ContinuationManager .cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.ApplicationModel.Activation;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

#if WINDOWS_PHONE_APP
    /// <summary>
    /// ContinuationManager is used to detect if the most recent activation was due
    /// to a continuation such as the FileOpenPicker or WebAuthenticationBroker
    /// </summary>
public class ContinuationManager
{
    IContinuationActivatedEventArgs args = null;
    bool handled = false;
    Guid id = Guid.Empty;

    /// <summary>
    /// Sets the ContinuationArgs for this instance. Using default Frame of current Window
    /// Should be called by the main activation handling code in App.xaml.cs
    /// </summary>
    /// <param name="args">The activation args</param>
    internal void Continue(IContinuationActivatedEventArgs args)
    {
        Continue(args, Window.Current.Content as Frame);
    }

    /// <summary>
    /// Sets the ContinuationArgs for this instance. Should be called by the main activation
    /// handling code in App.xaml.cs
    /// </summary>
    /// <param name="args">The activation args</param>
    /// <param name="rootFrame">The frame control that contains the current page</param>
    internal void Continue(IContinuationActivatedEventArgs args, Frame rootFrame)
    {
        if (args == null)
            throw new ArgumentNullException("args");

        if (this.args != null && !handled)
            throw new InvalidOperationException("Can't set args more than once");

        this.args = args;
        this.handled = false;
        this.id = Guid.NewGuid();

        if (rootFrame == null)
            return;

        switch (args.Kind)
        {
            case ActivationKind.PickFileContinuation:
                var fileOpenPickerPage = rootFrame.Content as IFileOpenPickerContinuable;
                if (fileOpenPickerPage != null)
                {
                    fileOpenPickerPage.ContinueFileOpenPicker(args as FileOpenPickerContinuationEventArgs);
                }
                break;

            case ActivationKind.PickSaveFileContinuation:
                var fileSavePickerPage = rootFrame.Content as IFileSavePickerContinuable;
                if (fileSavePickerPage != null)
                {
                    fileSavePickerPage.ContinueFileSavePicker(args as FileSavePickerContinuationEventArgs);
                }
                break;

            case ActivationKind.PickFolderContinuation:
                var folderPickerPage = rootFrame.Content as IFolderPickerContinuable;
                if (folderPickerPage != null)
                {
                    folderPickerPage.ContinueFolderPicker(args as FolderPickerContinuationEventArgs);
                }
                break;

            case ActivationKind.WebAuthenticationBrokerContinuation:
                var wabPage = rootFrame.Content as IWebAuthenticationContinuable;
                if (wabPage != null)
                {
                    wabPage.ContinueWebAuthentication(args as WebAuthenticationBrokerContinuationEventArgs);
                }
                break;
        }
    }

    /// <summary>
    /// Marks the contination data as 'stale', meaning that it is probably no longer of
    /// any use. Called when the app is suspended (to ensure future activations don't appear
    /// to be for the same continuation) and whenever the continuation data is retrieved 
    /// (so that it isn't retrieved on subsequent navigations)
    /// </summary>
    internal void MarkAsStale()
    {
        this.handled = true;
    }

    /// <summary>
    /// Retrieves the continuation args, if they have not already been retrieved, and 
    /// prevents further retrieval via this property (to avoid accidentla double-usage)
    /// </summary>
    public IContinuationActivatedEventArgs ContinuationArgs
    {
        get
        {
            if (handled)
                return null;
            MarkAsStale();
            return args;
        }
    }

    /// <summary>
    /// Unique identifier for this particular continuation. Most useful for components that 
    /// retrieve the continuation data via <see cref="GetContinuationArgs"/> and need
    /// to perform their own replay check
    /// </summary>
    public Guid Id { get { return id; } }

    /// <summary>
    /// Retrieves the continuation args, optionally retrieving them even if they have already
    /// been retrieved
    /// </summary>
    /// <param name="includeStaleArgs">Set to true to return args even if they have previously been returned</param>
    /// <returns>The continuation args, or null if there aren't any</returns>
    public IContinuationActivatedEventArgs GetContinuationArgs(bool includeStaleArgs)
    {
        if (!includeStaleArgs && handled)
            return null;
        MarkAsStale();
        return args;
    }
}

/// <summary>
/// Implement this interface if your page invokes the file open picker
/// API.
/// </summary>
interface IFileOpenPickerContinuable
{
    /// <summary>
    /// This method is invoked when the file open picker returns picked
    /// files
    /// </summary>
    /// <param name="args">Activated event args object that contains returned files from file open picker</param>
    void ContinueFileOpenPicker(FileOpenPickerContinuationEventArgs args);
}

/// <summary>
/// Implement this interface if your page invokes the file save picker
/// API
/// </summary>
interface IFileSavePickerContinuable
{
    /// <summary>
    /// This method is invoked when the file save picker returns saved
    /// files
    /// </summary>
    /// <param name="args">Activated event args object that contains returned file from file save picker</param>
    void ContinueFileSavePicker(FileSavePickerContinuationEventArgs args);
}

/// <summary>
/// Implement this interface if your page invokes the folder picker API
/// </summary>
interface IFolderPickerContinuable
{
    /// <summary>
    /// This method is invoked when the folder picker returns the picked
    /// folder
    /// </summary>
    /// <param name="args">Activated event args object that contains returned folder from folder picker</param>
    void ContinueFolderPicker(FolderPickerContinuationEventArgs args);
}

/// <summary>
/// Implement this interface if your page invokes the web authentication
/// broker
/// </summary>
interface IWebAuthenticationContinuable
{
    /// <summary>
    /// This method is invoked when the web authentication broker returns
    /// with the authentication result
    /// </summary>
    /// <param name="args">Activated event args object that contains returned authentication token</param>
    void ContinueWebAuthentication(WebAuthenticationBrokerContinuationEventArgs args);
}

#endif