Teil 4: Vollständiger Code (Windows Store-Apps mit C#/VB und XAML)
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Teil 4: Vollständiger Code (Windows Store-Apps mit C#/VB und XAML)

[ Dieser Artikel richtet sich an Windows 8.x- und Windows Phone 8.x-Entwickler, die Windows-Runtime-Apps schreiben. Wenn Sie für Windows 10 entwickeln, finden Sie weitere Informationen unter neueste Dokumentation ]

Dieses Thema enthält das im Lernprogramm Teil 4: Dateizugriff und -auswahl verwendete vollständige Codebeispiel.

Wichtig  Dieses Lernprogramm ist für Microsoft Visual Studio 2013 und Windows 8.1 konzipiert. Teile des Lernprogramms funktionieren in Verbindung mit Microsoft Visual Studio 2012 und Windows 8 nicht ordnungsgemäß.
 

Dieses Thema enthält die folgenden Abschnitte:

Downloadort

Dieses Beispiel kann nicht heruntergeladen werden.

Technologien

ProgrammiersprachenC#, Visual Basic .NET
ProgrammiermodelleWindows Runtime

Anforderungen

Unterstützte Mindestversion (Client)Windows 8.1
Unterstützte Mindestversion (Server)Windows Server 2012 R2
Mindestens erforderliches SDKMicrosoft Visual Studio Express 2012 für Windows 8

Anzeigen des Codes (XAML)

App.xaml

App.xaml enthält nur generierten Code.

App.xaml.cs/vb

App.xaml.cs/vb wurde unverändert aus Teil 2 übernommen.

MainPage.xaml

MainPage.xaml wurde unverändert aus Teil 3 übernommen.

MainPage.xaml.cs/vb

MainPage.xaml.cs/vb wurde unverändert aus Teil 3 übernommen.

PhotoPage.xaml



<Page
    x:Name="pageRoot"
    x:Class="HelloWorld.PhotoPage"
    DataContext="{Binding DefaultViewModel, RelativeSource={RelativeSource Self}}"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:HelloWorld"
    xmlns:common="using:HelloWorld.Common"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d" NavigationCacheMode="Enabled" 
    SizeChanged="PhotoPage_SizeChanged">

    <Page.Resources>
        <common:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter"/>
        <!-- TODO: Delete this line if the key AppName is declared in App.xaml -->
        <x:String x:Key="AppName">Hello, photo!</x:String>
    </Page.Resources>

    <!--
        This grid acts as a root panel for the page that defines two rows:
        * Row 0 contains the back button and page title
        * Row 1 contains the rest of the page layout
    -->
    <Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
        <Grid.ChildrenTransitions>
            <TransitionCollection>
                <EntranceThemeTransition/>
            </TransitionCollection>
        </Grid.ChildrenTransitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="140"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!-- Back button and page title -->
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="120"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>
            <AppBarButton x:Name="backButton" Icon="Back" Height="95" Margin="10,46,10,0"
                          Command="{Binding NavigationHelper.GoBackCommand, ElementName=pageRoot}" 
                          Visibility="{Binding IsEnabled, Converter={StaticResource BooleanToVisibilityConverter}, RelativeSource={RelativeSource Mode=Self}}"
                          AutomationProperties.Name="Back"
                          AutomationProperties.AutomationId="BackButton"
                          AutomationProperties.ItemType="Navigation Button"/>
            <TextBlock x:Name="pageTitle" Text="{StaticResource AppName}" Style="{StaticResource HeaderTextBlockStyle}" Grid.Column="1" 
                       IsHitTestVisible="false" TextWrapping="NoWrap" VerticalAlignment="Bottom" Margin="0,0,30,40"/>
        </Grid>
        <Grid x:Name="contentGrid" Grid.Row="1" Margin="120,0,0,120">
            <Grid.RowDefinitions>
                <RowDefinition Height="50"/>
                <RowDefinition Height="70"/>
                <RowDefinition/>
            </Grid.RowDefinitions>
            <Button Content="Get photo" Click="GetPhotoButton_Click"/>
            <TextBlock Grid.Row="1" TextWrapping="Wrap" Text="{Binding DisplayName}" Style="{ThemeResource SubheaderTextBlockStyle}"/>
            <StackPanel x:Name="imagePanel" Grid.Row="2" Orientation="Horizontal">
                <Border BorderBrush="Gray" BorderThickness="1" Background="Gray">
                    <Image x:Name="displayImage" Source="Assets/Logo.png"/>
                </Border>
                <StackPanel Margin="20,0,0,0">
                    <TextBlock TextWrapping="Wrap" Text="File name:" 
                               Style="{ThemeResource CaptionTextBlockStyle}"/>
                    <TextBlock TextWrapping="Wrap" Text="{Binding Name}" 
                               Style="{ThemeResource BodyTextBlockStyle}" Margin="10,0,0,30"/>
                    <TextBlock TextWrapping="Wrap" Text="Path:"
                               Style="{ThemeResource CaptionTextBlockStyle}"/>
                    <TextBlock TextWrapping="Wrap" Text="{Binding Path}"
                               Style="{ThemeResource BodyTextBlockStyle}" Margin="10,0,0,30"/>
                    <TextBlock TextWrapping="Wrap" Text="Date created:" 
                               Style="{ThemeResource CaptionTextBlockStyle}"/>
                    <TextBlock TextWrapping="Wrap" Text="{Binding DateCreated.Date}"
                               Style="{ThemeResource BodyTextBlockStyle}"  Margin="10,0,0,30" />
                </StackPanel>
            </StackPanel>
        </Grid>
        <VisualStateManager.VisualStateGroups>
            <VisualStateGroup>
                <VisualState x:Name="DefaultLayout">
                    <Storyboard>
                    </Storyboard>
                </VisualState>

                <VisualState x:Name="PortraitLayout">
                    <Storyboard>
                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(StackPanel.Orientation)" 
                                                       Storyboard.TargetName="imagePanel">
                            <DiscreteObjectKeyFrame KeyTime="0">
                                <DiscreteObjectKeyFrame.Value>
                                    <Orientation>Vertical</Orientation>
                                </DiscreteObjectKeyFrame.Value>
                            </DiscreteObjectKeyFrame>
                        </ObjectAnimationUsingKeyFrames>
                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(FrameworkElement.Margin)" 
                                                       Storyboard.TargetName="imagePanel">
                            <DiscreteObjectKeyFrame KeyTime="0">
                                <DiscreteObjectKeyFrame.Value>
                                    <Thickness>0,0,20,0</Thickness>
                                </DiscreteObjectKeyFrame.Value>
                            </DiscreteObjectKeyFrame>
                        </ObjectAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>
            </VisualStateGroup>
        </VisualStateManager.VisualStateGroups>
    </Grid>
</Page>


PhotoPage.xaml.cs/vb


using HelloWorld.Common;
using System;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;

// The Basic Page item template is documented at http://go.microsoft.com/fwlink/p/?LinkID=234237

namespace HelloWorld
{
    /// <summary>
    /// A basic page that provides characteristics common to most applications.
    /// </summary>
    public sealed partial class PhotoPage : Page
    {
        private string mruToken = null;
        private NavigationHelper navigationHelper;
        private ObservableDictionary defaultViewModel = new ObservableDictionary();

        /// <summary>
        /// This can be changed to a strongly typed view model.
        /// </summary>
        public ObservableDictionary DefaultViewModel
        {
            get { return this.defaultViewModel; }
        }

        /// <summary>
        /// NavigationHelper is used on each page to aid in navigation and 
        /// process lifetime management
        /// </summary>
        public NavigationHelper NavigationHelper
        {
            get { return this.navigationHelper; }
        }


        public PhotoPage()
        {
            this.InitializeComponent();
            this.navigationHelper = new NavigationHelper(this);
            this.navigationHelper.LoadState += navigationHelper_LoadState;
            this.navigationHelper.SaveState += navigationHelper_SaveState;
        }

        /// <summary>
        /// Populates the page with content passed during navigation.  Any saved state is also
        /// provided when recreating a page from a prior session.
        /// </summary>
        /// <param name="navigationParameter">The parameter value passed to
        /// <see cref="Frame.Navigate(Type, Object)"/> when this page was initially requested.
        /// </param>
        /// <param name="pageState">A dictionary of state preserved by this page during an earlier
        /// session.  This will be null the first time a page is visited.</param>
        private async void navigationHelper_LoadState(object sender, LoadStateEventArgs e)
        {

            if (e.PageState != null && e.PageState.ContainsKey("mruToken"))
            {
                object value = null;
                if (e.PageState.TryGetValue("mruToken", out value))
                {
                    if (value != null)
                    {
                        mruToken = value.ToString();

                        // Open the file via the token that you stored when adding this file into the MRU list.
                        Windows.Storage.StorageFile file =
                            await Windows.Storage.AccessCache.StorageApplicationPermissions.MostRecentlyUsedList.GetFileAsync(mruToken);

                        if (file != null)
                        {
                            // Open a stream for the selected file.
                            Windows.Storage.Streams.IRandomAccessStream fileStream =
                                await file.OpenAsync(Windows.Storage.FileAccessMode.Read);

                            // Set the image source to a bitmap.
                            Windows.UI.Xaml.Media.Imaging.BitmapImage bitmapImage =
                                new Windows.UI.Xaml.Media.Imaging.BitmapImage();

                            bitmapImage.SetSource(fileStream);
                            displayImage.Source = bitmapImage;

                            // Set the data context for the page.
                            this.DataContext = file;
                        }
                    }
                }
            }
        }

        /// <summary>
        /// Preserves state associated with this page in case the application is suspended or the
        /// page is discarded from the navigation cache.  Values must conform to the serialization
        /// requirements of <see cref="SuspensionManager.SessionState"/>.
        /// </summary>
        /// <param name="pageState">An empty dictionary to be populated with serializable state.</param>
        private void navigationHelper_SaveState(object sender, SaveStateEventArgs e)
        {
            if (!string.IsNullOrEmpty(mruToken))
            {
                e.PageState["mruToken"] = mruToken;
            }

        }

        #region NavigationHelper registration

        /// The methods provided in this section are simply used to allow
        /// NavigationHelper to respond to the page's navigation methods.
        /// 
        /// Page specific logic should be placed in event handlers for the  
        /// <see cref="GridCS.Common.NavigationHelper.LoadState"/>
        /// and <see cref="GridCS.Common.NavigationHelper.SaveState"/>.
        /// The navigation parameter is available in the LoadState method 
        /// in addition to page state preserved during an earlier session.

        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            navigationHelper.OnNavigatedTo(e);
        }

        protected override void OnNavigatedFrom(NavigationEventArgs e)
        {
            navigationHelper.OnNavigatedFrom(e);
        }

        #endregion

        private async void GetPhotoButton_Click(object sender, RoutedEventArgs e)
        {
            Windows.Storage.Pickers.FileOpenPicker openPicker = new Windows.Storage.Pickers.FileOpenPicker();
            openPicker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.PicturesLibrary;
            openPicker.ViewMode = Windows.Storage.Pickers.PickerViewMode.Thumbnail;

            // Filter to include a sample subset of file types.
            openPicker.FileTypeFilter.Clear();
            openPicker.FileTypeFilter.Add(".bmp");
            openPicker.FileTypeFilter.Add(".png");
            openPicker.FileTypeFilter.Add(".jpeg");
            openPicker.FileTypeFilter.Add(".jpg");

            // Open the file picker.
            Windows.Storage.StorageFile file = await openPicker.PickSingleFileAsync();

            // file is null if user cancels the file picker.
            if (file != null)
            {
                // Open a stream for the selected file.
                Windows.Storage.Streams.IRandomAccessStream fileStream =
                    await file.OpenAsync(Windows.Storage.FileAccessMode.Read);

                // Set the image source to the selected bitmap.
                Windows.UI.Xaml.Media.Imaging.BitmapImage bitmapImage =
                    new Windows.UI.Xaml.Media.Imaging.BitmapImage();

                bitmapImage.SetSource(fileStream);
                displayImage.Source = bitmapImage;
                this.DataContext = file;

                // Add picked file to MostRecentlyUsedList.
                mruToken = Windows.Storage.AccessCache.StorageApplicationPermissions.MostRecentlyUsedList.Add(file);
            }
        }

        private void PhotoPage_SizeChanged(object sender, SizeChangedEventArgs e)
        {
            if (e.NewSize.Height / e.NewSize.Width >= 1)
            {    
                VisualStateManager.GoToState(this, "PortraitLayout", true);
            }
            else
            {
                VisualStateManager.GoToState(this, "DefaultLayout", true);
            }
        }
    }
}


 

 

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