Fix full screen gallery

Author: FrayxRulez

Telegram/Controls/OverlayWindow.cs

@@ -13,7 +13,6 @@
 using Telegram.Views.Host;
 using Windows.Devices.Input;
 using Windows.UI;
-using Windows.UI.Core.Preview;
 using Windows.UI.ViewManagement;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
@@ -28,6 +27,7 @@ public abstract class OverlayWindow : ContentControl, INavigablePage
         private Popup _popupHost;
 
         private bool _closing;
+        private bool _watching;
 
         private TaskCompletionSource<ContentDialogResult> _callback;
         private ContentDialogResult _result;
@@ -79,6 +79,34 @@ private void OnXamlRootChanged(XamlRoot sender, XamlRootChangedEventArgs args)
             UpdateViewBase();
         }
 
+        /// <summary>
+        /// Subscribed from <see cref="ShowAsync"/> rather than from the popup's Opened, which the
+        /// XAML core raises asynchronously: a Loaded handler runs synchronously inside the tick
+        /// that opens the popup, and the gallery's enters full screen from there. Subscribing
+        /// afterwards races the resize, and losing it leaves the overlay at its windowed size for
+        /// as long as it stays open.
+        /// </summary>
+        private void WatchWindow(bool watch)
+        {
+            if (_watching == watch || XamlRoot == null)
+            {
+                return;
+            }
+
+            _watching = watch;
+
+            if (watch)
+            {
+                XamlRoot.Changed += OnXamlRootChanged;
+                Window.CloseRequested += OnCloseRequested;
+            }
+            else
+            {
+                XamlRoot.Changed -= OnXamlRootChanged;
+                Window.CloseRequested -= OnCloseRequested;
+            }
+        }
+
         protected virtual void MaskTitleAndStatusBar(WindowContext window)
         {
             if (window.Content is IPopupHost host)
@@ -146,12 +174,16 @@ public async Task<ContentDialogResult> ShowAsync()
 
             _closing = false;
             _popupHost.XamlRoot = XamlRoot;
+
+            WatchWindow(true);
+            UpdateViewBase();
+
             _popupHost.IsOpen = true;
 
             return await _callback.Task;
         }
 
-        private void OnCloseRequested(object sender, SystemNavigationCloseRequestedPreviewEventArgs e)
+        private void OnCloseRequested(object sender, WindowCloseRequestedEventArgs e)
         {
             var args = new BackRequestedRoutedEventArgs();
             OnBackRequested(args);
@@ -204,19 +236,13 @@ public void PopupClosed()
         private void PopupHost_Opened(object sender, object e)
         {
             MaskTitleAndStatusBar(Window);
-
-            _popupHost.XamlRoot.Changed += OnXamlRootChanged;
-            SystemNavigationManagerPreview.GetForCurrentView().CloseRequested += OnCloseRequested;
         }
 
         private void PopupHost_Closed(object sender, object e)
         {
             UnmaskTitleAndStatusBar(Window);
 
             //_callback.TrySetResult(_result);
-
-            _popupHost.XamlRoot.Changed -= OnXamlRootChanged;
-            SystemNavigationManagerPreview.GetForCurrentView().CloseRequested -= OnCloseRequested;
         }
 
         public void OnBackRequested(BackRequestedRoutedEventArgs e)
@@ -287,6 +313,11 @@ public void Hide(ContentDialogResult result)
             _result = result;
             _popupHost.IsOpen = false;
 
+            // Paired with ShowAsync, not with the popup's Closed: that one arrives late enough for
+            // a re-show to have already opened the popup again, and it would unsubscribe the live
+            // instance.
+            WatchWindow(false);
+
             if (_instances.TryGetValue(XamlRoot, out OverlayWindow window))
             {
                 if (window == this)

Telegram/Controls/WindowContent.cs

@@ -5,86 +5,15 @@
 // file LICENSE or copy at https://www.gnu.org/licenses/gpl-3.0.txt)
 //
 
-using System;
-using System.Threading.Tasks;
 using Telegram.Common;
 using Telegram.Navigation;
 using Telegram.Views.Host;
-using Windows.Foundation;
 using Windows.UI;
-using Windows.UI.Core.Preview;
 using Windows.UI.ViewManagement;
 using Windows.UI.Xaml;
 
 namespace Telegram.Controls
 {
-    /// <summary>
-    /// Raised by <see cref="WindowContent.OnWindowCloseRequested"/>. Wraps the UWP args rather
-    /// than exposing them, so a root only ever sees Handled and a deferral - the two things
-    /// every caller actually used, and the two an island host can supply by other means.
-    /// </summary>
-    public class WindowCloseRequestedEventArgs : EventArgs
-    {
-        private readonly SystemNavigationCloseRequestedPreviewEventArgs _args;
-        private TaskCompletionSource<bool> _deferral;
-        private bool _handled;
-
-        internal WindowCloseRequestedEventArgs(SystemNavigationCloseRequestedPreviewEventArgs args)
-        {
-            _args = args;
-        }
-
-        /// <summary>
-        /// Raised by the app rather than by the system - the window's own close button. Handled is
-        /// then just a bool, and the deferral has to be honoured by whoever raised it.
-        /// </summary>
-        internal WindowCloseRequestedEventArgs()
-        {
-        }
-
-        public bool Handled
-        {
-            get => _args?.Handled ?? _handled;
-            set
-            {
-                if (_args != null)
-                {
-                    _args.Handled = value;
-                }
-                else
-                {
-                    _handled = value;
-                }
-            }
-        }
-
-        public Deferral GetDeferral()
-        {
-            if (_args != null)
-            {
-                return _args.GetDeferral();
-            }
-
-            // Allocated only when a handler actually asks to defer, which is the uncommon case.
-            _deferral ??= new TaskCompletionSource<bool>();
-            return new Deferral(CompleteDeferral);
-        }
-
-        private void CompleteDeferral()
-        {
-            _deferral.TrySetResult(true);
-        }
-
-        /// <summary>
-        /// Completes once every handler that took a deferral has released it. Only meaningful for
-        /// an app-raised request: the system waits on its own.
-        /// </summary>
-        internal Task WaitAsync()
-        {
-            return _deferral?.Task ?? Task.CompletedTask;
-        }
-    }
-
     /// <summary>
     /// Base for anything assigned to <see cref="WindowContext.Content"/> - the root of a window,
     /// though not a window itself. Was WindowEx, declared at the bottom of VoipWindow.xaml.cs.
@@ -137,7 +66,7 @@ protected virtual void OnPopupClosed()
 
         /// <summary>
         /// Wired once, here, rather than in each root: what raises these is the part that differs
-        /// between a CoreWindow and an island host, and this is the only place that should know.
+        /// between a CoreWindow and an island host, and no root should have to know.
         ///
         /// OnLoaded rather than the constructor or the raw Loaded event: roots used to subscribe
         /// from their constructors and never unsubscribe, keeping themselves reachable from the
@@ -153,10 +82,9 @@ protected override void OnLoaded()
             {
                 window.Activated += OnWindowActivatedCore;
                 window.VisibilityChanged += OnWindowVisibilityChangedCore;
+                window.CloseRequested += OnCloseRequestedCore;
             }
 
-            SystemNavigationManagerPreview.GetForCurrentView().CloseRequested += OnCloseRequestedCore;
-
             var view = ApplicationView.GetForCurrentView();
             view.Consolidated += OnConsolidatedCore;
             view.VisibleBoundsChanged += OnVisibleBoundsChangedCore;
@@ -168,10 +96,9 @@ protected override void OnUnloaded()
             {
                 window.Activated -= OnWindowActivatedCore;
                 window.VisibilityChanged -= OnWindowVisibilityChangedCore;
+                window.CloseRequested -= OnCloseRequestedCore;
             }
 
-            SystemNavigationManagerPreview.GetForCurrentView().CloseRequested -= OnCloseRequestedCore;
-
             var view = ApplicationView.GetForCurrentView();
             view.Consolidated -= OnConsolidatedCore;
             view.VisibleBoundsChanged -= OnVisibleBoundsChangedCore;
@@ -187,9 +114,9 @@ private void OnWindowVisibilityChangedCore(object sender, WindowVisibilityEventA
             OnWindowVisibilityChanged(args.IsVisible);
         }
 
-        private void OnCloseRequestedCore(object sender, SystemNavigationCloseRequestedPreviewEventArgs args)
+        private void OnCloseRequestedCore(object sender, WindowCloseRequestedEventArgs args)
         {
-            OnWindowCloseRequested(new WindowCloseRequestedEventArgs(args));
+            OnWindowCloseRequested(args);
         }
 
         // Neither carries a payload worth forwarding: the one caller of Consolidated ignored its
@@ -218,24 +145,6 @@ protected virtual void OnWindowCloseRequested(WindowCloseRequestedEventArgs args
         {
         }
 
-        /// <summary>
-        /// The window's own close button, routed into the same override the system's close request
-        /// uses: a root has one place to intercept a close, whatever asked for it. Returns false
-        /// when the root refused.
-        ///
-        /// Awaited, because the answer can be a question: the web app window takes a deferral and
-        /// asks the user whether to discard the bot's changes.
-        /// </summary>
-        internal async Task<bool> RequestCloseAsync()
-        {
-            var args = new WindowCloseRequestedEventArgs();
-            OnWindowCloseRequested(args);
-
-            await args.WaitAsync();
-
-            return !args.Handled;
-        }
-
         protected virtual void OnWindowConsolidated()
         {
         }

Telegram/Navigation/WindowContext.Uwp.cs

@@ -22,6 +22,7 @@
 using Windows.UI;
 using Windows.UI.Composition;
 using Windows.UI.Core;
+using Windows.UI.Core.Preview;
 using Windows.UI.ViewManagement;
 using Windows.UI.WindowManagement;
 using Windows.UI.Xaml;
@@ -152,6 +153,25 @@ private void OnVisibleBoundsChanged(ApplicationView sender, object args)
             VisibleBoundsChanged?.Invoke(this, args);
         }
 
+        partial void AttachCloseRequested()
+        {
+            SystemNavigationManagerPreview.GetForCurrentView().CloseRequested += OnCloseRequested;
+        }
+
+        partial void DetachCloseRequested()
+        {
+            SystemNavigationManagerPreview.GetForCurrentView().CloseRequested -= OnCloseRequested;
+        }
+
+        /// <summary>
+        /// The system's own request. Raised and returned rather than awaited: the system honours
+        /// the deferrals its args hand out, so there is nothing here to wait for.
+        /// </summary>
+        private void OnCloseRequested(object sender, SystemNavigationCloseRequestedPreviewEventArgs args)
+        {
+            RaiseCloseRequested(new WindowCloseRequestedEventArgs(args));
+        }
+
         public void Close()
         {
             _ = ConsolidateAsync();

Telegram/Navigation/WindowContext.Win32.cs

@@ -147,7 +147,7 @@ private async void CloseRequestedAsync()
                 return;
             }
 
-            if (Content is WindowContent root && !await root.RequestCloseAsync())
+            if (!await RequestCloseAsync())
             {
                 return;
             }