C# Windows.RunAsync方法代码示例

        public Task<List<FlickrImage>> SearchAsync(string searchTerm, Windows.UI.Core.CoreDispatcher dispatcher)
        {
            return Task.Run<List<FlickrImage>>(() =>
            {
                var flickrImages = new List<FlickrImage>();

                var photos = _Flickr.PhotosSearch(new PhotoSearchOptions(this.Username, string.Empty, TagMode.None, searchTerm));

                foreach (var photo in photos)
                {
                    dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
                    {
                        flickrImages.Add(new FlickrImage(null, photo.SmallUrl, photo.DoesLargeExist ? photo.LargeUrl : photo.Medium640Url, photo.Title, photo.DateTaken, photo.Description));
                    });
                }
                return flickrImages;
            });
        }

        public Task<IList<FlickrImageSet>> LoadAsync(Windows.UI.Core.CoreDispatcher dispatcher)
        {
            var task = Task.Run(() =>
            {
                var flickrUser = _GetUserProfileAsync(this.Username).Result;
                var photoSetCollection = _GetPhotosetCollectionAsync(flickrUser.UserId).Result;

                foreach (var photoSet in photoSetCollection)
                {
                    FlickrImageSet imageSet = null;

                    dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
                    {
                        imageSet = new FlickrImageSet(photoSet.PhotosetSmallUrl, photoSet.Title, photoSet.DateUpdated, photoSet.Description);
                        this.ImageSets.Add(imageSet);
                        base.OnPropertyChanged("ImageSets");
                    }
                    );

                    var photosetPhotosCollection = _GetCollectionForSetAsync(photoSet.PhotosetId).Result;

                    foreach (var photo in photosetPhotosCollection)
                    {
                        dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
                        {
                            var image = new FlickrImage(imageSet, photo.SmallUrl, photo.DoesLargeExist ? photo.LargeUrl : photo.Medium640Url, photo.Title, photo.DateTaken, photoSet.Description);
                            imageSet.Collection.Add(image);

                        });
                    }
                }

                return this.ImageSets;
            });

            return task;
        }

        private async void ReadAndSort(Windows.UI.Core.CoreDispatcher Dispatcher)
        {
            //Identify that it is ID3
            if (GetString(3).Equals("ID3"))
            {
                //Unwanted space between "ID3" tag and frame name
                for (int i = 0; i < 7; i++)
                    data.ReadByte();

                //Loop through the rest of the file, looking directly for specific frame names, reading their properties, and scrapping the rest.
                while (data.UnconsumedBufferLength > 3)
                {
                    //Use our Frame Name constant (4) to seek the identity of the tag (if it's one we care about).
                    //Otherwise, we loop through the bytes we don't care about.
                    String identity = GetString(ID3FrameNameLength);
                    identity = new ID3FrameDictionary().GetIdentity(identity);

                    //ID3 -- assuming no one took liberties extending this during encoding -- reserves 4 bytes following
                    //the frame name to tell decoders
                    byte[] byteCounter = new byte[4] { 0, 0, 0, 0 };
                    for (int i = 0; i < 4; i++)
                    {
                        byteCounter[i] = data.ReadByte();
                    }

                    //Since we're dealing with encoding and dealing primarily with Hex values, all values should be unsigned. 
                    //I don't actually know is there is padding between the frame name and the value count. If there is, this following operation doesn't hurt anything
                    //and is set in case the 4 bytes following are all possibly used. Accounted for by 64-bit integer.
                    UInt64 intCounter = (ulong)((byteCounter[0] << (8 * 3)) + (byteCounter[1] << (8 * 2)) + (byteCounter[2] << (8 * 1)) + (byteCounter[3] << (8 * 0)));
                    

                    //Padding of 00 00 between the 64-bit value count and the frame value. Read through the padding.
                    data.ReadByte();
                    data.ReadByte();

                    //Check if frame name is one we care about. (Album, Artist, Title, Cover)
                    if (identity != null)
                    {
                        //APIC (Album Picture) is the only frame that we could care about that can't be interpreted as a string.
                        if (identity.Equals("Image"))
                        {
                            //We get the byte array, but WinRT/Windows 8 makes the process of converting a byte array into a Random Access Stream difficult.
                            //A custom library was made for this that converts a Stream (MemoryStream) into IRandomAccessStream, so we can create a bitmap image.
                            MemoryStream ms = new MemoryStream(GetImage(intCounter));
                            MemoryRandomAccessStream randomAccessStream = new MemoryRandomAccessStream(ms);
                            
                            //Create new BitmapImage inside this thread, as it isn't possible to know that this variable will come out of the UI thread operation.
                            BitmapImage bt = null;

                            //Grab UI Thread to create a new BitmapImage instance, and to take care of operations involving the UI.
                            await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.High,
                             async () =>
                             {
                                 bt = new BitmapImage();
                                 try
                                 {
                                     await bt.SetSourceAsync(randomAccessStream);
                                     cover.Source = bt;
                                     cover.MaxWidth = bt.PixelWidth;
                                     cover.MaxHeight = bt.PixelHeight;
                                 }
                                 catch (Exception e)
                                 {
                                     //In case setting the source throws an exception due to corrupt extraction.
                                 }
                             });
                        }
                        else
                        {
                            //Convert the bytes following the frame value count into a readable string. It skips over characters that aren't used in the English Language.
                            String idValue = GetString(intCounter);
                            fileData[identity] = idValue;
                            Debug.WriteLine(idValue);
                        }
                    }
                    else
                    {
                        //Read over the bytes we don't care about. If there is some sort of wrong interpretation of the intCounter value, the loop is broken
                        //so there is no attempt of reading beyond the file's length.
                        if (intCounter > data.UnconsumedBufferLength)
                            break;
                        for (uint i = 0; i < intCounter; i++)
                            data.ReadByte();
                    }
                }
            }
            //We don't need this anymore. Let's dispose of it.
            data.Dispose();
        }