Windows 8 XAML: Displaying a list of images in a G

问题:

I am trying to write a Windows 8 app in C# in which I want to display a list of images that the user selects through FileOpenPicker. I wish to display these images in a GridView using XAML Data-binding. I have tried a few things but the data-binding doesn't seem to work. I am not sure at what location exactly do I need to set the itemssource of the GridView. If I do it in the MainPage constructor then the GridView doesn't get refreshed as the data-bound list gets populated later as the user selects the images.

How do I fix this?

回答1:

UPDATE 1

If you want to bind GridView, then you need to add few things. See I have updated my answer with some comment lines. You need to add those lines to supply ItemsSource via XAML

---

Here you go.

C#

private async void btnBrowsePhotos_Click(object sender, RoutedEventArgs e)
{
    //var objImageItem = new ImageItem();   
    FileOpenPicker openPicker = new FileOpenPicker();

    openPicker.ViewMode = PickerViewMode.Thumbnail;
    openPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
    openPicker.FileTypeFilter.Add(".jpg");
    openPicker.FileTypeFilter.Add(".jpeg");
    openPicker.FileTypeFilter.Add(".png");

    var files = await openPicker.PickMultipleFilesAsync();
    List<ImageItem> ImageList = new List<ImageItem>();
    foreach (var file in files)
    {
        using (var stream = await file.OpenAsync(FileAccessMode.Read))
        {
            //objImageItem.ImageList.Add(new ImageItem(stream, file.Name));
            ImageList.Add(new ImageItem(stream, file.Name)); 
        }
    }

    gv.ItemsSource = ImageList;
    //gv.DataContext = objImageItem;
}

public class ImageItem //: INotifyPropertyChanged 
{
    /*private ObservableCollection<ImageItem> _ImageList = new ObservableCollection<ImageItem>();
    public ObservableCollection<ImageItem> ImageList
    {
         get { return _ImageList; }
         set { _ImageList = value; OnPropertyChanged("ImageList"); }
    }*/

    public BitmapImage Source { get; set; }
    public string Name { get; set; }

    public ImageItem()
    {

    }

    public ImageItem(IRandomAccessStream stream, string name)
    {
        BitmapImage bmp = new BitmapImage();
        bmp.SetSource(stream);
        Source = bmp;
        Name = name;
    }
}

XAML

<Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
    <StackPanel>
        <Button Click="btnBrowsePhotos_Click" Style="{StaticResource BrowsePhotosAppBarButtonStyle}" />

        <!-- Add ItemsSource="{Binding ImageList}" to GridView -->

        <GridView x:Name="gv">
            <GridView.ItemTemplate>
                <DataTemplate>
                    <Grid>
                        <Image Stretch="Fill" Source="{Binding Source}" Height="192" Width="342" />
                        <Border Opacity=".8" Background="Black" VerticalAlignment="Bottom" >
                            <TextBlock Text="{Binding Name}" FontSize="18"/>
                        </Border>
                    </Grid>
                </DataTemplate>
            </GridView.ItemTemplate>
            <GridView.ItemsPanel>
                <ItemsPanelTemplate>
                    <WrapGrid MaximumRowsOrColumns="3" />
                </ItemsPanelTemplate>
            </GridView.ItemsPanel>
        </GridView>
    </StackPanel>
</Grid>