private async Task Download(TDownloadTask task)
{
IncrementCounter();
var args = new DownloadStartingEventArgs();
task.DownloadStarting(args);
if (await args.DeferralAwaiter)
{
await DownloadInternal(task);
}
await DecrementCounterAsync();
}
public override async void DownloadStarting(DownloadStartingEventArgs args)
{
var deferral = args.GetDeferral();
if (!App.AppViewModel.AppSetting.OverwriteDownloadedFile && File.Exists(Destination))
{
ProgressPercentage = 100;
CurrentState = DownloadState.Completed;
deferral.Complete(false);
return;
}
if (App.AppViewModel.AppSetting.UseFileCache && await App.AppViewModel.Cache.TryGetAsync <IRandomAccessStream>(IllustrationViewModel.Illustration.GetIllustrationOriginalImageCacheKey()) is { } stream)
{
// fast path
deferral.Complete(false);
ProgressPercentage = 100;
try
{
using (stream)
{
IOHelper.CreateParentDirectories(Destination);
await using var fs = File.Open(Destination, FileMode.Create, FileAccess.ReadWrite, FileShare.None);
await stream.AsStreamForRead().CopyToAsync(fs);
}
}
catch (Exception e)
{
CurrentState = DownloadState.Error;
ErrorCause = e;
return;
}
CurrentState = DownloadState.Completed;
}
// slow path
deferral.Complete(true);
}
public override async void DownloadStarting(DownloadStartingEventArgs args)
{
args.GetDeferral().Complete(false);
await IOHelper.CreateAndWriteToFileAsync(Stream, Destination);
}
public override void DownloadStarting(DownloadStartingEventArgs args)
{
args.GetDeferral().Complete(App.AppViewModel.AppSetting.OverwriteDownloadedFile || !File.Exists(Destination));
}
