forked from MapComplete/MapComplete
39 lines
1 KiB
TypeScript
39 lines
1 KiB
TypeScript
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import { FeatureSource } from "../FeatureSource"
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import { Feature } from "geojson"
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import { Store, UIEventSource } from "../../UIEventSource"
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export class IfVisibleFeatureSource<T extends Feature> implements FeatureSource<T> {
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private readonly _features: UIEventSource<T[]> = new UIEventSource<T[]>([])
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public readonly features: Store<T[]> = this._features
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constructor(upstream: FeatureSource<T>, visible: Store<boolean>) {
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let dirty = false
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upstream.features.addCallbackAndRun(features => {
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if (!visible.data) {
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console.log(">>> not writing data as not visible")
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dirty = true
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return
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}
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this._features.set(features)
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dirty = false
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})
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visible.addCallbackAndRun(isVisible => {
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if (isVisible && dirty) {
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this._features.set(upstream.features.data)
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dirty = false
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}
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if (!visible) {
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this._features.set([])
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}
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})
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}
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}
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