After trying Hraban's two suggestions to resolve the problem of a caption ('title=') for an image across a two-page spread (and I have tried a variety of adaptations of those two possible solutions), I still have not resolved the issue.

To repeat what Hans gave me, to resolve the 2-page spread in the first instance:

\startpostponing
    \setuppagenumbering[state=stop]
    \startspread
        \startplacefigure[location=here,title={This is a cow!}]
        \externalfigure[cow.pdf][height=\textheight]%
        \stopplacefigure
    \stopspread
    \setuppagenumbering[state=start]
\stoppostponing

The problem I have is that the figure has a title/caption much longer than 'This is a cow', and the end result is that it commences on the verso page but then runs across (repeats, part of it) on the recto page. Hraban suggests, first of all:

title={\hbox to \textwidth{\vbox{Your lengthy caption}}}
but this results in the first part of the caption properly located left-flushed on the verso page, and the other part right-flushed (and to the right of the figure, so running off the page) on the recto page.

The second solution is
title={\framedtext[width=\textwidth,frame=off,align=right]{Your lengthy caption}}
and this almost works, but this time part of the caption repeats on the left  of the recto page more or less within the inner margin, so I can live with that, knowing that it will not be visible ultimately at the binding stage.

Of course, what I really want to achieve is that the caption (aka 'title') appears either on the verso or the recto page, but not both. Is that achievable? The actual coding for all this as I have it at the moment is as follows:

\startpostponing
    \setuppagenumbering[state=stop]
    \startspread
        \startplacefigure[location=here,title={{\sc Plates 12/13.} \switchtobodyfont[9.5pt] My very, very, very long\\ caption for this figure}]
        \externalfigure[plate12-13.jpg][height=.8\textheight]%
        \stopplacefigure
    \stopspread
    \setuppagenumbering[state=start]
\stoppostponing

but

...very long caption
for this ...

is repeated on the recto page. This is what I want to avoid.
Julian

On 5/5/20 4:18 pm, Henning Hraban Ramm wrote:

      

        
Am 05.05.2020 um 03:31 schrieb jbf <roma83537@gmail.com>:

The following excellent solution (see below) to a 2-page spread of an image was given me by Hans (I had been completely unaware of the command \startspread. It appears to be recent and undocumented, but it certainly simplifies matters).

But in my case the title is a lengthy sentence, rather than the 4-word 'This is a cow'. And even though I have been able to split the line, e.g. title={this is my very, very, very,\\ very etc. etc. long title}, what happens is that part of the caption still appears on the right-hand page of the spread.

Is there a way that I can limit the appearance of the caption to just one (the left-hand) page? In other words, so the figure is spread but not the caption? Or alternatively, have the caption neatly split across the two pages with appropriate space inbetween? I tried various combinations, including an \hfill halfway through the title, but to no avail. Perhaps this is asking too much, but there may be a workaround.


      

      
I guess you need something like

title={\hbox to \textwidth{\vbox{Your lengthy caption}}}

or

title={\framedtext[width=\textwidth,frame=off,align=right]{Your lengthy caption}}


HTH
Hraban
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________