Solid black boxes in multiline chaper titles

Me again... very close to the layout I'm looking for already, but not quite there yet. ;-)

For chapter headers, I am trying to get this look for chapter headings:

I.e.,

• \thechapter centered,
• with a solid black box (the same height as the numbers) to the left and to the right, spanning the width of the text area.
• The name of the chapter on the next line, also centered, without the boxes.

I got the "Chapter" string removed, I got the ".0" appended to the chapter number (thanks to Stefan for helping with that one), and contentet myself with writing \chapter{MYCHAPTER} instead of trying to get LaTeX doing the uppercasing for me. I get "1.0 MYCHAPTER" written for a chapter header - so far so good.

But now I am stuck. I read and googled, and found plenty of examples using \@startsection for adding boxes around headers, lines above and lines below and backdrops behind them, getting increasingly more complex and daunting - but couldn't figure out how to do those black boxes to the left and the right of the chapter numbers.

Help?

-

With the titlesec package I can get you some of the way there:

\usepackage{titlesec}
\titleformat{\chapter}[display]{\normalfont\huge\bfseries}{\hrulefill\thechapter.0\hrulefill}{20pt}{\Huge\center}


I've basically copied the standard definition, but changed the third mandatory argument to \hrulefill\thechapter.0\hrulefill. What \hrulefill does is fill the available horizontal space with a rule.

With a \rule you could create your thick rules as follows: \rule{10em}{1ex} which would give a rule 10em long and 1ex thick. I don't know how to get a "thick" \hrulefill though.

I hope this goes some way towards solving your problem.

-
See this answer to another question for making a "thick" \hrulefill. –  You Aug 9 '11 at 12:03
You could as well redefine \thechapter: \renewcommand{\thechapter}{\arabic{chapter}.0}. –  ℝaphink Aug 9 '11 at 12:19
@Raphink: Already did so. –  DevSolar Aug 9 '11 at 12:55

Seamus and You got me on the right track. This is a combination of their hints:

% Ignore-The-Height (ith), used to avoid additional vspace
% e.g. with umlauts. See http://tex.stackexchange.com/questions/29911.
\newcommand{\ith}[1]
{\leavevmode\smash{\uppercase{#1}}}

% Variable-width rulers, default width 14pt
\newcommand*\varhrulefill[1][14pt]

\usepackage{titlesec}

\titleformat{\chapter}[display]
{\normalfont\huge\bfseries}
{\varhrulefill\enskip\thechapter\enskip\varhrulefill}
{12pt}
{\center\ith}

• I changed the default height of \varhrulefill from You's link to 14pt as that is my desired default size;
• I added a \enskip to push the boxes a bit away from the chapter numbers;
• I added an \uppercase to the after command so I actually don't have to write the chapter title in uppercase myself.
• I came back two months later to include this improvement and the general evolution of the solution to this answer.

The result is pretty much exactly what I were looking for:

Thanks, guys. You are awesome.

-
I give the "correct answer" to Seamus because he got me on the right track. –  DevSolar Aug 9 '11 at 12:19