Implement PickerAvoidingView and PickerStateProvider

...which provide tools for ensuring that a picker is not covered by its
own modal on iOS.

Call scrollToInput() only on iOS, basing on an observation that this
method was designed to handle iOS modal specifically.

Author: cubuspl42

index.d.ts

@@ -92,3 +92,11 @@ declare class Picker extends React.Component<PickerSelectProps> {
 }
 
 export default Picker;
+
+type PickerStateProviderProps = {
+    readonly children: React.ReactChild;
+};
+
+export const PickerStateProvider: React.ComponentType<PickerStateProviderProps>;
+
+export const PickerAvoidingView: React.ComponentType<React.PropsWithChildren>;

src/PickerAvoidingView/index.ios.js

@@ -0,0 +1,33 @@
+import React from 'react';
+import { StyleSheet, View } from 'react-native';
+import { PickerStateContext } from '../PickerStateProvider';
+import { IOS_MODAL_HEIGHT } from '../constants';
+
+/**
+ * PickerAvoidingView is a React component that adjusts the view layout to avoid
+ * being covered by an open iOS picker modal. It's meant to be similar to
+ * the built-in KeyboardAvoidingView component, but specifically tailored for
+ * iOS picker modals.
+ *
+ * In order for this component to work correctly, all the pickers and the
+ * PickerAvoidingView should have a PickerStateProvider ancestor.
+ *
+ * @param {React.ReactNode} props.children - The child components that should be
+ * protected from obstruction by the picker modal
+ */
+export function PickerAvoidingView(props) {
+    const context = React.useContext(PickerStateContext);
+    const isModalShown = context && context.isModalShown;
+
+    const style = props.enabled
+        ? StyleSheet.compose(props.style, {
+              paddingBottom: isModalShown ? IOS_MODAL_HEIGHT : 0,
+          })
+        : props.style;
+
+    return <View style={style}>{props.children}</View>;
+}
+
+PickerAvoidingView.defaultProps = {
+    enabled: true,
+};

src/PickerAvoidingView/index.js

@@ -0,0 +1,15 @@
+import React from 'react';
+import { View } from 'react-native';
+
+/**
+ * As, currently, only on iOS the picker's modal resembles the software keyboard
+ * in any way, the default implementation doesn't have any avoiding logic.
+ *
+ * @param {React.ReactNode} props.children - The child components to render
+ * within the PickerAvoidingView.
+ */
+export function PickerAvoidingView(props) {
+    // eslint-disable-next-line no-unused-vars
+    const { enabled, ...viewProps } = props;
+    return <View {...viewProps}>{props.children}</View>;
+}

src/PickerStateProvider.js

@@ -0,0 +1,43 @@
+import React from 'react';
+
+/**
+ * @typedef {Object} PickerStateData
+ * @property {boolean} isModalOpen - Indicates whether a picker-related modal is
+ * currently being shown. Note that currently modal is opened for pickers only
+ * on iOS.
+ *
+ * PickerStateContext is a context that gives access to PickerStateData.
+ */
+export const PickerStateContext = React.createContext();
+
+/**
+ * PickerStateProvider provides PickerStateContext and manages the necessary
+ * state.
+ *
+ * This component should be used as a single top-level provider for all picker
+ * instances in your application.
+ */
+export class PickerStateProvider extends React.Component {
+    constructor(props) {
+        super(props);
+
+        this.state = {
+            isModalShown: false,
+        };
+    }
+
+    render() {
+        const context = {
+            isModalShown: this.state.isModalShown,
+            setIsModalShown: (isModalShown) => {
+                this.setState({ isModalShown });
+            },
+        };
+
+        return (
+            <PickerStateContext.Provider value={context}>
+                {this.props.children}
+            </PickerStateContext.Provider>
+        );
+    }
+}

src/constants.js

@@ -0,0 +1,3 @@
+// Measuring the modal before rendering is not working reliably, so we need to hardcode the height
+// This height was tested thoroughly on several iPhone models (iPhone SE, from iPhone 8 to 14 Pro, and 14 Pro Max)
+export const IOS_MODAL_HEIGHT = 262;

src/index.js

@@ -5,16 +5,17 @@ import isEqual from 'lodash.isequal';
 import { Picker } from '@react-native-picker/picker';
 import { defaultStyles } from './styles';
 import { Dimensions } from 'react-native';
-
-// Measuring the modal before rendering is not working reliably, so we need to hardcode the height
-// This height was tested thoroughly on several iPhone Models (from iPhone 8 to 14 Pro)
-const IOS_MODAL_HEIGHT = 262;
+import { PickerAvoidingView } from './PickerAvoidingView';
+import { PickerStateContext, PickerStateProvider } from './PickerStateProvider';
+import { IOS_MODAL_HEIGHT } from './constants';
 
 const preserveSpaces = (label) => {
     return label.replace(/ /g, '\u00a0');
 };
 
 export default class RNPickerSelect extends PureComponent {
+    static contextType = PickerStateContext;
+
     static propTypes = {
         onValueChange: PropTypes.func.isRequired,
         items: PropTypes.arrayOf(
@@ -245,23 +246,34 @@ export default class RNPickerSelect extends PureComponent {
             // If TextInput is below picker modal, scroll up
             if (textInputBottomY > modalY) {
                 this.props.scrollViewRef.current.scrollTo({
-                    y: textInputBottomY - modalY + this.props.scrollViewContentOffsetY,
+                    // Add 10 pixels for a more visually pleasant effect
+                    y: textInputBottomY + 10 - modalY + this.props.scrollViewContentOffsetY,
                 });
             }
         });
     }
 
-    triggerOpenCloseCallbacks() {
+    triggerCallbacks() {
         const { onOpen, onClose } = this.props;
         const { showPicker } = this.state;
 
         if (!showPicker && onOpen) {
             onOpen();
-            this.scrollToInput();
         }
 
-        if (showPicker && onClose) {
-            onClose();
+        if (showPicker) {
+            if (onClose) {
+                onClose();
+            }
+
+            // If the picker is currently shown, toggling it will start closing
+            // the modal on iOS. Let's handle this here, instead on relying on
+            // Modal's onDismiss, because onDismiss is fired _after_ the modal
+            // closing animation ends. PickerAvoidingView behaves better
+            // (visually) when it adjusts right after the modal closing starts.
+            if (this.context) {
+                this.context.setIsModalShown(false);
+            }
         }
     }
 
@@ -291,7 +303,7 @@ export default class RNPickerSelect extends PureComponent {
             return;
         }
 
-        this.triggerOpenCloseCallbacks();
+        this.triggerCallbacks();
 
         if (Keyboard.isVisible()) {
             const keyboardListener = Keyboard.addListener('keyboardDidHide', () => {
@@ -481,6 +493,13 @@ export default class RNPickerSelect extends PureComponent {
                     supportedOrientations={['portrait', 'landscape']}
                     onOrientationChange={this.onOrientationChange}
                     {...modalProps}
+                    onShow={() => {
+                        if (this.context) {
+                            this.context.setIsModalShown(true);
+                        }
+
+                        this.scrollToInput();
+                    }}
                 >
                     <TouchableOpacity
                         style={[defaultStyles.modalViewTop, style.modalViewTop]}
@@ -635,4 +654,4 @@ export default class RNPickerSelect extends PureComponent {
     }
 }
 
-export { defaultStyles };
+export { defaultStyles, PickerStateProvider, PickerAvoidingView };