private async Task <bool> Down(LibraryHierarchyNode libraryHierarchyNode, IList <LibraryBrowserFrame> frames, bool updateSelection)
{
var libraryHierarchyNodes = this.LibraryHierarchyBrowser.GetNodes(libraryHierarchyNode);
if (!libraryHierarchyNodes.Any())
{
return(false);
}
var frame = new LibraryBrowserFrame(
libraryHierarchyNode,
new[]
{
LibraryHierarchyNode.Empty
}.Concat(libraryHierarchyNodes)
);
if (object.ReferenceEquals(this.Frames, frames))
{
await Windows.Invoke(() => frames.Add(frame)).ConfigureAwait(false);
}
else
{
frames.Add(frame);
}
if (updateSelection && object.ReferenceEquals(this.Frames, frames))
{
await Windows.Invoke(() => this.SelectedItem = libraryHierarchyNodes.FirstOrDefault()).ConfigureAwait(false);
}
return(true);
}
protected virtual bool Validate(LibraryBrowserFrame frame)
{
if (frame.Items == null)
{
return(false);
}
if (object.ReferenceEquals(frame.ItemsSource, LibraryHierarchyNode.Empty))
{
//Root frame.
return(frame.Items.SequenceEqual(this.Items));
}
//Child frame, first element is "back" button.
return(frame.Items.Skip(1).SequenceEqual(this.LibraryHierarchyBrowser.GetNodes(frame.ItemsSource)));
}