Use Customized LazyAsync class to load image instead of the weird way of updating lazy class async

Author: taooceros

Flow.Launcher.Infrastructure/Image/ImageLoader.cs

@@ -18,6 +18,8 @@ public static class ImageLoader
         private static readonly ConcurrentDictionary<string, string> GuidToKey = new ConcurrentDictionary<string, string>();
         private static IImageHashGenerator _hashGenerator;
         private static bool EnableImageHash = true;
+        public static ImageSource defaultImage { get; } = new BitmapImage(new Uri(Constant.MissingImgIcon));
+
 
         private static readonly string[] ImageExtensions =
         {
@@ -37,6 +39,7 @@ public static void Initialize()
 
             var usage = LoadStorageToConcurrentDictionary();
 
+
             foreach (var icon in new[] { Constant.DefaultIcon, Constant.MissingImgIcon })
             {
                 ImageSource img = new BitmapImage(new Uri(icon));
@@ -213,13 +216,10 @@ private static BitmapSource GetThumbnail(string path, ThumbnailOptions option =
 
         public static bool CacheContainImage(string path)
         {
-            return ImageCache.ContainsKey(path);
-        }
-        public static ImageSource LoadDefault(bool loadFullImage = false)
-        {
-            return LoadInternal(Constant.MissingImgIcon, loadFullImage).ImageSource;
+            return ImageCache.ContainsKey(path) && ImageCache[path] != null;
         }
 
+
         public static ImageSource Load(string path, bool loadFullImage = false)
         {
             var imageResult = LoadInternal(path, loadFullImage);
@@ -230,7 +230,7 @@ public static ImageSource Load(string path, bool loadFullImage = false)
                 string hash = EnableImageHash ? _hashGenerator.GetHashFromImage(img) : null;
                 if (hash != null)
                 {
-                    
+
                     if (GuidToKey.TryGetValue(hash, out string key))
                     { // image already exists
                         img = ImageCache[key] ?? img;

Flow.Launcher/ViewModel/ResultViewModel.cs

@@ -8,18 +8,57 @@
 using Flow.Launcher.Infrastructure.Logger;
 using Flow.Launcher.Infrastructure.UserSettings;
 using Flow.Launcher.Plugin;
-
+using Microsoft.FSharp.Core;
 
 namespace Flow.Launcher.ViewModel
 {
     public class ResultViewModel : BaseModel
     {
+        public class LazyAsync<T> : Lazy<Task<T>>
+        {
+            private T defaultValue;
+
+
+            private readonly Action _updateCallback;
+            public T Value
+            {
+                get
+                {
+                    if (!IsValueCreated)
+                    {
+                        base.Value.ContinueWith(_ =>
+                        {
+                            _updateCallback();
+                        });
+                        return defaultValue;
+                    }
+                    else if (!base.Value.IsCompleted)
+                    {
+                        return defaultValue;
+                    }
+                    else return base.Value.Result;
+                }
+            }
+            public LazyAsync(Func<Task<T>> factory, T defaultValue, Action updateCallback) : base(factory)
+            {
+                if (defaultValue != null)
+                {
+                    this.defaultValue = defaultValue;
+                }
+                _updateCallback = updateCallback;
+                
+            }
+        }
+
         public ResultViewModel(Result result, Settings settings)
         {
             if (result != null)
             {
                 Result = result;
-                Image = new Lazy<ImageSource>(SetImage);
+                Image = new LazyAsync<ImageSource>(SetImage, ImageLoader.defaultImage, () =>
+                    {
+                        OnPropertyChanged(nameof(Image));
+                    });
             }
 
             Settings = settings;
@@ -39,9 +78,9 @@ public ResultViewModel(Result result, Settings settings)
                                                 ? Result.SubTitle
                                                 : Result.SubTitleToolTip;
 
-        public Lazy<ImageSource> Image { get; set; }
+        public LazyAsync<ImageSource> Image { get; set; }
 
-        private ImageSource SetImage()
+        private async Task<ImageSource> SetImage()
         {
             var imagePath = Result.IcoPath;
             if (string.IsNullOrEmpty(imagePath) && Result.Icon != null)
@@ -62,14 +101,9 @@ private ImageSource SetImage()
                 return ImageLoader.Load(imagePath);
             else
             {
-                Task.Run(() =>
-                {
-                    Image = new Lazy<ImageSource>(() => ImageLoader.Load(imagePath));
-                    OnPropertyChanged(nameof(Image));
-                });
-
-                return ImageLoader.LoadDefault();
+                return await Task.Run(() => ImageLoader.Load(imagePath));
             }
+
         }
 
         public Result Result { get; }