feat: add overlayColor prop to modal component for customisable background overlay (#46322)

Summary:
Solves these issues:
- https://github.com/facebook/react-native/issues/18398
- https://github.com/facebook/react-native/issues/12478

Solves this proposal: https://github.com/react-native-community/discussions-and-proposals/discussions/774

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[GENERAL] [ADDED] - added overlayColor prop to modal component for customisable background overlay

**Motivation:**
Currently, the React Native Modal component only allows the background to be set to either `transparent` or `white`. This limits the ability to dim the background or apply custom colors, which is essential for creating a more polished and user-friendly interface.

**Change Log:**

Modal Component Enhancements:

- Introduced a new optional prop `overlayColor` to the Modal component.
- Updated the background color logic to prioritize `overlayColor` when transparent is `false`.
- Ensured backward compatibility by defaulting to `white` when `overlayColor` is not provided.

Pull Request resolved: https://github.com/facebook/react-native/pull/46322

Test Plan:
- Test the changes on both iOS and Android devices/emulators to ensure consistent behavior.
- Added example in **rn-tester** app

**Sample screenshot with custom overlayColor passed as 'red'.**

![simulator_screenshot_4F112217-7AD5-4030-8A18-6260AD32988A](https://github.com/user-attachments/assets/52f16ef2-874b-487c-908b-1aa2a1b8fafb)

Reviewed By: cipolleschi

Differential Revision: D62201559

Pulled By: alanleedev

fbshipit-source-id: e990d7f18f5edf61f0107026ea899c5f22d47bfd

packages/react-native/Libraries/Modal/Modal.d.ts

@@ -10,6 +10,7 @@
 import type * as React from 'react';
 import {ViewProps} from '../Components/View/ViewPropTypes';
 import {NativeSyntheticEvent} from '../Types/CoreEventTypes';
+import {ColorValue} from '../StyleSheet/StyleSheet';
 
 export interface ModalBaseProps {
   /**
@@ -43,6 +44,12 @@ export interface ModalBaseProps {
    * The `onShow` prop allows passing a function that will be called once the modal has been shown.
    */
   onShow?: ((event: NativeSyntheticEvent<any>) => void) | undefined;
+
+  /**
+   * The `overlayColor` props sets the color of the modal's background overlay.
+   * Defaults to `white` if not provided and transparent is `false`. Ignored if `transparent` is `true`.
+   */
+  overlayColor?: ColorValue | undefined;
 }
 
 export interface ModalPropsIOS {

packages/react-native/Libraries/Modal/Modal.js

@@ -157,6 +157,12 @@ export type Props = $ReadOnly<{|
    * See https://reactnative.dev/docs/modal#onorientationchange
    */
   onOrientationChange?: ?DirectEventHandler<OrientationChangeEvent>,
+
+  /**
+   * The `overlayColor` props sets the color of the modal's background overlay.
+   * Defaults to `white` if not provided and transparent is `false`. Ignored if `transparent` is `true`.
+   */
+  overlayColor?: ?string,
 |}>;
 
 function confirmProps(props: Props) {
@@ -249,7 +255,9 @@ class Modal extends React.Component<Props, State> {
 
     const containerStyles = {
       backgroundColor:
-        this.props.transparent === true ? 'transparent' : 'white',
+        this.props.transparent === true
+          ? 'transparent'
+          : this.props.overlayColor ?? 'white',
     };
 
     let animationType = this.props.animationType || 'none';

packages/react-native/Libraries/__tests__/__snapshots__/public-api-test.js.snap

@@ -6377,6 +6377,7 @@ export type Props = $ReadOnly<{|
     | \\"landscape-right\\",
   >,
   onOrientationChange?: ?DirectEventHandler<OrientationChangeEvent>,
+  overlayColor?: ?string,
 |}>;
 type State = {
   isRendered: boolean,

packages/rn-tester/js/examples/Modal/ModalPresentation.js

@@ -34,6 +34,8 @@ const supportedOrientations = [
   'landscape-right',
 ];
 
+const overlayColors = ['red', 'blue', undefined];
+
 function ModalPresentation() {
   const onDismiss = React.useCallback(() => {
     alert('onDismiss');
@@ -63,10 +65,12 @@ function ModalPresentation() {
     onDismiss: undefined,
     onShow: undefined,
     visible: false,
+    overlayColor: undefined,
   });
   const presentationStyle = props.presentationStyle;
   const hardwareAccelerated = props.hardwareAccelerated;
   const statusBarTranslucent = props.statusBarTranslucent;
+  const overlayColor = props.overlayColor;
 
   const [currentOrientation, setCurrentOrientation] = React.useState('unknown');
 
@@ -211,6 +215,26 @@ function ModalPresentation() {
           />
         </View>
       </View>
+      <View style={styles.block}>
+        <Text style={styles.title}>Overlay Color ⚫️</Text>
+        <View style={styles.row}>
+          {overlayColors.map(type => (
+            <RNTOption
+              key={type}
+              style={styles.option}
+              label={type === undefined ? 'default' : type}
+              multiSelect={true}
+              onPress={() =>
+                setProps(prev => ({
+                  ...prev,
+                  overlayColor: type,
+                }))
+              }
+              selected={type === overlayColor}
+            />
+          ))}
+        </View>
+      </View>
     </>
   );