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diff --git a/doc/context/sources/general/manuals/bidi/bidi.tex b/doc/context/sources/general/manuals/bidi/bidi.tex new file mode 100644 index 000000000..abd3f64fa --- /dev/null +++ b/doc/context/sources/general/manuals/bidi/bidi.tex @@ -0,0 +1,505 @@ +% language=uk + +% \showglyphs + +\usemodule[abr-04] + +\dontcomplain + +\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] + +\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] + +\definefontfallback + [Mono] [almfixed*none] + [arabic] [force=yes] + +\definefontfallback + [Mono] [sileot*none] + [hebrew] [force=yes,factor=1] % factor forces a monospace + +\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. In the \LUA\ interface we still support the: + +\startitemize[packed] +\startitem + \type {TLT} and \type {TRT} keywords for local par nodes +\stopitem +\startitem + \type {+TLT}, \type {-TLT}, \type {+TRT} and \type {-TRT} keywords for + direction nodes +\stopitem +\stopitemize + +However, because we use dedicated nodes, and because nodes actually store numbers +and not strings we also expose the numeric model: + +\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 \NC \NR +\NC 3 \NC \type {RTT} \NC not used in context \NC \NR +\stoptabulate + +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 + +The \type {dir} field uses the strings, the \type {direction} field the number +(both of course share the same internal node variable). + +\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! ? |