feat: add APIs to support mojave dark modes (electron#14755)

* feat: add APIs to support mojave dark mode

Closes electron#13387

* docs: fix system-prefs typo

atom/browser/api/atom_api_system_preferences.cc

@@ -77,6 +77,12 @@ void SystemPreferences::BuildPrototype(
       .SetMethod("removeUserDefault", &SystemPreferences::RemoveUserDefault)
       .SetMethod("isSwipeTrackingFromScrollEventsEnabled",
                  &SystemPreferences::IsSwipeTrackingFromScrollEventsEnabled)
+      .SetMethod("getEffectiveAppearance",
+                 &SystemPreferences::GetEffectiveAppearance)
+      .SetMethod("getAppLevelAppearance",
+                 &SystemPreferences::GetAppLevelAppearance)
+      .SetMethod("setAppLevelAppearance",
+                 &SystemPreferences::SetAppLevelAppearance)
 #endif
       .SetMethod("isInvertedColorScheme",
                  &SystemPreferences::IsInvertedColorScheme)

atom/browser/api/atom_api_system_preferences.h

@@ -89,6 +89,12 @@ class SystemPreferences : public mate::EventEmitter<SystemPreferences>
                       mate::Arguments* args);
   void RemoveUserDefault(const std::string& name);
   bool IsSwipeTrackingFromScrollEventsEnabled();
+
+  // TODO(MarshallOfSound): Write tests for these methods once we
+  // are running tests on a Mojave machine
+  v8::Local<v8::Value> GetEffectiveAppearance(v8::Isolate* isolate);
+  v8::Local<v8::Value> GetAppLevelAppearance(v8::Isolate* isolate);
+  void SetAppLevelAppearance(mate::Arguments* args);
 #endif
   bool IsDarkMode();
   bool IsInvertedColorScheme();

atom/browser/api/atom_api_system_preferences_mac.mm

@@ -8,13 +8,58 @@
 
 #import <Cocoa/Cocoa.h>
 
+#include "atom/browser/mac/atom_application.h"
 #include "atom/browser/mac/dict_util.h"
 #include "atom/common/native_mate_converters/gurl_converter.h"
 #include "atom/common/native_mate_converters/value_converter.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/values.h"
+#include "native_mate/object_template_builder.h"
 #include "net/base/mac/url_conversions.h"
 
+namespace mate {
+template <>
+struct Converter<NSAppearance*> {
+  static bool FromV8(v8::Isolate* isolate,
+                     v8::Local<v8::Value> val,
+                     NSAppearance** out) {
+    if (val->IsNull()) {
+      *out = nil;
+      return true;
+    }
+
+    std::string name;
+    if (!mate::ConvertFromV8(isolate, val, &name)) {
+      return false;
+    }
+
+    if (name == "light") {
+      *out = [NSAppearance appearanceNamed:NSAppearanceNameAqua];
+      return true;
+    } else if (name == "dark") {
+      *out = [NSAppearance appearanceNamed:NSAppearanceNameDarkAqua];
+      return true;
+    }
+
+    return false;
+  }
+
+  static v8::Local<v8::Value> ToV8(v8::Isolate* isolate, NSAppearance* val) {
+    if (val == nil) {
+      return v8::Null(isolate);
+    }
+    if (val.name == NSAppearanceNameAqua) {
+      return mate::ConvertToV8(isolate, "light");
+    }
+    if (val.name == NSAppearanceNameDarkAqua) {
+      return mate::ConvertToV8(isolate, "dark");
+    }
+
+    return mate::ConvertToV8(isolate, "unknown");
+  }
+};
+}  // namespace mate
+
 namespace atom {
 
 namespace api {
@@ -323,6 +368,35 @@
   return [NSEvent isSwipeTrackingFromScrollEventsEnabled];
 }
 
+v8::Local<v8::Value> SystemPreferences::GetEffectiveAppearance(
+    v8::Isolate* isolate) {
+  if (@available(macOS 10.14, *)) {
+    return mate::ConvertToV8(
+        isolate, [NSApplication sharedApplication].effectiveAppearance);
+  }
+  return v8::Null(isolate);
+}
+
+v8::Local<v8::Value> SystemPreferences::GetAppLevelAppearance(
+    v8::Isolate* isolate) {
+  if (@available(macOS 10.14, *)) {
+    return mate::ConvertToV8(isolate,
+                             [NSApplication sharedApplication].appearance);
+  }
+  return v8::Null(isolate);
+}
+
+void SystemPreferences::SetAppLevelAppearance(mate::Arguments* args) {
+  if (@available(macOS 10.14, *)) {
+    NSAppearance* appearance;
+    if (args->GetNext(&appearance)) {
+      [[NSApplication sharedApplication] setAppearance:appearance];
+    } else {
+      args->ThrowError("Invalid app appearance provided as first argument");
+    }
+  }
+}
+
 }  // namespace api
 
 }  // namespace atom

atom/browser/mac/atom_application.h

@@ -6,6 +6,21 @@
 #include "base/mac/scoped_nsobject.h"
 #include "base/mac/scoped_sending_event.h"
 
+// Forward Declare Appareance APIs
+@interface NSApplication (HighSierraSDK)
+@property(copy, readonly)
+    NSAppearance* effectiveAppearance API_AVAILABLE(macosx(10.14));
+@property(copy, readonly) NSAppearance* appearance API_AVAILABLE(macosx(10.14));
+- (void)setAppearance:(NSAppearance*)appearance API_AVAILABLE(macosx(10.14));
+@end
+
+extern "C" {
+#if !defined(MAC_OS_X_VERSION_10_14) || \
+    MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_14
+BASE_EXPORT extern NSString* const NSAppearanceNameDarkAqua;
+#endif  // MAC_OS_X_VERSION_10_14
+}  // extern "C"
+
 @interface AtomApplication : NSApplication <CrAppProtocol,
                                             CrAppControlProtocol,
                                             NSUserActivityDelegate> {

atom/browser/mac/atom_application.mm

@@ -11,6 +11,11 @@
 #include "base/strings/sys_string_conversions.h"
 #include "content/public/browser/browser_accessibility_state.h"
 
+#if !defined(MAC_OS_X_VERSION_10_14) || \
+    MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_14
+NSString* const NSAppearanceNameDarkAqua = @"NSAppearanceNameDarkAqua";
+#endif  // MAC_OS_X_VERSION_10_14
+
 namespace {
 
 inline void dispatch_sync_main(dispatch_block_t block) {

default_app/default_app.js

@@ -1,4 +1,4 @@
-const { app, BrowserWindow } = require('electron')
+const { app, BrowserWindow, systemPreferences } = require('electron')
 const path = require('path')
 
 let mainWindow = null
@@ -11,6 +11,10 @@ app.on('window-all-closed', () => {
 exports.load = async (appUrl) => {
   await app.whenReady()
 
+  if (process.platform === 'darwin') {
+    systemPreferences.startAppLevelAppearanceTrackingOS()
+  }
+
   const options = {
     width: 900,
     height: 600,

docs/api/system-preferences.md

@@ -35,6 +35,14 @@ Returns:
 * `invertedColorScheme` Boolean - `true` if an inverted color scheme, such as
   a high contrast theme, is being used, `false` otherwise.
 
+### Event: 'appearance-changed' _macOS_
+
+Returns:
+
+* `newAppearance` String - Can be `dark` or `light`
+
+**NOTE:** This event is only emitted after you have called `startAppLevelAppearanceTrackingOS`
+
 ## Methods
 
 ### `systemPreferences.isDarkMode()` _macOS_
@@ -274,3 +282,51 @@ Returns `Boolean` - `true` if an inverted color scheme, such as a high contrast
 theme, is active, `false` otherwise.
 
 [windows-colors]:https://msdn.microsoft.com/en-us/library/windows/desktop/ms724371(v=vs.85).aspx
+
+### `systemPreferences.getEffectiveAppearance()` _macOS_
+
+Returns `String` - Can be `dark`, `light` or `unknown`.
+
+Gets the macOS appearance setting that is currently applied to your application,
+maps to [NSApplication.effectiveAppearance](https://developer.apple.com/documentation/appkit/nsapplication/2967171-effectiveappearance?language=objc)
+
+Please note that until Electron is built targeting the 10.14 SDK, your application's
+`effectiveAppearance` will default to 'light' and won't inherit the OS preference. In
+the interim we have provided a helper method `startAppLevelAppearanceTrackingOS()`
+which emulates this behavior.
+
+### `systemPreferences.getAppLevelAppearance()` _macOS_
+
+Returns `String` | `null` - Can be `dark`, `light` or `unknown`.
+
+Gets the macOS appearance setting that you have declared you want for
+your application, maps to [NSApplication.appearance](https://developer.apple.com/documentation/appkit/nsapplication/2967170-appearance?language=objc).
+You can use the `setAppLevelAppearance` API to set this value.
+
+### `systemPreferences.setAppLevelAppearance(appearance)` _macOS_
+
+* `appearance` String | null - Can be `dark` or `light`
+
+Sets the appearance setting for your application, this should override the
+system default and override the value of `getEffectiveAppearance`.
+
+### `systemPreferences.startAppLevelAppearanceTrackingOS()` _macOS_
+
+This is a helper method to make your application's "appearance" setting track the
+user's OS level appearance setting.  I.e. your app will have dark mode enabled if
+the user's system has dark mode enabled.
+
+You can track this automatic change with the `appearance-changed` event.
+
+**Note:** This method is exempt from our standard deprecation cycle and will be removed
+without deprecation in an upcoming major release of Electron as soon as we target the 10.14
+SDK
+
+### `systemPreferences.stopAppLevelAppearanceTrackingOS()` _macOS_
+
+This is a helper method to stop your application tracking the OS level appearance
+setting.  It is a no-op if you have not called `startAppLevelAppearanceTrackingOS()`
+
+**Note:** This method is exempt from our standard deprecation cycle and will be removed
+without deprecation in an upcoming major release of Electron as soon as we target the 10.14
+SDK

lib/browser/api/system-preferences.js

@@ -1,10 +1,47 @@
 'use strict'
 
+const { app } = require('electron')
 const { EventEmitter } = require('events')
 const { systemPreferences, SystemPreferences } = process.atomBinding('system_preferences')
 
 // SystemPreferences is an EventEmitter.
 Object.setPrototypeOf(SystemPreferences.prototype, EventEmitter.prototype)
 EventEmitter.call(systemPreferences)
 
+if (process.platform === 'darwin') {
+  let appearanceTrackingSubscriptionID = null
+
+  systemPreferences.startAppLevelAppearanceTrackingOS = () => {
+    if (appearanceTrackingSubscriptionID !== null) return
+
+    const updateAppearanceBasedOnOS = () => {
+      const newAppearance = systemPreferences.isDarkMode()
+        ? 'dark'
+        : 'light'
+
+      if (systemPreferences.getAppLevelAppearance() !== newAppearance) {
+        systemPreferences.setAppLevelAppearance(newAppearance)
+        // TODO(MarshallOfSound): Once we remove this logic and build against 10.14
+        // SDK we should re-implement this event as a monitor of `effectiveAppearance`
+        systemPreferences.emit('appearance-changed', newAppearance)
+      }
+    }
+
+    appearanceTrackingSubscriptionID = systemPreferences.subscribeNotification(
+      'AppleInterfaceThemeChangedNotification',
+      updateAppearanceBasedOnOS
+    )
+
+    updateAppearanceBasedOnOS()
+  }
+
+  systemPreferences.stopAppLevelAppearanceTrackingOS = () => {
+    if (appearanceTrackingSubscriptionID === null) return
+
+    systemPreferences.unsubscribeNotification(appearanceTrackingSubscriptionID)
+  }
+
+  app.on('quit', systemPreferences.stopAppLevelAppearanceTrackingOS)
+}
+
 module.exports = systemPreferences