http://blog.csdn.net/johnsuna/article/details/1895169

TextDecorations="Strikethrough" FontSize="72" FontFamily="Arial">A
这里TextDecorations属性可以设置为：OverLine, Strikethrough, Baseline, Underline或None,如果没有设置TextDecorations属性，则默认为None,即不带划线修饰。

TextDecorations="Underline"

(2)使用C#代码：
private void SetDefaultStrikethrough()
{
textBlock1.TextDecorations = TextDecorations.Strikethrough;
}

彩笔效果：


PenOffset="10" PenOffsetUnit="Pixel" PenThicknessUnit="Pixel">

















GOOD

C#关键代码：
private void SetLinearGradientUnderline()
{
TextDecoration myUnderline = new TextDecoration();

Pen myPen = new Pen();
myPen.Brush = new LinearGradientBrush(Colors.Yellow, Colors.Red, new Point(0, 0.5), new Point(1, 0.5));
myPen.Brush.Opacity = 0.8;
myPen.Thickness = 5;
myPen.DashStyle = DashStyles.Dash;
myUnderline.Pen = myPen;
myUnderline.PenThicknessUnit = TextDecorationUnit.FontRecommended;

TextDecorationCollection myCollection = new TextDecorationCollection();
myCollection.Add(myUnderline);
textBlockGood.TextDecorations = myCollection;
}

字体颜色设置：

Foreground="Blue"