CameraPage.xaml.cs

//-----------------------------------------------------------------------------------
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using System;
using Microsoft.Practices.ServiceLocation;
using PhotoSharingApp.Universal.Serialization;
using PhotoSharingApp.Universal.ViewModels;
using Windows.Foundation.Metadata;
using Windows.Graphics.Display;
using Windows.Phone.UI.Input;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;

namespace PhotoSharingApp.Universal.Views
{
    /// <summary>
    /// The page that allows taking a photo or opening
    /// a photo from the device's photos library.
    /// </summary>
    public sealed partial class CameraPage : Page
    {
        private CameraViewModel _viewModel;

        public CameraPage()
        {
            InitializeComponent();

            LayoutUpdated += CameraPage_LayoutUpdated;

            if (ApiInformation.IsTypePresent("Windows.Phone.UI.Input.HardwareButtons"))
            {
                HardwareButtons.CameraPressed += HardwareButtons_CameraPressed;
            }
        }

        private void CameraPage_LayoutUpdated(object sender, object e)
        {
            var min = Math.Min(cameraPreviewContainer.ActualWidth, cameraPreviewContainer.ActualHeight);

            capturePreview.Width = min;
            capturePreview.Height = min;
        }

        private void HardwareButtons_CameraPressed(object sender, CameraEventArgs e)
        {
            if (_viewModel.TakePhotoCommand.CanExecute(null))
            {
                _viewModel.TakePhotoCommand.Execute(null);
            }
        }

        protected override async void OnNavigatedFrom(NavigationEventArgs e)
        {
            base.OnNavigatedFrom(e);

            DisplayInformation.AutoRotationPreferences = DisplayOrientations.None;
            await _viewModel.UnloadCamera();
        }

        protected override async void OnNavigatedTo(NavigationEventArgs e)
        {
            base.OnNavigatedTo(e);

            DisplayInformation.AutoRotationPreferences = DisplayOrientations.Portrait;

            _viewModel = ServiceLocator.Current.GetInstance<CameraViewModel>();
            DataContext = _viewModel;

            if (e.Parameter != null)
            {
                var args = SerializationHelper.Deserialize<CameraViewModelArgs>(e.Parameter as string);
                await _viewModel.LoadState(args);
            }
            else
            {
                await _viewModel.LoadState(new CameraViewModelArgs());
            }

            if (_viewModel.CanTakePhoto)
            {
                await _viewModel.LoadCamera(capturePreview);
            }
        }
    }
}