Implement full-screen video playback feature in PLib video library manager. Add toggle functionality for full-screen mode in VideoPlayerViewModel and corresponding UI updates in VideoPlayerView and MainWindow. Adjust key event handling for full-screen toggling and enhance README.md to document new features and usage instructions.

README.md

@@ -14,8 +14,8 @@
   в `settings.json` и подхватывается без перезапуска.
 - Светлая, тёмная и системная темы; выбор запоминается.
 - Встроенный плеер: клик по карточке открывает страницу медиа прямо в окне — видео,
-  перемотка, громкость, кнопка «назад». Внешний плеер и «показать в папке» остались
+  перемотка, громкость, кнопка «назад». Полноэкранный режим по F11 или кнопке, выход —
-  в контекстном меню карточки.
+  Escape. Внешний плеер и «показать в папке» остались в контекстном меню карточки.
 
 ## Требования
 
@@ -86,6 +86,9 @@ dotnet test
   дублировать это состояние во вьюмодель значило бы держать вторую копию и синхронизировать её.
   Закрытие страницы обнуляет `OpenedVideo`, вью уходит из дерева, `DestroyNativeControlCore`
   гасит плеер.
+  По той же причине в полноэкранном режиме остаётся тонкая полоса управления внизу:
+  всплывающего оверлея поверх видео нативная поверхность не допускает, а движение мыши над
+  ней до Avalonia не доходит — автоскрытию не на что реагировать.
   Готовый `MediaPlayer.Controls` пробовали до этого: декодер работал, но кадры до экрана
   не доходили — чёрный экран и на GPU-, и на CPU-пути, при полностью рабочем в приложении
   `OpenGlControlBase`. Свой контрол ни от чьей версии Avalonia не зависит.

src/PLib.Desktop/ViewModels/MainWindowViewModel.cs

@@ -61,6 +61,7 @@ public sealed partial class MainWindowViewModel : ViewModelBase
     private readonly ObservableAsPropertyHelper<bool> _isEmpty;
     private readonly ObservableAsPropertyHelper<bool> _isSettingsOpen;
     private readonly ObservableAsPropertyHelper<bool> _isPlayerOpen;
+    private readonly ObservableAsPropertyHelper<bool> _isVideoFullScreen;
 
     public MainWindowViewModel(
         IServiceScopeFactory scopeFactory,
@@ -109,6 +110,16 @@ public sealed partial class MainWindowViewModel : ViewModelBase
             () => { OpenedVideo = null; },
             this.WhenAnyValue(x => x.IsPlayerOpen));
 
+        // Follow whichever page is open: Switch drops the previous page's flag when the
+        // page is replaced, so a closed player can never leave the window without chrome.
+        _isVideoFullScreen = this
+            .WhenAnyValue(x => x.OpenedVideo)
+            .Select(video => video is null
+                ? Observable.Return(false)
+                : video.WhenAnyValue(x => x.IsFullScreen))
+            .Switch()
+            .ToProperty(this, x => x.IsVideoFullScreen);
+
         // Cancellation the ReactiveUI way: the scan runs as an observable, and cancelling
         // simply unsubscribes it, which cancels the token Observable.StartAsync handed out.
         ScanCommand = ReactiveCommand.CreateFromObservable(
@@ -161,6 +172,9 @@ public sealed partial class MainWindowViewModel : ViewModelBase
 
     public bool IsPlayerOpen => _isPlayerOpen.Value;
 
+    /// <summary>True while the media page has taken over the whole window.</summary>
+    public bool IsVideoFullScreen => _isVideoFullScreen.Value;
+
     /// <summary>
     /// The settings panel while it is on screen, or <c>null</c>. Its presence is what the
     /// overlay binds to — settings live in this window rather than a second one.

src/PLib.Desktop/ViewModels/VideoPlayerViewModel.cs

@@ -1,5 +1,6 @@
 using PLib.Desktop.Services;
 using ReactiveUI;
+using ReactiveUI.SourceGenerators;
 using RxVoid = ReactiveUI.Primitives.RxVoid;
 
 namespace PLib.Desktop.ViewModels;
@@ -9,7 +10,7 @@ namespace PLib.Desktop.ViewModels;
 /// commands around the player — transport state belongs to the media control itself, which
 /// already exposes position, duration and playback as bindable properties.
 /// </summary>
-public sealed class VideoPlayerViewModel : ViewModelBase
+public sealed partial class VideoPlayerViewModel : ViewModelBase
 {
     public VideoPlayerViewModel(VideoCardViewModel card, ISystemShell shell, Action close)
     {
@@ -23,6 +24,7 @@ public sealed class VideoPlayerViewModel : ViewModelBase
                 .Where(part => !string.IsNullOrWhiteSpace(part)));
 
         CloseCommand = ReactiveCommand.Create(close);
+        ToggleFullScreenCommand = ReactiveCommand.Create(() => { IsFullScreen = !IsFullScreen; });
         OpenExternallyCommand = ReactiveCommand.Create(() => shell.OpenFile(FullPath));
         RevealCommand = ReactiveCommand.Create(() => shell.RevealInFileManager(FullPath));
     }
@@ -39,6 +41,16 @@ public sealed class VideoPlayerViewModel : ViewModelBase
 
     public ReactiveCommand<RxVoid, RxVoid> CloseCommand { get; }
 
+    public ReactiveCommand<RxVoid, RxVoid> ToggleFullScreenCommand { get; }
+
+    /// <summary>
+    /// True while the window is given over to the video. The page hides its own header and
+    /// the window hides its chrome; the transport strip stays, because a native video
+    /// surface cannot be drawn over and a floating overlay is therefore impossible.
+    /// </summary>
+    [Reactive]
+    public partial bool IsFullScreen { get; set; }
+
     public ReactiveCommand<RxVoid, RxVoid> OpenExternallyCommand { get; }
 
     public ReactiveCommand<RxVoid, RxVoid> RevealCommand { get; }

src/PLib.Desktop/Views/MainWindow.axaml

@@ -103,7 +103,7 @@
   <Grid RowDefinitions="Auto,*,Auto">
 
     <!-- ======================= Header ======================= -->
-    <Border Grid.Row="0" Classes="appBar">
+    <Border Grid.Row="0" Classes="appBar" IsVisible="{Binding !IsVideoFullScreen}">
       <Grid ColumnDefinitions="Auto,*,Auto" ColumnSpacing="20">
 
         <StackPanel Grid.Column="0" Orientation="Horizontal" Spacing="10" VerticalAlignment="Center">
@@ -236,7 +236,7 @@
     </Grid>
 
     <!-- ======================= Status bar ======================= -->
-    <Border Grid.Row="2" Classes="statusBar">
+    <Border Grid.Row="2" Classes="statusBar" IsVisible="{Binding !IsVideoFullScreen}">
       <Grid ColumnDefinitions="Auto,*,Auto" ColumnSpacing="14">
 
         <ProgressBar Grid.Column="0"

src/PLib.Desktop/Views/MainWindow.axaml.cs

@@ -24,23 +24,32 @@ public sealed partial class MainWindow : ReactiveWindow<MainWindowViewModel>
 
     private void OnPreviewKeyDown(object? sender, KeyEventArgs e)
     {
-        if (e.Key is not Key.Escape || DataContext is not MainWindowViewModel viewModel)
+        if (DataContext is not MainWindowViewModel viewModel)
         {
             return;
         }
 
-        // The settings panel sits above the media page, so it is the one Escape dismisses
+        // Escape peels one layer at a time: the settings panel sits above everything, then
-        // first; only once it is gone does Escape mean "back to the library".
+        // full screen is given up, and only a plain media page means "back to the library".
-        if (viewModel.IsSettingsOpen)
+        switch (e.Key)
         {
+            case Key.F11 when viewModel.OpenedVideo is { } video:
+                video.ToggleFullScreenCommand.Execute().Subscribe();
+                break;
+
+            case Key.Escape when viewModel.IsSettingsOpen:
                 viewModel.CloseSettingsCommand.Execute().Subscribe();
-        }
+                break;
-        else if (viewModel.IsPlayerOpen)
+
-        {
+            case Key.Escape when viewModel.OpenedVideo is { IsFullScreen: true } fullScreen:
+                fullScreen.IsFullScreen = false;
+                break;
+
+            case Key.Escape when viewModel.IsPlayerOpen:
                 viewModel.ClosePlayerCommand.Execute().Subscribe();
-        }
+                break;
-        else
+
-        {
+            default:
                 return;
         }
 

src/PLib.Desktop/Views/VideoPlayerView.axaml

@@ -26,7 +26,7 @@
   <Grid RowDefinitions="Auto,*,Auto">
 
     <!-- ======================= Page header ======================= -->
-    <Border Grid.Row="0" Classes="panelHeader" Padding="16,10">
+    <Border Grid.Row="0" Classes="panelHeader" Padding="16,10" IsVisible="{Binding !IsFullScreen}">
       <Grid ColumnDefinitions="Auto,*,Auto" ColumnSpacing="12">
 
         <Button Grid.Column="0"
@@ -84,7 +84,7 @@
 
     <!-- ======================= Transport ======================= -->
     <Border Grid.Row="2" Classes="panelFooter" Padding="16,10">
-      <Grid ColumnDefinitions="Auto,Auto,*,Auto,Auto,Auto" ColumnSpacing="10">
+      <Grid ColumnDefinitions="Auto,Auto,*,Auto,Auto,Auto,Auto" ColumnSpacing="10">
 
         <Button Grid.Column="0" Name="PlayPauseButton" Classes="transport">
           <icons:MaterialIcon Name="PlayPauseIcon" Kind="Pause" Width="20" Height="20" />
@@ -112,6 +112,13 @@
                 Value="0.8"
                 VerticalAlignment="Center" />
 
+        <Button Grid.Column="6"
+                Classes="transport"
+                Command="{Binding ToggleFullScreenCommand}"
+                ToolTip.Tip="Во весь экран (F11)">
+          <icons:MaterialIcon Name="FullScreenIcon" Kind="Fullscreen" Width="19" Height="19" />
+        </Button>
+
       </Grid>
     </Border>
 

src/PLib.Desktop/Views/VideoPlayerView.axaml.cs

@@ -2,9 +2,11 @@ using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
+using System.Reactive.Disposables;
 using Avalonia.Interactivity;
 using PLib.Desktop.Controls;
 using PLib.Desktop.ViewModels;
+using ReactiveUI;
 
 namespace PLib.Desktop.Views;
 
@@ -23,6 +25,11 @@ public sealed partial class VideoPlayerView : UserControl
     /// <summary>True while the user is dragging the seek bar, so playback must not fight them.</summary>
     private bool _isScrubbing;
 
+    private readonly CompositeDisposable _subscriptions = [];
+
+    /// <summary>The window state to come back to when full screen is switched off.</summary>
+    private WindowState _stateBeforeFullScreen = WindowState.Normal;
+
     public VideoPlayerView()
     {
         InitializeComponent();
@@ -43,14 +50,56 @@ public sealed partial class VideoPlayerView : UserControl
 
     }
 
+    protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+    {
+        base.OnAttachedToVisualTree(e);
+
+        if (DataContext is VideoPlayerViewModel viewModel)
+        {
+            _subscriptions.Add(viewModel
+                .WhenAnyValue(x => x.IsFullScreen)
+                .Subscribe(ApplyFullScreen));
+        }
+    }
+
     protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
     {
         base.OnDetachedFromVisualTree(e);
 
+        _subscriptions.Clear();
+
+        // Closing the page while full screen would otherwise strand the window with no chrome.
+        ApplyFullScreen(false);
+
         // Leaving the page has to stop the decoder; nothing else will.
         Player.Stop();
     }
 
+    private void ApplyFullScreen(bool isFullScreen)
+    {
+        if (TopLevel.GetTopLevel(this) is not Window window)
+        {
+            return;
+        }
+
+        if (isFullScreen)
+        {
+            if (window.WindowState != WindowState.FullScreen)
+            {
+                _stateBeforeFullScreen = window.WindowState;
+                window.WindowState = WindowState.FullScreen;
+            }
+        }
+        else if (window.WindowState == WindowState.FullScreen)
+        {
+            window.WindowState = _stateBeforeFullScreen;
+        }
+
+        FullScreenIcon.Kind = isFullScreen
+            ? Material.Icons.MaterialIconKind.FullscreenExit
+            : Material.Icons.MaterialIconKind.Fullscreen;
+    }
+
     private void OnPlayPause(object? sender, RoutedEventArgs e)
     {
         if (Player.IsPlaying)