Windows Phone 8位图分配使我的相机应用程序崩溃

Question

I'm having a weird memory allocation problem with my windows phone 8 application.

What I'm trying to achieve is pretty simple, take a picture, save it to the isolated storage, then add it to a collection of pictures in my datacontext.

Context of application is I have an appointment during which I take pictures, then when I get back to my appointment in my in-app calendar, i get to see all pictures related to the appointment.

I have three pages, a calendar page, when i click on an appointment, i get to a detail view of the appointment, and in it i have a button sending me to a camera application (mine, not the one from the phone). The following code is in my camera.xaml.cs file.

Here's the faulty code, in the camera page:

 public void cam_CaptureThumbnailAvailable(object sender, ContentReadyEventArgs e)
    {
        string fileName;
        string imageName = "PHOTO_" +
                            DateTime.Now.ToString("yyyy-dd-MM-hh-mm") +
                            "_" +
                            _savedcounter +
                            "_th.jpg";

        if ((App.Current as App).CurrentAppointment != null
            &&
           !string.IsNullOrEmpty((App.Current as App).CurrentAppointment.Reference))
        {
            fileName = (App.Current as App).CurrentAppointment.Reference +
                        "\\" +
                        imageName;

        }
        else
        {
            fileName = _savedcounter + "_th.jpg";

        }

        try
        {


            //Making sure I'm at the beginning of the stream
            e.ImageStream.Seek(0, SeekOrigin.Begin);

The following line crash the program:

BitmapImage bi = new BitmapImage(); //This line.
bi.SetSource(e.ImageStream);
            WriteableBitmap wb = new WriteableBitmap(bi);
            int index = (App.Current as App).CurrentAppointment.Pictures.Count - 1;


            MyPicture newPic = new MyPicture(wb,
                                                 imageName,
                                                 index,
                                                 false
                                                    );
            e.ImageStream.Seek(0, SeekOrigin.Begin);

Rest of the code works fine (no crash if I comment the instructions above.

            // Save thumbnail as JPEG to the local folder.
            using (IsolatedStorageFile isoStore = 
                            IsolatedStorageFile.GetUserStoreForApplication())
            {

                using (IsolatedStorageFileStream targetStream =
                                                isoStore.OpenFile(
                                                fileName,
                                                FileMode.Create,
                                                FileAccess.Write
                                                )
                      )
                {
                    // Initialize the buffer for 4KB disk pages.
                    byte[] readBuffer = new byte[4096];
                    int bytesRead = -1;

                    // Copy the thumbnail to the local folder. 
                    while ((bytesRead = e.ImageStream.Read(readBuffer, 0, readBuffer.Length)) > 0)
                    {
                        targetStream.Write(readBuffer, 0, bytesRead);
                    }

                }
            }


        }
        finally
        {
            // Close image stream
            e.ImageStream.Close();

        }

I honestly have no idea why this is crashing... Would gladly take any suggestions.

Answer 1

Ok sorry for the non answered post but I figured it out.

It was a threading problem, my bitmap creation being in the UI thread. By using a Task.Run(()=>bitmap_creation) everything works fine.