WPF C＃刷新/重新綁定列表框

Question

我正在嘗試刷新WPF應用程序中的列表框，但它似乎不起作用。

如果我在添加值后重新加載應用程序，則確實會添加值。

我有一個變量和一個名為“ listboxData”的屬性：

    ObservableCollection<ITimeLineDataItem> listboxData = new ObservableCollection<ITimeLineDataItem>();
    public ObservableCollection<ITimeLineDataItem> ListBoxData
    {
        get
        {
            return listboxData;
        }        
    }

我已將列表框的值綁定到此屬性：

<ListBox x:Name="ListSrc" ItemsSource="{Binding Path=ListBoxData}" dd:DragDrop.IsDragSource="True" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" BorderBrush="Transparent" BorderThickness="0">

當用戶添加一個值時，此代碼將被調用：

public void RefreshListbox()
{

        listboxData.Clear();

        foreach (podiaPublish.Marker pMarker in Global.gChapter.MarkerList)
        {
            foreach (podiaPublish.Content pContent in pMarker.ContentList)
            {

                //FOR SLIDES THAT HAVE JUST BEEN IMPORTED, THERE WILL BE NO FILES ON THE SERVER (SO NO CHECKSUMS AVAILABLE)

                if (File.Exists(Global.TempFolder + "\\" + (string.IsNullOrEmpty(pContent.AlternateMarkup) ? pContent.Markup : pContent.AlternateMarkup)))
                {
                    //KLUDGE TO RESIZE THE THUMBNAILS
                    System.IO.FileStream fs = new System.IO.FileStream(Global.TempFolder + "\\" + (string.IsNullOrEmpty(pContent.AlternateMarkup) ? pContent.Markup : pContent.AlternateMarkup), FileMode.Open, FileAccess.Read);
                    Bitmap bm = new Bitmap(fs);
                    var bitmapSource = Imaging.CreateBitmapSourceFromHBitmap(bm.GetHbitmap(),
                                                                        IntPtr.Zero,
                                                                        Int32Rect.Empty,
                                                                        BitmapSizeOptions.FromEmptyOptions()
                    );
                    bm.Dispose();
                    fs.Close();

                    if (pContent.Markup.Contains(".png"))
                    {
                        var brush = new ImageBrush(bitmapSource);

                        var lb1 = new TempDataType()
                        {
                            Name = pContent.Markup,
                            BackgroundImage = brush
                        };

                        listboxData.Add(lb1);
                    }
                }
            }
        }
    }

因此，我首先清除了“ listboxData”，然后如您在foreach循環中所見，我重新添加了新值。 調試時，這將返回正確的值。

編輯：

列表框的屬性綁定在：

    <DataTemplate  DataType="{x:Type tt:TempDataType}">
        <Border BorderThickness="1"
                BorderBrush="Black"
                Background="{Binding BackgroundImage}"
                CornerRadius="3"
                Height="120">
            <StackPanel Orientation="Vertical">
                <Image Source="{Binding BackgroundImage}" />
                <TextBlock Text="{Binding Name}" />
            </StackPanel>
        </Border>
    </DataTemplate>

TempDataType類的結構如下：

public class TempDataType : ITimeLineDataItem, INotifyPropertyChanged
{
    public TimeSpan? StartTime { get; set; }
    public TimeSpan? EndTime { get; set; }
    public ImageBrush BackgroundImage { get; set; }
    public Boolean TimelineViewExpanded { get; set; }
    public String Name { get; set; }
}

Answer 1

我相信您使用的是MVVM模式，但是如果您未使用MVVM，則無法以任何方式在代碼中看到屬性更改事件（INotifyPropertyChanged），然后直接使用Listbox對象在列表中添加項目：

    public ObservableCollection<ITimeLineDataItem> ListBoxData
    {
        get
        {
            return this.listboxData;
        }
        set
        {
                this.listboxData = value;
                this.RaisePropertyChanged(() => this.ListBoxData);

        }
    }

Answer 2

我已經在viewmodel中實現了接口，請參見以下代碼：

class YourViewModel:INotifyPropertyChanged
{


    #region INotifyPropertyChanged Members

    public event PropertyChangedEventHandler PropertyChanged;

    //method to fire the property changed event ...
    void OnPropertyChanged(string propertyName)
    {

        var handler = PropertyChanged;

        if (handler != null)
            handler(this, new PropertyChangedEventArgs(propertyName));
    }

    //To raise the changes in property ...
    protected void RaisePropertyChanged<T>(Expression<Func<T>> propertyExpression)
    {
        var propertyName = PropertySupport.ExtractPropertyName(propertyExpression);
        this.OnPropertyChanged(propertyName);
    }

    #endregion
}