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Diffstat (limited to 'doc/context/sources/general/manuals/bidi/bidi.tex')
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1 files changed, 20 insertions, 498 deletions
diff --git a/doc/context/sources/general/manuals/bidi/bidi.tex b/doc/context/sources/general/manuals/bidi/bidi.tex index fb3705a37..c6fedacdf 100644 --- a/doc/context/sources/general/manuals/bidi/bidi.tex +++ b/doc/context/sources/general/manuals/bidi/bidi.tex @@ -1,506 +1,28 @@ -% language=uk +% Because we cross a threshold in the amount of content the sources +% have been split into components. This is typical a manual that +% grows. Feel free to send suggestions and improvements. -% \showglyphs +\environment bidi-style -\usemodule[abr-04] +\startdocument -\dontcomplain + \component bidi-titlepage -\startbuffer[preamble-fonts] -\definefontfallback - [Serif] [scheherazaderegular*arabic] - [arabic] [force=yes,rscale=1.5] -\definefontfallback - [SerifBold] [scheherazadebold*arabic] - [arabic] [force=yes,rscale=1.5] -\definefontfallback - [SerifItalic] [scheherazaderegular*arabic] - [arabic] [force=yes,rscale=1.5] -\definefontfallback - [SerifBoldItalic] [scheherazadebold*arabic] - [arabic] [force=yes,rscale=1.5] + \startfrontmatter + \component bidi-contents + \component bidi-introduction + \stopfrontmatter -\definefontfallback - [Serif] [sileot*hebrew] - [hebrew] [force=yes] -\definefontfallback - [SerifBold] [sileot*hebrew] - [hebrew] [force=yes] -\definefontfallback - [SerifItalic] [sileot*hebrew] - [hebrew] [force=yes] -\definefontfallback - [SerifBoldItalic] [sileot*hebrew] - [hebrew] [force=yes] + \startbodymatter + \component bidi-fonts + \component bidi-mixed + \component bidi-numbering -\definefontfallback - [Mono] [almfixed*none] - [arabic] [force=yes] + % work in progress / dev: + \component bidi-tables -\definefontfallback - [Mono] [sileot*none] - [hebrew] [force=yes,factor=1] % factor forces a monospace + \component bidi-lua + \component bidi-vertical + \stopbodymatter -\setupbodyfont - [dejavu,10pt] -\stopbuffer - -\startbuffer[preamble-languages] -\setuplanguage[ar][font=arabic,bidi=right] -\setuplanguage[he][font=hebrew,bidi=right] -\stopbuffer - -\getbuffer[preamble-fonts] -\getbuffer[preamble-languages] - -\setuplayout - [backspace=15mm, - topspace=15mm, - footer=0pt, - width=middle, - height=middle] - -\setuptyping - [color=middleblue] - -\setuptype - [color=middleblue] - -\definecolor - [maincolor] - [middleblue] - -\setupwhitespace - [big] - -\setuphead - [color=darkyellow] - -\setuphead - [chapter] - [style=\bfc] - -\setuphead - [section] - [style=\bfb] - -\setuphead - [subsection] - [style=\bfa] - -%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% - -\startluacode - local report = logs.reporter("directions","check") - local line = 0 - function nodes.tracers.checkdirections(head) - line = line + 1 - report("line: %i",line) - for n in nodes.traverse_id(nodes.nodecodes.dir,head) do - report(" %s (%i,%i)",n.dir,n.subtype,n.direction) - end - return head, false - end - - nodes.tasks.appendaction("contributers","after","nodes.tracers.checkdirections") - nodes.tasks.disableaction("contributers","nodes.tracers.checkdirections") -\stopluacode - -\installtextracker - {directions.check} - {\ctxlua{nodes.tasks.enableaction("contributers","nodes.tracers.checkdirections")}} - {\ctxlua{nodes.tasks.disableaction("contributers","nodes.tracers.checkdirections")}} - -% \enabletrackers[directions.check] -% \disabletrackers[directions.check] - -%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% - -\starttext - -\startMPpage - - picture p, q, r, s ; - - p := textext("l2r") xsized .9PaperWidth ; - q := textext("r2l") xsized .9PaperWidth ; - r := textext("a few tips") xsized .9PaperWidth ; - s := textext("\bf\ss hans\quad\space\quad hagen") xsized .5bbheight(p); - - p := p shifted - llcorner p ; - q := q shifted - llcorner q ; - r := r shifted - llcorner r ; - s := s shifted - llcorner s ; - - fill Page withcolor "darkyellow" ; - - p := p shifted (.05PaperWidth,ypart .5[ulcorner Page, urcorner Page]-1.1bbheight(p)) ; - q := q shifted (.05PaperWidth,ypart .5[ulcorner Page, urcorner Page]-1.1bbheight(p)-1.15bbheight(q)) ; - r := r shifted (.05PaperWidth,ypart .5[llcorner Page, lrcorner Page]+0.3bbheight(r)) ; - s := s shifted (.66PaperWidth,ypart .5[llcorner Page, lrcorner Page]+1.5bbheight(s)) ; - - draw p withcolor "lightgray" ; - draw q withcolor "lightgray" ; - draw r withcolor "middleblue" ; - draw s withcolor "lightgray" ; - -\stopMPpage - -\startchapter[title=Introduction] - -With \CONTEXT\ you can typeset in two directions: from left to right and from -right to left. In fact you can also combine these two directions, like this: - -\startbuffer -There are many {\righttoleft \maincolor \it scripts in use} and some run into the -other direction. However, there is {\righttoleft \maincolor \it no fixed relation -{\lefttoright \black \it between the} direction of the script} and cars being -driven left or right of the road. -\stopbuffer - -\typebuffer - -\getbuffer - -Even someone not familiar with right to left typesetting can see what happens -here, or not? In fact Luigi Scarso pointed out that the \type {fixed} reversed -into {\righttoleft \type {fixed}} but not in the example where {\bf fixed} -becomes {\righttoleft \bf fixed}. This signals an important property of the way -the text gets processed: you input something, at some points font features get -applied (like ligatures) and in the end the resulting glyph stream is reversed. -By that time the combination of {\bf f}+{\bf i} has become {\bf fi}! So, be -prepared for surprises. - -This manual is written by a left to right user so don't expect a manual on -semitic typesetting. Also don't expect a (yet) complete manual. I'll add whatever -comes to mind. This is not a manual about Hebrew or Arabic, if only because I -can't read any of those scripts (languages). I leave that to others to cover. - -{\em This is work in progress! So expect errors and typos.} - -\startlines -Hans Hagen -Hasselt, NL -\stoplines - -\stopchapter - -\startchapter[title={Setting up fonts}] - -So let's see how Arabic and Hebrew come out: - -\startbuffer -The sentence \quotation {I have no clue what this means.} is translated (by -Google Translate) into \quotation {\ar \righttoleft ليس لدي أي فكرة عما يعنيه هذا.} -which is then translated back to \quotation {I have no idea what this means.} so -maybe arabic has no clue what a clue is. The suggested Arabic pronunciation is -\quotation {lays laday 'ayu fikrat eamaa yaenih hadha}. Hebrew also likes ideas -more: \quotation {\he \righttoleft אין לי מושג מה זה אומר}. -\stopbuffer - -\typebuffer - -\getbuffer - -According to Idris Hamid the Arabic should actually be this: \quotation {\ar -لَيْسَ لَدَيَّ أَيُّ فِكْرَةٍ عَمَّا يَعْنِيهِ هٰذَا} and the transliteration \quotation {Laysa -ladayya ayyu fikratin ʿammā yaʿnihi hādhā}. - -The \CONTEXT\ (or any \TEX) ecosystem deals with languages and fonts. Languages -(that relate to scripts) have specific characteristics, like running from right -to left, and fonts provide a repertoire of glyphs and features. There is no real -(standard) relationship between these. In for instance browsers, there are -automatic fallback systems for missing characters in a font: another font is -taken. These fallbacks are often not easy to tweak. - -In this document we use Dejavu and although that font has Arabic shapes in its -monospace variant, the serifs come without them (at least when I write this -down). Before we actually define the bodyfont we hook in some fallbacks. The -typescript for Dejavu has lines like this: - -\starttyping -\definefontsynonym - [SerifBoldItalic] - [name:dejavuserifbolditalic] - [features=default, - fallbacks=SerifBoldItalic] -\stoptyping - -This permits us to do this: - -\typebuffer[preamble-fonts] - -In addition we set up the languages: - -\typebuffer[preamble-languages] - -The following example demonstrates what the effects of these commands are: - -\startbuffer -{لَيْسَ لَدَيَّ أَيُّ فِكْرَةٍ عَمَّا يَعْنِيهِ هٰذَا.} -{אין לי מושג מה זה אומר.} -{\righttoleft لَيْسَ لَدَيَّ أَيُّ فِكْرَةٍ عَمَّا يَعْنِيهِ هٰذَا.} -{\righttoleft אין לי מושג מה זה אומר.} -{\ar \righttoleft لَيْسَ لَدَيَّ أَيُّ فِكْرَةٍ عَمَّا يَعْنِيهِ هٰذَا.} -{\he \righttoleft אין לי מושג מה זה אומר.} -{\ar لَيْسَ لَدَيَّ أَيُّ فِكْرَةٍ عَمَّا يَعْنِيهِ هٰذَا.} -{\he אין לי מושג מה זה אומר.} -\stopbuffer - -\typebuffer - -\startlines -\getbuffer -\stoplines - -In principle you can also rely on automatic direction changes, for instance -by using the following command: - -\starttyping -\setupdirections - [bidi=global, - method=three] -\stoptyping - -But that doesn't do a font switch for you, nor does it do any of the other -language related settings. It really helps if you properly tag your -document content, as in: - -\starttyping -{\ar لَيْسَ لَدَيَّ أَيُّ فِكْرَةٍ عَمَّا يَعْنِيهِ هٰذَا.} -{\he אין לי מושג מה זה אומר.} -\stoptyping - -One reason to set the \type {font} parameter for a language is that it will -activate the right features in a font. Instead of falling back on some default, -we can be very specific in what we want to enable. - -\stopchapter - -\startchapter[title=A mixed layout] - -The typesetting engine normally works from left to right and top to bottom. Going -from right to left actually involved two decisions: - -\startitemize[packed] -\startitem the direction of the display elements, the paragraphs \stopitem -\startitem the direction of the inline text, the lines \stopitem -\stopitemize - -The first one is kept track of in a state variable. Every paragraph starts with -a node that carries, among other information, that state. This node is added -automatically and does not interfere with the typesetting. The inline direction -is more intrusive as it is marked by nodes that indicate the beginning and end -of a reversed strip. This mechanism is rather reliable and normally works out -well. Take this: - -\startbuffer -left {\righttoleft right} left -left{ \righttoleft right} left -left {\righttoleft right }left -left{ \righttoleft right }left -\stopbuffer - -\typebuffer - -You can see that we need to be careful with spaces as they can end up inside or -outside a substream and by swapping next to each other: - -\startlines -\getbuffer -\stoplines - -We can wrap the lines in boxes as in: - -\startbuffer -\hbox{left\space{\bf\righttoleft right}\space left} -\hbox{left{\bf\space \righttoleft right}\space left} -\hbox{left\space{\bf\righttoleft right\space}left} -\hbox{left{\bf\space\righttoleft right\space}left} -\stopbuffer - -\typebuffer - -\definecolor[ShineThrough][s=0,a=1,t=.2] - -When visualize the spaces we get this: - -\startlines\ShineThrough -\showmakeup[space,hbox]\getbuffer -\stoplines - -The space of a normal and bold font in the same family normally is the same but -let's mix with a larger size: - -\startbuffer -\hbox{left {\bfa\righttoleft right} left} -\hbox{left{\bfa\space \righttoleft right} left} -\hbox{left {\bfa\righttoleft right }left} -\hbox{left{\bfa\space\righttoleft right }left} -\stopbuffer - -\typebuffer - -Now we get the following. As you can see, it really matters where we put the -braces. - -\startlines -\ShineThrough\showmakeup[space,hbox]\getbuffer -\stoplines - -Once you are accustomed to tagging and \TEX\ you will probably not fall into -these traps. In \in {figure} [fig:spaces] we show a large version. - -\startplacefigure[location=top,title={Watch your spaces!},reference=fig:spaces] - \scale - [width=\hsize] - {\vbox{\ShineThrough\showmakeup[space,hbox]\getbuffer}} -\stopplacefigure - - -The \type {\righttoleft} command actually has two meanings. This can best be seen -from an example. - -\startbuffer -\righttoleft \bf How will this come out? -\stopbuffer - -\typebuffer - -\start \getbuffer \par \stop - -\startbuffer -And \righttoleft \bf how will this come out? -\stopbuffer - -\typebuffer - -\start \getbuffer \par \stop - -When we start a paragraph (or in \TEX\ speak: when we are still in vertical mode) -the paragraph direction as well as the inline direction is set. Otherwise only -the inline direction is set. There are low level \TEX\ commands (primitives) to -set the direction but you can best {\em not} use these because we need to do a -bit more than that. - -There are quite some low level commands related to changing directions. Some deal -with the layout, some with boxes. We might provide more in the future. - -\starttabulate[|l|p|] -\FL -\NC \type {\lefttoright} \NC l2r dir node or paragraph property \NC \NR -\NC \type {\righttoleft} \NC r2l dir node or paragraph property \NC \NR -\NC \type {\checkedlefttoright} \NC l2r dir node or paragraph property (unless already set) \NC \NR -\NC \type {\checkedrighttoleft} \NC r2l dir node or paragraph property (unless already set) \NC \NR -\ML -\NC \type {\synchronizeinlinedirection} \NC pickup a (possibly) reset state \NC \NR -\NC \type {\synchronizelayoutdirection} \NC pickup a (possibly) reset state \NC \NR -\NC \type {\synchronizedisplaydirection} \NC pickup a (possibly) reset state \NC \NR -\ML -\NC \type {\righttolefthbox} \NC r2l \type {\hbox} \NC \NR -\NC \type {\lefttorighthbox} \NC l2r \type {\hbox} \NC \NR -\NC \type {\righttoleftvbox} \NC r2l \type {\vbox} \NC \NR -\NC \type {\lefttorightvbox} \NC l2r \type {\vbox} \NC \NR -\NC \type {\righttoleftvtop} \NC r2l \type {\vtop} \NC \NR -\NC \type {\lefttorightvtop} \NC l2r \type {\vtop} \NC \NR -\ML -\NC \type {\leftorrighthbox} \NC l2r or r2l \type {\hbox} \NC \NR -\NC \type {\leftorrightvbox} \NC l2r or r2l \type {\vbox} \NC \NR -\NC \type {\leftorrightvtop} \NC l2r or r2l \type {\vtop} \NC \NR -\ML -\NC \type {\autodirhbox} \NC l2r or r2l \type {\hbox} (a bit more clever) \NC \NR -\NC \type {\autodirvbox} \NC l2r or r2l \type {\vbox} (a bit more clever) \NC \NR -\NC \type {\autodirvtop} \NC l2r or r2l \type {\vtop} (a bit more clever) \NC \NR -\ML -\NC \type {\bidilre} \NC character \type {U+202A}, enforce l2r state \NC \NR -\NC \type {\bidirle} \NC character \type {U+202B}, enforce r2l state \NC \NR -\NC \type {\bidipop} \NC character \type {U+202C}, return to last state \NC \NR -\NC \type {\bidilro} \NC character \type {U+202D}, override l2r state \NC \NR -\NC \type {\bidirlo} \NC character \type {U+202E}, override r2l state \NC \NR -\NC \type {\lefttorightmark} \type {\lrm} \NC character \type {U+200E}, l2r indicator \NC \NR -\NC \type {\righttoleftmark} \type {\rlm} \NC character \type {U+200F}, r2l indicator \NC \NR -\ML -\NC \type {\dirlre} \NC switch to l2r mode using \type {\bidilre} or \lefttoright \NC \NR -\NC \type {\dirrle} \NC switch to r2l mode using \type {\bidirle} or \righttoleft \NC \NR -\NC \type {\dirlro} \NC enforce l2r mode using \type {\bidilro} or \lefttoright \NC \NR -\NC \type {\dirrlo} \NC enforce r2l mode using \type {\bidirlo} or \righttoleft \NC \NR -\ML -\NC \type {\naturalhbox} \NC a normal l2r \type {hbox} \NC \NR -\NC \type {\naturalvbox} \NC a normal l2r \type {vbox} \NC \NR -\NC \type {\naturalvtop} \NC a normal l2r \type {vtop} \NC \NR -\NC \type {\naturalhpack} \NC a normal l2r \type {hpack} \NC \NR -\NC \type {\naturalvpack} \NC a normal l2r \type {vpack} \NC \NR -\LL -\stoptabulate - -When we talk about layout, we mean the overall layout, concerning the document as -a whole. We can have a dominantly l2r, dominantly r2l or mixed setup. In a next -chapter we will give more details on the dominant setup. Here we stick to -mentioning that the document flow direction is set with - -\starttyping -\setupalign[r2l] % or r2l -\stoptyping - -When a command to setup an environment has a \type {align} parameter, the same -keywords can be uses as part of the specification. \footnote {We haven't tested -all situations and possible interferences. Just report anomalies to the mailing -list.} - -\stopchapter - -\startchapter[title={Numbering and positioning}] - -todo: columns (direction key), numbers (conversionsets), margins (begin/end), etc - -\stopchapter - -\startchapter[title={The \LUA\ interface}] - -We assume that you run \CONTEXT\ \MKIV\ in combination with \LUATEX. Direction -support in this engine has been improved over time. Originally the \OMEGA\ -(\ALEPH) direction model was used but in the meantime it has been stripped to the -basics, and what used to be so called whatsits (extension nodes) are now first -class nodes. Of the many directions only four are kept in \LUATEX\ and they are -indicated by three letters: - -\starttabulate[|l|l|l|] -\NC 0 \NC \type {TLT} \NC left to right \NC \NR -\NC 1 \NC \type {TRT} \NC right to left \NC \NR -\NC 2 \NC \type {LTL} \NC not used in context (obsolete) \NC \NR -\NC 3 \NC \type {RTT} \NC not used in context (obsolete) \NC \NR -\stoptabulate - -In \LUAMETATEX, and therefore \CONTEXT\ \LMTX\ we only have the first two. -Therefore in \LMTX\ you normally don't have to worry about checking for them at -the \LUA\ end because they are irrelevant for calculations (the vertical ones -swapped the horizontal and vertical progression). Also, when really needed, we -use the \type {direction} keys with numerical indicators, so zero for \type {l2r} -and one for \type {r2l}. These values are used for local par nodes as well as -direction nodes. In addition a direction node has a subtype: - -\starttabulate[|l|l|l|] -\NC 0 \NC \type {normal} \NC comparable to \type {+} \NC \NR -\NC 1 \NC \type {cancel} \NC comparable to \type {-} \NC \NR -\stoptabulate - -\stopchapter - -\startchapter[title={Going vertical}] - -Normally the term bidi is reserved for horizontal direction swapping but there is -no reason to limit our view to that. So, here I will spend some words on how we -can deal with vertical directions. - -{\em I will move some (not yet public) explanation from elsewhere to here in due -time.} - -\stopchapter - -\stoptext - -% \defineconversionset [\s!default] [] [numbers] -% \defineconversionset [\v!number] [] [numbers] -% \defineconversionset [\v!pagenumber] [] [numbers] -% \defineconversionset [\v!appendix:\s!default] [Romannumerals,Characters] [numbers] -% \defineconversionset [\v!formula] [numbers,characters] % no \v! ? +\stopdocument |