[NTG-context] how to simulate \hss in luametatex?

[黄复雄]

Hans,
thank you.
By your and Max's answers, I understand that
there must be box.glueset for the glues in the box.list to actually work.

Best regards

Huang Fusyong(黄复雄)

Hans Hagen via ntg-context <ntg-context at ntg.nl> 于2022年11月11日周五 18:52写道：
>
> On 11/11/2022 10:53 AM, Max Chernoff via ntg-context wrote:
> > Hi,
> >
> >> I want to  simulate \hss  in lua end in ConTeXt/luametatex environment.
> >> For example,
> >>
> >> ```ConTeXt
> >> a{\raise 1.5ex\hbox to 0pt{\hss b}}c
> >> ```
> >
> >> And in lua, I do as follows(part of my app seen in attachment):
> >
> > Your code doesn't compile as is. I think that this is the same thing
> > though:
> >
> >     \starttext
> >     \startluacode
> >     local a = node.new"glyph"
> >     a.char = string.byte("a")
> >     a.font = font.current()
> >
> >     local b = node.new"glyph"
> >     b.char = string.byte("b")
> >     b.font = font.current()
> >
> >     local c = node.new"glyph"
> >     c.char = string.byte("c")
> >     c.font = font.current()
> >
> >     local hss = node.new("glue")
> >     hss.stretch = 65536
> >     hss.stretchorder = 2
> >     hss.shrink = 65536
> >     hss.shrinkorder = 2
> >     hss.width = 0
> >     b = node.insertbefore(b, b, hss)
> >
> >     local box = node.new("hlist", "box")
> >     box.head = b
> >     box.width = 0
> >     box.shift = -tex.sp("1ex")
> >
> >     tex.forcehmode()
> >     node.write(a + box + c)
> >     \stopluacode
> >     \stoptext
> >
> >> And got 'b' on top of 'c' in pdf as follows:
> >>
> >> ```pdf
> >>    b
> >> ac
> >> ```
> >
> > The \hss isn't the problem here. The problem is actually with the box.
> > When you manually make the \hbox like that, I think (although I could be
> > wrong) that you're bypassing all of TeX's glue calculations. You should
> > probably use "node.hpack" instead:
> >
> >     \starttext
> >     \startluacode
> >     local a = node.new"glyph"
> >     a.char = string.byte("a")
> >     a.font = font.current()
> >
> >     local b = node.new"glyph"
> >     b.char = string.byte("b")
> >     b.font = font.current()
> >
> >     local c = node.new"glyph"
> >     c.char = string.byte("c")
> >     c.font = font.current()
> >
> >     local hss = node.new("glue")
> >     hss.stretch = 65536
> >     hss.stretchorder = 2
> >     hss.shrink = 65536
> >     hss.shrinkorder = 2
> >     hss.width = 0
> >
> >     local box = node.hpack(hss + b, "exactly", 0)
> >     box.shift = -tex.sp("1ex")
> >
> >     tex.forcehmode()
> >     a.next = box
> >     box.next = c
> >     node.write(a)
> >     \stopluacode
> >     \stoptext
> indeed, an dafter that you can check it
>
>   box.glueorder  : 2
>   box.glueset    : 6.6683349609375
>   box.gluesign   : 2
>
> which will be applied (in the backend) to glues
>
> Hans
>
> -----------------------------------------------------------------
>                                            Hans Hagen | PRAGMA ADE
>                Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>         tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
> -----------------------------------------------------------------
>
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
>
> maillist : ntg-context at ntg.nl / https://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : https://www.pragma-ade.nl / http://context.aanhet.net
> archive  : https://bitbucket.org/phg/context-mirror/commits/
> wiki     : https://contextgarden.net
> ___________________________________________________________________________________