Export the DevSettings module, add addMenuItem method (#25848)

Summary:
I wanted to configure the RN dev menu without having to write native code. This is pretty useful in a greenfield app since it avoids having to write a custom native module for both platforms (and might enable the feature for expo too).

This ended up a bit more involved than planned since callbacks can only be called once. I needed to convert the `DevSettings` module to a `NativeEventEmitter` and use events when buttons are clicked. This means creating a JS wrapper for it. Currently it does not export all methods, they can be added in follow ups as needed.

## Changelog

[General] [Added] - Export the DevSettings module, add `addMenuItem` method
Pull Request resolved: #25848

Test Plan:
Tested in an app using the following code.

```js
if (__DEV__) {
 DevSettings.addMenuItem('Show Dev Screen', () => {
    dispatchNavigationAction(
      NavigationActions.navigate({
        routeName: 'dev',
      }),
    );
  });
}
```

Added an example in RN tester

![devmenu](https://user-images.githubusercontent.com/2677334/62000297-71624680-b0a1-11e9-8403-bc95c4747f0c.gif)

Differential Revision: D17394916

Pulled By: cpojer

fbshipit-source-id: f9d2c548b09821c594189d1436a27b97cf5a5737

Libraries/FBReactNativeSpec/FBReactNativeSpec/FBReactNativeSpec-generated.mm

@@ -801,6 +801,10 @@ + (RCTManagedPointer *)JS_NativeAsyncStorage_SpecGetAllKeysCallbackError:(id)jso
       return static_cast<ObjCTurboModule&>(turboModule).invokeObjCMethod(rt, VoidKind, "toggleElementInspector", @selector(toggleElementInspector), args, count);
     }
 
+    static facebook::jsi::Value __hostFunction_NativeDevSettingsSpecJSI_addMenuItem(facebook::jsi::Runtime& rt, TurboModule &turboModule, const facebook::jsi::Value* args, size_t count) {
+      return static_cast<ObjCTurboModule&>(turboModule).invokeObjCMethod(rt, VoidKind, "addMenuItem", @selector(addMenuItem:), args, count);
+    }
+
     static facebook::jsi::Value __hostFunction_NativeDevSettingsSpecJSI_setIsShakeToShowDevMenuEnabled(facebook::jsi::Runtime& rt, TurboModule &turboModule, const facebook::jsi::Value* args, size_t count) {
       return static_cast<ObjCTurboModule&>(turboModule).invokeObjCMethod(rt, VoidKind, "setIsShakeToShowDevMenuEnabled", @selector(setIsShakeToShowDevMenuEnabled:), args, count);
     }
@@ -824,6 +828,9 @@ + (RCTManagedPointer *)JS_NativeAsyncStorage_SpecGetAllKeysCallbackError:(id)jso
         methodMap_["toggleElementInspector"] = MethodMetadata {0, __hostFunction_NativeDevSettingsSpecJSI_toggleElementInspector};
 
 
+        methodMap_["addMenuItem"] = MethodMetadata {1, __hostFunction_NativeDevSettingsSpecJSI_addMenuItem};
+
+
         methodMap_["setIsShakeToShowDevMenuEnabled"] = MethodMetadata {1, __hostFunction_NativeDevSettingsSpecJSI_setIsShakeToShowDevMenuEnabled};
 
 

Libraries/FBReactNativeSpec/FBReactNativeSpec/FBReactNativeSpec.h

@@ -743,6 +743,7 @@ namespace facebook {
 - (void)setIsDebuggingRemotely:(BOOL)isDebuggingRemotelyEnabled;
 - (void)setProfilingEnabled:(BOOL)isProfilingEnabled;
 - (void)toggleElementInspector;
+- (void)addMenuItem:(NSString *)title;
 - (void)setIsShakeToShowDevMenuEnabled:(BOOL)enabled;
 
 @end

Libraries/NativeModules/specs/NativeDevSettings.js

@@ -19,6 +19,7 @@ export interface Spec extends TurboModule {
   +setIsDebuggingRemotely: (isDebuggingRemotelyEnabled: boolean) => void;
   +setProfilingEnabled: (isProfilingEnabled: boolean) => void;
   +toggleElementInspector: () => void;
+  +addMenuItem: (title: string) => void;
 
   // iOS only.
   +setIsShakeToShowDevMenuEnabled: (enabled: boolean) => void;

Libraries/Utilities/DevSettings.js

@@ -0,0 +1,52 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * @format
+ */
+
+import NativeDevSettings from '../NativeModules/specs/NativeDevSettings';
+import NativeEventEmitter from '../EventEmitter/NativeEventEmitter';
+
+class DevSettings extends NativeEventEmitter {
+  _menuItems: Map<string, () => mixed>;
+
+  constructor() {
+    super(NativeDevSettings);
+
+    this._menuItems = new Map();
+  }
+
+  addMenuItem(title: string, handler: () => mixed) {
+    // Make sure items are not added multiple times. This can
+    // happen when hot reloading the module that registers the
+    // menu items. The title is used as the id which means we
+    // don't support multiple items with the same name.
+    const oldHandler = this._menuItems.get(title);
+    if (oldHandler != null) {
+      this.removeListener('didPressMenuItem', oldHandler);
+    } else {
+      NativeDevSettings.addMenuItem(title);
+    }
+
+    this._menuItems.set(title, handler);
+    this.addListener('didPressMenuItem', event => {
+      if (event.title === title) {
+        handler();
+      }
+    });
+  }
+
+  reload() {
+    NativeDevSettings.reload();
+  }
+
+  // TODO: Add other dev setting methods exposed by the native module.
+}
+
+// Avoid including the full `NativeDevSettings` class in prod.
+class NoopDevSettings {
+  addMenuItem(title: string, handler: () => mixed) {}
+  reload() {}
+}
+
+module.exports = __DEV__ ? new DevSettings() : new NoopDevSettings();

RNTester/js/examples/DevSettings/DevSettingsExample.js

@@ -0,0 +1,47 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ * @flow
+ */
+
+'use strict';
+
+import * as React from 'react';
+import {Alert, Button, DevSettings} from 'react-native';
+
+exports.title = 'DevSettings';
+exports.description = 'Customize the development settings';
+exports.examples = [
+  {
+    title: 'Add dev menu item',
+    render(): React.Element<any> {
+      return (
+        <Button
+          title="Add"
+          onPress={() => {
+            DevSettings.addMenuItem('Show Secret Dev Screen', () => {
+              Alert.alert('Showing secret dev screen!');
+            });
+          }}
+        />
+      );
+    },
+  },
+  {
+    title: 'Reload the app',
+    render(): React.Element<any> {
+      return (
+        <Button
+          title="Reload"
+          onPress={() => {
+            DevSettings.reload();
+          }}
+        />
+      );
+    },
+  },
+];

RNTester/js/utils/RNTesterList.android.js

@@ -156,6 +156,10 @@ const APIExamples: Array<RNTesterExample> = [
     key: 'DatePickerAndroidExample',
     module: require('../examples/DatePicker/DatePickerAndroidExample'),
   },
+  {
+    key: 'DevSettings',
+    module: require('../examples/DevSettings/DevSettingsExample'),
+  },
   {
     key: 'Dimensions',
     module: require('../examples/Dimensions/DimensionsExample'),

RNTester/js/utils/RNTesterList.ios.js

@@ -235,6 +235,10 @@ const APIExamples: Array<RNTesterExample> = [
     module: require('../examples/Crash/CrashExample'),
     supportsTVOS: false,
   },
+  {
+    key: 'DevSettings',
+    module: require('../examples/DevSettings/DevSettingsExample'),
+  },
   {
     key: 'Dimensions',
     module: require('../examples/Dimensions/DimensionsExample'),

React/Modules/RCTDevSettings.h

@@ -7,6 +7,7 @@
 
 #import <React/RCTBridge.h>
 #import <React/RCTDefines.h>
+#import <React/RCTEventEmitter.h>
 
 @protocol RCTPackagerClientMethod;
 
@@ -29,7 +30,7 @@
 
 @end
 
-@interface RCTDevSettings : NSObject
+@interface RCTDevSettings : RCTEventEmitter
 
 - (instancetype)initWithDataSource:(id<RCTDevSettingsDataSource>)dataSource;
 

React/Modules/RCTDevSettings.mm

@@ -16,6 +16,8 @@
 #import "RCTProfile.h"
 #import "RCTUtils.h"
 
+#import <React/RCTDevMenu.h>
+
 static NSString *const kRCTDevSettingProfilingEnabled = @"profilingEnabled";
 static NSString *const kRCTDevSettingHotLoadingEnabled = @"hotLoadingEnabled";
 static NSString *const kRCTDevSettingIsInspectorShown = @"showInspector";
@@ -111,8 +113,6 @@ @interface RCTDevSettings () <RCTBridgeModule, RCTInvalidating> {
 
 @implementation RCTDevSettings
 
-@synthesize bridge = _bridge;
-
 RCT_EXPORT_MODULE()
 
 + (BOOL)requiresMainQueueSetup
@@ -152,8 +152,7 @@ - (instancetype)initWithDataSource:(id<RCTDevSettingsDataSource>)dataSource
 
 - (void)setBridge:(RCTBridge *)bridge
 {
-  RCTAssert(_bridge == nil, @"RCTDevSettings module should not be reused");
-  _bridge = bridge;
+  [super setBridge:bridge];
 
 #if ENABLE_PACKAGER_CONNECTION
   RCTBridge *__weak weakBridge = bridge;
@@ -197,6 +196,11 @@ - (void)invalidate
   [[NSNotificationCenter defaultCenter] removeObserver:self];
 }
 
+- (NSArray<NSString *> *)supportedEvents
+{
+  return @[@"didPressMenuItem"];
+}
+
 - (void)_updateSettingWithValue:(id)value forKey:(NSString *)key
 {
   [_dataSource updateSettingWithValue:value forKey:key];
@@ -210,7 +214,7 @@ - (id)settingForKey:(NSString *)key
 - (BOOL)isNuclideDebuggingAvailable
 {
 #if RCT_ENABLE_INSPECTOR
-  return _bridge.isInspectable;
+  return self.bridge.isInspectable;
 #else
   return false;
 #endif // RCT_ENABLE_INSPECTOR
@@ -227,12 +231,12 @@ - (BOOL)isRemoteDebuggingAvailable
 
 - (BOOL)isHotLoadingAvailable
 {
-  return _bridge.bundleURL && !_bridge.bundleURL.fileURL; // Only works when running from server
+  return self.bridge.bundleURL && !self.bridge.bundleURL.fileURL; // Only works when running from server
 }
 
 RCT_EXPORT_METHOD(reload)
 {
-  [_bridge reload];
+  [self.bridge reload];
 }
 
 RCT_EXPORT_METHOD(setIsShakeToShowDevMenuEnabled : (BOOL)enabled)
@@ -285,10 +289,10 @@ - (void)_profilingSettingDidChange
   BOOL enabled = self.isProfilingEnabled;
   if (self.isHotLoadingAvailable && enabled != RCTProfileIsProfiling()) {
     if (enabled) {
-      [_bridge startProfiling];
+      [self.bridge startProfiling];
     } else {
-      [_bridge stopProfiling:^(NSData *logData) {
-        RCTProfileSendResult(self->_bridge, @"systrace", logData);
+      [self.bridge stopProfiling:^(NSData *logData) {
+        RCTProfileSendResult(self.bridge, @"systrace", logData);
       }];
     }
   }
@@ -302,9 +306,9 @@ - (void)_profilingSettingDidChange
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
       if (enabled) {
-        [_bridge enqueueJSCall:@"HMRClient" method:@"enable" args:@[] completion:NULL];
+        [self.bridge enqueueJSCall:@"HMRClient" method:@"enable" args:@[] completion:NULL];
       } else {
-        [_bridge enqueueJSCall:@"HMRClient" method:@"disable" args:@[] completion:NULL];
+        [self.bridge enqueueJSCall:@"HMRClient" method:@"disable" args:@[] completion:NULL];
       }
 #pragma clang diagnostic pop
     }
@@ -329,6 +333,14 @@ - (BOOL)isHotLoadingEnabled
   }
 }
 
+RCT_EXPORT_METHOD(addMenuItem:(NSString *)title)
+{
+  __weak __typeof(self) weakSelf = self;
+  [self.bridge.devMenu addItem:[RCTDevMenuItem buttonItemWithTitle:title handler:^{
+    [weakSelf sendEventWithName:@"didPressMenuItem" body:@{@"title": title}];
+  }]];
+}
+
 - (BOOL)isElementInspectorShown
 {
   return [[self settingForKey:kRCTDevSettingIsInspectorShown] boolValue];
@@ -347,17 +359,17 @@ - (BOOL)isPerfMonitorShown
 - (void)setExecutorClass:(Class)executorClass
 {
   _executorClass = executorClass;
-  if (_bridge.executorClass != executorClass) {
+  if (self.bridge.executorClass != executorClass) {
     // TODO (6929129): we can remove this special case test once we have better
     // support for custom executors in the dev menu. But right now this is
     // needed to prevent overriding a custom executor with the default if a
     // custom executor has been set directly on the bridge
-    if (executorClass == Nil && _bridge.executorClass != objc_lookUpClass("RCTWebSocketExecutor")) {
+    if (executorClass == Nil && self.bridge.executorClass != objc_lookUpClass("RCTWebSocketExecutor")) {
       return;
     }
 
-    _bridge.executorClass = executorClass;
-    [_bridge reload];
+    self.bridge.executorClass = executorClass;
+    [self.bridge reload];
   }
 }
 
@@ -386,7 +398,7 @@ - (void)_synchronizeAllSettings
 
 - (void)jsLoaded:(NSNotification *)notification
 {
-  if (notification.userInfo[@"bridge"] != _bridge) {
+  if (notification.userInfo[@"bridge"] != self.bridge) {
     return;
   }
 

ReactAndroid/src/androidTest/java/com/facebook/react/testing/ReactSettingsForTests.java

@@ -52,4 +52,7 @@ public void setRemoteJSDebugEnabled(boolean remoteJSDebugEnabled) {}
   public boolean isStartSamplingProfilerOnInit() {
     return false;
   }
+
+  @Override
+  public void addMenuItem(String title) {}
 }

ReactAndroid/src/main/java/com/facebook/react/CoreModulesPackage.java

@@ -139,7 +139,7 @@ public NativeModule getModule(String name, ReactApplicationContext reactContext)
       case DeviceEventManagerModule.NAME:
         return new DeviceEventManagerModule(reactContext, mHardwareBackBtnHandler);
       case DevSettingsModule.NAME:
-        return new DevSettingsModule(mReactInstanceManager.getDevSupportManager());
+        return new DevSettingsModule(reactContext, mReactInstanceManager.getDevSupportManager());
       case ExceptionsManagerModule.NAME:
         return new ExceptionsManagerModule(mReactInstanceManager.getDevSupportManager());
       case HeadlessJsTaskSupportModule.NAME:

ReactAndroid/src/main/java/com/facebook/react/devsupport/DevInternalSettings.java

@@ -123,6 +123,11 @@ public boolean isStartSamplingProfilerOnInit() {
     return mPreferences.getBoolean(PREFS_START_SAMPLING_PROFILER_ON_INIT, false);
   }
 
+  @Override
+  public void addMenuItem(String title) {
+    // Not supported.
+  }
+
   public interface Listener {
     void onInternalSettingsChanged();
   }

ReactAndroid/src/main/java/com/facebook/react/modules/debug/DevSettingsModule.java

@@ -6,23 +6,31 @@
  */
 package com.facebook.react.modules.debug;
 
-import com.facebook.react.bridge.BaseJavaModule;
+import com.facebook.react.bridge.Arguments;
+import com.facebook.react.bridge.ReactApplicationContext;
+import com.facebook.react.bridge.ReactContextBaseJavaModule;
 import com.facebook.react.bridge.ReactMethod;
 import com.facebook.react.bridge.UiThreadUtil;
+import com.facebook.react.bridge.WritableMap;
+import com.facebook.react.devsupport.interfaces.DevOptionHandler;
 import com.facebook.react.devsupport.interfaces.DevSupportManager;
 import com.facebook.react.module.annotations.ReactModule;
+import com.facebook.react.modules.core.DeviceEventManagerModule.RCTDeviceEventEmitter;
 
 /**
  * Module that exposes the URL to the source code map (used for exception stack trace parsing) to JS
  */
 @ReactModule(name = DevSettingsModule.NAME)
-public class DevSettingsModule extends BaseJavaModule {
+public class DevSettingsModule extends ReactContextBaseJavaModule {
 
   public static final String NAME = "DevSettings";
 
   private final DevSupportManager mDevSupportManager;
 
-  public DevSettingsModule(DevSupportManager devSupportManager) {
+  public DevSettingsModule(
+      ReactApplicationContext reactContext, DevSupportManager devSupportManager) {
+    super(reactContext);
+
     mDevSupportManager = devSupportManager;
   }
 
@@ -63,4 +71,20 @@ public void setProfilingEnabled(boolean isProfilingEnabled) {
   public void toggleElementInspector() {
     mDevSupportManager.toggleElementInspector();
   }
+
+  @ReactMethod
+  public void addMenuItem(final String title) {
+    mDevSupportManager.addCustomDevOption(
+        title,
+        new DevOptionHandler() {
+          @Override
+          public void onOptionSelected() {
+            WritableMap data = Arguments.createMap();
+            data.putString("title", title);
+            getReactApplicationContext()
+                .getJSModule(RCTDeviceEventEmitter.class)
+                .emit("didPressMenuItem", data);
+          }
+        });
+  }
 }