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GeoWKTer is a JavaScript library designed to convert Well-Known Text (WKT) representations of geometries into GeoJSON format. This tool is useful for developers and GIS specialists who need to work with geographic data across different standards.
此脚本不应直接安装，它是一个供其他脚本使用的外部库。如果您需要使用该库，请在脚本元属性加入：// @require https://update.greasyfork.org/scripts/523986/1537670/GeoWKTer.js
// ==UserScript==
// @name GeoWKTer
// @namespace https://github.com/JS55CT
// @description geoWKTer is a JavaScript library designed to convert WKT data into GeoJSON format efficiently. It supports conversion of Point, LineString, Polygon, and MultiGeometry elements.
// @version 2.1.0
// @author JS55CT
// @license MIT
// @match *://this-library-is-not-supposed-to-run.com/*
// ==/UserScript==
/***************************************
* GeoWKTer Constructor Function
* The `GeoWKTer` function serves as a constructor for creating instances that
* manage the conversion of Well-Known Text (WKT) strings into GeoJSON representations.
* It initializes regex patterns used for parsing WKT, and offers a structure to hold
* spatial features processed from those strings.
*
* MIT License
* Copyright (c) 2022 hu de yi
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
* GeoWKTer inspired by the work of Wicket.js <https://github.com/arthur-e/Wicket> (GPL-3.0 licensed)
* and terraformer <https://github.com/terraformer-js/terraformer/tree/main> (MIT licensed)
****************************************/
var GeoWKTer = (function () {
function GeoWKTer() {
this.features = []; // Initialize an array to store parsed feature data
this.regExes = {
// Regular expressions for parsing WKT strings
typeStr: /^\s*(\w+)\s*\((.*)\)\s*$/, // Capture geometry type and contents
spaces: /\s+|\+/, // Detect spaces or plus signs for splitting coordinates
comma: /\s*,\s*/, // Capture commas surrounded by optional whitespace
parenComma: /\)\s*,\s*\(/, // Split on closing parentheses followed by a comma and opening parentheses
};
}
/*****************************************
* Clean WKT String
*
* This function processes a Well-Known Text (WKT) string,
* removing unnecessary spaces and newlines within
* parenthesized coordinate lists. It ensures commas have
* consistent spacing, typically immediately following
* coordinate values. Primarily targets complex geometries
* like MULTIPOLYGON, optimizing coordinate definition
* clarity and compactness.
*
* @param {string} wkt - The WKT string to clean.
* @returns {string} - The cleaned WKT string, with optimized spacing.
*****************************************/
GeoWKTer.prototype.cleanWKTString = function (wkt) {
return wkt
.replace(/[\n\r]+/g, " ") // Replace newlines with a single space
.replace(/\s\s+/g, " ") // Replace multiple spaces with a single space
.replace(/([A-Z]+)\s*\(/g, "$1(") // Ensure no space between type and opening parenthesis
.replace(/\(\s+/g, "(") // Remove spaces after opening parentheses
.replace(/\s+\)/g, ")") // Remove spaces before closing parentheses
.replace(/,\s+/g, ",") // Remove spaces after commas
.replace(/\s+,/g, ",") // Remove spaces before commas
.trim(); // Trim leading and trailing whitespaces
};
/***************************************
* Read WKT and Convert to Internal Representation
* This function takes a Well-Known Text (WKT) string, processes it to produce
* a cleaned and standardized version, and then converts it to an internal data
* structure that represents the geometry for further processing or transformation
* to GeoJSON. This step is crucial for understanding and manipulating spatial data.
*
* @param {string} wktText - The original WKT string representing a geometry or
* collection of geometries (e.g., POINT, POLYGON).
* @param {string} label - A descriptive label or identifier associated with the
* geometry, which will be stored for use in GeoJSON properties.
* @returns {Object[]} - An array containing a single object with:
* - type: the type of geometry (e.g., POINT, POLYGON).
* - components: the coordinates or geometries depending on type.
* - label: the provided label for this geometry.
* @throws {Error} - Throws an error if the WKT is malformed or cannot be processed,
* indicating the WKT string is invalid or unsupported.
*
* Procedure:
* 1. Clean WKT String: Utilize `cleanWKTString` to standardize the WKT input,
* handling cases like whitespace normalization, and ensuring it matches expected format.
*
* 2. Convert to GeoJSON: Pass the cleaned WKT string to `wktToGeoJSON` for transformation
* into a GeoJSON-like structure. This process involves parsing the WKT syntax into
* an object with a `type` and relevant coordinates or geometries attribute.
*
* 3. Construct Internal Representation: Return the parsed structure as a new object with:
* - `type`: Captured from the GeoJSON object.
* - `components`: The coordinates (or geometries array) reflecting the parsed data.
* - `label`: Passed through for later use in properties or identifications.
*
* 4. Error Handling: Any failure in parsing triggers an exception with a descriptive message,
* alerting the user or developer to malformed or unsupported inputs.
****************************************/
GeoWKTer.prototype.read = function (wktText, label) {
try {
// Clean and standardize the input WKT string
const cleanedWKT = this.cleanWKTString(wktText);
// Convert the cleaned WKT to a GeoJSON-like structure
const geoJSON = this.wktToGeoJSON(cleanedWKT);
// Return the internal representation with the given label
return [
{
type: geoJSON.type, // Extract the geometry type
components: geoJSON.coordinates || geoJSON.geometries, // Choose coordinates or geometries attribute based on type
label, // Add the provided label for future reference
},
];
} catch (error) {
// Handle and throw errors related to malformed or unsupported WKT
throw new Error(error.message);
}
};
/***************************************
* Convert Internal Data Array to GeoJSON
* This function takes an array of internal data objects—each representing
* parsed WKT geometries—and converts them into a valid GeoJSON object.
* Specifically, it structures these geometries into GeoJSON features within
* a FeatureCollection, appropriately handling both individual geometries
* and collections of geometries.
*
* @param {Object[]} dataArray - An array of objects where each contains:
* - type: the geometric type (e.g., POINT, POLYGON).
* - components: either the coordinates of a
* single geometry or an array of geometries.
* - label: optional description used as a property.
* @returns {Object} - GeoJSON object formatted as a FeatureCollection, comprising
* individual features with their associated geometries and properties.
*
* Steps Involved:
* 1. Initialize `features`: Accumulate each processed geometry into this array
* as a GeoJSON `Feature`, maintaining a list to be included in the final
* `FeatureCollection`.
*
* 2. Iterate Over Data Array: For each geometry object from the parsed internal
* data:
*
* - **Geometry Collections**:
* - Identify the `GEOMETRYCOLLECTION` type and ensure `components` is an array.
* - Iterate through each geometry in the collection, converting each into
* a GeoJSON `Feature` by specifying its type and coordinates, and pushing
* it to the `features` list.
*
* - **Other Geometries**:
* - Construct a GeoJSON `Feature` using the individual geometry's `type` and
* `coordinates` directly.
* - Append each to `features`, ensuring they include property details.
*
* 3. Construct FeatureCollection: Wrap the accumulated features array into a
* GeoJSON formatted object by designating it as a `FeatureCollection`.
*
* WARNING: The input WKT geometries do not include spatial reference system (SRS) information.
* This function purely reformats the WKT to GeoJSON without assuming or verifying any particular
* coordinate reference system. If the input geometries are not in the standard EPSG:4326 (WGS 84),
* the resulting GeoJSON will also lack standard CRS information, which may lead to incorrect spatial
* data representation or interpretation.
* Users should ensure that the input data is in the intended coordinate system for their applications.
****************************************/
GeoWKTer.prototype.toGeoJSON = function (dataArray) {
// Reduce the internal data array into a GeoJSON features array
const features = dataArray.reduce((accum, data) => {
const { type, components, label } = data; // Destructure for ease of use
if (type === "GEOMETRYCOLLECTION" && Array.isArray(components)) {
// If it's a geometry collection, iterate over its components
components.forEach((geometry) => {
accum.push({
// Push each as a Feature to the GeoJSON features list
type: "Feature",
geometry: {
// Define the geometry object for GeoJSON
type: geometry.type,
coordinates: geometry.coordinates,
},
properties: {
// Attach properties, including label if provided
Name: label || "",
},
});
});
} else {
// Handle non-collection geometries directly as a single GeoJSON feature
accum.push({
type: "Feature",
geometry: {
// Assign geometry details
type: type,
coordinates: components,
},
properties: {
Name: label || "", // Include label as a property if available
},
});
}
return accum; // Return the accumulator for the next iteration
}, []);
// Return the complete GeoJSON FeatureCollection
return {
type: "FeatureCollection",
features: features, // Embed the compiled features
};
};
/***************************************
* Convert WKT to GeoJSON
* @param {string} wkt - The WKT string.
* @returns {Object} - GeoJSON object.
* @throws {Error} - Throws if WKT is unsupported or invalid.
****************************************/
GeoWKTer.prototype.wktToGeoJSON = function (wkt) {
const match = this.regExes.typeStr.exec(wkt);
if (!match) throw new Error("Invalid WKT");
const type = match[1].toUpperCase();
const data = match[2];
const parsers = {
POINT: this.parsePoint,
LINESTRING: this.parseLineString,
POLYGON: this.parsePolygon,
MULTIPOINT: this.parseMultiPoint,
MULTILINESTRING: this.parseMultiLineString,
MULTIPOLYGON: this.parseMultiPolygon,
GEOMETRYCOLLECTION: this.parseGeometryCollection,
};
if (!parsers[type]) {
throw new Error(`Unsupported WKT type: ${type}`);
}
const result = parsers[type].call(this, data);
if (type === "GEOMETRYCOLLECTION") {
return { type, geometries: result };
}
return { type, coordinates: result };
};
/***************************************
* Parse Point Geometry
* @param {string} str - The WKT coordinates string.
* @returns {number[]} - Array of numbers representing the point.
****************************************/
GeoWKTer.prototype.parsePoint = function (str) {
return str.trim().split(" ").map(Number);
};
/***************************************
* Parse LineString Geometry
* @param {string} str - The WKT coordinates string.
* @returns {number[][]} - Array of arrays representing the linestring.
****************************************/
GeoWKTer.prototype.parseLineString = function (str) {
return str.split(",").map((pair) => {
return pair.trim().split(" ").map(Number);
});
};
/***************************************
* Parse Polygon Geometry
* @param {string} str - The WKT coordinates string.
* @returns {number[][][]} - Array of arrays representing the polygon.
****************************************/
GeoWKTer.prototype.parsePolygon = function (str) {
return str.match(/\([^()]+\)/g).map((ring) => {
return ring
.replace(/[()]/g, "")
.split(",")
.map((pair) => {
return pair.trim().split(" ").map(Number);
});
});
};
/***************************************
* Parse MultiPoint Geometry
* @param {string} str - The WKT coordinates string.
* @returns {number[][]} - Array of points representing the multipoint.
****************************************/
GeoWKTer.prototype.parseMultiPoint = function (str) {
// If the WKT includes nested parentheses
const matchParenPoints = str.match(/\(\s*([^()]+)\s*\)/g);
if (matchParenPoints) {
return matchParenPoints.map((pointStr) => {
return this.parsePoint(pointStr.replace(/[()]/g, "").trim());
});
} else {
return str.split(",").map(this.parsePoint.bind(this));
}
};
/***************************************
* Parse MultiLineString Geometry
* @param {string} str - The WKT coordinates string.
* @returns {number[][][]} - Array of linestrings representing the multilinestring.
****************************************/
GeoWKTer.prototype.parseMultiLineString = function (str) {
return str.match(/\(([^()]+)\)/g).map((linestring) => {
return this.parseLineString(linestring.replace(/[()]/g, "").trim());
});
};
/***************************************
* Parse MultiPolygon Geometry
* @param {string} str - The WKT coordinates string.
* @returns {number[][][][]} - Array of polygons representing the multipolygon.
****************************************/
GeoWKTer.prototype.parseMultiPolygon = function (str) {
// Match groups of polygons within MULTIPOLYGON
const polygonMatches = str.match(/\(\([^)]+\)\)/g);
if (!polygonMatches) {
throw new Error("Invalid MULTIPOLYGON WKT format");
}
return polygonMatches.map((polygonStr) => {
// Each match represents a polygon, stripping the outer parentheses
const cleanedPolygonStr = polygonStr.slice(1, -1); // Removes the outermost two parenthesis levels
return this.parsePolygon(cleanedPolygonStr);
});
};
/***************************************
* Extract Geometries from WKT GeometryCollection
* This function scans through a WKT formatted string that represents a
* GEOMETRYCOLLECTION and identifies individual geometry components within
* it. The function splits the string into manageable parts, each corresponding
* to a distinct geometry (e.g., POINT, LINESTRING).
*
* @param {string} str - The WKT string containing the collection of geometries.
* @returns {string[]} - An array of WKT strings, each representing a
* single geometry component from the GEOMETRYCOLLECTION.
*
* Procedure:
* 1. Initialize an array `geometries` to collect extracted WKT segments.
* 2. Define `geometryTypes`, an array containing the WKT keywords for supported
* geometry types, which are POINT, LINESTRING, POLYGON, MULTIPOINT,
* MULTILINESTRING, and MULTIPOLYGON.
* 3. Utilize two variables, `depth` and `start`, to track the nesting level
* of parentheses and the start position of each geometry component.
*
* Main Loop:
* - Iterate over each character in the string.
* - Adjust `depth` to reflect the current level of parenthesis nesting,
* incrementing with '(' and decrementing with ')'.
* - Upon reaching `depth` 0, examine the current location in the string
* for potential geometry type keywords.
* - When a geometry type is detected at `depth` 0, mark the end of the
* preceding geometry segment, if any, and append it to `geometries`.
* - Set `start` to the current index, marking the beginning of the next geometry.
*
* Finalization:
* - After exiting the loop, capture any remaining geometry from `start` to
* the end of the string, appending it to the `geometries` list.
*
* This approach ensures each nested geometry in a GEOMETRYCOLLECTION is
* accurately isolated as its own distinct WKT segment, ready for parsing.
****************************************/
GeoWKTer.prototype.extractGeometries = function (str) {
const geometries = []; // Array to store each extracted geometry WKT
const geometryTypes = ["POINT", "LINESTRING", "POLYGON", "MULTIPOINT", "MULTILINESTRING", "MULTIPOLYGON"]; // Known geometry types
let depth = 0; // Tracks current depth level of parentheses
let start = 0; // Marks the start index of the current geometry segment
// Iterate over each character in the WKT string
for (let i = 0; i < str.length; i++) {
if (str[i] === "(") depth++; // Increment depth for each opening parenthesis
if (str[i] === ")") depth--; // Decrement depth for each closing parenthesis
// Check if we're at a zero depth, potentially between geometries
if (depth === 0) {
// Explore possible starts of a new geometry type
geometryTypes.forEach((type) => {
if (str.startsWith(type, i)) {
// Check if this point indicates a new geometry type
if (i > start) {
// Ensure there's a segment before this new start
const geometry = str.slice(start, i).trim(); // Extract the previous geometry segment
if (geometry) {
// Ensure it's non-empty
geometries.push(geometry); // Add to the list of extracted geometries
}
}
start = i; // Update start to the current position for the new geometry
}
});
}
}
// Process the final segment if there's any left
if (start < str.length) {
const geometry = str.slice(start).trim(); // Extract remaining geometry segment
if (geometry) {
// Ensure non-empty
geometries.push(geometry); // Add last geometry
}
}
return geometries; // Return all extracted geometry components
};
/***************************************
* Parse GeometryCollection
* This function processes a Well-Known Text (WKT) input string that represents
* a GEOMETRYCOLLECTION, and converts it into an array of geometry objects
* (not features at this stage) with identifying characteristics to be
* transformed into GeoJSON later.
*
* @param {string} str - The WKT string for the geometry collection, usually in the form
* 'GEOMETRYCOLLECTION(POINT(...), LINESTRING(...), ...)'.
* @param {string} [label] - An optional label for each geometry parsed, which may be used
* later as a name property in GeoJSON.
* @returns {Object[]} - An array of geometry objects, each containing:
* - type: the type of geometry (e.g., POINT, LINESTRING).
* - coordinates: numerical array(s) representing the geometry's
* spatial data.
*
* The following steps are performed:
* 1. Setting up parsers: Retrieve the appropriate parsing functions for each
* known geometry type, such as POINT or POLYGON, from a predefined map of
* methods.
*
* 2. Extract geometries: Invoke `extractGeometries` to decompose the WKT string
* into its respective geometry components based on delimiters and nesting,
* isolating each geometry's WKT sub-string.
*
* 3. Parse each geometry: Iterate through the extracted geometries:
* - Use regular expressions to identify the type and retrieve the coordinate details.
* - Apply the corresponding parser to transform WKT coordinates into numerical arrays.
* - Store the result as an object with `type` and `coordinates` attributes.
*
* 4. Error Handling: If a geometry type is unsupported or if parsing fails, an
* exception is raised to indicate incorrect or unsupported formatting.
*
* This function does not wrap the geometries in GeoJSON features but prepares
* the data in a way that can be easily transformed into GeoJSON format by
* following processes.
****************************************/
GeoWKTer.prototype.parseGeometryCollection = function (str, label = "") {
const components = []; // Array to hold parsed geometry objects
// Map for geometry type to the appropriate parsing function
const parsers = {
POINT: this.parsePoint,
LINESTRING: this.parseLineString,
POLYGON: this.parsePolygon,
MULTIPOINT: this.parseMultiPoint,
MULTILINESTRING: this.parseMultiLineString,
MULTIPOLYGON: this.parseMultiPolygon,
};
// Extract each geometry from the GeometryCollection WKT string
const geometries = this.extractGeometries(str);
// Process each individual WKT geometry
geometries.forEach((geometryWKT) => {
// Match the geometry type and coordinate section
const match = geometryWKT.match(/([A-Z]+)\s*\((.*)\)/i);
if (match) {
const type = match[1].toUpperCase(); // Capture geometry type
const parser = parsers[type]; // Get parser for this geometry type
if (parser) {
// Parse coordinates using the relevant parser function
const coordinates = parser.call(this, match[2].trim());
components.push({
type: type, // Store geometry type
coordinates: coordinates, // Store parsed coordinates
});
} else {
// Raise error if unsupported geometry type is encountered
throw new Error(`Unsupported geometry type: ${type}`);
}
} else {
// Raise error if WKT parsing fails
throw new Error("Failed to parse geometry WKT");
}
});
return components; // Return the array of parsed geometry objects
};
return GeoWKTer;
})();