RichTextBox：第一个字符的不同颜色

Question

我在 WPF 中有一个 RichTextBox (Name="txtGoTo")，我只需要第一个字符为红色（而其余字符为默认黑色）。

这是我尝试过的（在网上找到的），但它不起作用：

    Dim rtb As RichTextBox = txtGoTo
    Dim Text As String = New TextRange(rtb.Document.ContentStart, rtb.Document.ContentEnd).Text

    If Not String.IsNullOrEmpty(Text) Then

        Dim RangeAisle As TextPointer = rtb.Document.ContentStart
        Dim RangeShelf As TextPointer = rtb.Document.ContentStart.GetPositionAtOffset(1)

        Dim tr As New TextRange(RangeAisle, RangeShelf)
        tr.ApplyPropertyValue(RichTextBox.ForegroundProperty, Brushes.Red)
    End If

Answer 1

您的问题是 rtb.Document.ContentStart.GetPositionAtOffset(1) 不返回第一个字母。它更像是3的索引

下面的代码将获取第一个字母的位置并变为红色。

Dim position As TextPointer = rtb.Document.ContentStart
While position IsNot Nothing
    If position.GetPointerContext(LogicalDirection.Forward) = TextPointerContext.Text Then
        Dim start As TextPointer = position.GetPositionAtOffset(0, LogicalDirection.Forward)
        Dim [end] As TextPointer = position.GetPositionAtOffset(1, LogicalDirection.Backward)
        New TextRange(start, [end]).ApplyPropertyValue(TextElement.ForegroundProperty, Brushes.Red)
        Exit While
    End If
    position = position.GetNextContextPosition(LogicalDirection.Forward)
End While