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POUsing SynchronizationContext for sending events back to the UI for WinForms or WPF
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copied!<p>I'm using a SynchronizationContext to marshal events back to the UI thread from my DLL that does a lot of multi-threaded background tasks.</p> <p>I know the singleton pattern isn't a favorite, but I'm using it for now to store a reference of the UI's SynchronizationContext when you create foo's parent object.</p> <pre><code>public class Foo { public event EventHandler FooDoDoneEvent; public void DoFoo() { //stuff OnFooDoDone(); } private void OnFooDoDone() { if (FooDoDoneEvent != null) { if (TheUISync.Instance.UISync != SynchronizationContext.Current) { TheUISync.Instance.UISync.Post(delegate { OnFooDoDone(); }, null); } else { FooDoDoneEvent(this, new EventArgs()); } } } } </code></pre> <p>This didn't work at all in WPF, the TheUISync instances UI sync (which is feed from the main window) never matches the current SynchronizationContext.Current. In windows form when I do the same thing they will match after an invoke and we'll get back to the correct thread.</p> <p>My fix, which i hate, looks like</p> <pre><code>public class Foo { public event EventHandler FooDoDoneEvent; public void DoFoo() { //stuff OnFooDoDone(false); } private void OnFooDoDone(bool invoked) { if (FooDoDoneEvent != null) { if ((TheUISync.Instance.UISync != SynchronizationContext.Current) && (!invoked)) { TheUISync.Instance.UISync.Post(delegate { OnFooDoDone(true); }, null); } else { FooDoDoneEvent(this, new EventArgs()); } } } } </code></pre> <p>So I hope this sample makes enough sense to follow.</p>

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