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

Updated MainPage.xaml.cs

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);
        }
    }
}

About the Author

Eric Vogel is a Senior Software Developer for Red Cedar Solutions Group in Okemos, Michigan. He is the president of the Greater Lansing User Group for .NET. Eric enjoys learning about software architecture and craftsmanship, and is always looking for ways to create more robust and testable applications. Contact him at [email protected].

comments powered by Disqus

Featured

  • ML.NET Improves Object Detection

    Microsoft improved the object detection capabilities of its ML.NET machine learning framework for .NET developers, adding the ability to train custom models with Model Builder in Visual Studio.

  • More Improvements for VS Code's New Python Language Server

    Microsoft announced more improvements for the new Python language server for Visual Studio Code, Pylance, specializing in rich type information.

  • Death of the Dev Machine?

    Here's a takeaway from this week's Ignite 2020 event: An advanced Azure cloud portends the death of the traditional, high-powered dev machine packed with computing, memory and storage components.

  • COVID-19 Is Ignite 2020's Elephant in the Room: 'Frankly, It Sucks'

    As in all things of our new reality, there was no escaping the drastic changes in routine caused by the COVID-19 pandemic during Microsoft's big Ignite 2020 developer/IT pro conference, this week shifted to an online-only event after drawing tens of thousands of in-person attendees in years past.

  • Visual Studio 2019 v16.8 Preview Update Adds Codespaces

    To coincide with the Microsoft Ignite 2020 IT pro/developer event, the Visual Studio dev team shipped a new update, Visual Studio 2019 v16.8 Preview 3.1, with the main attraction being support for cloud-hosted Codespaces, now in a limited beta.

Upcoming Events