Add option for automatic dark theme (#2759)

Summary:
Add an setting option to allow automatic dark theme

A feature requested by swrobel https://github.com/facebook/flipper/issues/2708

## Changelog

### UI change
Replace the `Enable Dark Theme` Toggle button with a Radio group containing three Radio buttons.

The available options are `Dark`, `Light` and `Use System Default`, of which `Use System Default` is the default value

<img width="548" alt="Screenshot 2021-08-31 at 3 32 44 PM" src="https://user-images.githubusercontent.com/410850/131462798-4e74f757-41fc-4a3f-ba28-53d00fc1cf03.png">

### Data structure change

The `darkMode` property of [Settings](c0cd32564a/desktop/app/src/reducers/settings.tsx (L20)) is changed from `boolean` to `string`, the available values are `dark`, `light` and `auto`

Pull Request resolved: https://github.com/facebook/flipper/pull/2759

Test Plan:
### Test 1
- Step: Choose `Dark` in the Settings page and click on `Apply and Restart` button
- Expect: The application is displayed in Dark mode
### Test 2
- Step: Choose `Light` in the Settings page and click on `Apply and Restart` button
- Expect: The application is displayed in Light mode
### Test 3
- Step: Choose `Use System Default` in the Settings page and click on `Apply and Restart` button
- Expect: The application is displayed in System Default mode

Reviewed By: mweststrate

Differential Revision: D30666966

Pulled By: passy

fbshipit-source-id: a63e91f2d0dbff96890e267062cb75bffd0007f4

desktop/app/src/chrome/SettingsSheet.tsx

@@ -7,8 +7,9 @@
  * @format
  */
 
-import {Button} from '../ui';
+import {Button, FlexColumn} from '../ui';
 import React, {Component, useContext} from 'react';
+import {Radio} from 'antd';
 import {updateSettings, Action} from '../reducers/settings';
 import {
   Action as LauncherAction,
@@ -245,18 +246,23 @@ class SettingsSheet extends Component<Props, State> {
             }));
           }}
         />
-        <ToggledSection
-          label="Enable dark theme"
-          toggled={darkMode}
-          onChange={(enabled) => {
+        <FlexColumn style={{paddingLeft: 15, paddingBottom: 10}}>
+          Theme Selection
+          <Radio.Group
+            value={darkMode}
+            onChange={(event) => {
               this.setState((prevState) => ({
                 updatedSettings: {
                   ...prevState.updatedSettings,
-                darkMode: enabled,
+                  darkMode: event.target.value,
                 },
               }));
-          }}
-        />
+            }}>
+            <Radio.Button value="dark">Dark</Radio.Button>
+            <Radio.Button value="light">Light</Radio.Button>
+            <Radio.Button value="system">Use System Setting</Radio.Button>
+          </Radio.Group>
+        </FlexColumn>
         <ToggledSection
           label="React Native keyboard shortcuts"
           toggled={reactNative.shortcuts.enabled}

desktop/app/src/init.tsx

@@ -49,7 +49,7 @@ import styled from '@emotion/styled';
 import {CopyOutlined} from '@ant-design/icons';
 import {getVersionString} from './utils/versionString';
 import {PersistGate} from 'redux-persist/integration/react';
-import {ipcRenderer} from 'electron';
+import {ipcRenderer, remote} from 'electron';
 
 if (process.env.NODE_ENV === 'development' && os.platform() === 'darwin') {
   // By default Node.JS has its internal certificate storage and doesn't use
@@ -213,14 +213,26 @@ function init() {
   sideEffect(
     store,
     {name: 'loadTheme', fireImmediately: false, throttleMs: 500},
-    (state) => ({
-      dark: state.settingsState.darkMode,
-    }),
-    (theme) => {
+    (state) => {
+      const theme = state.settingsState.darkMode;
+      let shouldUseDarkMode = remote.nativeTheme.shouldUseDarkColors;
+      if (theme === 'dark') {
+        shouldUseDarkMode = true;
+      } else if (theme === 'light') {
+        shouldUseDarkMode = false;
+      } else if (theme === 'system') {
+        shouldUseDarkMode = remote.nativeTheme.shouldUseDarkColors;
+      }
+      return {
+        shouldUseDarkMode: shouldUseDarkMode,
+        theme: theme,
+      };
+    },
+    (result) => {
       (
         document.getElementById('flipper-theme-import') as HTMLLinkElement
-      ).href = `themes/${theme.dark ? 'dark' : 'light'}.css`;
-      ipcRenderer.send('setTheme', theme.dark ? 'dark' : 'light');
+      ).href = `themes/${result.shouldUseDarkMode ? 'dark' : 'light'}.css`;
+      ipcRenderer.send('setTheme', result.theme);
     },
   );
 }

desktop/app/src/reducers/settings.tsx

@@ -43,7 +43,7 @@ export type Settings = {
       openDevMenu: string;
     };
   };
-  darkMode: boolean;
+  darkMode: string;
   showWelcomeAtStartup: boolean;
   suppressPluginErrors: boolean;
 };
@@ -78,7 +78,7 @@ const initialState: Settings = {
       openDevMenu: 'Alt+Shift+D',
     },
   },
-  darkMode: false,
+  darkMode: 'auto',
   showWelcomeAtStartup: true,
   suppressPluginErrors: false,
 };

desktop/app/src/utils/useIsDarkMode.tsx

@@ -8,6 +8,7 @@
  */
 
 import {useStore} from './useStore';
+import {remote} from 'electron';
 
 /**
  * This hook returns whether dark mode is currently being used.
@@ -15,5 +16,15 @@ import {useStore} from './useStore';
  * which will provide colors that reflect the theme
  */
 export function useIsDarkMode(): boolean {
-  return useStore((state) => state.settingsState.darkMode);
+  return useStore((state) => {
+    const darkMode = state.settingsState.darkMode;
+    if (darkMode === 'dark') {
+      return true;
+    } else if (darkMode === 'light') {
+      return false;
+    } else if (darkMode === 'system') {
+      return remote.nativeTheme.shouldUseDarkColors;
+    }
+    return false;
+  });
 }

desktop/static/main.ts

@@ -109,9 +109,7 @@ if (argv['disable-gpu'] || process.env.FLIPPER_DISABLE_GPU === '1') {
 }
 
 process.env.CONFIG = JSON.stringify(config);
-if (config.darkMode) {
-  nativeTheme.themeSource = 'dark';
-}
+nativeTheme.themeSource = config.darkMode || 'light';
 
 // possible reference to main app window
 let win: BrowserWindow;
@@ -290,7 +288,7 @@ ipcMain.on('getLaunchTime', (event) => {
   }
 });
 
-ipcMain.on('setTheme', (_e, mode: 'light' | 'dark') => {
+ipcMain.on('setTheme', (_e, mode: 'light' | 'dark' | 'system') => {
   nativeTheme.themeSource = mode;
 });
 
@@ -382,7 +380,7 @@ function createWindow() {
       configPath,
       JSON.stringify({
         ...config,
-        darkMode: nativeTheme.themeSource === 'dark',
+        darkMode: nativeTheme.themeSource,
         lastWindowPosition: {
           x,
           y,

desktop/static/setup.ts

@@ -24,7 +24,7 @@ export type Config = {
   launcherMsg?: string | undefined;
   updaterEnabled?: boolean;
   launcherEnabled?: boolean;
-  darkMode?: boolean;
+  darkMode: 'system' | 'light' | 'dark';
 };
 
 export default function setup(argv: any) {
@@ -38,6 +38,7 @@ export default function setup(argv: any) {
   let config: Config = {
     pluginPaths: [],
     disabledPlugins: [],
+    darkMode: 'light',
   };
 
   try {