Re: a proper whiteout function

[Alexander Kobel]

On 04/29/2015 03:03 PM, Kieren MacMillan wrote:
> Hi Francisco,
>
> > To achieve a whiteout that is useful for music, I think a thick
> > default 'middle' stroke in white on a lower layer would work.
> > See example.
>
> YES! This is exactly the kind of thing I’m hoping for.

+1.

> Do you think this “function” (bad choice of words here, I know) could be made 
> to handle arbitrary [music] grobs, or would one always have to manually work 
> through all 4 (?) steps of the process for each grob?

I guess Francisco's example was handmade in Inkscape or similar 
software, but it should be possible to automize it.
AFAIK, all output from Lilypond is laid out in Postscript first, which 
offers support for these operations (at least for text) - see the 
attached example and, e.g., the following page.
  http://paulbourke.net/dataformats/postscript/
The Postscript code for this is as follows:

%!PS-Adobe-3.0
/Times-Bold findfont 30 scalefont setfont

100 400 moveto
(Hello World!)
true charpath
5 setlinewidth
0.5 setgray
stroke

100 400 moveto
(Hello World!)
0 setgray
show

showpage

The main idea is to typeset the object/path/glyph/grob, you name it, 
twice: once in white, non-filled, with thick stroke, and once in the 
actual color. IIUC, this could be achieved by some stencil which is on 
top of the PS-output-stencil.
Unfortunately, I could not make it work with glyphshow, which is what is 
used for the embedded fonts (at least by Lilypond)...


Best,
Alexander

hello.ps
Description: PostScript document