FluentAvalonia/samples/FluentAvaloniaSamples/ViewModels/ResourcesPageViewModel.cs

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Avalonia;
using Avalonia.Collections;
using Avalonia.Controls;
using Avalonia.Media;
using Avalonia.Threading;
using FluentAvalonia.Styling;

namespace FluentAvaloniaSamples.ViewModels;

public class ResourcesPageViewModel : ViewModelBase
{
    public ResourcesPageViewModel()
    {
    }


    public DataGridCollectionView ResourceView
    {
        get
        {
            if (_colView == null)
            {
                lock (this)
                {
                    LoadResources();
                    Dispatcher.UIThread.Post(() => RaisePropertyChanged(nameof(ResourceView)), DispatcherPriority.Background);
                }
            }

            return _colView;
        }
    }

    public string SearchText
    {
        get => _searchText;
        set
        {
            if (RaiseAndSetIfChanged(ref _searchText, value))
            {
                // I don't want to regenerate the entire list again, but for some reason Filter isn't resetting the DataGrid
                // even though all the events are called
                lock (this)
                {
                    LoadResources();
                    Dispatcher.UIThread.Post(() => RaisePropertyChanged(nameof(ResourceView)), DispatcherPriority.Background);
                }
            }
        }
    }

    private async void LoadResources()
    {
        var l = await LoadResourcesForTheme();
        _colView = new DataGridCollectionView(new AvaloniaList<ResourceItemBase>(l))
        {
            Filter = !string.IsNullOrEmpty(_searchText) ? FilterView : null
        };
    }

    private bool FilterView(object arg)
    {
        if (string.IsNullOrEmpty(_searchText))
        {
            return true;
        }

        if (arg is ResourceItemBase rib)
        {
            var res = rib.ResourceKey.Contains(_searchText, StringComparison.OrdinalIgnoreCase);
            return res;
        }

        return false;
    }

    private async Task<List<ResourceItemBase>> LoadResourcesForTheme()
    {
        static void AddResource(IList<ResourceItemBase> l, KeyValuePair<object, object> kvp)
        {
            if (kvp.Value.GetType().IsAssignableTo(typeof(IBrush)))
            {
                l.Add(new BrushResourceItem { Brush = (IBrush)kvp.Value, ResourceKey = kvp.Key.ToString() });
            }
            else if (kvp.Value.GetType() == typeof(Color))
            {
                l.Add(new ColorResourceItem { Color = (Color)kvp.Value, ResourceKey = kvp.Key.ToString() });
            }
            else if (kvp.Value.GetType() == typeof(FontFamily))
            {
                l.Add(new FontFamilyResourceItem { FontFamily = (FontFamily)kvp.Value, ResourceKey = kvp.Key.ToString() });
            }
            else
            {
                l.Add(new PrimitiveResourceItem { Value = kvp.Value, ResourceKey = kvp.Key.ToString() });
            }
        }

        return await Task.Run(() =>
        {
            //var thm = AvaloniaLocator.Current.GetService<FluentAvaloniaTheme>();
            //var themeResourcesDictionary =
            //    thm.GetType().GetField("_themeResources", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance)
            //    .GetValue(thm) as ResourceDictionary;

            var l = new List<ResourceItemBase>();

            //// Retreive the hidden System resources from the main resource dictionary
            //foreach (var kvp in themeResourcesDictionary)
            //{
            //    AddResource(l, kvp);
            //}

            //// Now retreive the base resources in the first merged dictionary
            //foreach (var kvp in (themeResourcesDictionary.MergedDictionaries[0] as ResourceDictionary))
            //{
            //    AddResource(l, kvp);
            //}

            //// And finally retreive the theme resources in the second merged dictionary
            //foreach (var kvp in (themeResourcesDictionary.MergedDictionaries[1] as ResourceDictionary))
            //{
            //    AddResource(l, kvp);
            //}

            return l;
        });
    }


    private DataGridCollectionView _colView;
    private string _currentTheme;
    private string _searchText;
}