How calulate the area of a polygon in react-native-maps? - react-native

Question

I am passing the array of co-ordinates to the polygon and want to find the area of the polygon through that co-ordinates. I have checked the documentation of the react-native-maps but there is no function provided.
Is there is any way to calculate the area.
Thanks in advance.

Answer 1

Library will not give you this functionality.
Try this
function calcArea(locations) {
if (!locations.length) {
return 0;
}
if (locations.length < 3) {
return 0;
}
let radius = 6371000;
const diameter = radius * 2;
const circumference = diameter * Math.PI;
const listY = [];
const listX = [];
const listArea = [];
// calculate segment x and y in degrees for each point
const latitudeRef = locations[0].latitude;
const longitudeRef = locations[0].longitude;
for (let i = 1; i < locations.length; i++) {
let latitude = locations[i].latitude;
let longitude = locations[i].longitude;
listY.push(this.calculateYSegment(latitudeRef, latitude, circumference));
listX.push(this.calculateXSegment(longitudeRef, longitude, latitude, circumference));
}
// calculate areas for each triangle segment
for (let i = 1; i < listX.length; i++) {
let x1 = listX[i - 1];
let y1 = listY[i - 1];
let x2 = listX[i];
let y2 = listY[i];
listArea.push(this.calculateAreaInSquareMeters(x1, x2, y1, y2));
}
// sum areas of all triangle segments
let areasSum = 0;
listArea.forEach(area => areasSum = areasSum + area)
// get abolute value of area, it can't be negative
let areaCalc = Math.abs(areasSum);// Math.sqrt(areasSum * areasSum);
return areaCalc;
}
function calculateAreaInSquareMeters(x1, x2, y1, y2) {
return (y1 * x2 - x1 * y2) / 2;
}
function calculateYSegment(latitudeRef, latitude, circumference) {
return (latitude - latitudeRef) * circumference / 360.0;
}
function calculateXSegment(longitudeRef, longitude, latitude, circumference) {
return (longitude - longitudeRef) * circumference * Math.cos((latitude * (Math.PI / 180))) / 360.0;
}
Reference