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POUsing WPF to Generate Images in a WCF service
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  1. POUsing WPF to Generate Images in a WCF service
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    copied!<p>I am generating WPF .png images in my WCF service. All works well for a while but eventually I get this error:</p> <pre><code> System.Windows.Markup.XamlParseException: Initialization of 'System.Windows.Controls.TextBlock' threw an exception. ---&gt; System.ComponentModel.Win32Exception: The system cannot find the file specified at MS.Win32.UnsafeNativeMethods.RegisterClassEx(WNDCLASSEX_D wc_d) at MS.Win32.HwndWrapper..ctor(Int32 classStyle, Int32 style, Int32 exStyle, Int32 x, Int32 y, Int32 width, Int32 height, String name, IntPtr parent, HwndWrapperHook[] hooks) at System.Windows.SystemResources.EnsureResourceChangeListener() at System.Windows.SystemResources.FindResourceInternal(Object key, Boolean allowDeferredResourceReference, Boolean mustReturnDeferredResourceReference) at System.Windows.StyleHelper.GetThemeStyle(FrameworkElement fe, FrameworkContentElement fce) at System.Windows.FrameworkElement.UpdateThemeStyleProperty() at System.Windows.FrameworkElement.OnInitialized(EventArgs e) at System.Windows.FrameworkElement.TryFireInitialized() at System.Windows.FrameworkElement.EndInit() at MS.Internal.Xaml.Runtime.ClrObjectRuntime.InitializationGuard(XamlType xamlType, Object obj, Boolean begin) --- End of inner exception stack trace --- at System.Windows.Markup.XamlReader.RewrapException(Exception e, IXamlLineInfo lineInfo, Uri baseUri) at System.Windows.Markup.WpfXamlLoader.Load(XamlReader xamlReader, IXamlObjectWriterFactory writerFactory, Boolean skipJournaledProperties, Object rootObject, XamlObjectWriterSettings settings, Uri baseUri) at System.Windows.Markup.WpfXamlLoader.LoadBaml(XamlReader xamlReader, Boolean skipJournaledProperties, Object rootObject, XamlAccessLevel accessLevel, Uri baseUri) at System.Windows.Markup.XamlReader.LoadBaml(Stream stream, ParserContext parserContext, Object parent, Boolean closeStream) at System.Windows.Application.LoadComponent(Object component, Uri resourceLocator) </code></pre> <p>I have never been able to create this error locally, only on my hosts web server. I have tried several fixes and workarounds including:</p> <p><a href="https://stackoverflow.com/questions/8995588/asp-net-throws-win32exception-when-creating-bitmapimage-cannot-find-file-specif">ASP.NET Throws Win32Exception when creating BitmapImage, cannot find file specified</a> <a href="http://www.thejoyofcode.com/Generating_images_using_WPF_on_the_Server.aspx" rel="nofollow noreferrer">http://www.thejoyofcode.com/Generating_images_using_WPF_on_the_Server.aspx</a></p> <p>However, I have yet to find a method which works. Can someone please post some code that does not throw this error or at least can work around it somehow. This is what my service does:</p> <pre><code>// Only one copy of the dispatcher (I have tried creating a new one each time too). private BackgroundStaDispatcher dispatcher = new BackgroundStaDispatcher(); public Stream GetImage() { WebOperationContext.Current.OutgoingResponse.ContentType = "image/png"; Stream stream = null; this.dispatcher.Invoke( () =&gt; { UserControl userControl = new UserControl() { DataContext = "Hello World" }; // Use PngBitmapEncoder to convert the control to a bitmap. stream = userControl.ToPng(173, 173); }); return stream; } </code></pre>
 

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