Latex color box inline with text

I'm trying to put together a LaTeX color box. The xcolor package \fcolorbox seem to be what I want, but I can't get the rendering quite correct. When I use

\fcolorbox{black}{red}{}

it renders a small box sunken to the bottom of the text line. The best I've managed to do is to fake it with a similar text color:

\fcolorbox{black}{red}{\textcolor{red}{--}}

However, I'm worried that th开发者_Python百科is won't render correctly in all situations with defined colors. Is there a way I can declare an empty text box with full in-line text height? Is there another solution?

I'm basically looking for the code that produces the color boxes all through the document at ftp://ftp.dante.de/pub/tex/macros/latex/contrib/xcolor/xcolor.pdf. The boxes I'm referring to are used throughout, but the first instance is on page 4. Thanks.

The xcolor.dtx file in the same directory as the pdf contains the source for the package and the source for the documentation. The relevant bits from the source for the documentation:

\def\testclr#1#{\@testclr{#1}}
\def\@testclr#1#2{{\fboxsep\z@\fbox{\colorbox#1{#2}{\phantom{XX}}}}}

...

(Answer: 40\% \testclr{green} $+$ 60\% \testclr{yellow} $=$ \testclr{green!40!yellow}, e.g., |\color{green!40!yellow}|)

Basically, use \phantom{} on the contents of your color box, and make sure that at least one of the phantom characters is full-height.

Also, https://tex.stackexchange.com/