C# 如何捕获此WPF位图加载异常？

我正在开发一个应用程序，它使用.NET3.5SP1和C#从web上加载位图

加载代码如下所示：

        try {
            CurrentImage = pics[unChosenPics[index]];
            bi = new BitmapImage(CurrentImage.URI);
            // BitmapImage.UriSource must be in a BeginInit/EndInit block.
            bi.DownloadCompleted += new EventHandler(bi_DownloadCompleted);
            AssessmentImage.Source = bi;
        }
        catch {
            System.Console.WriteLine("Something broke during the read!");
        }

bi_DownloadCompleted上要加载的代码是：

    void bi_DownloadCompleted(object sender, EventArgs e) {
        try {
            double dpi = 96;
            int width = bi.PixelWidth;
            int height = bi.PixelHeight;

            int stride = width * 4; // 4 bytes per pixel
            byte[] pixelData = new byte[stride * height];
            bi.CopyPixels(pixelData, stride, 0);

            BitmapSource bmpSource = BitmapSource.Create(width, height, dpi, dpi, PixelFormats.Bgra32, null, pixelData, stride);

            AssessmentImage.Source = bmpSource;
            Loading.Visibility = Visibility.Hidden;
            AssessmentImage.Visibility = Visibility.Visible;
        }
        catch {
            System.Console.WriteLine("Exception when viewing bitmap.");
        }
    }

每隔一段时间，就会出现一幅令读者心碎的图像。我想这是意料之中的。然而，异常并没有被这些try/catch块捕获，而是被抛出到我可以处理它的地方之外。我可以使用全局WPF异常来处理它，比如。然而，这将严重扰乱我的程序的控制流，如果可能的话，我希望避免这种情况

我必须进行双源分配，因为许多图像在microsoft位图加载程序期望的位置缺少宽度/高度参数。因此，第一个赋值似乎强制下载，而第二个赋值则正确地获得dpi/图像维度

如何捕获和处理此异常

如果要复制，请尝试将此图像作为uri加载：

http://i.pbase.com/o2/26/519326/1/123513540.Yub8hciV.Longford12.jpg

例外情况是：

System.ArgumentException in PresentationCore
Value does not fall within the expected range.

内部例外是：

An invalid character was found in text context.

堆栈跟踪：

   at MS.Internal.HRESULT.Check(Int32 hr)
   at System.Windows.Media.Imaging.BitmapFrameDecode.get_ColorContexts()
   at System.Windows.Media.Imaging.BitmapImage.FinalizeCreation()
   at System.Windows.Media.Imaging.BitmapImage.OnDownloadCompleted(Object sender, EventArgs e)
   at System.Windows.Media.UniqueEventHelper.InvokeEvents(Object sender, EventArgs args)
   at System.Windows.Media.Imaging.LateBoundBitmapDecoder.DownloadCallback(Object arg)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
   at System.Windows.Threading.DispatcherOperation.InvokeImpl()
   at System.Threading.ExecutionContext.runTryCode(Object userData)
   at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Windows.Threading.DispatcherOperation.Invoke()
   at System.Windows.Threading.Dispatcher.ProcessQueue()
   at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
   at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter)
   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
   at System.Windows.Threading.Dispatcher.TranslateAndDispatchMessage(MSG& msg)
   at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
   at System.Windows.Application.RunInternal(Window window)
   at LensComparison.App.Main() in C:\Users\Mark64\Documents\Visual Studio 2008\Projects\LensComparison\LensComparison\obj\Release\App.g.cs:line 48
   at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

这似乎有效：

try
{
    frame = BitmapFrame.Create(new Uri("http://i.pbase.com/o2/26/519326/1/123513540.Yub8hciV.Longford12.jpg"));
}
catch
{
    return;
}

---

BitmapFrame有一个DecodeFailed事件，但我无法钩住它，因为BitmapFrame在创建后被冻结。

此异常是图像中包含的“断开”颜色配置文件信息导致的。如果您不关心此信息（或希望在异常后再次尝试解析），请使用BitmapCreateOptions.IgnoreColorProfile标志

例如：

BitmapImage i = new BitmapImage();
i.BeginInit();
i.CreateOptions |= BitmapCreateOptions.IgnoreColorProfile;
i.UriSource = new Uri(@"http://www.bing.com/fd/hpk2/KiteFestival_EN-US2111991920.jpg");
i.EndInit();

---

如果您想了解更多信息，请查看。（我们今天都通过电子邮件就这个问题进行了沟通。）

碰撞这个。。。当使用与海报类似的技术从Flickr加载任意图像时，我看到了同样的问题。