How to update ObservableCollection?

Question

I have folder with images, which I show in my ListBox. ObservableCollection stores that images. In my program users could crop selected image and after cropping save that image. Problem is that after saving the image my ObservableCollection is not updated (although OnPropertyChange event is rise) and shows the same image. Does anybody have the same problem?

EDIT

I have BindingManager where I place my observableCollection.

public class BindingsManager:INotifyPropertyChanged
{
    private ObservableCollection<PhotoModel> _photoList;

    public ObservableCollection<PhotoModel> PhotoList
    {
        get {return _photoList;}
        set
        {
            _photoList = value;
            OnPropertyChanged(nameof(PhotoList));
        }
    }


    public event PropertyChangedEventHandler PropertyChanged;

    [NotifyPropertyChangedInvocator]
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

In Xaml file I bind source to PhotoList:

 <ListView x:Name="PhotoListView" ItemsSource="{Binding PhotoList, UpdateSourceTrigger=PropertyChanged}">

After double click on image, image will be opened in new window where user can crop it and save to DefaultDestFolder which is tracking by FileSystemWatcher:

     private void WatchDestinationFolder()
    {
        var watcher = new FileSystemWatcher
        {
            Path = BindingsManager.DefaultsManager.DefaultDestFolder,
            NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.Size | NotifyFilters.LastAccess | NotifyFilters.LastWrite,
            Filter = "*.*"
        };
        watcher.Changed += UpdatePhotoList;
        watcher.EnableRaisingEvents = true;
    }

And on change event i update my ObservableCollection but it doesn't work:

   private void UpdatePhotoList()
    {
        var files = Directory.GetFiles(BindingsManager.DefaultsManager.DefaultDestFolder, "*.*");
        BindingsManager.PhotoList = new ObservableCollection<PhotoModel>();

        foreach (var file in files)
        {
            Application.Current.Dispatcher.Invoke((Action)(() =>
            {
                var fileInfo = new FileInfo(file);

                BitmapImage img = new BitmapImage();
                img.BeginInit();
                img.CacheOption = BitmapCacheOption.OnLoad;
                img.UriSource = new Uri(file, UriKind.Absolute);
                img.EndInit();
                BindingsManager.PhotoList.Add(new PhotoModel()
                {
                    BitmapImage = img,
                    FullFileName = fileInfo.FullName,
                    ShortFileName = fileInfo.Name,
                    FileLastAccessTime = fileInfo.LastAccessTime,
                    FileSize = fileInfo.Length,
                    Width = (int)img.Width,
                    Height = (int)img.Height,
                    DirectoryName = fileInfo.DirectoryName,
                    FileCreationTime = fileInfo.CreationTime
                });
            }));
        }          
    }

EDIT

    <ScrollViewer Grid.Column="2">
        <ListView x:Name="PhotoListView" BorderThickness="0" 
                      ItemsSource="{Binding PhotoList, UpdateSourceTrigger=PropertyChanged}">
            <ListView.ItemsPanel>
                <ItemsPanelTemplate>
                    <WrapPanel/>
                </ItemsPanelTemplate>
            </ListView.ItemsPanel>
            <ListView.ItemTemplate>
                <DataTemplate>
                    <controls:Tile Style="{StaticResource TileStyle}">
                        <StackPanel Background="White" Width="190" Height="140" Orientation="Vertical">
                            <Image Margin="5" Width="180" Height="110" Stretch="Fill" Source="{Binding BitmapImage}"/>
                            <TextBlock Text="{Binding ShortFileName}" TextAlignment="Center"  Height="20" FontStyle="Italic" FontWeight="ExtraLight" Foreground="Black"></TextBlock>
                        </StackPanel>
                    </controls:Tile>
                </DataTemplate>
            </ListView.ItemTemplate>
            <ListView.ItemContainerStyle>
                <Style TargetType="ListViewItem">
                    <EventSetter Event="MouseDoubleClick" Handler="ItemMouseDoubleClick"></EventSetter>
                    <EventSetter Event="PreviewMouseLeftButtonUp" Handler="ItemMouseClick"></EventSetter>
                </Style>
            </ListView.ItemContainerStyle>
        </ListView>
    </ScrollViewer>

Please post some code to understand what do you do, and get the problem. — Henka Programmer, Aug 06 '16 at 15:02
ObservableCollections already contain the INotifyChanged interface in them, there is no need to implent it twice, and it may cause issues. — Dark Templar, Aug 06 '16 at 16:32
I removed INotifyPropertyChanged interface and still have the same problem — Ant, Aug 06 '16 at 18:33
Are you updating items already in the collection or just adding/remove items? — ChrisF, Aug 06 '16 at 19:34
After every changes in folder with my images(NotifyFilters.LastWrite | NotifyFilters.Size | NotifyFilters.LastAccess) the method UpdatePhotoList() is invoke. And also I call UpdatePhotoList() when the program starts. — Ant, Aug 06 '16 at 20:12
what if you try to set the listview source using c# instead of xaml? something like: listview.ItemSource = PhotoList; — Dark Templar, Aug 06 '16 at 20:37
How often do you create a new instance of `BindingsManager`? — 15ee8f99-57ff-4f92-890c-b56153, Aug 06 '16 at 21:06

score 3 · Accepted Answer · edited May 23 '17 at 12:24

3

I think binding isn't your main problem. You should check image caching. Try: Reloading an image in wpf

edited May 23 '17 at 12:24

Community

1
1

answered Aug 06 '16 at 21:08

Mateusz

194
7

How to update ObservableCollection?

1 Answers1