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diff --git a/doc/context/sources/general/manuals/bidi/bidi-mixed.tex b/doc/context/sources/general/manuals/bidi/bidi-mixed.tex new file mode 100644 index 000000000..851d6d8b4 --- /dev/null +++ b/doc/context/sources/general/manuals/bidi/bidi-mixed.tex @@ -0,0 +1,178 @@ +% language=us + +\startcomponent bidi-mixed + +\environment bidi-style + +\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 + +\stopcomponent |