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Custom Projection
This demo illustrates how to implement a custom projection. To do it, set the aspectRatio, to, and from properties. The Wagner-VI projection is used in this example.
www.wikipedia.org
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import React from 'react';
import VectorMap, {
Layer,
Export
} from 'devextreme-react/vector-map';
import * as mapsData from 'devextreme/dist/js/vectormap-data/world.js';
import { coordLinesData } from './data.js';
const RADIANS = Math.PI / 180;
const WAGNER_6_P_LAT = Math.PI / Math.sqrt(3);
const WAGNER_6_U_LAT = 2 / Math.sqrt(3) - 0.1;
const customProjection = {
aspectRatio: 2,
to([l, lt]) {
const x = l * RADIANS;
const y = Math.min(Math.max(lt * RADIANS, -WAGNER_6_P_LAT), +WAGNER_6_P_LAT);
const t = y / Math.PI;
return [
x / Math.PI * Math.sqrt(1 - 3 * t * t),
y * 2 / Math.PI
];
},
from([x, y]) {
y = Math.min(Math.max(y, -WAGNER_6_U_LAT), +WAGNER_6_U_LAT);
const t = y / 2;
return [
x * Math.PI / Math.sqrt(1 - 3 * t * t) / RADIANS,
y * Math.PI / 2 / RADIANS
];
}
};
export default function App() {
return (
<VectorMap
id="vector-map"
projection={customProjection}
title="Wagner VI projection"
>
<Layer
dataSource={mapsData.world} />
<Layer
dataSource={coordLinesData}
color="#aaa"
borderWidth={1}
hoverEanbled={false} />
<Export enabled={true}></Export>
</VectorMap>
);
}
import React from 'react';
import ReactDOM from 'react-dom';
import App from './App.js';
ReactDOM.render(
<App />,
document.getElementById('app')
);
<!DOCTYPE html>
<html>
<head>
<title>DevExtreme Demo</title>
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0" />
<link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/20.2.5/css/dx.common.css" />
<link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/20.2.5/css/dx.light.css" />
<link rel="stylesheet" type="text/css" href="styles.css" />
<script src="https://unpkg.com/core-js@2.4.1/client/shim.min.js"></script>
<script src="https://unpkg.com/systemjs@0.21.3/dist/system.js"></script>
<script type="text/javascript" src="config.js"></script>
<script type="text/javascript">
System.import('./index.js');
</script>
</head>
<body class="dx-viewport">
<div class="demo-container">
<div id="app"></div>
</div>
</body>
</html>
#vector-map {
height: 400px;
}
export const coordLinesData = {
type: 'FeatureCollection',
features: []
};
//add meridians
for (let longitude = -180; longitude <= 180; longitude += 30) {
const lineCoords = [];
for (let latitude = -90; latitude <= 90; latitude += 5) {
lineCoords.push([longitude, latitude]);
}
coordLinesData.features.push({
geometry: {
type: 'LineString',
coordinates: lineCoords
}
});
}
//add parallels
for (let latitude = -90; latitude <= 90; latitude += 30) {
coordLinesData.features.push({
geometry: {
type: 'LineString',
coordinates: [[ -180, latitude ], [ 180, latitude]]
}
});
}
System.config({
transpiler: 'plugin-babel',
meta: {
'devextreme/localization.js': {
"esModule": true
},
'devextreme/dist/js/vectormap-data/*': {
'esModule': true
},
},
paths: {
'npm:': 'https://unpkg.com/'
},
defaultExtension: 'js',
map: {
'react': 'npm:react@16.14.0/umd/react.development.js',
'react-dom': 'npm:react-dom@16.14.0/umd/react-dom.development.js',
'prop-types': 'npm:prop-types@15.7.2/prop-types.js',
'devextreme/dist/js/vectormap-data': 'js/vectormap-data',
'rrule': 'npm:rrule@2.6.6/dist/es5/rrule.js',
'luxon': 'npm:luxon@1.25.0/build/global/luxon.min.js',
'es6-object-assign': 'npm:es6-object-assign@1.1.0',
'devextreme': 'npm:devextreme@20.2.5',
'devextreme-react': 'npm:devextreme-react@20.2.5',
'jszip': 'npm:jszip@3.5.0/dist/jszip.min.js',
'devextreme-quill': 'npm:devextreme-quill@0.9.8/dist/dx-quill.min.js',
'devexpress-diagram': 'npm:devexpress-diagram@2.0.11/dist/dx-diagram.js',
'devexpress-gantt': 'npm:devexpress-gantt@2.0.18/dist/dx-gantt.js',
'preact': 'npm:preact@10.5.11/dist/preact.js',
'preact/hooks': 'npm:preact@10.5.11/hooks/dist/hooks.js',
// SystemJS plugins
'plugin-babel': 'npm:systemjs-plugin-babel@0.0.25/plugin-babel.js',
'systemjs-babel-build': 'npm:systemjs-plugin-babel@0.0.25/systemjs-babel-browser.js'
},
packages: {
'devextreme': {
defaultExtension: 'js'
},
'devextreme-react': {
main: 'index.js'
},
'devextreme/events/utils': {
main: 'index'
},
'devextreme/events': {
main: 'index'
},
'es6-object-assign': {
main: './index.js',
defaultExtension: 'js'
}
},
babelOptions: {
sourceMaps: false,
stage0: true,
react: true
}
});