绑定到集合的Icollectionview上的wpf datagrid拖动行 [英] wpf datagrid drag row on Icollectionview which bind to collection
问题描述
我有这样的数据网格
_productsPosition = new ObservableCollectionEx<NotifiedPositionInfo>();
_itemSourceList = new CollectionViewSource() { Source = _productsPosition };
_itemSourceList.Filter += new FilterEventHandler(FilteringProduct);
PositionsGrid.ItemsSource = _itemSourceList.View;
当我尝试在此datagrid上拖动行时,我可以在collectionview上获取行的索引。但是此索引不能帮助我在集合_productsPosition中获得相同的元素,因为collectionView已由过滤器修改。
and when I try to drag row on this datagrid, i can obtain the index of row on the collectionview. But this index can not help me get the same element in the collection _productsPosition, because the collectionView was modified by the filter.
因此,我有一个问题,我该如何只需将元素移动到collectionview上,而不是_productsPosition。这样的事情会引发异常:
Therefore, i have a question that how can i just move elements on the collectionview but not _productsPosition. Something like this which throws exception:
NotifiedPositionInfo prev_position = PositionsGrid.ItemContainerGenerator.Items[_prevRowIndex] as NotifiedPositionInfo;
PositionsGrid.Items.RemoveAt(_prevRowIndex);
PositionsGrid.Items.Insert(index, prev_position);
例外内容为:
未处理的异常:System.InvalidOperationException:使用ItemsSource时操作无效。
Unhandled Exception: System.InvalidOperationException: Operation is not valid while ItemsSource is in use. Access and modify elements with ItemsControl.ItemsSource instead.
在System.Windows.Controls.ItemCollection.CheckIsUsingInnerView()
at System.Windows.Controls.ItemCollection.CheckIsUsingInnerView()
在System.Windows.Controls.ItemCollection.RemoveAt(Int32 removeIndex)
at System.Windows.Controls.ItemCollection.RemoveAt(Int32 removeIndex)
工作示例:
<DataGrid Name="PositionsGrid" Background="AliceBlue" AutoGenerateColumns="False" CanUserAddRows="False" ItemsSource="{Binding}"
AllowDrop="True" GridLinesVisibility="Horizontal" HorizontalGridLinesBrush="#FFDEDEDE">
<DataGrid.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="#FF0096FD"/>
</DataGrid.Resources>
<DataGrid.Columns>
<DataGridTextColumn Header="Product Name" Width="130" IsReadOnly="True" Binding="{Binding ProductName}"/>
<DataGridTextColumn Header="Positions" Width="*" IsReadOnly="True" Binding="{Binding Position}"/>
</DataGrid.Columns>
</DataGrid>
拖动功能:
PositionsGrid.PreviewMouseLeftButtonDown += new MouseButtonEventHandler(positionsGrid_PreviewMouseLeftButtonDown);
PositionsGrid.Drop += new DragEventHandler(positionsGrid_Drop);
private bool isTheMouseOnTargetRow(Visual target, GetDragDropPosition pos)
{
try
{
Rect posBounds = VisualTreeHelper.GetDescendantBounds(target);
Point theMousePos = pos((IInputElement)target);
return posBounds.Contains(theMousePos);
}
catch (Exception)
{
return false;
}
}
private DataGridRow getDataGridRowItem(int index)
{
if (PositionsGrid.ItemContainerGenerator.Status != System.Windows.Controls.Primitives.GeneratorStatus.ContainersGenerated)
return null;
return PositionsGrid.ItemContainerGenerator.ContainerFromIndex(index) as DataGridRow;
}
private int getDataGridItemCurrentRowIndex(GetDragDropPosition pos)
{
int curIndex = -1;
for (int i = 0; i < PositionsGrid.Items.Count; i++)
{
DataGridRow item = getDataGridRowItem(i);
if (isTheMouseOnTargetRow(item, pos))
{
curIndex = i;
break;
}
}
return curIndex;
}
private int _prevRowIndex = -1;
private void positionsGrid_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
_prevRowIndex = getDataGridItemCurrentRowIndex(e.GetPosition);
if (_prevRowIndex < 0)
return;
PositionsGrid.SelectedIndex = _prevRowIndex;
NotifiedPositionInfo selected_positionInfo = PositionsGrid.Items[_prevRowIndex] as NotifiedPositionInfo;
if (selected_positionInfo == null)
return;
DragDropEffects dragdrop_effects = DragDropEffects.Move;
if (DragDrop.DoDragDrop(PositionsGrid, selected_positionInfo, dragdrop_effects) != DragDropEffects.None)
PositionsGrid.SelectedItem = selected_positionInfo;
}
private void positionsGrid_Drop(object sender, DragEventArgs e)
{
if (_prevRowIndex < 0)
return;
int index = this.getDataGridItemCurrentRowIndex(e.GetPosition);
if (index < 0)
return;
if (index == _prevRowIndex)
return;
if (index == PositionsGrid.Items.Count - 1)
{
MessageBox.Show("This row-index cannot be used for Drop Operations");
return;
}
NotifiedPositionInfo prev_position = PositionsGrid.ItemContainerGenerator.Items[_prevRowIndex] as NotifiedPositionInfo;
PositionsGrid.Items.RemoveAt(_prevRowIndex);
PositionsGrid.Items.Insert(index, prev_position);
}
推荐答案
好的,最后我解决了这个问题操作不灵巧的问题。当特定元素在集合视图中拖动时,我将其重置。此外,我更改排序事件以确保collectionView不会控制绑定到该集合的显示。
ok, finally i solve this problem with a not clever operation. I reset the specific element's position in the collection while it is dragged on the collectionview. Besides, i change the sorting event make sure the collectionView will not controll the display which binds to the collection.
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