private async Task <IEnumerable <PackageItemListViewModel> > LoadNextPageAsync(IPackageItemLoader currentLoader, CancellationToken token)
{
var progress = new Progress <IItemLoaderState>(
s => HandleItemLoaderStateChange(currentLoader, s));
// if searchResultTask is in progress then just wait for it to complete
// without creating new load task
if (_initialSearchResultTask != null)
{
token.ThrowIfCancellationRequested();
// update initial progress
var cleanState = SearchResult.Empty <IPackageSearchMetadata>();
await currentLoader.UpdateStateAndReportAsync(cleanState, progress, token);
var results = await _initialSearchResultTask;
token.ThrowIfCancellationRequested();
// update state and progress
await currentLoader.UpdateStateAndReportAsync(results, progress, token);
_initialSearchResultTask = null;
}
else
{
// trigger loading
await currentLoader.LoadNextAsync(progress, token);
}
await WaitForInitialResultsAsync(currentLoader, progress, token);
return(currentLoader.GetCurrent());
}
private void _loadingStatusBar_ShowMoreResultsClick(object sender, RoutedEventArgs e)
{
var packageItems = _loader?.GetCurrent() ?? Enumerable.Empty <PackageItemListViewModel>();
UpdatePackageList(packageItems, refresh: true);
_loadingStatusBar.ItemsLoaded = _loader?.State.ItemsCount ?? 0;
var desiredVisibility = EvaluateStatusBarVisibility(_loader, _loader.State);
if (_loadingStatusBar.Visibility != desiredVisibility)
{
_loadingStatusBar.Visibility = desiredVisibility;
}
}
private async Task LoadItemsCoreAsync(IPackageItemLoader currentLoader, CancellationToken token)
{
token.ThrowIfCancellationRequested();
var loadedItems = await LoadNextPageAsync(currentLoader, token);
token.ThrowIfCancellationRequested();
// multiple loads may occur at the same time as a result of multiple instances,
// makes sure we update using the relevant one.
if (currentLoader == _loader)
{
UpdatePackageList(loadedItems, refresh: false);
}
token.ThrowIfCancellationRequested();
await _joinableTaskFactory.Value.RunAsync(async() =>
{
await _joinableTaskFactory.Value.SwitchToMainThreadAsync();
_loadingStatusBar.ItemsLoaded = currentLoader.State.ItemsCount;
});
token.ThrowIfCancellationRequested();
// keep waiting till completion
await WaitForCompletionAsync(currentLoader, token);
token.ThrowIfCancellationRequested();
if (currentLoader == _loader &&
!loadedItems.Any() &&
currentLoader.State.LoadingStatus == LoadingStatus.Ready)
{
UpdatePackageList(currentLoader.GetCurrent(), refresh: false);
}
token.ThrowIfCancellationRequested();
}