Re: Blank figure hack: is there a better way?

[Hans Hagen <pragma@wxs.nl>]

Brooks Moses wrote:

> I'm doing a document which has a large logo in the upper right corner 
> of the page.  The logo (which is on a background layer) intrudes into 
> the text area by a small amount, and so it would be nice to have the 
> text wrap around it rather than having to do the wrapping by manual 
> spacers and line-breaks.
>
> The "obvious" solution that I came up with for this is to put a blank 
> right-aligned float at the top of each page (it's a presentation where 
> all the page breaks are hand-coded, so that's easy to do), of about 
> the size of the part of the logo that intrudes into the text.  I 
> defined a class of floats just for this:
>
>   \definefloat[logospacer][logospacer]
>
> (Using the same name for the singular and plural was a hack to get 
> around the fact that the manual doesn't indicate which of the two the 
> \setupfloat command uses.  Which is it?)
>
> So far, so good.  Except that it's exceptionally hard to _get_ a blank 
> float in ConTeXt, particularly one of a specified size.
>
> If I do this (and specify the size in a \setupfloat command):
>
>   \placelogospacer[right, force]{none}{}
>
> I get a nice float exactly the size I want, but with a frame around it 
> and the word "undefined" in the middle.
>
> If I put something in the float -- say, a letter, or a non-breaking 
> space:
>
>   \placelogospacer[right, force]{none}{~}
>
> The float suddenly becomes \textwidth wide, which is of course all 
> wrong, but at least I have a blank float that's not undefined.
>
> If I put an \hbox in the float, with a fixed width, it stops 
> stretching to fill the pagewidth, but unless I put something that 
> actually makes a mark on the page, it still comes up with 
> "undefined".  (The "~" that worked earlier doesn't work if it's in an 
> \hbox.)  I tried a number of tricks -- hiding the nothing in a macro, 
> using a zero-height rule, and so forth -- and ConTeXt was sufficiently 
> clever to see through them all.
>
> There's also the annoyance that I have to specify the size of the 
> float by the size of the \hbox, rather than in a convenient 
> [width=...,height=...] fashion.
>
> Eventually, what I came up with was putting the mark somewhere off the 
> page, with the following command:
>
>   \placelogospacer[right, force]{none}{\hbox to 1cm{\hskip 5cm x}}
>
> This of course gives "overfull \hbox" errors, and is a really ugly 
> hack, but the results are acceptable -- a float of size 1cm by 1 
> x-height, which doesn't put marks on the physical page.
>
> How can I do this better?  Better yet, how can I do this properly?

the placeholder can be set up quite easily: 

\starttext

\definefloat[logospacer][logospacer]
\setupfloat[logospacer][default={right,none},width=1mm,height=1mm,empty=yes]

\placelogospacer{}{}

\input ward

\stoptext

As you can see, we also can set the default placement. The 'empty=yes' is not documented (since it is not that old -) 

An alternative would have been 

\startsetups placeholder

  \placefigure[right,none]{}{\framed[width=1mm,height=1mm,frame=off]{}}

\stopsteups

..... \setups[placeholder] ....  

framed boxes without frames are quite handy 

Hans 

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