ImageEx: Added caching strategy and fixed caching of the Image.

Microsoft.Toolkit.Uwp.UI.Controls/ImageEx/CachingStrategy.cs

@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.Toolkit.Uwp.UI.Controls
+{
+    /// <summary>
+    /// The type of caching to be applied to <see cref="ImageEx"/>.
+    /// Default is <see cref="Custom"/>
+    /// </summary>
+    public enum ImageExCachingStrategy
+    {
+        /// <summary>
+        /// Caching is handled by <see cref="ImageEx"/>'s custom caching system.
+        /// </summary>
+        Custom,
+
+        /// <summary>
+        /// Caching is handled internally by UWP.
+        /// </summary>
+        Internal
+    }
+}

Microsoft.Toolkit.Uwp.UI.Controls/ImageEx/ImageExBase.Members.cs

@@ -45,6 +45,11 @@ public partial class ImageExBase
         /// </summary>
         public static readonly DependencyProperty IsCacheEnabledProperty = DependencyProperty.Register(nameof(IsCacheEnabled), typeof(bool), typeof(ImageExBase), new PropertyMetadata(false));
 
+        /// <summary>
+        /// Identifies the <see cref="CachingStrategy"/> dependency property.
+        /// </summary>
+        public static readonly DependencyProperty CachingStrategyProperty = DependencyProperty.Register(nameof(CachingStrategy), typeof(ImageExCachingStrategy), typeof(ImageExBase), new PropertyMetadata(ImageExCachingStrategy.Custom));
+
         /// <summary>
         /// Returns a mask that represents the alpha channel of an image as a <see cref="CompositionBrush"/>
         /// </summary>
@@ -125,5 +130,14 @@ public bool IsCacheEnabled
             get { return (bool)GetValue(IsCacheEnabledProperty); }
             set { SetValue(IsCacheEnabledProperty, value); }
         }
+
+        /// <summary>
+        /// Gets or sets a value indicating how the <see cref="ImageEx"/> will be cached.
+        /// </summary>
+        public ImageExCachingStrategy CachingStrategy
+        {
+            get { return (ImageExCachingStrategy)GetValue(CachingStrategyProperty); }
+            set { SetValue(CachingStrategyProperty, value); }
+        }
     }
 }

Microsoft.Toolkit.Uwp.UI.Controls/ImageEx/ImageExBase.Source.cs

@@ -121,60 +121,78 @@ private async Task LoadImageAsync(Uri imageUri)
         {
             if (_uri != null)
             {
-                if (IsCacheEnabled && _isHttpSource)
+                if (IsCacheEnabled)
                 {
-                    try
+                    switch (CachingStrategy)
                     {
-                        var propValues = new List<KeyValuePair<string, object>>();
-
-                        if (DecodePixelHeight > 0)
-                        {
-                            propValues.Add(new KeyValuePair<string, object>(nameof(DecodePixelHeight), DecodePixelHeight));
-                        }
-
-                        if (DecodePixelWidth > 0)
-                        {
-                            propValues.Add(new KeyValuePair<string, object>(nameof(DecodePixelWidth), DecodePixelWidth));
-                        }
-
-                        if (propValues.Count > 0)
-                        {
-                            propValues.Add(new KeyValuePair<string, object>(nameof(DecodePixelType), DecodePixelType));
-                        }
-
-                        var img = await ImageCache.Instance.GetFromCacheAsync(imageUri, true, _tokenSource.Token, propValues);
-
-                        lock (LockObj)
-                        {
-                            // If you have many imageEx in a virtualized listview for instance
-                            // controls will be recycled and the uri will change while waiting for the previous one to load
-                            if (_uri == imageUri)
-                            {
-                                AttachSource(img);
-                                ImageExOpened?.Invoke(this, new ImageExOpenedEventArgs());
-                                VisualStateManager.GoToState(this, LoadedState, true);
-                            }
-                        }
+                        case ImageExCachingStrategy.Custom when _isHttpSource:
+                            await SetHttpSourceCustomCached(imageUri);
+                            break;
+                        case ImageExCachingStrategy.Custom:
+                        case ImageExCachingStrategy.Internal:
+                        default:
+                            AttachSource(new BitmapImage(imageUri));
+                            break;
                     }
-                    catch (OperationCanceledException)
+                }
+                else
+                {
+                    AttachSource(new BitmapImage(_uri)
                     {
-                        // nothing to do as cancellation has been requested.
-                    }
-                    catch (Exception e)
+                        CreateOptions = BitmapCreateOptions.IgnoreImageCache
+                    });
+                }
+            }
+        }
+
+        private async Task SetHttpSourceCustomCached(Uri imageUri)
+        {
+            try
+            {
+                var propValues = new List<KeyValuePair<string, object>>();
+
+                if (DecodePixelHeight > 0)
+                {
+                    propValues.Add(new KeyValuePair<string, object>(nameof(DecodePixelHeight), DecodePixelHeight));
+                }
+
+                if (DecodePixelWidth > 0)
+                {
+                    propValues.Add(new KeyValuePair<string, object>(nameof(DecodePixelWidth), DecodePixelWidth));
+                }
+
+                if (propValues.Count > 0)
+                {
+                    propValues.Add(new KeyValuePair<string, object>(nameof(DecodePixelType), DecodePixelType));
+                }
+
+                var img = await ImageCache.Instance.GetFromCacheAsync(imageUri, true, _tokenSource.Token, propValues);
+
+                lock (LockObj)
+                {
+                    // If you have many imageEx in a virtualized listview for instance
+                    // controls will be recycled and the uri will change while waiting for the previous one to load
+                    if (_uri == imageUri)
                     {
-                        lock (LockObj)
-                        {
-                            if (_uri == imageUri)
-                            {
-                                ImageExFailed?.Invoke(this, new ImageExFailedEventArgs(e));
-                                VisualStateManager.GoToState(this, FailedState, true);
-                            }
-                        }
+                        AttachSource(img);
+                        ImageExOpened?.Invoke(this, new ImageExOpenedEventArgs());
+                        VisualStateManager.GoToState(this, LoadedState, true);
                     }
                 }
-                else
+            }
+            catch (OperationCanceledException)
+            {
+                // nothing to do as cancellation has been requested.
+            }
+            catch (Exception e)
+            {
+                lock (LockObj)
                 {
-                    AttachSource(new BitmapImage(_uri));
+                    if (_uri == imageUri)
+                    {
+                        ImageExFailed?.Invoke(this, new ImageExFailedEventArgs(e));
+                        VisualStateManager.GoToState(this, FailedState, true);
+                    }
                 }
             }
         }

docs/controls/ImageEx.md

@@ -8,7 +8,7 @@ keywords: windows 10, uwp, windows community toolkit, uwp community toolkit, uwp
 # ImageEx XAML Control
 
 The [ImageEx Control](https://docs.microsoft.com/dotnet/api/microsoft.toolkit.uwp.ui.controls.imageex) and [RoundImageEx Control](https://docs.microsoft.com/dotnet/api/microsoft.toolkit.uwp.ui.controls.roundimageex) downloads images asynchronously, while showing a loading indicator. Source images are then stored in the application's local cache to preserve resources and load time. ImageEx also extends the default *Image* and *ImageBrush* Platform controls respectively to improve performance through caching. You can also use a placeholder image that will be displayed while loading the main image.
- 
+
 ## Syntax
 
 ```xaml
@@ -33,6 +33,8 @@ On Windows 10.0.16299.0 or higher, `CornerRadius` is supported on ImageEx.  Use
 | Property | Type | Description |
 | -- | -- | -- |
 | NineGrid | Thickness | Gets or sets the nine-grid used by the image |
+| IsCacheEnabled | bool | Gets or sets a value indicating whether gets or sets cache state |
+| ImageExCachingStrategy | enum | Gets or sets a value indicating how the Image will be cached |
 
 ## RoundImageEx Properties