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如何：在文字方塊使用自訂內容功能表

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此範例示範如何定義及實作 的 TextBox 簡單自訂操作功能表。

定義自訂操作功能表

下列 Extensible Application Markup Language （XAML） 範例會定義包含 TextBox 自訂操作功能表的控制項。

操作功能表是使用 ContextMenu 元素來定義。 操作功能表本身是由一系列 MenuItem 元素和 Separator 元素所組成。 每個 MenuItem 元素都會在操作功能表中定義命令; Header 屬性會定義功能表命令的顯示文字，而 Click 屬性會為每個功能表項目指定處理常式方法。 元素 Separator 只會讓上一個功能表項目和後續功能表項目之間呈現分隔線。

<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>

實作自訂操作功能表

下列範例顯示上述操作功能表定義的實作程式碼，以及啟用和停用操作功能表的程式碼。 事件 Opened 是用來根據 的目前狀態 TextBox 動態啟用或停用特定命令。

若要還原預設操作功能表，請使用 ClearValue 方法來清除 屬性的值 ContextMenu 。 若要完全停用操作功能表，請將 屬性設定 ContextMenu 為 Null 參考 （ Nothing 在 Visual Basic 中）。

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;
}

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

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