我有一个DataGrid。它被绑定到名为People的Person的集合。
允许用户添加新行，我的意思是CanUserAddRows = true。
在我的DataGrid中输入键作为 TAB 键。
我的DataGrid有三列，分别是：FirstName，LastName，City。 FirstName是必需的。另外两个不是强制性的。
当用户在最后一行的第一个单元格（自动生成的行）上点击 Enter 时，如果该单元格为空，则计算机猜测该用户不想向DataGrid添加更多数据并且焦点移动到DataGrid外部的按钮。
到目前为止，一切正常。
问题：
在最后一行的第一个单元格中按 Enter 并保持为空，DataGrid外部的按钮会被聚焦。那时我不希望用户看到DataGrid中的最后一个空行。
我尝试了什么：
我尝试过两个事件：1。GotFocus和2. LostFocus
在DataGrid的GotFocus事件中，我设置了CanUserAddRows = true
在DataGrid的LostFocus事件中，我设置了CanUserAddRows = false
但不幸的是，当DataGrid的内容中的textBlock成为焦点时，DataGrid认为它失去了焦点。因此，CanUserAddRows设置为false，我收到错误。
我的代码：
person.cs
public class Person
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string City { get; set; }
}
MainWindowViewModel.cs
public class MainWindowViewModel : INotifyPropertyChanged
{
public MainWindowViewModel()
{
People = new ObservableCollection<Person>();
}
private ObservableCollection<Person> _people;
public ObservableCollection<Person> People
{
get
{
return _people;
}
set
{
_people = value;
OnPropertyChanged("People");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
MainWindow.xaml
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication1"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<local:MainWindowViewModel />
</Window.DataContext>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="65*"/>
<ColumnDefinition Width="9*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="93*"/>
<RowDefinition Height="14*"/>
</Grid.RowDefinitions>
<DataGrid x:Name="maindg" AutoGenerateColumns="True" ItemsSource="{Binding People}" Margin="0,0,0.4,-0.2" Grid.RowSpan="2" Grid.ColumnSpan="2"
PreviewKeyDown="DataGrid_KeyDown_1" SelectedIndex="0" GridLinesVisibility="Vertical"
SelectionMode="Single" SelectionUnit="CellOrRowHeader" >
</DataGrid>
<Button Height="20" Width="50" Content="Save" Margin="2.8,9.8,10.4,11.8" Grid.Column="1" Grid.Row="1" x:Name="btnSave" />
</Grid>
</Window>
MainWindow.xaml.cs
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private int FindRowIndex(DataGridRow row)
{
DataGrid dataGrid =
ItemsControl.ItemsControlFromItemContainer(row)
as DataGrid;
int index = dataGrid.ItemContainerGenerator.
IndexFromContainer(row);
return index;
}
private object ExtractBoundValue(DataGridRow row,
DataGridCell cell)
{
// find the column that this cell belongs to
DataGridBoundColumn col =
cell.Column as DataGridBoundColumn;
// find the property that this column is bound to
Binding binding = col.Binding as Binding;
string boundPropertyName = binding.Path.Path;
// find the object that is related to this row
object data = row.Item;
// extract the property value
PropertyDescriptorCollection properties =
TypeDescriptor.GetProperties(data);
PropertyDescriptor property = properties[boundPropertyName];
if (property != null)
{
object value = property.GetValue(data);
return value;
}
return null;
}
private void DataGrid_KeyDown_1(object sender, KeyEventArgs e)
{
if (e.Key != Key.Enter) return;
DependencyObject dep = (DependencyObject)e.OriginalSource;
//here we just find the cell got focused ...
//then we can use the cell key down or key up
// iteratively traverse the visual tree
while ((dep != null) && !(dep is DataGridCell) && !(dep is DataGridColumnHeader))
{
dep = VisualTreeHelper.GetParent(dep);
}
if (dep == null)
return;
if (dep is DataGridCell)
{
try
{
//cancel if datagrid in edit mode
maindg.CommitEdit();
//Check if selected cell is on first column and last row
if (maindg.CurrentColumn.DisplayIndex == 0)
{
DependencyObject dep1 = dep;
while ((dep1 != null) && !(dep1 is DataGridRow))
{
dep1 = VisualTreeHelper.GetParent(dep1);
}
DataGridRow row = dep1 as DataGridRow;
if (FindRowIndex(row) == maindg.Items.Count - 1)
{
if (ExtractBoundValue(row, dep as DataGridCell) == null)
{
btnSave.Focus();
return;
}
}
}
}
catch
{
maindg.CancelEdit();
}
//get current cell
DataGridCell cell = dep as DataGridCell;
//deselect current cell
cell.IsSelected = false;
//find next right cell
var nextCell = cell.PredictFocus(FocusNavigationDirection.Right);
//if next right cell null go for find next ro first cell
if (nextCell == null)
{
DependencyObject nextRowCell;
nextRowCell = cell.PredictFocus(FocusNavigationDirection.Down);
//if next row is null so we have no more row Return;
if (nextRowCell == null)
{
nextRowCell = dep;
while ((nextRowCell as DataGridCell).PredictFocus(FocusNavigationDirection.Left) != null)
nextRowCell = (nextRowCell as DataGridCell).PredictFocus(FocusNavigationDirection.Left);
//change current cell
maindg.CurrentCell = new DataGridCellInfo(nextRowCell as DataGridCell);
//change selected cell
(nextRowCell as DataGridCell).IsSelected = true;
return;
}
//we do this because we cant use FocusNavigationDirection.Next for function PredictFocus
//so we have to find it this way
while ((nextRowCell as DataGridCell).PredictFocus(FocusNavigationDirection.Left) != null)
nextRowCell = (nextRowCell as DataGridCell).PredictFocus(FocusNavigationDirection.Left);
//set new cell as next cell
nextCell = nextRowCell;
}
//change current cell
maindg.CurrentCell = new DataGridCellInfo(nextCell as DataGridCell);
//change selected cell
(nextCell as DataGridCell).IsSelected = true;
// start edit mode
maindg.BeginEdit();
}
//handl the default action of keydown
e.Handled = true;
}
}
答案 0 :(得分：2)
你快到了。在 GotFocus() 上，只需将 CanUserAddRows 设置为 True 即可。在 LostFocus() 处理程序中将其设置为 False 。
由于当焦点在网格中移动时也会调用LostFocus处理程序，因此您可以检查属性 IsKeyboardFocusWithin 以了解焦点是否在网格内。
private void maindg_GotFocus(object sender, RoutedEventArgs e)
{
if (!maindg.CanUserAddRows)
{
maindg.CanUserAddRows = true;
}
}
private void maindg_LostFocus(object sender, RoutedEventArgs e)
{
if (!maindg.IsKeyboardFocusWithin && maindg.CanUserAddRows)
{
maindg.CanUserAddRows = false;
}
}