How to setup this layout

Question

I am trying to replicate this page layout using context, but I am struggling.

I have read the context manual and tried changing parameters to see what happens, but I was unable to sort out the logic.

Can anyone give me some pointers?

Answer 1

Aligning the structure number in the margin can easily be achieved by means of a placement method. These are ordinary macros that take two arguments -- one for the number, the second for the heading text -- and determine how they are typeset in the body matter context. This way the presentation of structurals is limited only by your imagination and TEX skills. For this to work, the setup key alternative needs to be set to command and the key command to your macro. Also, the left margin will have to be configured so as to match the required flush left alignment. (For further information see the structural rendering source, strc-ren.mkiv.)

% macros=mkvi
\unprotect
%% 1. Create a placement alternative, i. e. a dyadic macro. % ······· %
\unexpanded\def\left_margin_placement#number#content{%
  \vbox{%
    \localheadsetup\begstrut\dontleavehmode
    \ifconditional\headshownumber\inleftmargin{#number}\fi
    {#content}%
  }
}

%% 2. Setup the alignment within the margin. % ······················ %
\setupmargindata [left]            [align=flushleft]
\setuplayout     [leftmargin=1cm]

%% 3. Hook the new method into the structurals. % ··················· %
\setuphead       [chapter,section] [
  alternative=\v!command,
  \c!command=\left_margin_placement,
]
\protect

%% 4. ... Profit?
\starttext % ························································ %
  \chapter{foo}
  \section{bar}
  \input knuth
\stoptext % ························································· %