NativeScript/apps/ui/src/scroll-view/scroll-enabled-page.ts

import { EventData, GestureStateTypes, PanGestureEventData, Page, View, ScrollView } from '@nativescript/core';

export function pageLoaded(args: EventData) {
	var page = <Page>args.object;
}

let currentDeltaY = 0;
export function panLayout(args: PanGestureEventData) {
	const view = <View>args.object;
	const scrollView = <ScrollView>view.parent;

	if (args.state === GestureStateTypes.began) {
		currentDeltaY = 0;
		scrollView.isScrollEnabled = false;
	} else if (args.state === GestureStateTypes.changed) {
		const diff = args.deltaY - currentDeltaY;
		view.translateY += diff;
		currentDeltaY = args.deltaY;
	} else if (args.state === GestureStateTypes.ended) {
		scrollView.isScrollEnabled = true;
	}
}