问题
I need to implement a custom copy + cut + paste for data (not text or CSV) to be copied between grids in a WPF application. Using standard ApplicationCommands and defining CommandBinding works really well but only if the DataGrid contains at least 1 row of data and when it's selected. When there are no rows or focus is not on any of them, all commands are disabled.
To fix the problem I tried calling CommandManager.InvalidateRequerySuggested() and setting Focusable=true and/or FocusManager.IsFocusScope=true on the DataGrid but it seems internally DataGrid as a whole is "not interested" in handling Copy/Paste operations, only it's rows are re-querying commands CanExecute state and calling Execute accordingly. It also ignores KeyBindings.
How to make DataGrid handle requerying ApplicationCommands?
Please find the example on which I tested the problem below:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<DataGrid x:Name="TheGrid">
<DataGrid.Columns>
<DataGridTextColumn Header="Number" Binding="{Binding}"/>
</DataGrid.Columns>
<DataGrid.InputBindings>
<KeyBinding Key="A" Command="{x:Static ApplicationCommands.New}"/>
</DataGrid.InputBindings>
<DataGrid.CommandBindings>
<CommandBinding Command="{x:Static ApplicationCommands.Paste}" CanExecute="CanPaste" Executed="Paste"/>
<CommandBinding Command="{x:Static ApplicationCommands.Copy}" CanExecute="CanCopy" Executed="Copy"/>
<CommandBinding Command="{x:Static ApplicationCommands.New}" CanExecute="CanAddNew" Executed="AddNew"/>
</DataGrid.CommandBindings>
<DataGrid.ContextMenu>
<ContextMenu>
<MenuItem Command="{x:Static ApplicationCommands.Copy}" Header="Copy"/>
<MenuItem Command="{x:Static ApplicationCommands.Paste}" Header="Paste"/>
<MenuItem Command="{x:Static ApplicationCommands.New}" Header="New row"/>
</ContextMenu>
</DataGrid.ContextMenu>
</DataGrid>
</Window>
And the code behind:
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Windows;
using System.Windows.Input;
namespace WpfApplication1
{
public partial class MainWindow
{
public MainWindow()
{
InitializeComponent();
TheGrid.ItemsSource = numbers;
// Following line enables commands when row is selected
numbers.Add(0);
}
private void Copy(object sender, ExecutedRoutedEventArgs e)
{
Clipboard.SetData(DataFormats.Text, string.Join(",", numbers));
}
private void CanCopy(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = numbers.Count > 0;
}
private void CanPaste(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = numbers.Count > 0;
e.Handled = true;
}
private void Paste(object sender, ExecutedRoutedEventArgs e)
{
Close();
}
private void CanAddNew(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = true;
e.Handled = true;
}
private void AddNew(object sender, ExecutedRoutedEventArgs e)
{
numbers.Add(numbers.Count);
}
private readonly ICollection<int> numbers = new ObservableCollection<int>();
}
}
Edit
The code only solution by Ayyappan Subramanian is the closest match to the application it will be used in. Eventually as I already inherit the grid because it has custom copy+paste format to work on, I added some code which ensures that focus is within a grid in 3 cases:
- Context menu is shown
- User clicks in the grid (empty) area when it's child visuals have no focus
- (Our app specific case) User clicks on a grid navigation TreeView which then brings focus to the grid so shortcuts will work straight away.
Relevant code:
public class MyDataGrid: DataGrid
{
protected override void OnContextMenuOpening(ContextMenuEventArgs e)
{
base.OnContextMenuOpening(e);
Focus();
}
protected override void OnMouseUp(MouseButtonEventArgs e)
{
base.OnMouseUp(e);
if(e.ChangedButton == MouseButton.Left && !IsKeyboardFocusWithin)
{
Focus();
}
}
}
回答1:
When the ContextMenu is openning then you can set the focus to the grid which will enable all the menu items. Good explanation is given in here http://www.wpftutorial.net/RoutedCommandsInContextMenu.html
Also for implementing the paste refer the SO post WPF datagrid pasting
WPF:
<DataGrid x:Name="TheGrid" CanUserAddRows="True"
ContextMenuOpening="TheGrid_ContextMenuOpening">
<DataGrid.Columns>
<DataGridTextColumn Header="Number" Binding="{Binding}"/>
</DataGrid.Columns>
<DataGrid.InputBindings>
<KeyBinding Key="A" Command="{x:Static ApplicationCommands.New}"/>
</DataGrid.InputBindings>
<DataGrid.CommandBindings>
<CommandBinding Command="{x:Static ApplicationCommands.Paste}"
CanExecute="CanPaste" Executed="Paste"/>
<CommandBinding Command="{x:Static ApplicationCommands.Copy}"
CanExecute="CanCopy" Executed="Copy"/>
<CommandBinding Command="{x:Static ApplicationCommands.New}"
CanExecute="CanAddNew" Executed="AddNew"/>
</DataGrid.CommandBindings>
<DataGrid.ContextMenu>
<ContextMenu>
<MenuItem Command="{x:Static ApplicationCommands.Copy}" Header="Copy"/>
<MenuItem Command="{x:Static ApplicationCommands.Paste}" Header="Paste"/>
<MenuItem Command="{x:Static ApplicationCommands.New}" Header="New row"/>
</ContextMenu>
</DataGrid.ContextMenu>
</DataGrid>
C# code:
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
TheGrid.ItemsSource = numbers;
}
private void Copy(object sender, ExecutedRoutedEventArgs e)
{
Clipboard.SetData(DataFormats.Text, string.Join(",", numbers));
}
private void CanCopy(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = true;
}
private void CanPaste(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = true;
e.Handled = true;
}
private void Paste(object sender, ExecutedRoutedEventArgs e)
{
Close();
}
private void CanAddNew(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = true;
e.Handled = true;
}
private void AddNew(object sender, ExecutedRoutedEventArgs e)
{
numbers.Add(numbers.Count);
}
private readonly ICollection<int> numbers = new ObservableCollection<int>();
private void TheGrid_ContextMenuOpening(object sender, ContextMenuEventArgs e)
{
TheGrid.Focus();
}
}
回答2:
Here is my VB.NET version. It takes a value and then fills it into all selected cells in the datagrid.
Private Sub gridpaste(ByVal pasteValue As String)
Dim rowInd As Integer = Nothing
Dim colind As Integer = Nothing
Dim add As Integer = 1
For Each c As DataGridCellInfo In LineListDataGrid.SelectedCells
colind = c.Column.DisplayIndex
rowInd = GetRowIndex(LineListDataGrid, c)
Try
LLDB.LineList.Rows(rowInd)(colind) = pasteValue
Catch err As Exception
MessageBox.Show(err.Message)
End Try
Next
End Sub
Public Shared Function GetRowIndex(dataGrid As DataGrid, dataGridCellInfo As DataGridCellInfo) As Integer
Dim dgrow As DataGridRow = DirectCast(dataGrid.ItemContainerGenerator.ContainerFromItem(dataGridCellInfo.Item), DataGridRow)
If dgrow IsNot Nothing Then
Return dgrow.GetIndex()
Else
Return -1
End If
End Function
来源：https://stackoverflow.com/questions/29630671/implement-custom-copy-and-paste-in-wpf-datagrid-which-works-when-there-are-no-ro