WPF：从文本框中获取“包装”文本

InputTextBox.ViewportWidth

<Window x:Class=\"TextFormatterForWrappedText.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\">
    <Grid>
        <TextBox Width=\"200\"
            x:Name=\"InputTextBox\"
            TextWrapping=\"Wrap\"
            VerticalScrollBarVisibility=\"Auto\"
            HorizontalScrollBarVisibility=\"Auto\" Margin=\"23,12,280,241\" />
        <TextBox x:Name=\"FormattedDisplayTextBox\" Height=\"172\"
                 HorizontalAlignment=\"Left\" VerticalAlignment=\"Top\"
                 Margin=\"23,105,0,0\" Width=\"438\" AcceptsReturn=\"True\"
                 TextWrapping=\"Wrap\" />
        <Button HorizontalAlignment=\"Left\" VerticalAlignment=\"Top\"
                Margin=\"257,12,0,0\" Height=\"23\" Content=\"Copy\"
                Name=\"CopyButton\" Width=\"129\" Click=\"CopyButton_Click\" />
    </Grid>
</Window>

private void CopyButton_Click(object sender, RoutedEventArgs e)
{
    List<string> stringList = GetTextAsStringList();
    StringBuilder sb = new StringBuilder();
    foreach (string s in stringList)
    {
        sb.Append(s);
        sb.Append(\"\\r\\n\");
    }

    Clipboard.SetData(System.Windows.DataFormats.Text, sb.ToString());

    FormattedDisplayTextBox.Clear();
    FormattedDisplayTextBox.Text = sb.ToString();
}

private List<string> GetTextAsStringList()
{
    List<string> stringList = new List<string>();
    int pos = 0;
    string inputText = InputTextBox.Text;

    CustomTextSource store = new CustomTextSource();
    store.Text = inputText;
    store.FontRendering = new FontRendering(InputTextBox.FontSize,
                                            InputTextBox.TextAlignment,
                                            null,
                                            InputTextBox.Foreground,
                                            new Typeface(InputTextBox.FontFamily,
                                                InputTextBox.FontStyle,
                                                InputTextBox.FontWeight,
                                                InputTextBox.FontStretch));

    using (TextFormatter formatter = TextFormatter.Create())
    {
        while (pos < store.Text.Length)
        {
            using (TextLine line = formatter.FormatLine(store,
                                    pos,
                                    InputTextBox.ViewportWidth,
                                    new GenericTextParagraphProperties(
                                        store.FontRendering),
                                    null))
            {
                stringList.Add(inputText.Substring(pos, line.Length - 1));
                pos += line.Length;
            }
        }
    }

    return stringList;
}

TextBlock

FormattedText ft = new FormattedText(textBox1.Text,
    System.Globalization.CultureInfo.CurrentCulture,
    textBox1.FlowDirection,
    new Typeface(textBox1.FontFamily,
        textBox1.FontStyle,
        textBox1.FontWeight,
        textBox1.FontStretch),
    textBox1.FontSize,
    textBox1.Foreground);
ft.TextAlignment = textBox1.TextAlignment;
ft.Trimming = TextTrimming.None;

ft.MaxTextWidth = textBox1.ViewportWidth;

textBlock1.Width = textBox1.ViewportWidth;
textBlock1.Height = ft.Height;

textBlock1.TextAlignment = textBox1.TextAlignment;
textBlock1.TextWrapping = textBox1.TextWrapping;
textBlock1.Text = textBox1.Text;

List<string>