let d;
/** @type {Array<number>} */
const lastNumbers = new Array(stride);
for (d = 0; d < stride; ++d) {
lastNumbers[d] = 0;
}
const numbers = decodeFloats(encoded, factor);
for (let i = 0, ii = numbers.length; i < ii; ) {
for (d = 0; d < stride; ++d, ++i) {
lastNumbers[d] += numbers[i];
numbers[i] = lastNumbers[d];
}
}
return numbers;
}
/**
* Encode a list of floating point numbers and return an encoded string
*
* Attention: This function will modify the passed array!
*
* @param {Array<number>} numbers A list of floating point numbers.
* @param {number} [factor] The factor by which the numbers will be
* multiplied. The remaining decimal places will get rounded away.
* Default is `1e5`.
* @return {string} The encoded string.
* @api
*/
export function encodeFloats(numbers, factor) {
factor = factor ? factor : 1e5;
for (let i = 0, ii = numbers.length; i < ii; ++i) {
numbers[i] = Math.round(numbers[i] * factor);
}
return encodeSignedIntegers(numbers);
}
/**
* Decode a list of floating point numbers from an encoded string
*
* @param {string} encoded An encoded string.
* @param {number} [factor] The factor by which the result will be divided.
* Default is `1e5`.
* @return {Array<number>} A list of floating point numbers.
* @api
*/
export function decodeFloats(encoded, factor) {
factor = factor ? factor : 1e5;
const numbers = decodeSignedIntegers(encoded);
for (let i = 0, ii = numbers.length; i < ii; ++i) {
numbers[i] /= factor;
}
return numbers;
}
/**
* Encode a list of signed integers and return an encoded string
*
* Attention: This function will modify the passed array!
*
* @param {Array<number>} numbers A list of signed integers.
* @return {string} The encoded string.
*/
export function encodeSignedIntegers(numbers) {
for (let i = 0, ii = numbers.length; i < ii; ++i) {
const num = numbers[i];
numbers[i] = num < 0 ? ~(num << 1) : num << 1;
}
return encodeUnsignedIntegers(numbers);
}
/**
* Decode a list of signed integers from an encoded string
*
* @param {string} encoded An encoded string.
* @return {Array<number>} A list of signed integers.
*/
export function decodeSignedIntegers(encoded) {
const numbers = decodeUnsignedIntegers(encoded);
for (let i = 0, ii = numbers.length; i < ii; ++i) {
const num = numbers[i];
numbers[i] = num & 1 ? ~(num >> 1) : num >> 1;
}
return numbers;
}
/**
* Encode a list of unsigned integers and return an encoded string
*
* @param {Array<number>} numbers A list of unsigned integers.
* @return {string} The encoded string.
*/
export function encodeUnsignedIntegers(numbers) {
let encoded = '';
for (let i = 0, ii = numbers.length; i < ii; ++i) {
encoded += encodeUnsignedInteger(numbers[i]);
}
return encoded;
}
/**
* Decode a list of unsigned integers from an encoded string
*
* @param {string} encoded An encoded string.
* @return {Array<number>} A list of unsigned integers.
*/
export function decodeUnsignedIntegers(encoded) {
const numbers = [];
let current = 0;
let shift = 0;
for (let i = 0, ii = encoded.length; i < ii; ++i) {
const b = encoded.charCodeAt(i) - 63;
current |= (b & 0x1f) << shift;
if (b < 0x20) {
numbers.push(current);
current = 0;
shift = 0;
} else {
shift += 5;
}
}
return numbers;
}
/**
* Encode one single unsigned integer and return an encoded string
*
* @param {number} num Unsigned integer that should be encoded.
* @return {string} The encoded string.
*/
export function encodeUnsignedInteger(num) {
let value,
encoded = '';
while (num >= 0x20) {
value = (0x20 | (num & 0x1f)) + 63;
encoded += String.fromCharCode(value);
num >>= 5;
}
value = num + 63;
encoded += String.fromCharCode(value);
return encoded;
}
export default Polyline;