Configuration: Added ExecuteCallbacksOnUIThread property (default disabled)

Author: daniel-luberda

source/FFImageLoading.Common/Config/Configuration.cs

@@ -29,6 +29,7 @@ public Configuration()
             VerboseLogging = false;
             SchedulerMaxParallelTasks = Math.Max(2, (int)(Environment.ProcessorCount / 2d));
             DiskCacheDuration = TimeSpan.FromDays(30d);
+            ExecuteCallbacksOnUIThread = false;
 		}
 
 		/// <summary>
@@ -189,6 +190,13 @@ public bool LoadWithTransparencyChannel
         /// </summary>
         /// <value>The duration of the cache.</value>
         public TimeSpan DiskCacheDuration { get; set; }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether callbacs (OnFinish, OnSuccess, etc) 
+        /// should execute on UI thread
+        /// </summary>
+        /// <value><c>true</c> if execute callbacks on UIT hread; otherwise, <c>false</c>.</value>
+        public bool ExecuteCallbacksOnUIThread { get; set; }
     }
 }
 

source/FFImageLoading.Common/Work/ImageLoaderTask.cs

@@ -214,8 +214,21 @@ public async virtual Task<bool> TryLoadFromMemoryCacheAsync()
                 if (result)
                 {
                     Logger.Debug(string.Format("Image loaded from cache: {0}", Key));
-                    Parameters?.OnSuccess?.Invoke(ImageInformation, LoadingResult.MemoryCache);
-                    Parameters?.OnFinish?.Invoke(this);
+
+                    if (Configuration.ExecuteCallbacksOnUIThread && (Parameters?.OnSuccess != null || Parameters?.OnFinish != null))
+                    {
+                        await MainThreadDispatcher.PostAsync(() =>
+                        {
+                            Parameters?.OnSuccess?.Invoke(ImageInformation, LoadingResult.MemoryCache);
+                            Parameters?.OnFinish?.Invoke(this);
+                        });
+                    }
+                    else
+                    {
+                        Parameters?.OnSuccess?.Invoke(ImageInformation, LoadingResult.MemoryCache);
+                        Parameters?.OnFinish?.Invoke(this);
+                    }
+
                     IsCompleted = true;
                 }
                 else
@@ -249,7 +262,18 @@ await ShowPlaceholder(Parameters.LoadingPlaceholderPath, KeyForLoadingPlaceholde
                 else
                 {
                     Logger.Error(string.Format("Image loading failed: {0}", Key), ex);
-                    Parameters?.OnError?.Invoke(ex);
+
+                    if (Configuration.ExecuteCallbacksOnUIThread && Parameters?.OnError != null)
+                    {
+                        await MainThreadDispatcher.PostAsync(() =>
+                        {
+                            Parameters?.OnError?.Invoke(ex);
+                        });
+                    }
+                    else
+                    {
+                        Parameters?.OnError?.Invoke(ex);
+                    }
                 }
             }
 
@@ -334,8 +358,19 @@ public async Task RunAsync()
 
                             if (loadingResult == LoadingResult.Internet)
                                 Logger?.Debug(string.Format("DownloadOnly success: {0}", Key));
-                            
-                            Parameters?.OnSuccess?.Invoke(ImageInformation, loadingResult);
+
+                            if (Configuration.ExecuteCallbacksOnUIThread && Parameters?.OnSuccess != null)
+                            {
+                                await MainThreadDispatcher.PostAsync(() =>
+                                {
+                                    Parameters?.OnSuccess?.Invoke(ImageInformation, loadingResult);
+                                });
+                            }
+                            else
+                            {
+                                Parameters?.OnSuccess?.Invoke(ImageInformation, loadingResult);
+                            }
+
                             return;
                         }
 
@@ -362,7 +397,17 @@ public async Task RunAsync()
                     }
                 }
 
-                Parameters?.OnSuccess?.Invoke(ImageInformation, loadingResult);
+                if (Configuration.ExecuteCallbacksOnUIThread && Parameters?.OnSuccess != null)
+                {
+                    await MainThreadDispatcher.PostAsync(() =>
+                    {
+                        Parameters?.OnSuccess?.Invoke(ImageInformation, loadingResult);
+                    });
+                }
+                else
+                {
+                    Parameters?.OnSuccess?.Invoke(ImageInformation, loadingResult);
+                }
             }
             catch (Exception ex)
             {
@@ -381,7 +426,18 @@ public async Task RunAsync()
                 else
                 {
                     Logger.Error(string.Format("Image loading failed: {0}", Key), ex);
-                    Parameters?.OnError?.Invoke(ex);
+
+                    if (Configuration.ExecuteCallbacksOnUIThread && Parameters?.OnError != null)
+                    {
+                        await MainThreadDispatcher.PostAsync(() =>
+                        {
+                            Parameters?.OnError?.Invoke(ex);
+                        });
+                    }
+                    else
+                    {
+                        Parameters?.OnError?.Invoke(ex);
+                    }
 
                     try
                     {
@@ -405,7 +461,18 @@ await ShowPlaceholder(Parameters.ErrorPlaceholderPath, KeyForErrorPlaceholder,
             {
                 using (Parameters)
                 {
-                    Parameters?.OnFinish?.Invoke(this);
+                    if (Configuration.ExecuteCallbacksOnUIThread && Parameters?.OnFinish != null)
+                    {
+                        await MainThreadDispatcher.PostAsync(() =>
+                        {
+                            Parameters?.OnFinish?.Invoke(this);
+                        });
+                    }
+                    else
+                    {
+                        Parameters?.OnFinish?.Invoke(this);
+                    }
+
                     ImageService.RemovePendingTask(this);
                 }