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import * as React from 'react'
import {
LayoutChangeEvent,
NativeScrollEvent,
StyleSheet,
View,
} from 'react-native'
import Animated, {
Easing,
useAnimatedReaction,
useAnimatedStyle,
useSharedValue,
withTiming,
runOnJS,
} from 'react-native-reanimated'
import {Pager, PagerRef, RenderTabBarFnProps} from 'view/com/pager/Pager'
import {TabBar} from './TabBar'
import {useWebMediaQueries} from 'lib/hooks/useWebMediaQueries'
import {OnScrollHandler} from 'lib/hooks/useOnMainScroll'
const SCROLLED_DOWN_LIMIT = 200
interface PagerWithHeaderChildParams {
headerHeight: number
onScroll: OnScrollHandler
isScrolledDown: boolean
}
export interface PagerWithHeaderProps {
testID?: string
children:
| (((props: PagerWithHeaderChildParams) => JSX.Element) | null)[]
| ((props: PagerWithHeaderChildParams) => JSX.Element)
items: string[]
isHeaderReady: boolean
renderHeader?: () => JSX.Element
initialPage?: number
onPageSelected?: (index: number) => void
onCurrentPageSelected?: (index: number) => void
}
export const PagerWithHeader = React.forwardRef<PagerRef, PagerWithHeaderProps>(
function PageWithHeaderImpl(
{
children,
testID,
items,
isHeaderReady,
renderHeader,
initialPage,
onPageSelected,
onCurrentPageSelected,
}: PagerWithHeaderProps,
ref,
) {
const {isMobile} = useWebMediaQueries()
const [currentPage, setCurrentPage] = React.useState(0)
const scrollYs = React.useRef<Record<number, number>>({})
const scrollY = useSharedValue(scrollYs.current[currentPage] || 0)
const [tabBarHeight, setTabBarHeight] = React.useState(0)
const [headerOnlyHeight, setHeaderOnlyHeight] = React.useState(0)
const [isScrolledDown, setIsScrolledDown] = React.useState(
scrollYs.current[currentPage] > SCROLLED_DOWN_LIMIT,
)
const headerHeight = headerOnlyHeight + tabBarHeight
// react to scroll updates
function onScrollUpdate(v: number) {
// track each page's current scroll position
scrollYs.current[currentPage] = Math.min(v, headerOnlyHeight)
// update the 'is scrolled down' value
setIsScrolledDown(v > SCROLLED_DOWN_LIMIT)
}
useAnimatedReaction(
() => scrollY.value,
v => runOnJS(onScrollUpdate)(v),
)
// capture the header bar sizing
const onTabBarLayout = React.useCallback(
(evt: LayoutChangeEvent) => {
setTabBarHeight(evt.nativeEvent.layout.height)
},
[setTabBarHeight],
)
const onHeaderOnlyLayout = React.useCallback(
(evt: LayoutChangeEvent) => {
setHeaderOnlyHeight(evt.nativeEvent.layout.height)
},
[setHeaderOnlyHeight],
)
// render the the header and tab bar
const headerTransform = useAnimatedStyle(
() => ({
transform: [
{
translateY: Math.min(
Math.min(scrollY.value, headerOnlyHeight) * -1,
0,
),
},
],
}),
[scrollY, headerHeight, tabBarHeight],
)
const renderTabBar = React.useCallback(
(props: RenderTabBarFnProps) => {
return (
<Animated.View
style={[
isMobile ? styles.tabBarMobile : styles.tabBarDesktop,
headerTransform,
]}>
<View onLayout={onHeaderOnlyLayout}>{renderHeader?.()}</View>
<View
onLayout={onTabBarLayout}
style={{
// Render it immediately to measure it early since its size doesn't depend on the content.
// However, keep it invisible until the header above stabilizes in order to prevent jumps.
opacity: isHeaderReady ? 1 : 0,
pointerEvents: isHeaderReady ? 'auto' : 'none',
}}>
<TabBar
items={items}
selectedPage={currentPage}
onSelect={props.onSelect}
onPressSelected={onCurrentPageSelected}
/>
</View>
</Animated.View>
)
},
[
items,
isHeaderReady,
renderHeader,
headerTransform,
currentPage,
onCurrentPageSelected,
isMobile,
onTabBarLayout,
onHeaderOnlyLayout,
],
)
// props to pass into children render functions
function onScrollWorklet(e: NativeScrollEvent) {
'worklet'
scrollY.value = e.contentOffset.y
}
const onPageSelectedInner = React.useCallback(
(index: number) => {
setCurrentPage(index)
onPageSelected?.(index)
},
[onPageSelected, setCurrentPage],
)
const onPageSelecting = React.useCallback(
(index: number) => {
setCurrentPage(index)
if (scrollY.value > headerHeight) {
scrollY.value = headerHeight
}
scrollY.value = withTiming(scrollYs.current[index] || 0, {
duration: 170,
easing: Easing.inOut(Easing.quad),
})
},
[scrollY, setCurrentPage, scrollYs, headerHeight],
)
return (
<Pager
ref={ref}
testID={testID}
initialPage={initialPage}
onPageSelected={onPageSelectedInner}
onPageSelecting={onPageSelecting}
renderTabBar={renderTabBar}
tabBarPosition="top">
{toArray(children)
.filter(Boolean)
.map((child, i) => {
let output = null
if (
child != null &&
// Defer showing content until we know it won't jump.
isHeaderReady &&
headerOnlyHeight > 0 &&
tabBarHeight > 0
) {
output = child({
headerHeight,
isScrolledDown,
onScroll: {
onScroll: i === currentPage ? onScrollWorklet : noop,
},
})
}
// Pager children must be noncollapsible plain <View>s.
return (
<View key={i} collapsable={false}>
{output}
</View>
)
})}
</Pager>
)
},
)
const styles = StyleSheet.create({
tabBarMobile: {
position: 'absolute',
zIndex: 1,
top: 0,
left: 0,
width: '100%',
},
tabBarDesktop: {
position: 'absolute',
zIndex: 1,
top: 0,
// @ts-ignore Web only -prf
left: 'calc(50% - 299px)',
width: 598,
},
})
function noop() {
'worklet'
}
function toArray<T>(v: T | T[]): T[] {
if (Array.isArray(v)) {
return v
}
return [v]
}
|
