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即時通訊開發一個Live Tile APP來顯示Live Tile上的當前網絡狀態。背景任務和XamlRenderingBackgroundTask＆RenderTargetBitmap
我已經有一個工作XamlRenderingBackgroundTask，我可以從XML文件加載自定義拼貼模板，我將它與RenderTargetBitmap渲染到PNG文件。
但是，如果我啓動APP並註冊後臺任務，我必須等到BackgroundTask開始查看更新的活動圖塊。
據我所知，不可能從主APP使用此代碼。 RendertargetBitmap需要XAML樹中的元素或XamlRenderingBackgroundTask。
那麼，如何在註冊任務後更新Live Tile direclty？
var small_folder = await Windows.ApplicationModel.Package.Current.InstalledLocation.GetFolderAsync("Assets");
var small_file = await small_folder.GetFileAsync("WWAN_Tile_small.xml");
string small_szCustomTileXML = await Windows.Storage.FileIO.ReadTextAsync(small_file);
Border small_tile = XamlReader.Load(small_szCustomTileXML) as Border;
if (null != small_tile)
{
Grid grid = small_tile.Child as Grid;
Image logo = grid.FindName("img_Center") as Image;
var logo_img = new BitmapImage() { CreateOptions = BitmapCreateOptions.None };
logo_img.UriSource = new Uri("ms-appx:///Assets/Signal/WWAN/big/3.png");
logo.Source = logo_img;
RenderTargetBitmap rtb = new RenderTargetBitmap();
await rtb.RenderAsync(small_tile, 71, 71);
IBuffer pixels = await rtb.GetPixelsAsync();
DataReader dReader = Windows.Storage.Streams.DataReader.FromBuffer(pixels);
byte[] data = new byte[pixels.Length];
dReader.ReadBytes(data);
var outputFile = await Windows.Storage.ApplicationData.Current.LocalFolder.CreateFileAsync("Square71x71Logo.scale-100.png", Windows.Storage.CreationCollisionOption.ReplaceExisting);
var outputStream = await outputFile.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);
BitmapEncoder enc = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, outputStream);
enc.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Premultiplied, (uint)rtb.PixelWidth, (uint)rtb.PixelHeight, 96, 96, data);
await enc.FlushAsync();
}