Chapter 14 samples

2026-06-20 12:23:09 +00:00 · 2023-09-23 15:10:27 -04:00
parent 800f0c3a8a
commit 7ec132eee3
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+using Microsoft.UI.Xaml.Controls;
+using MyMediaCollection.Interfaces;
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace MyMediaCollection.Services
+{
+    public class NavigationService : INavigationService
+    {
+        public NavigationService(Frame rootFrame)
+        {
+            AppFrame = rootFrame;
+        }
+
+        private readonly IDictionary<string, Type> _pages = new ConcurrentDictionary<string, Type>();
+
+        public const string RootPage = "(Root)";
+
+        public const string UnknownPage = "(Unknown)";
+
+        private static Frame AppFrame;
+
+        public void Configure(string page, Type type)
+        {
+            if (_pages.Values.Any(v => v == type))
+            {
+                throw new ArgumentException($"The {type.Name} view has already been registered under another name.");
+            }
+
+            _pages[page] = type;
+        }
+
+        /// <summary>
+        /// Gets the name of the currently displayed page.
+        /// </summary>
+        public string CurrentPage
+        {
+            get
+            {
+                var frame = AppFrame;
+
+                if (frame.BackStackDepth == 0)
+                    return RootPage;
+
+                if (frame.Content == null)
+                    return UnknownPage;
+
+                var type = frame.Content.GetType();
+
+                if (_pages.Values.All(v => v != type))
+                    return UnknownPage;
+
+                var item = _pages.Single(i => i.Value == type);
+
+                return item.Key;
+            }
+        }
+
+        public void NavigateTo(string page)
+        {
+            NavigateTo(page, null);
+        }
+
+        public void NavigateTo(string page, object parameter)
+        {
+            if (!_pages.ContainsKey(page))
+            {
+                throw new ArgumentException($"Unable to find a page registered with the name {page}.");
+            }
+
+            AppFrame.Navigate(_pages[page], parameter);
+        }
+
+        public void GoBack()
+        {
+            if (AppFrame?.CanGoBack == true)
+            {
+                AppFrame.GoBack();
+            }
+        }
+    }
+}