Thanks Taco,
I made some progress :
https://wiki.contextgarden.net/Talk:Cover_Pages
I now have two additional questions ... ;-)
- How can I deal with "space" characters (because current solution
requires to explicitly add the ~ character)
- What would be the work to do in order to make this mechanism directly
usable in metapost / metafun, within \startMPpage \stopMPpage,
- to avoid switching between \start\stopMPdrawing and TeX
- to have something like "draw followtext" in mp-blob.mpiv ?
%------------------------------------------------------------------------------
\setuppapersize [A4]
%------------------------------------------------------------------------------
\def\MyFont{\definedfont[name:%
texgyrepagellabold%
%exo2black%
%agaramondprobold%
*default at 55pt]}
%------------------------------------------------------------------------------
\startluacode
function document.outlinepaths(character)
local chardata = fonts.hashes.characters[true] -- by unicode
local shapedata = fonts.hashes.shapes[true] -- by index
local c = chardata[character]
if c and c.index and shapedata then
local shapeglyphs = shapedata.glyphs or { }
local glyph = shapeglyphs[c.index]
if glyph and (glyph.segments or glyph.sequence) then
local units = shapedata.units or 1000
local factor = 100/units
return fonts.metapost.paths(glyph,factor)
end
end
return { }
end
function document.defineoutline(char,target)
local outlines = document.outlinepaths(char)
local nofpaths = #outlines
context("\\startMPdrawing") -- ADDED by
garulfo
context("path %s[] ;",target)
context("numeric %sn ; %sn := %s ;",target,target,nofpaths)
for i=1,nofpaths do
context("%s[%i] := %s ; ",target,i,outlines[i])
end
context("\\stopMPdrawing") -- ADDED by
garulfo
end
\stopluacode
%------------------------------------------------------------------------------
\def\mpdefineoutlines#1#2{\ctxlua{document.defineoutline(\number`#1,"#2")}}
%------------------------------------------------------------------------------
\def\EmptyLetters#1%
{%
\resetMPdrawing
\MPtoks={}
%
\startMPdrawing
picture pic[], pictA ;
numeric wid[], len[], pos[], n ;
wid[0] := len[0] := pos[0] := n := 0 ;
numeric scaling;
path pictB , frame ;
pair shiftB ;
picture monImageA; monImageA := nullpicture;
picture monImageB; monImageB := nullpicture;
color colorframe; colorframe := 0.6white;
%
\stopMPdrawing
%
\MyFont\handletokens#1\with\whatever
%
\startMPdrawing
frame := unitsquare
xscaled ( (xpart urcorner monImageB - xpart llcorner
monImageB) + 5mm )
yscaled ( (ypart urcorner monImageB - ypart llcorner
monImageB) + 5mm );
frame := frame shifted (center monImageB - center frame);
addto monImageB contour
frame
withpostscript "evenodd"
withcolor transparent (1,1.,colorframe);
draw monImageB ;
draw monImageA ;
\stopMPdrawing
%
\MPdrawingdonetrue
\getMPdrawing}
%------------------------------------------------------------------------------
\def\whatever#1%
{\appendtoks#1\to\MPtoks
\setbox\MPbox=\hbox{\MyFont\the\MPtoks}%
%
\startMPdrawing
n := n + 1 ; len[n] := \the\wd\MPbox ;
\stopMPdrawing
%
\mpdefineoutlines{M}{MaLettre}
%
\startMPdrawing
pictA := textext.drt("\MyFont M") ;
pictB := MaLettre[1];
scaling := bbheight pictA / bbheight pictB;
\stopMPdrawing
%
\doifinstringelse{~}{#1}{}{% HOW TO PROPERLY COPE
WITH SPACES ?
\mpdefineoutlines{#1}{MyGlyph}
%
\startMPdrawing
string sb; sb := "i";
pic[n] := textext.drt("\MyFont\setstrut\strut#1") ;
%
shiftB := - llcorner pic[n];
pic[n] := pic[n] shifted shiftB ;
%
wid[n] := abs(xpart urcorner pic[n] - xpart llcorner pic[n]) ;
pos[n] := len[n]-wid[n] ;
%
addto monImageB contour
((MyGlyph[1] scaled scaling)
shifted ( (pos[n],0) + shiftB))
withpostscript "collect";
%
if MyGlyphn > 1 :
for ind=2 upto MyGlyphn :
if (((xpart llcorner MyGlyph[ind]) > (xpart llcorner
MyGlyph[1])) and
((ypart llcorner MyGlyph[ind]) > (ypart llcorner
MyGlyph[1])) and
((xpart urcorner MyGlyph[ind]) < (xpart urcorner
MyGlyph[1])) and
((ypart urcorner MyGlyph[ind]) < (ypart urcorner
MyGlyph[1]))) :
%
addto monImageA contour
(MyGlyph[ind] scaled scaling)
shifted ( (pos[n],0) + shiftB)
withcolor transparent (1,1.,colorframe);
else :
addto monImageB contour
(MyGlyph[ind] scaled scaling)
shifted ( (pos[n],0) + shiftB)
withpostscript "collect";
fi;
endfor;
fi;
\stopMPdrawing}}
%==============================================================================
%==============================================================================
\starttext
%------------------------------------------------------------------------------
\startuseMPgraphic{MyBackgroundGraphic}
path pathbackground ;
numeric dimA ; dimA := \the\paperwidth;
numeric dimB ; dimB := \the\paperheight;
pathbackground := unitsquare xscaled dimA yscaled dimB ;
fill pathbackground
withshademethod "linear"
withshadedirection(0,1)
withshadecolors (red,blue);
\stopuseMPgraphic
%------------------------------------------------------------------------------
\definelayer[MyBackgroundLayer]
\setlayer[MyBackgroundLayer]{\useMPgraphic{MyBackgroundGraphic}}
\setupbackgrounds[page][background={MyBackgroundLayer}]
%------------------------------------------------------------------------------
\EmptyLetters{MetaPost~is~fun!}
\EmptyLetters{ABCDEFGHIJ}
\EmptyLetters{KLMNOPQRST}
\EmptyLetters{UVWXYZ!?\&*}
\EmptyLetters{abcdefghij}
\EmptyLetters{klmnopqrst}
\EmptyLetters{uvwxyz<>;:@}
\EmptyLetters{0123456789}
%------------------------------------------------------------------------------
\stoptext
Le 21/12/2020 à 16:29, Taco Hoekwater a écrit :
On 21 Dec 2020, at 16:09, Garulfo <garu...@azules.eu> wrote:
Hi,
* I try to "remove the paths of text" from a metapost pictures to let
the background visible.
* Using
https://mailman.ntg.nl/pipermail/ntg-context/2018/thread.html#92725
* I was able to get the following with one glyph (MVE code below)
https://wiki.contextgarden.net/images/d/d2/test_extract_glyphs.pdf
2 questions:
1/ for some fonts (e.g. dejavu vs latin modern) the "encompassing" path
of the B glyph can switch from B[1] to B[Bn]. Is there a trick to
identify which id match with "the encompassing" path ?
What you get is the order of the paths as defined in the font, which is
arbitrary, as you discovered.
A quick trick (that will not always work, but should work quite well for font
variations of alphabetics) is to check the actual arclength of the paths. The
longest one will typically be the outer one.
But much depends on the font, so a generic solution is likely quite
complicated. Consider an outline font’s colon glyph ;)
2/ now, I would like to do the same, but for text... a kind of
derivative of "textext" or "outlinetext".
Would you please give me some guidelines ?
does it already exist ?
should I use something like \handletokens, \scantokens ?
do you have examples where I can get inspiration ?
Thanks again for your help,
Garulfo
%==============================================================================
\starttext
%------------------------------------------------------------------------------
\startluacode
function document.outlinepaths(character)
local chardata = fonts.hashes.characters[true] -- by unicode
local shapedata = fonts.hashes.shapes[true] -- by index
local c = chardata[character]
if c and c.index and shapedata then
local shapeglyphs = shapedata.glyphs or { }
local glyph = shapeglyphs[c.index]
if glyph and (glyph.segments or glyph.sequence) then
local units = shapedata.units or 1000
local factor = 100/units
return fonts.metapost.paths(glyph,factor)
end
end
return { }
end
function document.defineoutline(char,target)
local outlines = document.outlinepaths(char)
local nofpaths = #outlines
context("path %s[] ;",target)
context("numeric %sn ; %sn := %s ;",target,target,nofpaths)
for i=1,nofpaths do
context("%s[%i] := %s ; ",target,i,outlines[i])
end
end
\stopluacode
%------------------------------------------------------------------------------
\def\mpdefineoutlines#1#2{\ctxlua{document.defineoutline(\number`#1,"#2")}}
%------------------------------------------------------------------------------
\startMPpage
numeric dimA ; dimA := 20cm;
path pathbackground ;
pathbackground := unitsquare scaled dimA ;
fill pathbackground withshademethod "linear" withshadedirection(0,1)
withshadecolors (red,blue);
%--------------------------------------
\mpdefineoutlines{B}{B}
%--------------------------------------
numeric dimB ; dimB := 2cm;
numeric vratio ; vratio := 2;
path frame ;
frame := unitsquare
xscaled (dimA - 2 * dimB)
yscaled (dimA / vratio)
shifted (dimB , (dimA - (dimA / vratio))/2 );
%--------------------------------------
pair shift ; shift := center frame;
numeric scal ; scal := (0.9) * (10cm / (bbheight B[1])) ;
picture monImageB; monImageB := nullpicture;
addto monImageB contour
(B[1] shifted (- center B[1]) scaled scal)
shifted shift
withpostscript "collect";
addto monImageB contour
frame
withpostscript "evenodd";
for i=2 upto Bn :
addto monImageB contour
(B[i] shifted (- center B[1]) scaled scal)
shifted shift;
endfor ;
%--------------------------------------
draw monImageB withcolor white;
\stopMPpage
\stoptext
___________________________________________________________________________________
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
___________________________________________________________________________________
Taco Hoekwater
Elvenkind BV
___________________________________________________________________________________
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
___________________________________________________________________________________
___________________________________________________________________________________
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
___________________________________________________________________________________
