From 414791232a79c783d3d758fe11a864344d513660 Mon Sep 17 00:00:00 2001
From: Shelley Vohr <shelley.vohr@gmail.com>
Date: Tue, 10 Jan 2023 12:19:00 +0100
Subject: [PATCH] fix: RTL `WindowButtonsProxy` buttons (#36839)

* fix: RTL WindowButtonsProxy buttons

* chore: address review feedback
---
 shell/browser/browser.h                      |  2 ++
 shell/browser/browser_mac.mm                 | 35 ++++++++++++++++++++
 shell/browser/electron_browser_main_parts.cc |  1 +
 3 files changed, 38 insertions(+)

diff --git a/shell/browser/browser.h b/shell/browser/browser.h
index e8044308f3d1..5ce95cff4105 100644
--- a/shell/browser/browser.h
+++ b/shell/browser/browser.h
@@ -202,6 +202,8 @@ class Browser : public WindowListObserver {
   bool UpdateUserActivityState(const std::string& type,
                                base::Value::Dict user_info);
 
+  void ApplyForcedRTL();
+
   // Bounce the dock icon.
   enum class BounceType {
     kCritical = 0,        // NSCriticalRequest
diff --git a/shell/browser/browser_mac.mm b/shell/browser/browser_mac.mm
index aec95140526f..a8bb5e6d6a22 100644
--- a/shell/browser/browser_mac.mm
+++ b/shell/browser/browser_mac.mm
@@ -8,6 +8,7 @@
 #include <string>
 #include <utility>
 
+#include "base/i18n/rtl.h"
 #include "base/mac/bundle_locations.h"
 #include "base/mac/foundation_util.h"
 #include "base/mac/mac_util.h"
@@ -15,6 +16,7 @@
 #include "base/mac/scoped_cftyperef.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/sys_string_conversions.h"
+#include "chrome/browser/browser_process.h"
 #include "net/base/mac/url_conversions.h"
 #include "shell/browser/badging/badge_manager.h"
 #include "shell/browser/mac/dict_util.h"
@@ -37,6 +39,13 @@ namespace electron {
 
 namespace {
 
+bool IsAppRTL() {
+  const std::string& locale = g_browser_process->GetApplicationLocale();
+  base::i18n::TextDirection text_direction =
+      base::i18n::GetTextDirectionForLocaleInStartUp(locale.c_str());
+  return text_direction == base::i18n::RIGHT_TO_LEFT;
+}
+
 NSString* GetAppPathForProtocol(const GURL& url) {
   NSURL* ns_url = [NSURL
       URLWithString:base::SysUTF8ToNSString(url.possibly_invalid_spec())];
@@ -325,6 +334,32 @@ bool Browser::UpdateUserActivityState(const std::string& type,
   return prevent_default;
 }
 
+// Modified from chrome/browser/ui/cocoa/l10n_util.mm.
+void Browser::ApplyForcedRTL() {
+  NSUserDefaults* defaults = NSUserDefaults.standardUserDefaults;
+
+  auto dir = base::i18n::GetForcedTextDirection();
+
+  // An Electron app should respect RTL behavior of application locale over
+  // system locale.
+  auto should_be_rtl = dir == base::i18n::RIGHT_TO_LEFT || IsAppRTL();
+  auto should_be_ltr = dir == base::i18n::LEFT_TO_RIGHT || !IsAppRTL();
+
+  // -registerDefaults: won't do the trick here because these defaults exist
+  // (in the global domain) to reflect the system locale. They need to be set
+  // in Chrome's domain to supersede the system value.
+  if (should_be_rtl) {
+    [defaults setBool:YES forKey:@"AppleTextDirection"];
+    [defaults setBool:YES forKey:@"NSForceRightToLeftWritingDirection"];
+  } else if (should_be_ltr) {
+    [defaults setBool:YES forKey:@"AppleTextDirection"];
+    [defaults setBool:NO forKey:@"NSForceRightToLeftWritingDirection"];
+  } else {
+    [defaults removeObjectForKey:@"AppleTextDirection"];
+    [defaults removeObjectForKey:@"NSForceRightToLeftWritingDirection"];
+  }
+}
+
 Browser::LoginItemSettings Browser::GetLoginItemSettings(
     const LoginItemSettings& options) {
   LoginItemSettings settings;
diff --git a/shell/browser/electron_browser_main_parts.cc b/shell/browser/electron_browser_main_parts.cc
index f5a00aa2b55a..37a715dcf0eb 100644
--- a/shell/browser/electron_browser_main_parts.cc
+++ b/shell/browser/electron_browser_main_parts.cc
@@ -382,6 +382,7 @@ int ElectronBrowserMainParts::PreCreateThreads() {
 
 #if BUILDFLAG(IS_MAC)
   ui::InitIdleMonitor();
+  Browser::Get()->ApplyForcedRTL();
 #endif
 
   fake_browser_process_->PreCreateThreads();