Background

Regarding floats in columns, the wiki states:

By default, a title will be moved down to appear below a float, it will not be "wrapped" around a float like normal text.

Problem

The section title disappears, instead of being moved below the float. Ultimately, I'm trying to produce the following two layouts without changing the content (between starttext and stoptext):

As an aside, it is important that the content need not change as there are other layouts that use the same document structure. If content changes can be made universal such that the other layouts remain unaffected, for example by adding a new namespace and command, then that will work. This might resemble:

definenamespace[Photograph][

  type=module,

  name=Photograph,

  parent=Photograph,

  setup=list,

  version=1.0,

  style=yes,

  command=list,

]



% ...

starttext

  setupInsertPhotograph[

    author=Full Name,

    homepage=http://authorname.com/about.html,

    source=http://flickr.com/authorname/sunset.jpg,

  ]

  % Calls "placefigure" and "externalfigure" using the setup parameters.

  InsertPhotograph

% ...

stoptext

Then the InsertPhotograph macro could be used to customize how the photograph is typeset, independently of the layout.

Code

So far, I have the following code:

setupalign[hz,tolerant,]



setuphead[chapter][footer=empty,]

setuphead[section][page=yes,]



setuphead[subsection][

  before={vskip0.5em},

  after={vskip0.5em},

]



setuphead[chapter,section,subsection][header=none,number=no,]



defineitemgroup[Preparation]

setupitemgroup[Preparation][each][packed][

  before={empty},

]



setupexternalfigures[width=hsize,]



definecolumnset[BookColumns][n=2]

definecolumnsetspan[BookColumnSpan][n=2]



starttext

  startchapter[title=Chapter One]

  page

  startcolumnset[BookColumns]

    startsection[title=Section One]

      % This could be InsertPhotograph instead of placefigure...

      placefigure[tblr]{}{externalfigure[fake][]}



      startsubsection[title=Subsection]

      input douglas

      stopsubsection

      startsubsection[title=Preparation]

      startPreparation

      dorecurse{4} { startitem Pour liquid helium into flask. stopitem }

      stopPreparation

      stopsubsection

    stopsection

    startsection[title=Section Two]

      dorecurse{4} { input knuth }

    stopsection

  stopcolumnset

  stopchapter

stoptext

Question

How can the photograph float to the left of the section title when a figure is present, whilst the section title spans the page when no figure is present?

Here I present a solution which uses the second optional argument of the
sectioning commands.

The values can be retrieved with the command
structureuservariable. First, a custom head alternative is defined which
checks if the figure key is present. If it is, it includes the figure and
the section head, otherwise only the section head is included. Then the section head is set up to use the custom head alternative.

setupexternalfigures

  [location=default]



defineframed

  [headframe]

  [width=textwidth,

   frame=off]



defineheadalternative

  [graphiccolumn]

  [renderingsetup=graphiccolumn]



startsetups [graphiccolumn]

  headsetupspacing

  doifsomethingelse

    {structureuservariable{figure}}

    {headframe

      {externalfigure[structureuservariable{figure}]hfill

       headnumbercontentspaceheadtextcontent}}

    {headnumbercontentspaceheadtextcontent}

stopsetups



setuphead

  [section]

  [alternative=graphiccolumn]



starttext

  startsection [title=Alpha] [figure=cow]

    input ward

  stopsection



  startsection [title=Beta]

    input ward

  stopsection



  startsection [title=Gamma] [figure=hacker]

    input ward

  stopsection

stoptext

Creating a custom section to indicate when a photograph is present (sectionpicture) allows for that section to be wrapped in a two-column mode and its title made empty. This preserves the structure of the document allowing for a wide variety of layout possibilities.

It might also be possible to use:

deftrueref{true}

startsection[title=Section One][picture=trueref]

  Photograph

  % ...

stopsection

However, I could not get that approach to work. Instead, the code following the preview almost produces the correct result.

Preview:

Code:

setuppapersize[letter][letter]

setuplayout[width=fit,]

setupalign[hz,tolerant,]



setuphead[chapter,section,subsection][header=none,number=no,]



setuphead[chapter][footer=empty,after=page,]

setuphead[section][page=yes,]



setuphead[subsection][

  before={vskip0.5em},

  after={vskip0.5em},

  page=no,

]



setuphead[subsection][

  beforesection={startmixedcolumns[n=2,balance=no,]},

  aftersection={stopmixedcolumns},

  page=no,

]



definehead[sectionpicture][section][

  placehead=empty,

  before={startcolumns[n=2,]},

  after={vskip-1em},

]



defineitemgroup[Preparation]

setupitemgroup[Preparation][each][packed][

  before={empty},

]



setupexternalfigures[

  width=hsize,

  location={none,left,high},

]



definenamespace[Photograph][

  type=module,

  name=Photograph,

  parent=Photograph,

  setup=list,

  version=1.0,

  style=yes,

  command=list,

]



% Define parameters within the Photograph namespace.

setupPhotograph[

  author=,

  homepage=,

  source=,

  % Pass along the current section title into the Photograph macro.

  sectiontitle={namedstructurevariable{section}{title}},

  attribution=photo:,

  cite={%

    Word{Photographparameter{attribution}} %

    Photographparameter{author}},

]



setupcaptions[location=,]

definefloat[photograph][photographs][figure]



showframe



% Defines how the photograph is used.

defPhotograph{%

  placephotograph[top,left,force]{}{externalfigure[fake][]}

  columnbreak

  {switchtobodyfont[24pt]Photographparameter{sectiontitle}} par \

  Photographparameter{cite}

  stopcolumns

}



starttext

  startchapter[title=Chapter One]

    startsectionpicture[title=Section One]

      Photograph



      startsubsection[title=Subsection]

      input douglas

      stopsubsection



      startsubsection[title=Preparation]

      startPreparation

      dorecurse{3} { startitem Pour liquid helium into flask. stopitem }

      stopPreparation

      stopsubsection

    stopsectionpicture



    startsection[title=Section Two]

      startsubsection[title=Subsection]

      input knuth

      stopsubsection



      startsubsection[title=Preparation]

      startPreparation

      dorecurse{3} { startitem Pour CO$_2$ into beaker. stopitem }

      stopPreparation

      stopsubsection

    stopsection

  stopchapter

stoptext