feat: adds useCurrentTabScrollY hook

CHANGELOG.md

@@ -1,4 +1,4 @@
-# [5.0.0](https://github.com/PedroBern/react-native-collapsible-tab-view/compare/v5.0.0-rc.1...v5.0.0-rc.10) (2022-05-25)
+# [5.0.0](https://github.com/PedroBern/react-native-collapsible-tab-view/compare/v5.0.0-rc.1...v5.0.0-rc.10) (2022-06-29)
 
 ### Performance Improvements
 
@@ -16,6 +16,8 @@
 
 * custom label component ([51a7234](https://github.com/PedroBern/react-native-collapsible-tab-view/commit/51a7234fec8f19f384ed771789d883aee247260f))
 * `keepActiveTabCentered` property on scrollable MaterialTabBar to keep tab in the center ([6d35e31](https://github.com/PedroBern/react-native-collapsible-tab-view/commit/6d35e3151355d35830a8387af642c5af5a13c54d))
+* `useCurrentTabScrollY` ([73ee5d7](https://github.com/PedroBern/react-native-collapsible-tab-view/commit/73ee5d7c5e2b470551a5ad1dedae68413d3d5da0))
+
 ### Code Refactoring
 
 * remove obsolete HeaderComponent and FooterComponent ([cb2cb04](https://github.com/PedroBern/react-native-collapsible-tab-view/commit/cb2cb04bbcf1dd86484c2a77f273e10ee6ceabbe))
@@ -25,6 +27,7 @@
 
 * use `renderHeader` and `renderTabBar` instead of HeaderComponent and FooterComponent
 * a peer dependency on `react-native-pager-view@5` is now required
+* `useHeaderMeasurements` now returns the `height` as an `Animated.SharedValue`
 
 ## [4.5.2](https://github.com/PedroBern/react-native-collapsible-tab-view/compare/v4.5.1...v4.5.2) (2022-01-15)
 

README.md

@@ -317,6 +317,17 @@ Returns the top distance and the header height. See the animated header example
 const { top, height } = useHeaderMeasurements()
 ```
 
+### useCurrentTabScrollY
+
+Returns the vertical scroll position of the current tab as an Animated SharedValue.
+
+Because this library requires handling `onScroll` for its functionality, this is the only way to react to changes to the scroll position of the underlying scrollable component.
+
+```tsx
+const scrollY = useCurrentTabScrollY()
+```
+
+
 ## Default Tab Bar
 
 ### MaterialTabItem

documentation/README_TEMPLATE.md

@@ -167,6 +167,17 @@ Returns the top distance and the header height. See the animated header example
 const { top, height } = useHeaderMeasurements()
 ```
 
+### useCurrentTabScrollY
+
+Returns the vertical scroll position of the current tab as an Animated SharedValue.
+
+Because this library requires handling `onScroll` for its functionality, this is the only way to react to changes to the scroll position of the underlying scrollable component.
+
+```tsx
+const scrollY = useCurrentTabScrollY()
+```
+
+
 ## Default Tab Bar
 
 $TAB_BAR_API

example/src/AnimatedHeader.tsx

@@ -1,12 +1,15 @@
 import React from 'react'
-import { Text, StyleSheet, View } from 'react-native'
+import { StyleSheet, View } from 'react-native'
 import { useHeaderMeasurements } from 'react-native-collapsible-tab-view'
 import Animated, {
   interpolate,
   useAnimatedStyle,
+  useDerivedValue,
 } from 'react-native-reanimated'
 
+import { useCurrentTabScrollY } from '../../src/hooks'
 import ExampleComponent from './Shared/ExampleComponent'
+import ReText from './Shared/ReText'
 import { ExampleComponentType } from './types'
 
 const title = 'Animated Header'
@@ -15,15 +18,20 @@ const MIN_HEADER_HEIGHT = 48
 
 export const Header = () => {
   const { top, height } = useHeaderMeasurements()
+  const scrollY = useCurrentTabScrollY()
+
+  const scrollYText = useDerivedValue(
+    () => `Scroll Y is: ${scrollY.value.toFixed(2)}`
+  )
 
   const stylez = useAnimatedStyle(() => {
     return {
       transform: [
         {
           translateY: interpolate(
             top.value,
-            [0, -(height - MIN_HEADER_HEIGHT)],
-            [0, (height - MIN_HEADER_HEIGHT) / 2]
+            [0, -(height.value || 0 - MIN_HEADER_HEIGHT)],
+            [0, (height.value || 0 - MIN_HEADER_HEIGHT) / 2]
           ),
         },
       ],
@@ -33,7 +41,7 @@ export const Header = () => {
   return (
     <View style={[styles.root]}>
       <Animated.View style={[styles.container, stylez]}>
-        <Text style={styles.text}>{title}</Text>
+        <ReText style={styles.text} text={scrollYText} />
       </Animated.View>
     </View>
   )

example/src/Shared/Contacts.tsx

@@ -101,7 +101,11 @@ const renderItem = ({ item }: { item: Item }) => <ContactItem item={item} />
 const ListEmptyComponent = () => {
   const { top, height } = Tabs.useHeaderMeasurements()
   const translateY = useDerivedValue(() => {
-    return interpolate(-top.value, [0, height], [-height / 2, 0])
+    return interpolate(
+      -top.value,
+      [0, height.value || 0],
+      [-(height.value || 0) / 2, 0]
+    )
   }, [height])
 
   const stylez = useAnimatedStyle(() => {

example/src/Shared/ReText.tsx

@@ -0,0 +1,42 @@
+// courtesy of https://github.com/wcandillon/react-native-redash/blob/fd0b0ddb3b4c10ae88cf1f8a95890c7c5eb3c475/src/ReText.tsx
+
+import React from 'react'
+import type { TextProps as RNTextProps } from 'react-native'
+import { StyleSheet, TextInput } from 'react-native'
+import Animated, { useAnimatedProps } from 'react-native-reanimated'
+
+const styles = StyleSheet.create({
+  baseStyle: {
+    color: 'black',
+  },
+})
+Animated.addWhitelistedNativeProps({ text: true })
+
+interface TextProps {
+  text: Animated.SharedValue<string>
+  style?: Animated.AnimateProps<RNTextProps>['style']
+}
+
+const AnimatedTextInput = Animated.createAnimatedComponent(TextInput)
+
+const ReText = (props: TextProps) => {
+  const { text, style } = { style: {}, ...props }
+  const animatedProps = useAnimatedProps(() => {
+    return {
+      text: text.value,
+      // Here we use any because the text prop is not available in the type
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    } as any
+  })
+  return (
+    <AnimatedTextInput
+      underlineColorAndroid="transparent"
+      editable={false}
+      value={text.value}
+      style={[styles.baseStyle, style]}
+      {...{ animatedProps }}
+    />
+  )
+}
+
+export default ReText

example/src/Shared/SectionContacts.tsx

@@ -117,7 +117,11 @@ const renderItem = ({ item }: { item: Item }) => <ContactItem item={item} />
 const ListEmptyComponent = () => {
   const { top, height } = Tabs.useHeaderMeasurements()
   const translateY = useDerivedValue(() => {
-    return interpolate(-top.value, [0, height], [-height / 2, 0])
+    return interpolate(
+      -top.value,
+      [0, height.value || 0],
+      [-(height.value || 0) / 2, 0]
+    )
   }, [height])
 
   const stylez = useAnimatedStyle(() => {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "react-native-collapsible-tab-view",
-  "version": "5.0.0-rc.10",
+  "version": "5.0.0-rc.13",
   "description": "Collapsible tab view component for React Native",
   "main": "lib/commonjs/index.js",
   "react-native": "src/index.tsx",

src/Container.tsx

@@ -232,6 +232,7 @@ export const Container = React.memo(
               tabName: tabNames.value[i],
             })
             index.value = i
+            scrollYCurrent.value = scrollY.value[index.value] || 0
           }
         },
         []

src/hooks.tsx

@@ -568,25 +568,33 @@ export function useConvertAnimatedToValue<T>(
   return value
 }
 
-interface HeaderMeasurements {
+export interface HeaderMeasurements {
   /**
    * Animated value that represents the current Y translation of the header
    */
   top: Animated.SharedValue<number>
   /**
-   * The height of the header
+   * Animated value that represents the height of the header
    */
-  height: number
+  height: Animated.SharedValue<number | undefined>
 }
 
 export function useHeaderMeasurements(): HeaderMeasurements {
   const { headerTranslateY, headerHeight } = useTabsContext()
   return {
     top: headerTranslateY,
-    height: headerHeight.value || 0,
+    height: headerHeight,
   }
 }
 
+/**
+ * Returns the vertical scroll position of the current tab as an Animated SharedValue
+ */
+export function useCurrentTabScrollY(): Animated.SharedValue<number> {
+  const { scrollYCurrent } = useTabsContext()
+  return scrollYCurrent
+}
+
 /**
  * Returns the currently focused tab name
  */

src/index.tsx

@@ -40,10 +40,13 @@ export const Tabs = {
 
 export { Container, Tab, Lazy, FlatList, ScrollView, SectionList }
 export {
+  useCurrentTabScrollY,
   useHeaderMeasurements,
   useFocusedTab,
   useAnimatedTabIndex,
   useCollapsibleStyle,
 } from './hooks'
+export type { HeaderMeasurements } from './hooks'
+
 export { MaterialTabBar } from './MaterialTabBar/TabBar'
 export { MaterialTabItem } from './MaterialTabBar/TabItem'