Unnecessary blank area is created when scrolling down while keyboard is open #19642

src/components/SwipeableView/index.native.tsx

@@ -3,30 +3,40 @@ import {PanResponder, View} from 'react-native';
 import CONST from '@src/CONST';
 import SwipeableViewProps from './types';
 
-function SwipeableView({children, onSwipeDown}: SwipeableViewProps) {
+function SwipeableView({children, onSwipeDown, onSwipeUp}: SwipeableViewProps) {
     const minimumPixelDistance = CONST.COMPOSER_MAX_HEIGHT;
     const oldYRef = useRef(0);
+    const directionRef = useRef<'UP' | 'DOWN' | null>(null);
+
     const panResponder = useRef(
         PanResponder.create({
-            // The PanResponder gets focus only when the y-axis movement is over minimumPixelDistance & swipe direction is downwards
-            // eslint-disable-next-line @typescript-eslint/naming-convention
-            onMoveShouldSetPanResponderCapture: (_event, gestureState) => {
+            onMoveShouldSetPanResponderCapture: (event, gestureState) => {
                 if (gestureState.dy - oldYRef.current > 0 && gestureState.dy > minimumPixelDistance) {
+                    directionRef.current = 'DOWN';
+                    return true;
+                }
+
+                if (gestureState.dy - oldYRef.current < 0 && Math.abs(gestureState.dy) > minimumPixelDistance) {
+                    directionRef.current = 'UP';
                     return true;
                 }
                 oldYRef.current = gestureState.dy;
                 return false;
             },
 
-            // Calls the callback when the swipe down is released; after the completion of the gesture
-            onPanResponderRelease: onSwipeDown,
+            onPanResponderRelease: () => {
+                if (directionRef.current === 'DOWN' && onSwipeDown) {
+                    onSwipeDown();
+                } else if (directionRef.current === 'UP' && onSwipeUp) {
+                    onSwipeUp();
+                }
+                directionRef.current = null; // Reset the direction after the gesture completes
+            },
         }),
     ).current;
 
-    return (
-        // eslint-disable-next-line react/jsx-props-no-spreading
-        <View {...panResponder.panHandlers}>{children}</View>
-    );
+    // eslint-disable-next-line react/jsx-props-no-spreading
+    return <View {...panResponder.panHandlers}>{children}</View>;
 }
 
 SwipeableView.displayName = 'SwipeableView';

src/components/SwipeableView/index.tsx

@@ -1,4 +1,77 @@
+import React, {useEffect, useRef} from 'react';
+import {View} from 'react-native';
+import DomUtils from '@libs/DomUtils';
 import SwipeableViewProps from './types';
 
-// Swipeable View is available just on Android/iOS for now.
-export default ({children}: SwipeableViewProps) => children;
+// Min delta y in px to trigger swipe
+const MIN_DELTA_Y = 25;
+
+function SwipeableView({onSwipeUp, onSwipeDown, style, children}: SwipeableViewProps) {
+    const ref = useRef<View | null>(null);
+    const scrollableChildRef = useRef<HTMLElement | null>(null);
+    const startY = useRef(0);
+    const isScrolling = useRef(false);
+
+    useEffect(() => {
+        if (!ref.current) {
+            return;
+        }
+
+        const element = ref.current as unknown as HTMLElement;
+
+        const handleTouchStart = (event: TouchEvent) => {
+            startY.current = event.touches[0].clientY;
+        };
+
+        const handleTouchEnd = (event: TouchEvent) => {
+            const deltaY = event.changedTouches[0].clientY - startY.current;
+            const isSelecting = DomUtils.isActiveTextSelection();
+            let canSwipeDown = true;
+            let canSwipeUp = true;
+            if (scrollableChildRef.current) {
+                canSwipeUp = scrollableChildRef.current.scrollHeight - scrollableChildRef.current.scrollTop === scrollableChildRef.current.clientHeight;
+                canSwipeDown = scrollableChildRef.current.scrollTop === 0;
+            }
+
+            if (deltaY > MIN_DELTA_Y && onSwipeDown && !isSelecting && canSwipeDown && !isScrolling.current) {
+                onSwipeDown();
+            }
+
+            if (deltaY < -MIN_DELTA_Y && onSwipeUp && !isSelecting && canSwipeUp && !isScrolling.current) {
+                onSwipeUp();
+            }
+            isScrolling.current = false;
+        };
+
+        const handleScroll = (event: Event) => {
+            isScrolling.current = true;
+            if (!event.target || scrollableChildRef.current) {
+                return;
+            }
+            scrollableChildRef.current = event.target as HTMLElement;
+        };
+
+        element.addEventListener('touchstart', handleTouchStart);
+        element.addEventListener('touchend', handleTouchEnd);
+        element.addEventListener('scroll', handleScroll, true);
+
+        return () => {
+            element.removeEventListener('touchstart', handleTouchStart);
+            element.removeEventListener('touchend', handleTouchEnd);
+            element.removeEventListener('scroll', handleScroll);
+        };
+    }, [onSwipeDown, onSwipeUp]);
+
+    return (
+        <View
+            ref={ref}
+            style={style}
+        >
+            {children}
+        </View>
+    );
+}
+
+SwipeableView.displayName = 'SwipeableView';
+
+export default SwipeableView;

src/components/SwipeableView/types.ts

@@ -1,11 +1,18 @@
 import {ReactNode} from 'react';
+import {StyleProp, ViewStyle} from 'react-native';
 
 type SwipeableViewProps = {
     /** The content to be rendered within the SwipeableView */
     children: ReactNode;
 
     /** Callback to fire when the user swipes down on the child content */
-    onSwipeDown: () => void;
+    onSwipeDown?: () => void;
+
+    /** Callback to fire when the user swipes up on the child content */
+    onSwipeUp?: () => void;
+
+    /** Style for the wrapper View */
+    style?: StyleProp<ViewStyle>;
 };
 
 export default SwipeableViewProps;

src/hooks/useBlockViewportScroll/index.native.ts

@@ -0,0 +1,15 @@
+/**
+ * A hook that blocks viewport scroll when the keyboard is visible.
+ * It does this by capturing the current scrollY position when the keyboard is shown, then scrolls back to this position smoothly on 'touchend' event.
+ * This scroll blocking is removed when the keyboard hides.
+ * This hook is doing nothing on native platforms.
+ *
+ * @example
+ * useBlockViewportScroll();
+ */
+function useBlockViewportScroll() {
+    // This hook is doing nothing on native platforms.
+    // Check index.ts for web implementation.
+}
+
+export default useBlockViewportScroll;

src/hooks/useBlockViewportScroll/index.ts

@@ -0,0 +1,43 @@
+import {useEffect, useRef} from 'react';
+import Keyboard from '@libs/NativeWebKeyboard';
+
+/**
+ * A hook that blocks viewport scroll when the keyboard is visible.
+ * It does this by capturing the current scrollY position when the keyboard is shown, then scrolls back to this position smoothly on 'touchend' event.
+ * This scroll blocking is removed when the keyboard hides.
+ * This hook is doing nothing on native platforms.
+ *
+ * @example
+ * useBlockViewportScroll();
+ */
+function useBlockViewportScroll() {
+    const optimalScrollY = useRef(0);
+    const keyboardShowListenerRef = useRef(() => {});
+    const keyboardHideListenerRef = useRef(() => {});
+
+    useEffect(() => {
+        const handleTouchEnd = () => {
+            window.scrollTo({top: optimalScrollY.current, behavior: 'smooth'});
+        };
+
+        const handleKeybShow = () => {
+            optimalScrollY.current = window.scrollY;
+            window.addEventListener('touchend', handleTouchEnd);
+        };
+
+        const handleKeybHide = () => {
+            window.removeEventListener('touchend', handleTouchEnd);
+        };
+
+        keyboardShowListenerRef.current = Keyboard.addListener('keyboardDidShow', handleKeybShow);
+        keyboardHideListenerRef.current = Keyboard.addListener('keyboardDidHide', handleKeybHide);
+
+        return () => {
+            keyboardShowListenerRef.current();
+            keyboardHideListenerRef.current();
+            window.removeEventListener('touchend', handleTouchEnd);
+        };
+    }, []);
+}
+
+export default useBlockViewportScroll;

src/libs/DomUtils/index.native.ts

@@ -2,6 +2,21 @@ import GetActiveElement from './types';
 
 const getActiveElement: GetActiveElement = () => null;
 
+/**
+ * Checks if there is a text selection within the currently focused input or textarea element.
+ *
+ * This function determines whether the currently focused element is an input or textarea,
+ * and if so, it checks whether there is a text selection (i.e., whether the start and end
+ * of the selection are at different positions). It assumes that only inputs and textareas
+ * can have text selections.
+ * Works only on web. Throws an error on native.
+ *
+ * @returns True if there is a text selection within the focused element, false otherwise.
+ */
+const isActiveTextSelection = () => {
+    throw new Error('Not implemented in React Native. Use only for web.');
+};
+
 const requestAnimationFrame = (callback: () => void) => {
     if (!callback) {
         return;
@@ -12,5 +27,6 @@ const requestAnimationFrame = (callback: () => void) => {
 
 export default {
     getActiveElement,
+    isActiveTextSelection,
     requestAnimationFrame,
 };

src/libs/DomUtils/index.ts

@@ -2,7 +2,30 @@ import GetActiveElement from './types';
 
 const getActiveElement: GetActiveElement = () => document.activeElement;
 
+/**
+ * Checks if there is a text selection within the currently focused input or textarea element.
+ *
+ * This function determines whether the currently focused element is an input or textarea,
+ * and if so, it checks whether there is a text selection (i.e., whether the start and end
+ * of the selection are at different positions). It assumes that only inputs and textareas
+ * can have text selections.
+ * Works only on web. Throws an error on native.
+ *
+ * @returns True if there is a text selection within the focused element, false otherwise.
+ */
+const isActiveTextSelection = (): boolean => {
+    const focused = document.activeElement as HTMLInputElement | HTMLTextAreaElement | null;
+    if (!focused) {
+        return false;
+    }
+    if (typeof focused.selectionStart === 'number' && typeof focused.selectionEnd === 'number') {
+        return focused.selectionStart !== focused.selectionEnd;
+    }
+    return false;
+};
+
 export default {
     getActiveElement,
+    isActiveTextSelection,
     requestAnimationFrame: window.requestAnimationFrame.bind(window),
 };