Question

我使用过Datagrid并订阅了ScrollViewer.ScrollChanged事件。 Datagrid的Item源是一个简单的数据表（GDItems）。还有另一个数据表（GDAllItems），它保存从数据库中获取的实际数据集。

逻辑是这样写的：

在第一次将GDItems绑定到datagrid时，首先从GDAllItems中提取并显示50行。
当用户在底部向下滚动时，会触发滚动更改事件，并从GDAllItems中提取下一组50行并设置为GDItems，以便在datagrid中看到总共100行。这将继续，直到获取所有行。

现在主要的问题是ScrollViewer.ScrollChanged事件被连续触发并且调试器没有出现。

xaml中的大多数列都是“DataGridTextColumn”，除了两列设置为“DataGridTemplateColumn.CellTemplate”，因为其中需要可编辑的“TextBox”。如果删除这两列或将其类型更改为“DataGridTextColumn”，则代码将完美运行（ScrollViewer.ScrollChanged事件仅触发一次且不连续）。

我无法弄清楚使用“DataGridTemplateColumn.CellTemplate”与持续发生的事件之间的联系。

帮助感谢！

XAML代码：

<DataGrid Name="gridFinalResult" AutoGenerateColumns="False" 
ItemsSource="{Binding GDFinalResult,IsAsync=True}" 
SelectedItem="{Binding SelectedItemFinalResult}"                               RowDetailsVisibilityMode="VisibleWhenSelected"                                               CanUserSortColumns="True" IsSynchronizedWithCurrentItem="False"                                                  TextBlock.TextAlignment="Center" FrozenColumnCount="1"                                                  VirtualizingStackPanel.VirtualizationMode="Standard"                                                 SelectionMode="Single" HorizontalScrollBarVisibility="Auto"                                                  VerticalScrollBarVisibility="Auto" CanUserResizeRows="True"                                                  CanUserReorderColumns="True" HorizontalAlignment="Stretch"                                                  Width="Auto" ScrollViewer.CanContentScroll="False"                                                  Grid.Row="0" VerticalAlignment="Stretch"                                                  HeadersVisibility="Column" RowHeight="NaN"                                                  EnableColumnVirtualization="True" EnableRowVirtualization="True">

<DataGridTextColumn Binding="{Binding CompanyNo}" Header="Company&#x0a;(#)"
Width="60"/>
<DataGridTextColumn Binding="{Binding CompanyName}" Header="Company&#x0a;Name"
Width="110"/>


<DataGridTemplateColumn.CellTemplate>
<DataTemplate> <TextBox properties:Tracker.Property="Text" KeyboardNavigation.TabIndex="54"
Name="txtNewQty" Numeric:ZeroNumericMaskBehavior.Mask="NonNegativeNumber" MaxLength="6" Text="{Binding Path=FinalRecommendedQty, StringFormat='{}{0:#,0;}', Mode=TwoWay}"
LostFocus="txtNewQty_LostFocus" TextChanged="txtNewQty_TextChanged"
GotFocus="txtNewQty_GotFocus" IsTabStop="True" KeyboardNavigation.TabNavigation="Continue">
</TextBox> </DataTemplate></DataGridTemplateColumn.CellTemplate>

滚动更改的代码：

private void gridFinalResult_ScrollChanged(object sender, ScrollChangedEventArgs e)
{
    var scrollViewer = VisualTreeHelpers.FindChild<ScrollViewer>(gridFinalResult);
        if (rsoVM.GDFinalResult != null && rsoVM.GDFinalDBResult != null)
            {
                if (rsoVM.GDFinalDBResult.Rows.Count.ToString() == rsoVM.GDFinalResult.Rows.Count.ToString())
                {                    
                    return;
                }
            }

            if (scrollViewer.VerticalOffset > 0 && scrollViewer.ScrollableHeight > 0)
            {
                if (scrollViewer.VerticalOffset == scrollViewer.ScrollableHeight)
                {
                    DataTable dt = new DataTable("dt");
                    dt = rsoVM.GDFinalResult.Copy();

                    object getSelecteditem = null;

                    if (gridFinalResult.SelectedItem != null)
                        getSelecteditem = gridFinalResult.SelectedItem;

                    DataRow[] drRSOList = rsoVM.GDFinalResult.Select("RowID = MAX(RowID)");

                    if (drRSOList.Length > 0)
                    {
                        int i = 0;

                        for(Int32 j = Convert.ToInt32(drRSOList[0]["RowID"].ToString()) + 1 ; j <= Convert.ToInt32(drRSOList[0]["RowID"].ToString()) + 15; j++)
                        {
                            dt.ImportRow(rsoVM.GDFinalDBResult.Rows[j]);
                        }



                        Dispatcher.BeginInvoke(new Action(() =>
                        {
                            rsoVM.GDFinalResult = dt;
                            rsoVM.OnPropertyChanged("GDFinalResult");
                        }), System.Windows.Threading.DispatcherPriority.ContextIdle);

                            Dispatcher.BeginInvoke(new Action(() =>
                            {
                            scrollViewer.ScrollToVerticalOffset(scrollViewer.ScrollableHeight / 2);

                            if (getSelecteditem != null)
                            {
                                long ID = long.Parse(((System.Data.DataRowView)(getSelecteditem)).Row.ItemArray[0].ToString());
                                int index = CommonClass.GetIndex(rsoVM.GDFinalResult, ID, "RowID");
                                if (index != -1)
                                {
                                    gridFinalResult.SelectedItem = getSelecteditem;

                                    DataGridRow dgrow = (DataGridRow)gridFinalResult.ItemContainerGenerator.ContainerFromItem(gridFinalResult.Items[index]);
                                    if (dgrow != null)
                                        dgrow.MoveFocus(new TraversalRequest(FocusNavigationDirection.Next));
                                }
                            }
                        }),
                    System.Windows.Threading.DispatcherPriority.ContextIdle);
                    }
                }
            }            
        }

DataGrid ScrollViewer.ScrollChanged事件不断发生

0 个答案: