ThreadPool和Dispatcher共享Stream? [英] ThreadPool and Dispatcher sharing Stream?

问题描述

我正在尝试这样做:

 使用( var  albm = isoStore.CreateFile(  shared/media/" + dlSongInfo.id +  -NP"))
                        {
                            Deployment.Current.Dispatcher.BeginInvoke(()= > 
                             {
                                 BitmapImage图片= 新 BitmapImage();
                                 image.SetSource(e.Result);
                                 WriteableBitmap wb = 新 WriteableBitmap(image);

                                 wb.SaveJpeg(albm， 358 ， 358 ， 0 ， 100 )；
                             });
                        } 

但是它说在执行SaveJpeg时流是关闭的.我猜是因为在不同的线程中它无法访问它?我该如何做到这一点.还是在不需要使用UI线程的情况下从流写入位图图像的另一种方法?

P.S.这是在ThreadPool上执行的.在单核计算机上，您可能会在这里看到竞赛，因为有时它可以工作，但大多数情况下是不会的.只需不将所有这些内容放在using语句中，而是正常创建albm对象并将其放置在您要调用的委托中.

  var  albm = isoStore.CreateFile("  + dlSongInfo.id + "  ))；
Deployment.Current.Dispatcher.BeginInvoke(()= >  {
  尝试 {
    BitmapImage图片= 新 BitmapImage();
    image.SetSource(e.Result);
    WriteableBitmap wb = 新 WriteableBitmap(image);
    wb.SaveJpeg(albm， 358 ， 358 ， 0 ， 100 )；
  } 最终 {
    albm.Dispose();
  }
}); 

Im trying to do this:

using (var albm = isoStore.CreateFile("shared/media/" + dlSongInfo.id + "-NP"))
                        {
                            Deployment.Current.Dispatcher.BeginInvoke(() =>
                             {
                                 BitmapImage image = new BitmapImage();
                                 image.SetSource(e.Result);
                                 WriteableBitmap wb = new WriteableBitmap(image);

                                 wb.SaveJpeg(albm, 358, 358, 0, 100);
                             });
                        }

But it said that the stream is closed when doing the SaveJpeg. I guess that because there in different threads it can''t access it? How can I achieve this. Or is is an alternative way of writing a bitmap image from a stream without needing to use a UI thread?

P.S. This is execute on a ThreadPool.

解决方案

The using statement disposes your object before (in most cases) your Delegate gets executed. On single core machines you could see a race here, because sometimes it could work but mostly it won''t. Simply don''t put all this in a using statement but instead create the albm object normally and dispose it in the delegate you''re calling.

var albm = isoStore.CreateFile("shared/media/" + dlSongInfo.id + "-NP"));
Deployment.Current.Dispatcher.BeginInvoke(() => {
  try {
    BitmapImage image = new BitmapImage();
    image.SetSource(e.Result);
    WriteableBitmap wb = new WriteableBitmap(image);
    wb.SaveJpeg(albm, 358, 358, 0, 100);
  } finally {
    albm.Dispose();
  }
});

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