/// <summary>
/// 保留与此页关联的状态，以防挂起应用程序或
/// 从导航缓存中放弃此页。 值必须符合
/// <see cref="SuspensionManager.SessionState"/> 的序列化要求。
/// </summary>
///<param name="sender">事件的来源；通常为 <see cref="NavigationHelper"/></param>
///<param name="e">提供要使用可序列化状态填充的空字典
///的事件数据。</param>
///
// 退出页面时会调用 保存添加的Card
private async void navigationHelper_SaveState(object sender, SaveStateEventArgs e)
{
var mc = new MenuCard
{
Title = info.Title,
Description = info.Description,
Image = info.Image,
ImagePath = info.ImageFileName
};
MenuCardRepository.Instance.Cards.Add(mc);
var storage = new MenuCardStorage();
await storage.WriteMenuCardsAsync(MenuCardRepository.Instance.Cards.ToList());
}
private static async Task InitSampleDataAsync()
{
var storage = new MenuCardStorage();
var imageStorage = new MenuCardImageStorage();
if (await storage.IsRoamingFolderEmpty())
{
List<MenuCard> menuCards = MenuCardRepository.GetSampleMenuCards().ToList();
foreach (var card in menuCards)
{
RandomAccessStreamReference streamRef =
RandomAccessStreamReference.CreateFromUri(new Uri(card.ImagePath));
using (IRandomAccessStreamWithContentType stream =
await streamRef.OpenReadAsync())
{
card.ImagePath = string.Format("{0}.png", Guid.NewGuid());
await imageStorage.WriteImageAsync(stream, card.ImagePath);
}
}
await storage.WriteMenuCardsAsync(menuCards);
}
}
