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POOutOfMemoryException on WP8 (C# & Silverlight) because of WritableBitmap
 

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  1. POOutOfMemoryException on WP8 (C# & Silverlight) because of WritableBitmap
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    <p>I'm creating and application that needs to add and remove a lot of <code>UIElement</code> to a <code>Canvas</code>. Basically a <code>Canvas</code> contains a collection of <code>UIElement</code> and automatically renders/updates it on the screen depending what it contains.</p> <p>In order to avoid having a tons of <code>UIElements</code> who overlap each others on the screen I prefer to add all of them on a secondary <code>Canvas</code> then create a <code>Image</code> from it (thanks to <code>WritableBitmap</code>). Finally I add this <code>Image</code> on my current <code>Canvas</code>. By allowing to have only few image on my Canvas I expect to have better performance. Unfortunately it seems I can't delete completely the <code>WritableBitmap</code>, even if I set it to <code>null</code>.</p> <p>The following code illustrates it :</p> <pre><code>//My constructor public WP8Graphics() { //Here my collection DataBinded with the Canvas from the Mainpage this.UIElements = new ObservableCollection&lt;UIElement&gt;(); //The secondary Canvas GraphicCanvas = new Canvas(); GraphicCanvas.Height = MainPage.CurrentCanvasHeight; GraphicCanvas.Width = MainPage.CurrentCanvasWidth; } ///This method can be hit thousand times, it basically create a rectangle public void fillRect(int x, int y, int width, int height) { // some code // CREATE THE RECTANGLE rect GraphicCanvas.Children.Add(rect); // My secondary Canvas WriteableBitmap wb1 = new WriteableBitmap(GraphicCanvas, null); wb1.Invalidate(); WriteableBitmap wb2 = new WriteableBitmap((int)MainPage.CurrentCanvasWidth, (int)MainPage.CurrentCanvasHeight); for (int i = 0; i &lt; wb2.Pixels.Length; i++) { wb2.Pixels[i] = wb1.Pixels[i]; } wb2.Invalidate(); wb1 = null; Image thumbnail = new Image(); thumbnail.Height = MainPage.CurrentCanvasHeight; thumbnail.Width = MainPage.CurrentCanvasWidth; thumbnail.Source = wb2; this.UIElements.Add(thumbnail); } </code></pre> <p>After something like 24 <code>WriteableBitmap</code> created a <strong>OutOfMemoryException</strong> appears. I read many articles about this problem and in my case it seems the <code>WriteableBitmap</code> depends on my <strong>GraphicCanvas</strong> and remains because there still have a reference to it. I can't delete my Graphic Canvas nor set <strong>myImage</strong> source to null.</p> <p>I have 2 question :</p> <ul> <li>Is there another way to create an image from Canvas or a collection of UIElements ?</li> <li>Is it possible to remove the reference who keeps that WriteableBitmap alive ?</li> </ul> <p>I hope to be enough clear and easy to read. </p> <p>Thank you for reading.</p> <p><strong>EDITED with atomaras suggestion, but still the same problem</strong></p> <p><code>WriteableBitmap wb1 = new WriteableBitmap(GraphicCanvas, null);</code> This line still throws OutOfMemoryException.</p>
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