Como: Use a Custom Context Menu with a TextBox
Este exemplo mostra como definir e implementar um menu de contexto personalizado simples para um TextBox.
Exemplo
O exemplo a seguir Extensible Application Markup Language (XAML) define um controle TextBox que inclui um menu de contexto personalizado.
O menu de contexto é definido usando um elemento ContextMenu. O próprio menu de contexto consiste de uma série de elementos MenuItem e elementos Separator. Cada elemento MenuItem define um comando no menu de contexto; o atributo Header define o texto exibido para o comando de menu, e o atributo Click especifica um método de manipulador para cada item de menu. O elemento Separator simplesmente faz com que uma linha de separação seja renderizada entre os itens de menu anterior e posterior.
<TextBox
Name="cxmTextBox"
Grid.Row="1"
AcceptsReturn="True"
AcceptsTab="True"
VerticalScrollBarVisibility="Visible"
TextWrapping="Wrap"
>
<TextBox.ContextMenu>
<ContextMenu
Name="cxm"
Opened="CxmOpened"
>
<MenuItem
Header="Cut"
Name="cxmItemCut"
Click="ClickCut"
/>
<MenuItem
Header="Copy"
Name="cxmItemCopy"
Click="ClickCopy"
/>
<MenuItem
Header="Paste"
Name="cxmItemPaste"
Click="ClickPaste"
/>
<Separator/>
<MenuItem
Header="Select All"
Name="cxmItemSelectAll"
Click="ClickSelectAll"
/>
<MenuItem
Header="Select Current Line"
Name="cxmItemSelectLine"
Click="ClickSelectLine"
/>
<Separator/>
<MenuItem
Header="Undo Last Action"
Name="cxmItemUndo"
Click="ClickUndo"
/>
<MenuItem
Header="Redo Last Action"
Name="cxmItemRedo"
Click="ClickRedo"
/>
<Separator/>
<MenuItem
Header="Clear All Text"
Name="cxmItemClear"
Click="ClickClear"
/>
</ContextMenu>
</TextBox.ContextMenu>
This TextBox uses a simple custom context menu. The context menu can be disabled by checking
the CheckBox above, which simply sets the TextBox.ContextMenu property to null.
</TextBox>
O exemplo a seguir mostra o código de implementação para a definição de menu de contexto anteriores, bem como o código que ativa e desativa o menu de contexto. O evento Opened é usado para ativar ou desativar determinados comandos dinamicamente dependendo do estado atual de TextBox.
Para restaurar o menu de contexto padrão, use o método ClearValue para limpar o valor da propriedade ContextMenu. Para desativar totalmente o menu de contexto, defina a propriedade ContextMenu como uma referência nula (Nothing no Visual Basic).
Private Sub MenuChange(ByVal sender As Object, ByVal args As RoutedEventArgs)
Dim rb As RadioButton = CType(sender, RadioButton)
If myGrid.Children.Contains(cxmTextBox) Then
Select Case rb.Name
Case "rbCustom"
cxmTextBox.ContextMenu = cxm
Case "rbDefault"
'Clearing the value of the ContextMenu property
'restores the default TextBox context menu.
cxmTextBox.ClearValue(ContextMenuProperty)
Case "rbDisabled"
'Setting the ContextMenu propety to
'null disables the context menu.
cxmTextBox.ContextMenu = Nothing
End Select
Else : Return
End If
End Sub
Private Sub ClickPaste(ByVal sender As Object, ByVal args As RoutedEventArgs)
cxmTextBox.Paste()
End Sub
Private Sub ClickCopy(ByVal sender As Object, ByVal args As RoutedEventArgs)
cxmTextBox.Copy()
End Sub
Private Sub ClickCut(ByVal sender As Object, ByVal args As RoutedEventArgs)
cxmTextBox.Cut()
End Sub
Private Sub ClickSelectAll(ByVal sender As Object, ByVal args As RoutedEventArgs)
cxmTextBox.SelectAll()
End Sub
Private Sub ClickClear(ByVal sender As Object, ByVal args As RoutedEventArgs)
cxmTextBox.Clear()
End Sub
Private Sub ClickUndo(ByVal sender As Object, ByVal args As RoutedEventArgs)
cxmTextBox.Undo()
End Sub
Private Sub ClickRedo(ByVal sender As Object, ByVal args As RoutedEventArgs)
cxmTextBox.Redo()
End Sub
Private Sub ClickSelectLine(ByVal sender As Object, ByVal args As RoutedEventArgs)
Dim lineIndex As Integer = cxmTextBox.GetLineIndexFromCharacterIndex(cxmTextBox.CaretIndex)
Dim lineStartingCharIndex As Integer = cxmTextBox.GetCharacterIndexFromLineIndex(lineIndex)
Dim lineLength As Integer = cxmTextBox.GetLineLength(lineIndex)
cxmTextBox.Select(lineStartingCharIndex, lineLength)
End Sub
Private Sub CxmOpened(ByVal sender As Object, ByVal args As RoutedEventArgs)
'Only allow copy/cut if something is selected to copy/cut.
If cxmTextBox.SelectedText = "" Then
cxmItemCopy.IsEnabled = cxmItemCut.IsEnabled = False
Else
cxmItemCopy.IsEnabled = cxmItemCut.IsEnabled = True
'Only allow paste if there is text on the clipboard to paste.
If Clipboard.ContainsText() Then
cxmItemPaste.IsEnabled = True
Else
cxmItemPaste.IsEnabled = False
End If
End If
End Sub
private void MenuChange(Object sender, RoutedEventArgs ags)
{
RadioButton rb = sender as RadioButton;
if (rb == null || cxm == null) return;
switch (rb.Name)
{
case "rbCustom":
cxmTextBox.ContextMenu = cxm;
break;
case "rbDefault":
// Clearing the value of the ContextMenu property
// restores the default TextBox context menu.
cxmTextBox.ClearValue(ContextMenuProperty);
break;
case "rbDisabled":
// Setting the ContextMenu propety to
// null disables the context menu.
cxmTextBox.ContextMenu = null;
break;
default:
break;
}
}
void ClickPaste(Object sender, RoutedEventArgs args) { cxmTextBox.Paste(); }
void ClickCopy(Object sender, RoutedEventArgs args) { cxmTextBox.Copy(); }
void ClickCut(Object sender, RoutedEventArgs args) { cxmTextBox.Cut(); }
void ClickSelectAll(Object sender, RoutedEventArgs args) { cxmTextBox.SelectAll(); }
void ClickClear(Object sender, RoutedEventArgs args) { cxmTextBox.Clear(); }
void ClickUndo(Object sender, RoutedEventArgs args) { cxmTextBox.Undo(); }
void ClickRedo(Object sender, RoutedEventArgs args) { cxmTextBox.Redo(); }
void ClickSelectLine(Object sender, RoutedEventArgs args)
{
int lineIndex = cxmTextBox.GetLineIndexFromCharacterIndex(cxmTextBox.CaretIndex);
int lineStartingCharIndex = cxmTextBox.GetCharacterIndexFromLineIndex(lineIndex);
int lineLength = cxmTextBox.GetLineLength(lineIndex);
cxmTextBox.Select(lineStartingCharIndex, lineLength);
}
void CxmOpened(Object sender, RoutedEventArgs args)
{
// Only allow copy/cut if something is selected to copy/cut.
if (cxmTextBox.SelectedText == "")
cxmItemCopy.IsEnabled = cxmItemCut.IsEnabled = false;
else
cxmItemCopy.IsEnabled = cxmItemCut.IsEnabled = true;
// Only allow paste if there is text on the clipboard to paste.
if (Clipboard.ContainsText())
cxmItemPaste.IsEnabled = true;
else
cxmItemPaste.IsEnabled = false;
}
Consulte também
Tarefas
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