Fix blog save button highlight

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

CHANGELOG.md

@@ -47,6 +47,9 @@
 * [PostIt] Le changement de disposition de la page des blogs est différé
   sur le thread UI, évitant l'exception « Visual was invalidated during
   the render pass » au redimensionnement.
+* [PostIt] Le bouton d'enregistrement des billets reflète les modifications
+  non sauvegardées et réinitialise son surlignage après sauvegarde, sans
+  fermer l'éditeur ni perdre la sélection.
 
 ## [1.0.8-rc26] - unstable
 

src/PostIt/PostIt.Tests/PostItViewModelTests.cs

@@ -58,6 +58,7 @@ public class PostItViewModelTests
             Dispatcher.UIThread.RunJobs();
             Assert.Same(selected, page.PostsListBox.SelectedItem);
             Assert.Same(selected, vm.SelectedPost);
+            vm.IsEditing = true;
             Assert.DoesNotContain("modified", page.SaveButton.Classes);
             vm.DraftTitle = "Titre modifié";
             Dispatcher.UIThread.RunJobs();
@@ -67,11 +68,13 @@ public class PostItViewModelTests
             await vm.SaveAsync();
             Dispatcher.UIThread.RunJobs();
             Assert.Same(page, navigation.NavigationStack.Last());
+            Assert.True(vm.IsEditing);
             Assert.Same(selected, vm.SelectedPost);
             Assert.Same(selected, page.PostsListBox.SelectedItem);
             Assert.Equal("Titre modifié", vm.DraftTitle);
             Assert.Equal("Corps", vm.DraftArticle);
             Assert.DoesNotContain("modified", page.SaveButton.Classes);
+            Assert.Equal(Avalonia.Media.FontWeight.Normal, page.SaveButton.FontWeight);
         }
         finally
         {

src/PostIt/PostIt/Views/Blogs/BlogsPage.axaml

@@ -17,13 +17,6 @@
   <Design.DataContext>
     <vm:BlogsViewModel />
   </Design.DataContext>
-  <ContentPage.Styles>
-    <Style Selector="CommandBarButton.modified">
-      <Setter Property="Background" Value="#FFF0C2" />
-      <Setter Property="Foreground" Value="#663C00" />
-      <Setter Property="FontWeight" Value="Bold" />
-    </Style>
-  </ContentPage.Styles>
   <Grid x:Name="MainGrid"
     RowDefinitions="Auto,Auto,*,4,2*,Auto"
     Margin="5,5,10,5"

src/PostIt/PostIt/Views/Blogs/BlogsPage.axaml.cs

@@ -1,11 +1,13 @@
 
 using System.IO;
+using System.ComponentModel;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Layout;
 using Avalonia.Platform.Storage;
 using Avalonia.Controls.Primitives;
 using Avalonia.Interactivity;
+using Avalonia.Media;
 using CommunityToolkit.Mvvm.Input;
 using Markdown.Avalonia;
 
@@ -16,6 +18,7 @@ public partial class BlogsPage : ContentPage
     private static readonly RelayCommand<string?> DisabledLinkCommand =
         new(static _ => { }, static _ => false);
     private bool? _isWideLayout;
+    private ViewModels.BlogsViewModel? _observedViewModel;
 
     public BlogsPage()
     {
@@ -26,6 +29,13 @@ public partial class BlogsPage : ContentPage
             UpdateResponsiveLayout();
         });
         DataContextChanged += (_, _) => UpdateHyperlinkCommand();
+        AttachedToVisualTree += (_, _) => UpdateHyperlinkCommand();
+        DetachedFromVisualTree += (_, _) =>
+        {
+            if (_observedViewModel is not null)
+                _observedViewModel.PropertyChanged -= ViewModel_PropertyChanged;
+            _observedViewModel = null;
+        };
         UpdateHyperlinkCommand();
     }
 
@@ -68,13 +78,47 @@ public partial class BlogsPage : ContentPage
 
     private void UpdateHyperlinkCommand()
     {
+        if (_observedViewModel is not null)
+            _observedViewModel.PropertyChanged -= ViewModel_PropertyChanged;
+
+        _observedViewModel = DataContext as ViewModels.BlogsViewModel;
+        if (_observedViewModel is not null)
+            _observedViewModel.PropertyChanged += ViewModel_PropertyChanged;
+
         if (ArticleReader.Engine is IMarkdownEngine2 engine)
         {
-            if (DataContext is ViewModels.BlogsViewModel vm)
-                engine.HyperlinkCommand = vm.OpenResourceCommand;
+            if (_observedViewModel is not null)
+                engine.HyperlinkCommand = _observedViewModel.OpenResourceCommand;
             else
                 engine.HyperlinkCommand = DisabledLinkCommand;
         }
+
+        UpdateSaveButtonHighlight();
+    }
+
+    private void ViewModel_PropertyChanged(object? sender, PropertyChangedEventArgs e)
+    {
+        if (e.PropertyName == nameof(ViewModels.BlogsViewModel.IsDraftModified))
+            UpdateSaveButtonHighlight();
+    }
+
+    private void UpdateSaveButtonHighlight()
+    {
+        if (SaveButton is null)
+            return;
+
+        if (_observedViewModel?.IsDraftModified == true)
+        {
+            SaveButton.FontWeight = FontWeight.Bold;
+            SaveButton.Background = new SolidColorBrush(Color.Parse("#FFF0C2"));
+            SaveButton.Foreground = new SolidColorBrush(Color.Parse("#663C00"));
+        }
+        else
+        {
+            SaveButton.FontWeight = FontWeight.Normal;
+            SaveButton.ClearValue(TemplatedControl.BackgroundProperty);
+            SaveButton.ClearValue(TemplatedControl.ForegroundProperty);
+        }
     }
 
     protected override async void OnApplyTemplate(TemplateAppliedEventArgs e)