Show alerts about errors during startup

DisplayAlert fails showing alerts when MainPage is not ready
topeterk · Dec 4, 2021 · 64e4f56 · 64e4f56
1 parent 4fbf155
commit 64e4f56
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Showing 3 changed files with 52 additions and 11 deletions.
diff --git a/Source/HitCounterManager/Common/App.xaml.cs b/Source/HitCounterManager/Common/App.xaml.cs
@@ -21,6 +21,7 @@
 //SOFTWARE.
 
 using System;
+using System.Collections.Generic;
 using Xamarin.Forms;
 using HitCounterManager.Common.OsLayer;
 using HitCounterManager.Common.PlatformLayer;
@@ -39,6 +40,7 @@ public enum TimerIDs : uint { Shortcuts, ShortcutsCapture, GameTime, GameTimeGui
 
     public partial class App : Application
     {
+        private bool StartupDone = false;
         public readonly IOsLayer OsLayer;
         public readonly IPlatformLayer PlatformLayer;
         private HookHandle WindowHookHandle;
@@ -78,10 +80,51 @@ public App(IOsLayer osLayer, IPlatformLayer platformLayer)
                 MainPage = new NavigationPage(main);
 
             MainPage.Appearing += MainPage_Appearing;
+            PageAppearing += App_PageAppearing;
 
             ModalPopped += App_ModalPopped;
         }
 
+        private struct PostponedAlert
+        {
+            public string Title;
+            public string Message;
+            public string Cancel;
+
+            public PostponedAlert(string Title, string Message, string Cancel)
+            {
+                this.Title = Title;
+                this.Message = Message;
+                this.Cancel = Cancel;
+            }
+        }
+        private List<PostponedAlert> PostponedAlerts = new List<PostponedAlert>();
+
+        /// <summary>
+        /// Page.DisplayAlert but when no appeared yet, it will be postponed until MainPage has appeared
+        /// </summary>
+        /// <param name="Title"></param>
+        /// <param name="Message"></param>
+        /// <param name="Cancel"></param>
+        public void DisplayAlert(string Title, string Message, string Cancel)
+        {
+            if (StartupDone)
+                MainPage.DisplayAlert(Title, Message, Cancel);
+            else
+                PostponedAlerts.Add(new PostponedAlert(Title, Message, Cancel));
+        }
+
+        private void App_PageAppearing(object sender, Page e)
+        {
+            if (!StartupDone)
+            {
+                StartupDone = true;
+                foreach(var Alert in PostponedAlerts) MainPage.DisplayAlert(Alert.Title, Alert.Message, Alert.Cancel);
+                PostponedAlerts.Clear();
+                PostponedAlerts = null;
+            }
+        }
+
         private void App_ModalPopped(object sender, ModalPoppedEventArgs e)
         {
             IDisposable bindingContext = e.Modal.BindingContext as IDisposable;
@@ -128,12 +171,7 @@ private void MainPage_Appearing(object sender, EventArgs e)
                 // Register the hook function and hot keys
                 WindowHookHandle = PlatformLayer.HookInstall(WndProc, PlatformLayer.ApplicationWindowHandle);
                 bool Success = LoadAllHotKeySettings();
-#if TODO // Call DisplayAlert or anything like that?
-                if (!Success)
-                    MessageBox.Show("Not all enabled hot keys could be registered successfully!", "Error setting up hot keys!");
-#else
-                Success = !Success; // just to avoid compiler warning about (yet) unused variable
-#endif
+                if (!Success) DisplayAlert("Error setting up hot keys!", "Not all enabled hot keys could be registered successfully!", "OK");
             }
         }
 
@@ -187,6 +225,11 @@ private static IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam
             SaveSettings();
         }
 
+        /// <summary>
+        /// By definition ????:
+        /// GTK: After MainPage_Appearing
+        /// WPF: Before MainPage_Appearing
+        /// </summary>
         protected override void OnStart() { }
 
         /// <summary>

diff --git a/Source/HitCounterManager/Models/SaveModule.cs b/Source/HitCounterManager/Models/SaveModule.cs
@@ -75,7 +75,7 @@ public T ReadXML(bool EnableBackup, string Filename = null)
             catch (FileNotFoundException) { } // Exception.HResult == COR_E_FILENOTFOUND only be available since .Net 4.5, use overloading for older frameworks
             catch (Exception ex)
             {
-                Application.Current.MainPage.DisplayAlert("Error loading settings!", ex.Message + Environment.NewLine + "==> Using defaults", "OK");
+                App.CurrentApp.DisplayAlert("Error loading settings!", ex.Message + Environment.NewLine + "==> Using defaults", "OK");
             }
             finally
             {
@@ -102,7 +102,7 @@ public bool WriteXML(T data)
             catch (Exception ex)
             {
                 if (null != file) file.Close();
-                Application.Current.MainPage.DisplayAlert("Error writing settings!", ex.Message, "OK");
+                App.CurrentApp.DisplayAlert("Error writing settings!", ex.Message, "OK");
             }
             return false;
         }

diff --git a/Source/HitCounterManager/ViewModels/SettingsViewModel.cs b/Source/HitCounterManager/ViewModels/SettingsViewModel.cs
@@ -416,9 +416,7 @@ private void SetNextShortcutMethod(Shortcuts.SC_HotKeyMethod next)
                 case Shortcuts.SC_HotKeyMethod.SC_HotKeyMethod_LLKb: CallPropertyChanged(this, nameof(RadioHotKeyMethod_LLKb)); break;
                 default: break;
             }
-#if TODO // Make sure this can only happen after the OnAppearing event! Maybe DisplayAlert?
-            MessageBox.Show("Changes only take effect after restarting the application.", "Restart required", MessageBoxButtons.OK, MessageBoxIcon.Information);
-#endif
+            App.CurrentApp.DisplayAlert("Restart required", "Changes only take effect after restarting the application.", "OK");
         }
         public bool RadioHotKeyMethod_Sync
         {