Improve Theming (#1707)

* Improved theming logic and performance, also fixed some issues regarding changing the theme after vault timeout and fixed theme applying on password generator/history

* Removed messenger from theme update, and now the navigation stack is traversed and each IThemeDirtablePage gets theme updated

* Improved code on update theme on pages

src/Android/MainActivity.cs

@@ -1,25 +1,24 @@
-using Android.App;
-using Android.Content.PM;
-using Android.Runtime;
-using Android.OS;
-using Bit.Core;
-using System.Linq;
-using Bit.App.Abstractions;
-using Bit.Core.Utilities;
-using Bit.Core.Abstractions;
+using System;
 using System.IO;
-using System;
-using Android.Content;
-using Bit.Droid.Utilities;
-using Bit.Droid.Receivers;
-using Bit.App.Models;
-using Bit.Core.Enums;
-using Android.Nfc;
+using System.Linq;
 using System.Threading.Tasks;
+using Android.App;
+using Android.Content;
+using Android.Content.PM;
+using Android.Nfc;
+using Android.OS;
+using Android.Runtime;
 using AndroidX.Core.Content;
+using Bit.App.Abstractions;
+using Bit.App.Models;
 using Bit.App.Utilities;
+using Bit.Core;
+using Bit.Core.Abstractions;
+using Bit.Core.Enums;
+using Bit.Core.Utilities;
+using Bit.Droid.Receivers;
+using Bit.Droid.Utilities;
 using ZXing.Net.Mobile.Android;
-using Android.Util;
 
 namespace Bit.Droid
 {
@@ -120,6 +119,9 @@ namespace Bit.Droid
             base.OnResume();
             Xamarin.Essentials.Platform.OnResume();
             AppearanceAdjustments();
+
+            ThemeManager.UpdateThemeOnPagesAsync();
+
             if (_deviceActionService.SupportsNfc())
             {
                 try

src/App/App.xaml.cs

@@ -8,6 +8,7 @@ using Bit.Core;
 using Bit.Core.Abstractions;
 using Bit.Core.Utilities;
 using System;
+using System.Threading;
 using System.Threading.Tasks;
 using Xamarin.Forms;
 using Xamarin.Forms.Xaml;
@@ -216,7 +217,8 @@ namespace Bit.App
 
         private async void ResumedAsync()
         {
-            UpdateTheme();
+            await UpdateThemeAsync();
+
             await _vaultTimeoutService.CheckVaultTimeoutAsync();
             _messagingService.Send("startEventTimer");
             await ClearCacheIfNeededAsync();
@@ -228,6 +230,15 @@ namespace Bit.App
             }
         }
 
+        public async Task UpdateThemeAsync()
+        {
+            await Device.InvokeOnMainThreadAsync(() =>
+            {
+                ThemeManager.SetTheme(Device.RuntimePlatform == Device.Android, Current.Resources);
+                _messagingService.Send("updatedTheme");
+            });
+        }
+
         private void SetCulture()
         {
             // Calendars are removed by linker. ref https://bugzilla.xamarin.com/show_bug.cgi?id=59077
@@ -329,7 +340,7 @@ namespace Bit.App
             ThemeManager.SetTheme(Device.RuntimePlatform == Device.Android, Current.Resources);
             Current.RequestedThemeChanged += (s, a) =>
             {
-                UpdateTheme();
+                UpdateThemeAsync();
             };
             Current.MainPage = new HomePage();
             var mainPageTask = SetMainPageAsync();
@@ -353,15 +364,6 @@ namespace Bit.App
             });
         }
 
-        private void UpdateTheme()
-        {
-            Device.BeginInvokeOnMainThread(() =>
-            {
-                ThemeManager.SetTheme(Device.RuntimePlatform == Device.Android, Current.Resources);
-                _messagingService.Send("updatedTheme");
-            });
-        }
-
         private async Task LockedAsync(bool autoPromptBiometric)
         {
             await _stateService.PurgeAsync();

src/App/Pages/BaseContentPage.cs

@@ -30,9 +30,17 @@ namespace Bit.App.Pages
 
         public DateTime? LastPageAction { get; set; }
 
+        public bool IsThemeDirty { get; set; }
+
         protected override void OnAppearing()
         {
             base.OnAppearing();
+
+            if (IsThemeDirty)
+            {
+                UpdateOnThemeChanged();
+            }
+
             SaveActivity();
         }
 
@@ -123,5 +131,11 @@ namespace Bit.App.Pages
             SetServices();
             _storageService.SaveAsync(Constants.LastActiveTimeKey, _deviceActionService.GetActiveTime());
         }
+
+        public virtual Task UpdateOnThemeChanged()
+        {
+            IsThemeDirty = false;
+            return Task.CompletedTask;
+        }
     }
 }

src/App/Pages/Generator/GeneratorHistoryPage.xaml.cs

@@ -1,10 +1,12 @@
-using Bit.App.Resources;
-using System;
+using System;
+using System.Threading.Tasks;
+using Bit.App.Resources;
+using Bit.App.Styles;
 using Xamarin.Forms;
 
 namespace Bit.App.Pages
 {
-    public partial class GeneratorHistoryPage : BaseContentPage
+    public partial class GeneratorHistoryPage : BaseContentPage, IThemeDirtablePage
     {
         private GeneratorHistoryPageViewModel _vm;
 
@@ -28,6 +30,7 @@ namespace Bit.App.Pages
         protected override async void OnAppearing()
         {
             base.OnAppearing();
+
             await LoadOnAppearedAsync(_mainLayout, true, async () => {
                 await _vm.InitAsync();
             });
@@ -59,5 +62,12 @@ namespace Bit.App.Pages
                 await _vm.ClearAsync();
             }
         }
+
+        public override async Task UpdateOnThemeChanged()
+        {
+            await base.UpdateOnThemeChanged();
+
+            await _vm?.UpdateOnThemeChanged();
+        }
     }
 }

src/App/Pages/Generator/GeneratorHistoryPageViewModel.cs

@@ -1,9 +1,12 @@
-using Bit.App.Resources;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Bit.App.Resources;
 using Bit.Core.Abstractions;
 using Bit.Core.Models.Domain;
 using Bit.Core.Utilities;
-using System.Collections.Generic;
-using System.Threading.Tasks;
+#if !FDROID
+using Microsoft.AppCenter.Crashes;
+#endif
 using Xamarin.Forms;
 
 namespace Bit.App.Pages
@@ -19,8 +22,7 @@ namespace Bit.App.Pages
         public GeneratorHistoryPageViewModel()
         {
             _platformUtilsService = ServiceContainer.Resolve<IPlatformUtilsService>("platformUtilsService");
-            _passwordGenerationService = ServiceContainer.Resolve<IPasswordGenerationService>(
-                "passwordGenerationService");
+            _passwordGenerationService = ServiceContainer.Resolve<IPasswordGenerationService>("passwordGenerationService");
             _clipboardService = ServiceContainer.Resolve<IClipboardService>("clipboardService");
 
             PageTitle = AppResources.PasswordHistory;
@@ -57,5 +59,21 @@ namespace Bit.App.Pages
             _platformUtilsService.ShowToast("info", null,
                 string.Format(AppResources.ValueHasBeenCopied, AppResources.Password));
         }
+
+        public async Task UpdateOnThemeChanged()
+        {
+            try
+            {
+                await Device.InvokeOnMainThreadAsync(() => History.ResetWithRange(new List<GeneratedPasswordHistory>()));
+
+                await InitAsync();
+            }
+            catch (System.Exception ex)
+            {
+#if !FDROID
+                Crashes.TrackError(ex);
+#endif
+            }
+        }
     }
 }

src/App/Pages/Generator/GeneratorPage.xaml

@@ -63,6 +63,7 @@
                     </Frame>
                 </Grid>
                 <controls:MonoLabel
+                    x:Name="lblPassword"
                     StyleClass="text-lg, text-html"
                     Text="{Binding ColoredPassword, Mode=OneWay}"
                     Margin="0, 20"

src/App/Pages/Generator/GeneratorPage.xaml.cs

@@ -1,15 +1,15 @@
-using Bit.App.Resources;
-using System;
+using System;
 using System.Threading.Tasks;
+using Bit.App.Resources;
+using Bit.App.Styles;
 using Bit.Core.Abstractions;
 using Bit.Core.Utilities;
 using Xamarin.Forms;
-using Xamarin.Forms.PlatformConfiguration;
 using Xamarin.Forms.PlatformConfiguration.iOSSpecific;
 
 namespace Bit.App.Pages
 {
-    public partial class GeneratorPage : BaseContentPage
+    public partial class GeneratorPage : BaseContentPage, IThemeDirtablePage
     {
         private readonly IBroadcasterService _broadcasterService;
         
@@ -49,7 +49,7 @@ namespace Bit.App.Pages
             }
             if (isIos)
             {
-                _typePicker.On<iOS>().SetUpdateMode(UpdateMode.WhenFinished);
+                _typePicker.On<Xamarin.Forms.PlatformConfiguration.iOS>().SetUpdateMode(UpdateMode.WhenFinished);
             }
         }
 
@@ -61,18 +61,19 @@ namespace Bit.App.Pages
         protected async override void OnAppearing()
         {
             base.OnAppearing();
+
+            lblPassword.IsVisible = true;
+
             if (!_fromTabPage)
             {
                 await InitAsync();
             }
-            _broadcasterService.Subscribe(nameof(GeneratorPage), async (message) =>
+
+            _broadcasterService.Subscribe(nameof(GeneratorPage), (message) =>
             {
                 if (message.Command == "updatedTheme")
                 {
-                    Device.BeginInvokeOnMainThread(() =>
-                    {
-                        _vm.RedrawPassword();
-                    });
+                    Device.BeginInvokeOnMainThread(() => _vm.RedrawPassword());
                 }
             });
         }
@@ -80,6 +81,9 @@ namespace Bit.App.Pages
         protected override void OnDisappearing()
         {
             base.OnDisappearing();
+
+            lblPassword.IsVisible = false;
+
             _broadcasterService.Unsubscribe(nameof(GeneratorPage));
         }
 
@@ -141,5 +145,12 @@ namespace Bit.App.Pages
                 await Navigation.PopModalAsync();
             }
         }
+
+        public override async Task UpdateOnThemeChanged()
+        {
+            await base.UpdateOnThemeChanged();
+
+            await Device.InvokeOnMainThreadAsync(() => _vm?.RedrawPassword());
+        }
     }
 }

src/App/Styles/Black.xaml.cs

@@ -2,7 +2,7 @@
 
 namespace Bit.App.Styles
 {
-    public partial class Black : ResourceDictionary
+    public partial class Black : ResourceDictionary, IThemeResourceDictionary
     {
         public Black()
         {

src/App/Styles/Dark.xaml.cs

@@ -2,7 +2,7 @@
 
 namespace Bit.App.Styles
 {
-    public partial class Dark : ResourceDictionary
+    public partial class Dark : ResourceDictionary, IThemeResourceDictionary
     {
         public Dark()
         {

src/App/Styles/IThemeDirtablePage.cs

@@ -0,0 +1,15 @@
+using System.Threading.Tasks;
+
+namespace Bit.App.Styles
+{
+    /// <summary>
+    /// This is an interface to mark the pages that need theme update special treatment
+    /// given that they aren't updated automatically by the Forms theme system.
+    /// </summary>
+    public interface IThemeDirtablePage
+    {
+        bool IsThemeDirty { get; set; }
+
+        Task UpdateOnThemeChanged();
+    }
+}

src/App/Styles/IThemeResourceDictionary.cs

@@ -0,0 +1,6 @@
+namespace Bit.App.Styles
+{
+    public interface IThemeResourceDictionary
+    {
+    }
+}

src/App/Styles/Light.xaml.cs

@@ -2,7 +2,7 @@
 
 namespace Bit.App.Styles
 {
-    public partial class Light : ResourceDictionary
+    public partial class Light : ResourceDictionary, IThemeResourceDictionary
     {
         public Light()
         {

src/App/Styles/Nord.xaml.cs

@@ -2,7 +2,7 @@
 
 namespace Bit.App.Styles
 {
-    public partial class Nord : ResourceDictionary
+    public partial class Nord : ResourceDictionary, IThemeResourceDictionary
     {
         public Nord()
         {

src/App/Utilities/PageExtensions.cs

@@ -0,0 +1,53 @@
+using System;
+using System.Threading.Tasks;
+using Xamarin.Forms;
+
+namespace Bit.App.Utilities
+{
+    public static class PageExtensions
+    {
+        public static async Task TraverseNavigationRecursivelyAsync(this Page page, Func<Page, Task> actionOnPage)
+        {
+            if (page?.Navigation?.ModalStack != null)
+            {
+                foreach (var p in page.Navigation.ModalStack)
+                {
+                    if (p is NavigationPage modalNavPage)
+                    {
+                        await TraverseNavigationStackRecursivelyAsync(modalNavPage.CurrentPage, actionOnPage);
+                    }
+                    else
+                    {
+                        await TraverseNavigationStackRecursivelyAsync(p, actionOnPage);
+                    }
+                }
+            }
+
+            await TraverseNavigationStackRecursivelyAsync(page, actionOnPage);
+        }
+
+        private static async Task TraverseNavigationStackRecursivelyAsync(this Page page, Func<Page, Task> actionOnPage)
+        {
+            if (page is MultiPage<Page> multiPage && multiPage.Children != null)
+            {
+                foreach (var p in multiPage.Children)
+                {
+                    await TraverseNavigationStackRecursivelyAsync(p, actionOnPage);
+                }
+            }
+
+            if (page is NavigationPage && page.Navigation != null)
+            {
+                if (page.Navigation.NavigationStack != null)
+                {
+                    foreach (var p in page.Navigation.NavigationStack)
+                    {
+                        await TraverseNavigationStackRecursivelyAsync(p, actionOnPage);
+                    }
+                }
+            }
+
+            await actionOnPage(page);
+        }
+    }
+}

src/App/Utilities/ThemeManager.cs

@@ -4,6 +4,8 @@ using Bit.App.Services;
 using Bit.App.Styles;
 using Bit.Core;
 using Xamarin.Forms;
+using System.Linq;
+using System.Threading.Tasks;
 #if !FDROID
 using Microsoft.AppCenter.Crashes;
 #endif
@@ -15,12 +17,30 @@ namespace Bit.App.Utilities
         public static bool UsingLightTheme = true;
         public static Func<ResourceDictionary> Resources = () => null;
 
+        public static bool IsThemeDirty = false;
+
         public static void SetThemeStyle(string name, ResourceDictionary resources)
         {
             try
             {
                 Resources = () => resources;
 
+                var newTheme = NeedsThemeUpdate(name, resources);
+                if (newTheme is null)
+                {
+                    return;
+                }
+
+                var currentTheme = resources.MergedDictionaries.FirstOrDefault(md => md is IThemeResourceDictionary);
+                if (currentTheme != null)
+                {
+                    resources.MergedDictionaries.Remove(currentTheme);
+                    resources.MergedDictionaries.Add(newTheme);
+                    UsingLightTheme = newTheme is Light;
+                    IsThemeDirty = true;
+                    return;
+                }
+
                 // Reset styles
                 resources.Clear();
                 resources.MergedDictionaries.Clear();
@@ -28,40 +48,9 @@ namespace Bit.App.Utilities
                 // Variables
                 resources.MergedDictionaries.Add(new Variables());
 
-                // Themed variables
-                if (name == "dark")
-                {
-                    resources.MergedDictionaries.Add(new Dark());
-                    UsingLightTheme = false;
-                }
-                else if (name == "black")
-                {
-                    resources.MergedDictionaries.Add(new Black());
-                    UsingLightTheme = false;
-                }
-                else if (name == "nord")
-                {
-                    resources.MergedDictionaries.Add(new Nord());
-                    UsingLightTheme = false;
-                }
-                else if (name == "light")
-                {
-                    resources.MergedDictionaries.Add(new Light());
-                    UsingLightTheme = true;
-                }
-                else
-                {
-                    if (OsDarkModeEnabled())
-                    {
-                        resources.MergedDictionaries.Add(new Dark());
-                        UsingLightTheme = false;
-                    }
-                    else
-                    {
-                        resources.MergedDictionaries.Add(new Light());
-                        UsingLightTheme = true;
-                    }
-                }
+                // Theme
+                resources.MergedDictionaries.Add(newTheme);
+                UsingLightTheme = newTheme is Light;
 
                 // Base styles
                 resources.MergedDictionaries.Add(new Base());
@@ -93,6 +82,34 @@ namespace Bit.App.Utilities
             }
         }
 
+        static ResourceDictionary CheckAndGetThemeForMergedDictionaries(Type themeType, ResourceDictionary resources)
+        {
+            return resources.MergedDictionaries.Any(rd => rd.GetType() == themeType)
+                ? null
+                : Activator.CreateInstance(themeType) as ResourceDictionary;
+        }
+
+        static ResourceDictionary NeedsThemeUpdate(string themeName, ResourceDictionary resources)
+        {
+            switch (themeName)
+            {
+                case "dark":
+                    return CheckAndGetThemeForMergedDictionaries(typeof(Dark), resources);
+                case "black":
+                    return CheckAndGetThemeForMergedDictionaries(typeof(Black), resources);
+                case "nord":
+                    return CheckAndGetThemeForMergedDictionaries(typeof(Nord), resources);
+                case "light":
+                    return CheckAndGetThemeForMergedDictionaries(typeof(Light), resources);
+                default:
+                    if (OsDarkModeEnabled())
+                    {
+                        return CheckAndGetThemeForMergedDictionaries(typeof(Dark), resources);
+                    }
+                    return CheckAndGetThemeForMergedDictionaries(typeof(Light), resources);
+            }
+        }
+
         public static void SetTheme(bool android, ResourceDictionary resources)
         {
             SetThemeStyle(GetTheme(android), resources);
@@ -128,5 +145,34 @@ namespace Bit.App.Utilities
         {
             return (Color)Resources()[color];
         }
+
+        public static async Task UpdateThemeOnPagesAsync()
+        {
+            try
+            {
+                if (IsThemeDirty)
+                {
+                    IsThemeDirty = false;
+
+                    await Application.Current.MainPage.TraverseNavigationRecursivelyAsync(async p =>
+                    {
+                        if (p is IThemeDirtablePage themeDirtablePage)
+                        {
+                            themeDirtablePage.IsThemeDirty = true;
+                            if (p.IsVisible)
+                            {
+                                await themeDirtablePage.UpdateOnThemeChanged();
+                            }
+                        }
+                    });
+                }
+            }
+            catch (Exception ex)
+            {
+#if !FDROID
+                Crashes.TrackError(ex);
+#endif
+            }
+        }
     }
 }

src/iOS/AppDelegate.cs

@@ -216,6 +216,8 @@ namespace Bit.iOS
                 view.RemoveFromSuperview();
                 UIApplication.SharedApplication.SetStatusBarHidden(false, false);
             }
+
+            ThemeManager.UpdateThemeOnPagesAsync();
         }
 
         public override void WillEnterForeground(UIApplication uiApplication)