mirror of
https://github.com/inaturalist/iNaturalistReactNative.git
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b78be9243d
* (lint) MOB-1063 enforce trailing commas * autofix trailing commas * manually fix newly introduced maxlen violations * add trailing comma convention to i18n build
47 lines
1.5 KiB
TypeScript
47 lines
1.5 KiB
TypeScript
const TILE_SIZE = 256;
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let mPixelPositionX;
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let mPixelPositionY;
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let mTilePositionX;
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let mTilePositionY;
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/* Based on: https://developers.google.com/maps/documentation/javascript/examples/map-coordinates */
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const project = ( latitude: number, longitude: number ) => {
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let siny = Math.sin( ( latitude * Math.PI ) / 180 );
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// Truncating to 0.9999 effectively limits latitude to 89.189. This is
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// about a third of a tile past the edge of the world tile.
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siny = Math.min( Math.max( siny, -0.9999 ), 0.9999 );
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return [
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( 256 * ( 0.5 + longitude / 360 ) ),
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( 256 * ( 0.5 - Math.log( ( 1 + siny ) / ( 1 - siny ) ) / ( 4 * Math.PI ) ) ),
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];
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};
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/* Based on: https://developers.google.com/maps/documentation/javascript/examples/map-coordinates */
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const createUTFPosition = ( zoomLevel: number, latitude: number, longitude: number ) => {
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const scale = 2 ** Math.floor( zoomLevel );
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const worldCoordinate = project( latitude, longitude );
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mTilePositionX = Math.floor( ( worldCoordinate[0] * scale ) / TILE_SIZE );
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mTilePositionY = Math.floor( ( worldCoordinate[1] * scale ) / TILE_SIZE );
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const pixelCoordinate = [
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worldCoordinate[0] * scale,
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worldCoordinate[1] * scale,
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];
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mPixelPositionX = ( pixelCoordinate[0] - mTilePositionX * TILE_SIZE );
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mPixelPositionY = ( pixelCoordinate[1] - mTilePositionY * TILE_SIZE );
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return {
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mPixelPositionX,
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mPixelPositionY,
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mTilePositionX,
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mTilePositionY,
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};
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};
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export default createUTFPosition;
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