MessageDialogService.cs

//-----------------------------------------------------------------------------------
//  Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//  The MIT License (MIT)
// 
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
// 
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
// 
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.
//  ---------------------------------------------------------------------------------

using System;
using System.Threading.Tasks;
using Windows.ApplicationModel.Resources;
using Windows.UI.Core;
using Windows.UI.Popups;
using Windows.UI.Xaml;

namespace PhotoSharingApp.Universal.Views
{
    /// <summary>
    /// A dialog service that uses <see cref="MessageDialog"/> for showing
    /// messages to the user.
    /// </summary>
    public class MessageDialogService : IDialogService
    {
        private readonly CoreDispatcher _dispatcher;

        /// <summary>
        /// The constructor.
        /// </summary>
        public MessageDialogService()
        {
            _dispatcher = Window.Current.Dispatcher;
        }

        /// <summary>
        /// Shows a notification that there is an issue with communicating
        /// to the service.
        /// </summary>
        public async Task ShowGenericServiceErrorNotification()
        {
            await ShowNotification("ServiceError_Message", "GenericError_Title");
        }

        /// <summary>
        /// Shows the notification.
        /// </summary>
        /// <param name="message">The message.</param>
        /// <param name="title">The title.</param>
        /// <param name="useResourceLoader">
        /// if set to <c>true</c> the message and title
        /// parameters specify the resource id.
        /// </param>
        public async Task ShowNotification(string message, string title, bool useResourceLoader = true)
        {
            Action action = async () =>
            {
                // Load from resource loader if necessary
                if (useResourceLoader)
                {
                    var resourceLoader = ResourceLoader.GetForCurrentView();
                    message = resourceLoader.GetString(message);
                    title = resourceLoader.GetString(title);
                }

                var dialog = new MessageDialog(message, title);
                await dialog.ShowAsync();
            };

            // Some parts of the app like IncrementalLoadingCollection show error messages 
            // on a different thread than the UI thread, so we need to have them dispatched.
            if (_dispatcher.HasThreadAccess)
            {
                action();
            }
            else
            {
                await _dispatcher.RunAsync(CoreDispatcherPriority.Normal,
                    () => action());
            }
        }

        /// <summary>
        /// Shows a notification that lets the user choose between yes and no.
        /// </summary>
        /// <param name="message">The message.</param>
        /// <param name="title">The title.</param>
        /// <param name="useResourceLoader">
        /// if set to <c>true</c> the message and title
        /// parameters specify the resource id.
        /// </param>
        /// <returns>True, if user has chosen yes. Otherwise, false.</returns>
        public async Task<bool> ShowYesNoNotification(string message, string title, bool useResourceLoader = true)
        {
            var resourceLoader = ResourceLoader.GetForCurrentView();

            // Load from resource loader if necessary
            if (useResourceLoader)
            {
                message = resourceLoader.GetString(message);
                title = resourceLoader.GetString(title);
            }

            var yesCommand = new UICommand(resourceLoader.GetString("MessageDialog_Yes"));
            var noCommand = new UICommand(resourceLoader.GetString("MessageDialog_No"));

            var dialog = new MessageDialog(message, title);
            dialog.Commands.Add(yesCommand);
            dialog.Commands.Add(noCommand);

            var result = await dialog.ShowAsync();

            return result == yesCommand;
        }
    }
}