highlighting chars on a path

highlighting chars on a path

[Aurelien Giraud]

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Hello,

I am new to ConTeXt and I have looked on the internet for a way to do
something special. Unfortunately I have not found any solution.

I hope this is the right place for such a question. I apologise otherwise.

I would like to highlight (e.g. put in bold, or change the color...) any
character on a page which sits on a chosen path. I would like to be able to
position for instance an invisible circle on a page and have all the
characters "in contact" with this circle change color so that the circle
become visible via these characters. Is it something I could do with
ConTeXt?

Thanks in advance.

Aurelien

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Re: highlighting chars on a path

[luigi scarso]

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On Sun, Oct 18, 2009 at 9:11 PM, Aurelien Giraud <
aureliengiraud@googlemail.com> wrote:

> Hello,
>
> I am new to ConTeXt and I have looked on the internet for a way to do
> something special. Unfortunately I have not found any solution.
>
> I hope this is the right place for such a question. I apologise otherwise.
>
> I would like to highlight (e.g. put in bold, or change the color...) any
> character on a page which sits on a chosen path. I would like to be able to
> position for instance an invisible circle on a page and have all the
> characters "in contact" with this circle change color so that the circle
> become visible via these characters. Is it something I could do with
> ConTeXt?
>
> Thanks in advance.
>
> I think yes,but now  I have not time to try.
Something with metapost, maybe.
-- 
luigi

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___________________________________________________________________________________

Re: highlighting chars on a path

[Mojca Miklavec]

On Sun, Oct 18, 2009 at 21:11, Aurelien Giraud wrote:
> Hello,
>
> I am new to ConTeXt and I have looked on the internet for a way to do
> something special. Unfortunately I have not found any solution.
>
> I hope this is the right place for such a question. I apologise otherwise.
>
> I would like to highlight (e.g. put in bold, or change the color...) any
> character on a page which sits on a chosen path. I would like to be able to
> position for instance an invisible circle on a page and have all the
> characters "in contact" with this circle change color so that the circle
> become visible via these characters. Is it something I could do with
> ConTeXt?

This won't be of any help to you ...
... but I remember seeing one of early luatex showcases with
characters colored in the shape of circular wave (smoothly varying
color - really impressive), but I have no idea if that has ever been
published anywhere. (I'm writing this because I'm also interested to
see that masterpiece again.)

Mojca


I don't know how to do it, but I would bet that it is possible to
misuse luatex for it (before printing out a character you check its
position on page, do some basic math and output the desired color).
It's usually done by overwriting some lua function. Just a tiny
warning if you do get a solution from someone: LuaTeX might not be
absolutely stable in this respect yet, so you need to take in account
some slight possibility that the low level interface undergoes some
changes in future. In that case you might need to adapt your code
after a while. You should not worry about it now, it's just good to
keep it in mind.
___________________________________________________________________________________
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://tex.aanhet.net
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___________________________________________________________________________________

Re: highlighting chars on a path

[luigi scarso]

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On Mon, Oct 19, 2009 at 2:10 PM, Mojca Miklavec <
mojca.miklavec.lists@gmail.com> wrote:

> On Sun, Oct 18, 2009 at 21:11, Aurelien Giraud wrote:
> > Hello,
> >
> > I am new to ConTeXt and I have looked on the internet for a way to do
> > something special. Unfortunately I have not found any solution.
> >
> > I hope this is the right place for such a question. I apologise
> otherwise.
> >
> > I would like to highlight (e.g. put in bold, or change the color...) any
> > character on a page which sits on a chosen path. I would like to be able
> to
> > position for instance an invisible circle on a page and have all the
> > characters "in contact" with this circle change color so that the circle
> > become visible via these characters. Is it something I could do with
> > ConTeXt?
>
> If I remember well, there are in pdftex some primitives about (x,y)
positions of an object
in a page.
Maybe one can use these primitives to dissect a vbox
and analyze its nodelist to mark the glyph node that have x y such that

| (x-xc)^2 + (y-yc)^2 - r | ≤ 𝛜

where
(xc,yc) are the coordinate of the circle respect to the page
r >0 is the radius
𝛜 >0 is the tolerance

-- 
luigi

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___________________________________________________________________________________

Re: highlighting chars on a path

[Willi Egger]

Hi,

a possible approach could be "positional graphisc" please refer to  
the METAFUN manual p 139...

Willi
On Oct 19, 2009, at 10:33 AM, luigi scarso wrote:

>
>
> On Sun, Oct 18, 2009 at 9:11 PM, Aurelien Giraud  
> <aureliengiraud@googlemail.com> wrote:
> Hello,
>
> I am new to ConTeXt and I have looked on the internet for a way to  
> do something special. Unfortunately I have not found any solution.
>
> I hope this is the right place for such a question. I apologise  
> otherwise.
>
> I would like to highlight (e.g. put in bold, or change the  
> color...) any character on a page which sits on a chosen path. I  
> would like to be able to position for instance an invisible circle  
> on a page and have all the characters "in contact" with this circle  
> change color so that the circle become visible via these  
> characters. Is it something I could do with ConTeXt?
>
> Thanks in advance.
>
> I think yes,but now  I have not time to try.
> Something with metapost, maybe.
> -- 
> luigi
>
> ______________________________________________________________________ 
> _____________
> 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://tex.aanhet.net
> archive  : http://foundry.supelec.fr/projects/contextrev/
> wiki     : http://contextgarden.net
> ______________________________________________________________________ 
> _____________

___________________________________________________________________________________
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://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________