105 lines
3 KiB
C#
105 lines
3 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Threading.Tasks;
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using Avalonia.Threading;
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using CommunityToolkit.Mvvm.ComponentModel;
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using LANCommander.Launcher.ViewModels;
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namespace LANCommander.Launcher.Services;
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public record NavigationEntry(ViewModelBase ViewModel);
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public partial class NavigationService : ObservableObject, INavigationService
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{
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private const int MaxHistoryDepth = 20;
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private readonly Stack<NavigationEntry> _history = new();
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[ObservableProperty]
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[NotifyPropertyChangedFor(nameof(CanGoBack))]
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private ViewModelBase? _currentView;
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[ObservableProperty]
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private bool _isNavigating;
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public bool CanGoBack => _history.Count > 0;
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public async void NavigateTo(ViewModelBase viewModel, bool clearHistory = false, Func<Task>? initializeAsync = null)
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{
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if (clearHistory)
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{
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_history.Clear();
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}
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else if (CurrentView != null)
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{
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_history.Push(new NavigationEntry(CurrentView));
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// Trim oldest entries if we exceed the cap
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if (_history.Count > MaxHistoryDepth)
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{
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var trimmed = new Stack<NavigationEntry>(MaxHistoryDepth);
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var items = _history.ToArray();
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for (int i = MaxHistoryDepth - 1; i >= 0; i--)
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trimmed.Push(items[i]);
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_history.Clear();
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foreach (var entry in trimmed)
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_history.Push(entry);
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}
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}
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// Show the loading overlay and yield so the UI thread can paint it
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// BEFORE the heavy view creation from the ContentControl DataTemplate.
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IsNavigating = true;
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await Dispatcher.UIThread.InvokeAsync(() => { }, DispatcherPriority.Render).GetTask();
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CurrentView = viewModel;
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try
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{
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if (initializeAsync != null)
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await initializeAsync();
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// Yield again so the new view finishes layout/render
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// before we hide the overlay.
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await Dispatcher.UIThread.InvokeAsync(() => { }, DispatcherPriority.Background).GetTask();
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}
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catch
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{
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// Initialization errors are handled by the caller's callback.
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}
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finally
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{
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IsNavigating = false;
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}
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}
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public void GoBack()
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{
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if (_history.Count == 0)
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return;
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IsNavigating = true;
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// Post the actual view swap so the overlay paints first,
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// then yield after layout to hide it.
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Dispatcher.UIThread.Post(async () =>
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{
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try
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{
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var entry = _history.Pop();
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CurrentView = entry.ViewModel;
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await Dispatcher.UIThread.InvokeAsync(() => { }, DispatcherPriority.Background).GetTask();
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}
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finally
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{
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IsNavigating = false;
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}
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}, DispatcherPriority.Background);
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}
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public void ReplaceCurrent(ViewModelBase viewModel)
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{
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CurrentView = viewModel;
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}
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}
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