CustomRichTextBox StrikeThrough TextDecoration

Question

我想在自定义TextDecorations.Strikethrough中添加RichTextBox装饰按钮我正在使用以下代码添加和删除TextDecoration我得到的InvalidCastException: Unable to cast object of type 'MS.Internal.NamedObject' to type 'System.Windows.TextDecorationCollection'. {{1}当我选择的范围大于被击穿的范围并点击＆＃34; StrikeThrough＆＃34;按钮。

我的代码

private void StrikeOutButton_Click(object sender, RoutedEventArgs e)
    {
        TextRange range = new TextRange(this.MyRichTextBox.Selection.Start,
                                      this.MyRichTextBox.Selection.End);

        TextDecorationCollection tdc =
            (TextDecorationCollection)this.MyRichTextBox.
                 Selection.GetPropertyValue(Inline.TextDecorationsProperty);
        /*
        if (tdc == null || !tdc.Equals(TextDecorations.Strikethrough))
        {
            tdc = TextDecorations.Strikethrough;
        }
        else
        {
            tdc = new TextDecorationCollection();
        }
         * */
        if (tdc == null || !tdc.Contains(TextDecorations.Strikethrough[0]))
        {
            tdc = TextDecorations.Strikethrough;
        }
        else
        {
            tdc = new TextDecorationCollection();
        }

        range.ApplyPropertyValue(Inline.TextDecorationsProperty, tdc);
    }

注释掉代码也无效。

我打算发布ExceptionDetails，但我认为它非常清楚。

有人可以为我提供解决方法吗？

Answer 1

问题在于，如果您的完整文字未使用删除线进行修饰，您将获得DependencyProperty.UnsetValue。

因此，您可以检查DependencyProperty.UnsetValue并在这种情况下仅应用删除线。

我做了一个简短的测试，这个解决方案适合我：

private void StrikeOutButton_Click(object sender, RoutedEventArgs e)
    {
        TextRange textRange = new TextRange(TextBox.Selection.Start, TextBox.Selection.End);
        var currentTextDecoration = textRange.GetPropertyValue(Inline.TextDecorationsProperty);

        TextDecorationCollection newTextDecoration;

        if (currentTextDecoration != DependencyProperty.UnsetValue)
            newTextDecoration = ((TextDecorationCollection)currentTextDecoration == TextDecorations.Strikethrough) ? new TextDecorationCollection() : TextDecorations.Strikethrough;
        else
            newTextDecoration = TextDecorations.Strikethrough;

        textRange.ApplyPropertyValue(Inline.TextDecorationsProperty, newTextDecoration);
    }