2015-10-06 35 views
0

在自定义ListView控件上,我正在开发一个“导出到Excel”小按钮,将ListView的所有内容发送到Excel。由于此按钮嵌入在ListView控件内,我不知道列出了哪种对象或显示了哪些列。如何临时禁用WPF Listview虚拟化?

所以我的方法是通用的,只是解析所有列标题和所有行以将数据导出到Excel。但是当解析不可见的ListViewItem时,您会得到空结果。一个解决方案是在我的ListView上设置VirtualizingStackPanel.VirtualizationMode =“False”,但是当你有成千上万行时,它会强烈影响GUI体验。

我正在寻找一种方法来加载所有ListViewItem只是为了我的通用导出方法,并保持GUI的虚拟化。

有人可以帮我吗?

谢谢。

+0

我不明白你想要的,关闭虚拟化的唯一方法是设置'什么VirtualizingStackPanel .IsVirtualizingProperty'为false。您可以在完成您的方法后再次打开它。 – Hopeless

+1

您应该只为您的任务使用底层数据,而不是生成的UI容器。 – metacircle

+0

Uderlying数据是来自SQL数据库的表数据,即我显示的列(甚至是链表)的更多字段。我的应用程序中有很多ListView,这意味着我将不得不返回到每个视图并定义应该导出到Excel的内容。所以我正在寻找一种方法来强制ListView通过代码加载所有项目。 – Karnalta

回答

0

我终于做到了反思来解决我的问题。基本上,我首先解析所有列以找到绑定的属性名称。然后对ListView中的Items集合进行一些思考以找到属性值。

下面是代码(尚未打磨):

private void OnExportToExcel(object sender, ExecutedRoutedEventArgs args) 
    { 
     if (this.Items.Count > 0) 
     { 
      // Ensure we have a visible and selected item 
      if (this.SelectedItem == null) 
       this.SelectedItem = this.Items[0]; 
      this.ScrollIntoView(this.SelectedItem); 

      // Allow UI thread to update first or our selected lvi will be null if not visible 
      UIHelpers.AllowUIToUpdate(); 

      List<string> columnPropertyBindingPathList = new List<string>(); 
      int colIndex = 0; 

      // Get column binding path of underlying data 
      foreach (GridViewColumn h in ((GridView)this.View).Columns) 
      { 
       string bindingPath = ""; 

       if (h.DisplayMemberBinding != null) 
       { 
        bindingPath = (h.DisplayMemberBinding as Binding).Path.Path; 
       } 
       else 
       { 
        ListViewItem lvi = this.ItemContainerGenerator.ContainerFromIndex(this.SelectedIndex) as ListViewItem; 
        if (lvi != null) 
        { 
         GridViewRowPresenter gvp = UIHelpers.FindVisualChild<GridViewRowPresenter>(lvi); 
         DependencyObject col = VisualTreeHelper.GetChild(gvp, colIndex); 
         TextBlock tb = col as TextBlock; 
         if (tb == null) 
         { 
          tb = UIHelpers.FindVisualChild<TextBlock>(col); 
          bindingPath = BindingOperations.GetBinding(tb, TextBlock.TextProperty).Path.Path; 
         } 
        } 
       } 

       colIndex++; 
       if (bindingPath != "") 
        columnPropertyBindingPathList.Add(bindingPath); 
      } 

      if (columnPropertyBindingPathList.Count > 0) 
      { 
       Mouse.SetCursor(Cursors.Wait); 

       // Init array to export to excel 
       object[,] dataArray = new object[this.Items.Count + 1, columnPropertyBindingPathList.Count]; 

       // Add column header 
       for (int colCnt = 0; colCnt < columnPropertyBindingPathList.Count; colCnt++) 
        dataArray[0, colCnt] = columnPropertyBindingPathList[colCnt]; 

       // Reflection to read underlying objects 
       int rowCnt = 1; 
       foreach (object obj in this.Items) 
       { 
        for (int colCnt = 0; colCnt < columnPropertyBindingPathList.Count; colCnt++) 
         dataArray[rowCnt, colCnt] = UIHelpers.GetPropValue(columnPropertyBindingPathList[colCnt], obj); 

        rowCnt++; 
       } 

       Mouse.SetCursor(Cursors.Arrow); 

       // Throw event 
       RoutedEventArgs newEventArgs = new RoutedEventArgs(EmListView.ExportToExcelEvent); 
       newEventArgs.Source = dataArray; 
       RaiseEvent(newEventArgs); 
      } 
      else 
      { 
       // Throw event 
       RoutedEventArgs newEventArgs = new RoutedEventArgs(EmListView.ExportToExcelEvent); 
       newEventArgs.Source = null; 
       RaiseEvent(newEventArgs); 
      } 
     } 
     else 
     { 
      // Throw event 
      RoutedEventArgs newEventArgs = new RoutedEventArgs(EmListView.ExportToExcelEvent); 
      newEventArgs.Source = null; 
      RaiseEvent(newEventArgs); 
     } 
    } 

UIHelpers方法:

/// <summary> 
    /// Give the UI thread the time to refresh 
    /// </summary> 
    public static void AllowUIToUpdate() 
    { 
     DispatcherFrame frame = new DispatcherFrame(); 

     Dispatcher.CurrentDispatcher.BeginInvoke(DispatcherPriority.Render, new DispatcherOperationCallback(delegate(object parameter) 
     { 
      frame.Continue = false; 
      return null; 
     }), null); 

     Dispatcher.PushFrame(frame); 
    } 

    /// <summary> 
    /// Find a visual child type inside a DependencyObject 
    /// </summary> 
    /// <typeparam name="T"></typeparam> 
    /// <param name="obj"></param> 
    /// <returns></returns> 
    public static T FindVisualChild<T>(DependencyObject obj) where T : DependencyObject 
    { 
     for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++) 
     { 
      DependencyObject child = VisualTreeHelper.GetChild(obj, i); 
      if (child != null && child is T) 
       return (T)child; 
      else 
      { 
       T childOfChild = FindVisualChild<T>(child); 
       if (childOfChild != null) 
        return childOfChild; 
      } 
     } 
     return null; 
    } 

    /// <summary> 
    /// Find a property value inside a object (even for multi level property) 
    /// </summary> 
    /// <param name="name"></param> 
    /// <param name="obj"></param> 
    /// <returns></returns> 
    public static Object GetPropValue(String name, Object obj) 
    { 
     foreach (String part in name.Split('.')) 
     { 
      if (obj == null) { return null; } 

      Type type = obj.GetType(); 
      PropertyInfo info = type.GetProperty(part); 

      if (info == null) { return null; } 

      obj = info.GetValue(obj, null); 
     } 

     return obj; 
    }