1

我有这个奇怪的问题。

我在主线程上的代码：

WebClient client = new WebClient();
client.OpenReadCompleted += new OpenReadCompletedEventHandler((ss, ee) =>
{
    Dispatcher.BeginInvoke(() =>
    {
        try
        {
            BitmapImage bi = new BitmapImage();
            bi.SetSource(ee.Result);
            WriteableBitmap wb = new WriteableBitmap(bi);
            _okAction.Invoke(linkTexBox.Text, wb);

            theProgressBarDialog.Close();
        }
        catch (Exception)
        {
            theProgressBarDialog.Close();

            string msg = "Cannot fetch the image.  Please make sure the image URL is correct";
            MessageBox.Show(msg);
        }
    });
});
client.OpenReadAsync(new Uri("Image URL without cross domain problem"));
theProgressBarDialog.Show();

图像已成功加载，并在我的画布上呈现。

奇怪的行为有时是，我的整个 Silverlight 应用程序似乎冻结，该应用程序不响应任何用户操作，除了右键单击，它会弹出默认的 Silverlight 上下文菜单。

按钮被强制禁用。

调试时，不会抛出异常。

编辑：如果我设置client.AllowReadStreamBuffering = false，我会得到异常：

{System.NotSupportedException: Read is not supported on the main thread when buffering is disabled.
   at MS.Internal.InternalNetworkStream.Read(Byte[] buffer, Int32 offset, Int32 count)
   at System.Windows.Media.Imaging.BitmapSource.ReadStream(Stream streamSource, Byte[]& buffer, Int32& position)
   at System.Windows.Media.Imaging.BitmapSource.SetSourceInternal(Stream streamSource)
   at System.Windows.Media.Imaging.BitmapImage.SetSourceInternal(Stream streamSource)
   at System.Windows.Media.Imaging.BitmapSource.SetSource(Stream streamSource)
   at ToonGui.ImportImageDialog.<>c__DisplayClass2.<OKButton_Click>b__1()}
    [System.NotSupportedException]: {System.NotSupportedException: Read is not supported on the main thread when buffering is disabled.
   at MS.Internal.InternalNetworkStream.Read(Byte[] buffer, Int32 offset, Int32 count)
   at System.Windows.Media.Imaging.BitmapSource.ReadStream(Stream streamSource, Byte[]& buffer, Int32& position)
   at System.Windows.Media.Imaging.BitmapSource.SetSourceInternal(Stream streamSource)
   at System.Windows.Media.Imaging.BitmapImage.SetSourceInternal(Stream streamSource)
   at System.Windows.Media.Imaging.BitmapSource.SetSource(Stream streamSource)
   at ToonGui.ImportImageDialog.<>c__DisplayClass2.<OKButton_Click>b__1()}
    Data: {System.Collections.ListDictionaryInternal}
    InnerException: null
    Message: "Read is not supported on the main thread when buffering is disabled."
    StackTrace: "   at MS.Internal.InternalNetworkStream.Read(Byte[] buffer, Int32 offset, Int32 count)\r\n   at System.Windows.Media.Imaging.BitmapSource.ReadStream(Stream streamSource, Byte[]& buffer, Int32& position)\r\n   at System.Windows.Media.Imaging.BitmapSource.SetSourceInternal(Stream streamSource)\r\n   at System.Windows.Media.Imaging.BitmapImage.SetSourceInternal(Stream streamSource)\r\n   at System.Windows.Media.Imaging.BitmapSource.SetSource(Stream streamSource)\r\n   at ToonGui.ImportImageDialog.<>c__DisplayClass2.<OKButton_Click>b__1()"

我是否必须使用一个BackgroundWorker类来让下载任务在另一个线程中运行？

4

1 回答 1

1

谢谢各位，终于找到答案了。这是一个 Siverlight 错误，这是微软的错。

正如我的一位朋友所说微软。。。总是有一堆令人想杀人的问题（这意味着Microsoft.... always has some issues that drive you crazy enough so that you want to shoot someone）

原因是theProgressBarDialogwhich is a ChildWindow，这是一个愚蠢的错误：关闭后，有时它会禁用父窗口（主应用程序）。

  1. Silverlight：Modal ChildWindow 在关闭后保持父级变灰：（也尝试调用 this.DialogResult = true 而不是 Close 方法。） Silverlight：Modal ChildWindow 在关闭后保持父级变灰

  2. Silverlight 4 ChildWindow 在关闭后使父级禁用：http: //social.msdn.microsoft.com/Forums/en-US/silverlightbugs/thread/56d0dc0b-3711-4643-b56f-2c94344e3d3a/

解决方案是：

        private void ChildWindow_Closed(object sender, System.EventArgs e)
        {
// TODO: should we use apply this fix to all ChildWindow? (make a TnChildWindow)
//   1. Silverlight: Modal ChildWindow keeps parent grayed after closing:
//      (Also try calling this.DialogResult = true instead of the Close method.)
//      https://stackoverflow.com/questions/6456952/silverlight-modal-childwindow-keeps-parent-grayed-after-closing
//   2. Silverlight 4 ChildWindow leaves parent disabled after closing:
//      http://social.msdn.microsoft.com/Forums/en-US/silverlightbugs/thread/56d0dc0b-3711-4643-b56f-2c94344e3d3a/
            Application.Current.RootVisual.SetValue(Control.IsEnabledProperty, true);
        }
于 2013-01-06T09:36:54.980 回答