Building a Windows 8 Metro App, Part 3: Listing 8

Updated MainPage.xaml.cs

• By Eric Vogel
• 02/14/2012

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Windows.Foundation;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Data;
using VSMWinRTDemo.RSS;
using Windows.Storage;
using Windows.ApplicationModel.DataTransfer;
using VSMWinRTDemo.Storage;

namespace VSMWinRTDemo.UI
{
    partial class MainPage
    {
        private int _maxFeeds = 20;
        private RSSClient _client = new RSSClient();
        private DataTransferManager _dataTransferManager;
        const string DEFAULT_FEED_KEY = "DefaultFeedUri";
        const string MAX_FEED_ITEMS_KEY = "MaxFeedItems";

        public MainPage()
        {
            InitializeComponent();
            Loaded += new RoutedEventHandler(MainPage_Loaded);
            FeedListView.SelectionChanged += new SelectionChangedEventHandler(FeedListView_SelectionChanged);
            FetchButton.Click += new RoutedEventHandler(FetchButton_Click);
            _dataTransferManager = DataTransferManager.GetForCurrentView();
            _dataTransferManager.DataRequested += new TypedEventHandler<DataTransferManager, 
            DataRequestedEventArgs>(MainPage_DataRequested);
            NumFeeds.LostFocus += new RoutedEventHandler(NumFeeds_LostFocus);
        }

        void NumFeeds_LostFocus(object sender, RoutedEventArgs e)
        {
            if (!String.IsNullOrWhiteSpace(NumFeeds.Text))
            {
                _maxFeeds = int.Parse(NumFeeds.Text);
                SettingsStorage.SetLocalSetting(MAX_FEED_ITEMS_KEY, _maxFeeds);
            }
        }

        void MainPage_DataRequested(DataTransferManager sender, DataRequestedEventArgs args)
        {
            // have a selected RSS feed item?
            if (FeedListView.SelectedItem != null)
            {
                RSSItem selectedItem = FeedListView.SelectedItem as RSSItem;
                args.Request.Data.Properties.Title = selectedItem.Title;
                args.Request.Data.Properties.Description = selectedItem.Description;
                args.Request.Data.SetText(selectedItem.Description);
                args.Request.Data.SetHtml(selectedItem.Description);

                if (selectedItem.Links.Count > 0)
                {
                    args.Request.Data.SetUri(selectedItem.Links[0].Link);
                }
            }
            else if (!String.IsNullOrWhiteSpace(FeedUrl.Text))
            {
                // share the loaded Feed URL
                args.Request.Data.Properties.Title = FeedTitle.Text;
                args.Request.Data.Properties.Description = "An RSS feed link from Daily Reader.";
                args.Request.Data.SetUri(new Uri(FeedUrl.Text));
            }
        }

        void FeedListView_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            ListView rssFeeds = (sender as ListView);
            RSSItem selectedItem = rssFeeds.SelectedItem as RSSItem;

            if (selectedItem != null && selectedItem.Links.Count > 0)
            {
                RSSItemWebView.Navigate(selectedItem.Links[0].Link);
            }
        }

        async void MainPage_Loaded(object sender, RoutedEventArgs e)
        {
            // load local settings
            string defaultFeedUri = SettingsStorage.GetLocalSetting<string>(DEFAULT_FEED_KEY);
            int maxFeeds = SettingsStorage.GetLocalSetting<int>(MAX_FEED_ITEMS_KEY);

            if (maxFeeds > 0)
            {
                _maxFeeds = maxFeeds;
            }

            NumFeeds.Text = _maxFeeds.ToString();

            if (defaultFeedUri != null)
            {
                FeedUrl.Text = defaultFeedUri;
                await GetFeeds(defaultFeedUri);
            }
        }

        private async void FetchButton_Click(object sender, RoutedEventArgs e)
        {
            if (!String.IsNullOrWhiteSpace(FeedUrl.Text))
            {
                await GetFeeds(FeedUrl.Text);
            }
        }

        private async Task GetFeeds(string url)
        {
            RSSFeed feeds = null;

            if (LocalStorage.ContainsItem(url))
            {
                feeds = LocalStorage.GetItem<RSSFeed>(url);
                Cached.Visibility = Windows.UI.Xaml.Visibility.Visible;
            }
            else
            {
                Cached.Visibility = Windows.UI.Xaml.Visibility.Collapsed;
                feeds = await _client.GetFeeds(url, _maxFeeds);
            }

            BindFeeds(feeds, url);
        }

        private void BindFeeds(RSSFeed feeds, string url)
        {
            this.DataContext = feeds;
            LocalStorage.Data[url] = feeds;
        }

        private void SetDefaultButton_Click(object sender, RoutedEventArgs e)
        {
            SettingsStorage.SetLocalSetting(DEFAULT_FEED_KEY, FeedUrl.Text);
        }
    }
}