windows-phone-8 – 使用远程图像创建CycleTile

为了支持CycleTileData中的远程图像,您需要在定期后台代理中下载图像,将它们保存到IsoStore,然后使用这些图像更新CycleTileData.推送通知在这里不起作用,因为图像需要是本地的,ShellTileSchedule也不是.

确保将图像保存到“/ Shared / ShellContent”下的IsoStore,并将其URI设置为“isostore：/Shared/Shellcontent/myImage.png”,否则开始屏幕图块将无法访问它们.

让我们看一个例子.首先,我们首先编写一个并行线程算法,启动9个下载线程,等待结果,然后更新磁贴：

private IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication();

private void MainPage_Loaded(object sender,RoutedEventArgs e)
{
        var threadFinishEvents = new List<WaitHandle>();

        DownloadImages(threadFinishEvents);

        new Thread(()=>
        {
            Mutex.WaitAll(threadFinishEvents.ToArray());

            UpdateTiles();

            isoStore.Dispose();
        }).Start();
}

接下来,我们将9个图像下载到IsoStore“/ Shared / ShellContent”.我们将特别注意为每个Web下载添加新的线程标记,并在文件位于IsoStore时将标志设置为已完成.

private void DownloadImages(List<WaitHandle> threadFinishEvents)
{
    for (int i = 0; i < 9; i++)
    {
        var localI = i;

        var threadFinish = new EventWaitHandle(false,EventResetMode.ManualReset);
        threadFinishEvents.Add(threadFinish);

        var request = WebRequest.CreateHttp("http://www.justinangel.net/storage/691x336.png");
        request.BeginGetResponse(ir =>
        {
            var result = request.EndGetResponse(ir);
            using (var isoStoreFile = isoStore.OpenFile("shared/shellcontent/myImage" + localI + ".png",FileMode.Create,FileAccess.ReadWrite))
            using (var response = result.GetResponseStream())
            {
                var dataBuffer = new byte[1024];
                while (response.Read(dataBuffer,dataBuffer.Length) > 0)
                {
                    isoStoreFile.Write(dataBuffer,dataBuffer.Length);
                }
            }

            threadFinish.Set();
        },null);
    }
}

最后,我们将更新实时磁贴以在IsoStore中使用新映像.

private void UpdateTiles()
{
    ShellTile.ActiveTiles
        .First()
        .Update(new CycleTileData()
        {
            Title = "Cyclical",CycleImages = new Uri[]
            {
                new Uri("isostore:/Shared/ShellContent/myImage0.png",UriKind.Absolute),new Uri("isostore:/Shared/ShellContent/myImage1.png",new Uri("isostore:/Shared/ShellContent/myImage2.png",new Uri("isostore:/Shared/ShellContent/myImage3.png",new Uri("isostore:/Shared/ShellContent/myImage4.png",new Uri("isostore:/Shared/ShellContent/myImage5.png",new Uri("isostore:/Shared/ShellContent/myImage6.png",new Uri("isostore:/Shared/ShellContent/myImage7.png",new Uri("isostore:/Shared/ShellContent/myImage8.png",}
        });
}

有几件有趣的事情需要考虑：

>定期后台代理程序只有25秒完成其操作,因此在激活Mutex.WaitAll时添加计时器thresehold并使其正常失败可能是有意义的.>在某些网络条件下,在25秒内下载9张图像可能根本无法正常工作,因此最好对其进行优化.您可以使用较少的图像,也可以每30分钟仅更新一些图像.>将CycleTileData更新为相同的文件URI不会触发磁贴更新(AFAIK).所以你需要更好的文件名,然后是myImage0,而是拥有图像的唯一文件名.