64 lines
2 KiB
TypeScript
64 lines
2 KiB
TypeScript
import { Tiles } from "../../Models/TileRange"
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export default class TileFreshnessCalculator {
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/**
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* All the freshnesses per tile index
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* @private
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*/
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private readonly freshnesses = new Map<number, Date>()
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/**
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* Marks that some data got loaded for this layer
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* @param tileId
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* @param freshness
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*/
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public addTileLoad(tileId: number, freshness: Date) {
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const existingFreshness = this.freshnessFor(...Tiles.tile_from_index(tileId))
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if (existingFreshness >= freshness) {
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return
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}
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this.freshnesses.set(tileId, freshness)
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// Do we have freshness for the neighbouring tiles? If so, we can mark the tile above as loaded too!
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let [z, x, y] = Tiles.tile_from_index(tileId)
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if (z === 0) {
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return
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}
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x = x - (x % 2) // Make the tiles always even
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y = y - (y % 2)
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const ul = this.freshnessFor(z, x, y)?.getTime()
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if (ul === undefined) {
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return
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}
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const ur = this.freshnessFor(z, x + 1, y)?.getTime()
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if (ur === undefined) {
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return
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}
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const ll = this.freshnessFor(z, x, y + 1)?.getTime()
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if (ll === undefined) {
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return
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}
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const lr = this.freshnessFor(z, x + 1, y + 1)?.getTime()
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if (lr === undefined) {
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return
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}
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const leastFresh = Math.min(ul, ur, ll, lr)
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const date = new Date()
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date.setTime(leastFresh)
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this.addTileLoad(Tiles.tile_index(z - 1, Math.floor(x / 2), Math.floor(y / 2)), date)
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}
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public freshnessFor(z: number, x: number, y: number): Date {
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if (z < 0) {
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return undefined
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}
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const tileId = Tiles.tile_index(z, x, y)
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if (this.freshnesses.has(tileId)) {
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return this.freshnesses.get(tileId)
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}
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// recurse up
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return this.freshnessFor(z - 1, Math.floor(x / 2), Math.floor(y / 2))
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}
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}
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