Fix safe area calcs for navigation page (#21221)

* fix safe area calcs for navigation page

* update nav bar effective height on safe area change

* reset nav bar height if visibility changes

* add tests

src/Avalonia.Controls/Page/NavigationPage.cs

@@ -639,6 +639,9 @@ namespace Avalonia.Controls
                     "Direct assignment to NavigationPage.Pages is not supported. Use PushAsync, PopAsync, InsertPage, RemovePage, or ReplaceAsync to modify the navigation stack.");
             }
 
+            if (change.Property == SafeAreaPaddingProperty)
+                UpdateEffectiveBarHeight();
+
             base.OnPropertyChanged(change);
         }
 
@@ -750,7 +753,10 @@ namespace Avalonia.Controls
         {
             if (_contentHost != null && _navBar != null)
             {
-                _navBar.Padding = new Thickness(SafeAreaPadding.Left, SafeAreaPadding.Top, SafeAreaPadding.Right, 0);
+                var safeAreaPadding = IsNavBarEffectivelyVisible ? new Thickness(SafeAreaPadding.Left, 0, SafeAreaPadding.Right, SafeAreaPadding.Bottom) : SafeAreaPadding;
+                _navBar.Padding = IsNavBarEffectivelyVisible
+                    ? new Thickness(SafeAreaPadding.Left, SafeAreaPadding.Top, SafeAreaPadding.Right, 0)
+                    : default;
 
                 if (_pagePresenter != null)
                     _pagePresenter.Padding = Padding;
@@ -759,8 +765,8 @@ namespace Avalonia.Controls
 
                 if (CurrentPage != null)
                 {
-                    var remainingSafeArea = Padding.GetRemainingSafeAreaPadding(SafeAreaPadding);
+                    var remainingSafeArea = Padding.GetRemainingSafeAreaPadding(safeAreaPadding);
-                    CurrentPage.SafeAreaPadding = new Thickness(remainingSafeArea.Left, 0, remainingSafeArea.Right, remainingSafeArea.Bottom);
+                    CurrentPage.SafeAreaPadding = new Thickness(remainingSafeArea.Left, remainingSafeArea.Top, remainingSafeArea.Right, remainingSafeArea.Bottom);
                 }
 
                 foreach (var modal in _modalStack)
@@ -2148,8 +2154,11 @@ namespace Avalonia.Controls
 
         private void UpdateEffectiveBarHeight()
         {
-            EffectiveBarHeight = (CurrentPage != null ? GetBarHeightOverride(CurrentPage) : null) ?? BarHeight;
+            var contentBarHeight = (CurrentPage != null ? GetBarHeightOverride(CurrentPage) : null) ?? BarHeight;
-            PseudoClasses.Set(":nav-bar-compact", EffectiveBarHeight < 40);
+            EffectiveBarHeight = contentBarHeight + SafeAreaPadding.Top;
+            PseudoClasses.Set(":nav-bar-compact", contentBarHeight < 40);
+
+            UpdateContentSafeAreaPadding();
         }
 
         private void ApplyNavBarVisibility()

tests/Avalonia.Controls.UnitTests/NavigationPageTests.cs

@@ -1385,6 +1385,19 @@ public class NavigationPageTests
             var nav = new NavigationPage { IsGestureEnabled = value };
             Assert.Equal(value, nav.IsGestureEnabled);
         }
+
+        [Fact]
+        public async Task SafeAreaPadding_Affeccts_Nav_Bar_Height()
+        {
+            var nav = new NavigationPage()
+            {
+                SafeAreaPadding = new Thickness(10)
+            };
+            var page = new ContentPage();
+            NavigationPage.SetBarHeightOverride(page, 60.0);
+            await nav.PushAsync(page);
+            Assert.Equal(70.0, nav.EffectiveBarHeight);
+        }
     }
 
     public class AttachedPropertyTests : ScopedTestBase