推荐一个最好的，包括源码：
http://home.hccnet.nl/p.zylstra/downloads/ruler.zip
A horizontal ruler component similar like the one used in Word(Pad).
- Adjustable left and right margins.
- Run/designtime adjustable first, hanging, left and right indent markers.
- Tabs can be added/removed at runtime and designtime.
- Tabs support left, center, right, decimal and wordbar alignment.
- Units: Centimeters, Inches, Millimeters, Picas, Pixels and Points.
- Supports right-to-left mode (BiDiMode) for the Middle Eastern versions of Windows (Hebrew, Arabic).
- Zoom capability.
- Table editing capabilities for TRichView.
A vertical ruler component similar like the one used in Word.
- Adjustable top and bottom margins.
- Units: Centimeters, Inches, Millimeters, Picas, Pixels and Points.
It includes a demo that demonstrates how TRuler could be used together with TRichView. The TRichView package itself is not included but a trial version can be downloaded here.
