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POImageTools AnimatedImage not releasing memory
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  1. POImageTools AnimatedImage not releasing memory
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    copied!<p>I have a WindowsPhone 7.8 application, that needs to display animated GIFs as well as images that are supported directly by Silverlight. Therefor we created a custom user control <code>public sealed partial class ExtendedImageControl : UserControl, IDisposable</code>, which has a DependancyProperty called ImageSource. This property is bound to a URL. The code behind will then either insert a regular Image control into the LayoutRoot, or a AnimatedImage. However, the AnimatedImage will not release its memory when it gets out of view or the containing page is closed.</p> <p>The loading logic is the following:</p> <pre><code>ExtendedImage loadedImage = (ExtendedImage)await Utils.Caching.Image.LoadCachedImageFromUrlAsync&lt;ExtendedImage&gt;(loadedLocation); if (ImageSource == loadedLocation) { AnimatedImage image = new AnimatedImage(); image.Stretch = stretch; image.Source = loadedImage; LayoutRoot.Children.Add(image); CurrentImageMode = ExtendedImageMode.AnimatedImage; loadedImage = null; #if DEBUG App.logger.log("Loaded {0} as animated image", loadedLocation); #endif imageDisplay = image; raiseImageUpdated(); } </code></pre> <p>Ultimately, the image is loaded with</p> <pre><code> WebClient client = new WebClient(); ExtendedImage image = new ExtendedImage(); using (Stream source = await client.OpenReadTaskAsync(location)) { if (location.ToString().EndsWith("gif", StringComparison.InvariantCultureIgnoreCase)) { image.SetSource(source); TaskCompletionSource&lt;ExtendedImage&gt; imageLoaded = new TaskCompletionSource&lt;ExtendedImage&gt;(); EventHandler loadingCompleteHandler = new EventHandler((sender, e) =&gt; { imageLoaded.SetResult(image); }); EventHandler&lt;UnhandledExceptionEventArgs&gt; loadingFailedHandler = new EventHandler&lt;UnhandledExceptionEventArgs&gt;((sender, e) =&gt; { imageLoaded.SetResult(image); #if DEBUG if (System.Diagnostics.Debugger.IsAttached) System.Diagnostics.Debugger.Break(); #endif }); image.LoadingCompleted += loadingCompleteHandler; image.LoadingFailed += loadingFailedHandler; image = await imageLoaded.Task; //Remove handlers, otherwise the object might be kept in the memory image.LoadingCompleted -= loadingCompleteHandler; image.LoadingFailed -= loadingFailedHandler; } else { //... load with native Silverlight methods } } return image; </code></pre> <p>We noticed the memory problem very early on, so the control implements the IDisposable interface with</p> <pre><code> public void Dispose() { unloadImage(); GC.SuppressFinalize(this); } private void unloadImage() { SmartDispatcher.BeginInvoke(() =&gt; { if (imageDisplay != null) { if (imageDisplay is AnimatedImage) { if ((imageDisplay as AnimatedImage).Source != null &amp; (imageDisplay as AnimatedImage).Source.Frames != null) (imageDisplay as AnimatedImage).Source.Frames.Clear(); (imageDisplay as AnimatedImage).Stop(); (imageDisplay as AnimatedImage).Source = null; } else if (imageDisplay is Image &amp;&amp; ((Image)imageDisplay).Source != GIFplaceholder) { (imageDisplay as Image).Source = null; } imageDisplay = null; } }); } </code></pre> <p>However, the Dispose method is never called on the image.</p> <p>What can I do to find out why this object isn't picked up by the GC? I'm not registering any eventhandlers so as far as I understand, it should be collected when the Application page is navigated away from. I tried adding a destructor as well, however this one is not called as well.</p>
 

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