owen/dotted-map-no-alaska
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feat: add simple cache mechanism for the grid

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This commit is contained in:
Basile Bruneau
2020-05-06 23:05:47 +02:00
parent b4b84d8d6b
commit 3024527ff7
1 changed files with 18 additions and 11 deletions
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index.js
+18 -11
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@@ -7,6 +7,8 @@ const geojsonByCountry = geojsonWorld.features.reduce((countries, feature) => {
return countries; return countries;
}, {}); }, {});
const CACHE = {};
const DEFAULT_WORLD_REGION = { const DEFAULT_WORLD_REGION = {
lat: { min: -56, max: 71 }, lat: { min: -56, max: 71 },
lng: { min: -179, max: 179 }, lng: { min: -179, max: 179 },
@@ -50,7 +52,7 @@ const computeGeojsonBox = (geojson) => {
} }
}; };
function DottedMap({ height = 0, width = 0, countries = [], region, grid = 'vertocam' }) { function DottedMap({ height = 0, width = 0, countries = [], region, grid = 'vertical' }) {
if (height <= 0 && width <= 0) { if (height <= 0 && width <= 0) {
throw new Error('height or width is required'); throw new Error('height or width is required');
} }
@@ -68,6 +70,8 @@ function DottedMap({ height = 0, width = 0, countries = [], region, grid = 'vert
region = DEFAULT_WORLD_REGION; region = DEFAULT_WORLD_REGION;
} }
const cacheKey = [JSON.stringify(region), grid, height, width, JSON.stringify(countries)].join(' ');
const [X_MIN, Y_MIN] = proj4(proj4.defs('GOOGLE'), [region.lng.min, region.lat.min]); const [X_MIN, Y_MIN] = proj4(proj4.defs('GOOGLE'), [region.lng.min, region.lat.min]);
const [X_MAX, Y_MAX] = proj4(proj4.defs('GOOGLE'), [region.lng.max, region.lat.max]); const [X_MAX, Y_MAX] = proj4(proj4.defs('GOOGLE'), [region.lng.max, region.lat.max]);
const X_RANGE = X_MAX - X_MIN; const X_RANGE = X_MAX - X_MIN;
@@ -79,22 +83,25 @@ function DottedMap({ height = 0, width = 0, countries = [], region, grid = 'vert
height = Math.round((width * Y_RANGE) / X_RANGE); height = Math.round((width * Y_RANGE) / X_RANGE);
} }
const points = {}; const points = { ...CACHE[cacheKey] } || {};
const ystep = grid === 'diagonal' ? Math.sqrt(3) / 2 : 1; const ystep = grid === 'diagonal' ? Math.sqrt(3) / 2 : 1;
for (let y = 0; y * ystep < height; y += 1) { if (!CACHE[cacheKey]) {
for (let x = 0; x < width; x += 1) { for (let y = 0; y * ystep < height; y += 1) {
const localx = y % 2 === 0 && grid === 'diagonal' ? x + 0.5 : x; for (let x = 0; x < width; x += 1) {
const localy = y * ystep; const localx = y % 2 === 0 && grid === 'diagonal' ? x + 0.5 : x;
const localy = y * ystep;
const pointGoogle = [(localx / width) * X_RANGE + X_MIN, Y_MAX - (localy / height) * Y_RANGE]; const pointGoogle = [(localx / width) * X_RANGE + X_MIN, Y_MAX - (localy / height) * Y_RANGE];
const wgs84Point = proj4(proj4.defs('GOOGLE'), proj4.defs('WGS84'), pointGoogle); const wgs84Point = proj4(proj4.defs('GOOGLE'), proj4.defs('WGS84'), pointGoogle);
if (inside.feature(geojson, wgs84Point) !== -1) { if (inside.feature(geojson, wgs84Point) !== -1) {
points[[x, y].join(';')] = { x: localx, y: localy }; points[[x, y].join(';')] = { x: localx, y: localy };
}
} }
} }
CACHE[cacheKey] = points;
} }
return { return {