From cdacd21dfdffc676cbfe290dbe68f6111c0e850f Mon Sep 17 00:00:00 2001
From: Nobody <no-reply@google.com>
Date: Mon, 3 Apr 2023 08:02:15 -0700
Subject: [PATCH] [NavigationSuite] Add delegate API that allows users to set a
 callback block that is called when the layout changed under automatic mode.

PiperOrigin-RevId: 521460143
---
 .../src/MDCBottomNavigationBarController.m         | 14 +++++++-------
 .../src/MDCBottomNavigationBarControllerDelegate.h | 14 ++++++++++++++
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/components/BottomNavigation/src/MDCBottomNavigationBarController.m b/components/BottomNavigation/src/MDCBottomNavigationBarController.m
index c2632d719..f94d384dd 100644
--- a/components/BottomNavigation/src/MDCBottomNavigationBarController.m
+++ b/components/BottomNavigation/src/MDCBottomNavigationBarController.m
@@ -238,15 +238,10 @@ static UIViewController *_Nullable DecodeViewController(NSCoder *coder, NSString
   if (self.layoutMode != MDCBottomNavigationBarLayoutModeAutomatic) {
     return;
   }
-  BOOL shouldUseVerticalLayout = [self useVerticalLayoutAfterTransitioningToSize:size];
-  if (shouldUseVerticalLayout == self.enableVerticalLayout) {
+  BOOL enableVerticalLayout = [self useVerticalLayoutAfterTransitioningToSize:size];
+  if (enableVerticalLayout == self.enableVerticalLayout) {
     return;
   }
-  [self enableVerticalLayout:shouldUseVerticalLayout withTransitionCoordinator:coordinator];
-}
-
-- (void)enableVerticalLayout:(BOOL)enableVerticalLayout
-    withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator {
   // The setter is not used here since the setter also sets the navigationBar's enableVerticalLayout
   // flag and we set that here manually to control animations.
   _enableVerticalLayout = enableVerticalLayout;
@@ -280,6 +275,11 @@ static UIViewController *_Nullable DecodeViewController(NSCoder *coder, NSString
                             options:UIViewAnimationOptionCurveEaseOut
                          animations:lastAnimations
                          completion:nil];
+
+        if ([self.delegate
+                respondsToSelector:@selector(bottomNavigationBarControllerDidUpdateLayout)]) {
+          [self.delegate bottomNavigationBarControllerDidUpdateLayout];
+        }
       }];
 }
 
diff --git a/components/BottomNavigation/src/MDCBottomNavigationBarControllerDelegate.h b/components/BottomNavigation/src/MDCBottomNavigationBarControllerDelegate.h
index f18b26aa4..db49d4e6f 100644
--- a/components/BottomNavigation/src/MDCBottomNavigationBarControllerDelegate.h
+++ b/components/BottomNavigation/src/MDCBottomNavigationBarControllerDelegate.h
@@ -16,6 +16,8 @@
 
 #import "MDCMinimumOS.h"  // IWYU pragma: keep
 
+NS_ASSUME_NONNULL_BEGIN
+
 @class MDCBottomNavigationBarController;
 
 /**
@@ -43,4 +45,16 @@
             (nonnull MDCBottomNavigationBarController *)bottomNavigationBarController
            shouldSelectViewController:(nonnull UIViewController *)viewController;
 
+/**
+ Delegates may implement this method if they want to execute some code right
+ after the controller changes layout in @c MDCBottomNavigationBarLayoutModeAutomatic
+ mode.
+ @warning Do not rely on this method when
+ @c MDCBottomNavigationBarLayoutModeVertical or
+ @c MDCBottomNavigationBarLayoutModeHorizontal mode is used.
+ */
+- (void)bottomNavigationBarControllerDidUpdateLayout;
+
 @end
+
+NS_ASSUME_NONNULL_END