% interface=en engine=luatex language=uk % author : Hans Hagen % copyright : PRAGMA ADE & ConTeXt Development Team % license : Creative Commons Attribution ShareAlike 4.0 International % reference : pragma-ade.nl | contextgarden.net | texlive (related) distributions % origin : the ConTeXt distribution % % comment : Because this manual is distributed with TeX distributions it comes with a rather % liberal license. We try to adapt these documents to upgrades in the (sub)systems % that they describe. Using parts of the content otherwise can therefore conflict % with existing functionality and we cannot be held responsible for that. Many of % the manuals contain characteristic graphics and personal notes or examples that % make no sense when used out-of-context. % % comment : Some chapters might have been published in TugBoat, the NTG Maps, the ConTeXt % Group journal or otherwise. Thanks to the editors for corrections. Also thanks % to users for testing, feedback and corrections. \setupbodyfont [dejavu,10pt] \setuphead [section] [style=\bfb] \setupwhitespace [big] \setuplayout [header=15mm, topspace=15mm, footer=0mm, bottomspace=20mm, height=middle, backspace=20mm, cutspace=20mm, width=middle] \usemodule[x][setups-basics] \loadsetups[context-en] \loadsetups[i-linefiller] \startdocument \startMPpage StartPage ; linecap := butt ; fill Page withcolor .25[yellow/4,green/2] ; path p ; p := (ulcorner Page .. urcorner Page .. lrcorner Page) ; draw image ( for i=1/200 step 1/200 until 1 : draw p scaled i dashed dashpattern (on 4 randomized 2 off 4 randomized 2) ; endfor ; ) withcolor white ; draw anchored.urt( textext("\ss RULES") xsized .5PaperWidth, urcorner Page shifted(-15mm,-20mm) ) withcolor white ; draw anchored.urt( textext("\ss HANS HAGEN") xsized .5PaperWidth, lrcorner Page shifted(-15mm,40mm) ) withcolor white ; draw anchored.urt( textext("\ss A CONTEXT MKIV MANUAL") xsized .5PaperWidth, lrcorner Page shifted(-15mm,20mm) ) withcolor white ; setbounds currentpicture to Page ; StopPage ; \stopMPpage \startsubject[title=Introduction] This manual describes just one type of rules: those that somehow magically are bound to the typeset text. We will mention a few mechanisms that relate to this in the sense that they share some of the underlaying code and logic. The term \quotation {rules} should be interpreted liberally as we can kick in some \METAPOST\ which then can get us away from straight rules. This manual will not be that extensive, after all these mechanisms are not that complex to configure. \stopsubject \startsubject[title=Underlining and overstriking] Already in \CONTEXT\ \MKII\ we had underlining available but with some limitations. We could handle more than one word but at some point you hit the limits of the engine. The \MKIV\ implementation is more flexible. In fact you can underline a whole document (which was actually a request from a user). This feature was also used by a collegue who was experimenting with texts for dyslectic readers. This mechanism is generic in the sense that a framework is provided to define rules that run alongside text. Take this: \setupbars[foregroundcolor=darkyellow,color=darkred] \startbuffer \underbars {drawing \underbar{bars} under words is a typewriter leftover} \overstrikes {striking words makes them \overstrike {unreadable} but sometimes even \overbar {top lines} come into view.} \stopbuffer \typebuffer This shows up as: \getbuffer We can best explain what happens by looking at how these commands are defined: \starttyping \definebar[overbar] [method=1,dy=0.4, offset=1.8, continue=yes] \definebar[underbar] [method=1,dy=-0.4,offset=-0.3,continue=yes] \definebar[overstrike][method=0,dy=0.4, offset=0.5, continue=yes] \definebar [understrike] [method=0, offset=1.375, rulethickness=2.5, continue=yes, order=background] \definebar[overbars] [overbar] [continue=no] \definebar[underbars] [underbar] [continue=no] \definebar[overstrikes] [overstrike] [continue=no] \definebar[understrikes][understrike][continue=no] \stoptyping The formal definitions of the commands are show in \definition [definebar, setupbar]. \showdefinition{definebar} \showdefinition{setupbar} The \type {dy} parameter specifies the shift up or down. The offset defines how nested bars are shifted. The \type {method} determines centering of the bar: we set it to zero when we want an overstrike. The \type {continue} parameter is responsible for drawing over spaces and the \type {order} determines the layering. The units are either hard coded values like points or relate to the font at the spot of the bar. Here are some examples: \startbuffer \setupbars[unit=mm,rulethickness=1] bar \underbar{foo} bar\quad \setupbars[unit=ex,rulethickness=1] bar \underbar{foo} bar\quad \setupbars[unit=pt,rulethickness=1] bar \underbar{foo} bar\quad \setupbars[unit=pt,rulethickness=10pt] bar \underbar{foo} bar \stopbuffer \typebuffer \blank \start \getbuffer \stop \blank As if underlining wasn't already bad enough, of course at some point there came a request for dashed lines. \startbuffer test \underrandoms{test me} and \underrandom{test} or \underrandom{grep} test \underdashes {test me} and \underdash {test} or \underdash {grep} test \underdots {test me} and \underdot {test} or \underdot {grep} \stopbuffer \typebuffer The above variants are predefined and render as: \startlines \tfb \getbuffer \stoplines A graphic is defined as follows. It boils down to drawing one or more shapes. In this example we also force a specific boundingbox so that the result gets positioned right. \starttyping \startuseMPgraphic{rules:under:...} draw ((0,RuleDepth) -- (RuleWidth,RuleDepth)) shifted (0,RuleFactor*RuleOffset) withpen pencircle scaled RuleThickness withcolor RuleColor ; setbounds currentpicture to unitsquare xysized(RuleWidth,RuleHeight) ; \stopuseMPgraphic \stoptyping The following variables are available: \starttabulate[|T|||] \BC variable \BC type \BC meaning \NC \NR \ML \NC RuleDirection \NC string \NC the direction of the line \NC \NR \NC RuleOption \NC string \NC whatever the caller finds useful \NC \NR \NC RuleWidth \NC number \NC the requested width of the rule \NC \NR \NC RuleHeight \NC number \NC the requested height of the rule \NC \NR \NC RuleDepth \NC number \NC the requested depth of the rule \NC \NR \NC RuleThickness \NC number \NC the linewidth \NC \NR \NC RuleFactor \NC number \NC the set factor (e.g. an \type {ex}) \NC \NR \NC RuleOffset \NC number \NC an (optional) offset in case of nesting \NC \NR \NC RuleColor \NC color \NC the color \NC \NR \stoptabulate The \type {RuleFactor} can be used as multiplier for the \type {RuleOffset}. Later we will see an example of how to use the \type {RuleDirection} and \type {RuleOption}. The extra under commands are defined as follows. Watch the \type {mp} parameter: it refers to a graphic. \starttyping \definebar [undergraphic] [mp=rules:under:dash, offset=-.2, order=background] \definebar[underrandom] [undergraphic][mp=rules:under:random] \definebar[underrandoms][underrandom] [continue=yes] \definebar[underdash] [undergraphic][mp=rules:under:dash] \definebar[underdashes] [underdash] [continue=yes] \definebar[underdot] [undergraphic][mp=rules:under:dots] \definebar[underdots] [underdot] [continue=yes] \stoptyping A nasty side effect of the implementation is that because we look mostly at glyphs, optionally separated by glue or kern some text might get unseen and therefore not treated. \startbuffer \underbars{We see this \high{\tfxx ®} symbol \runninghbox to 1cm{\hss} often.} \underbar {We see this \high{\tfxx ®} symbol \runninghbox to 1cm{\hss} often.} \stopbuffer \typebuffer This gives: \startlines \getbuffer \stoplines A running box is seen as text. As you (probably) expect, a nested ornamental rule is supported as well: \startbuffer \underbars{We see this \high{\tfxx\underdot{®}} symbol \runninghbox to 1cm{\hss} often.} \underbar {We see this \high{\tfxx\underdot{®}} symbol \runninghbox to 1cm{\hss} often.} \stopbuffer \typebuffer This time we get (you might need a magnifier to see it): \startlines \getbuffer \stoplines \stopsubject \startsubject[title=Shifting] We mention shifting here because it shares code with the bars. There are two shifts defined but you can define more: \starttyping \defineshift [shiftup] [method=0, dy=-1, unit=ex, continue=yes, style=\txx] \defineshift [shiftdown] [method=1, dy=.3, unit=ex, continue=yes, style=\txx, color=] \stoptyping An example of using the commands defined this way is: \startbuffer Let's go \shiftup{up} and \shiftdown{down} a bit! \stopbuffer \typebuffer or: \inlinebuffer\ Here we just shift words but you can shift more than that although I haven't yet seen a useful example of that: \startbuffer We can \shiftup {\input{tufte}} whole paragraphs if we really want. \stopbuffer \typebuffer \getbuffer The formal definitions are given in \definition[defineshift, setupshift, startshift]. The \type {align} switch is there for directional (and testing) purposes and is normally not used (or even useful in a line). The \type {dy} is multiplied by the \type {factor} that itself can depend on the used font. \showdefinition{defineshift} \showdefinition{setupshift} \showdefinition{startshift} \stopsubject \startsubject[title=Fillers] The possibility of line fillers was mentioned by Mojca on the \CONTEXT\ mailing list and it's actually not that hard to implement them. The only need I ever had for it was to fill out lines on some legal form and that was actually just some fun challenge in \MKII\ times. The code got lost and never made it into \CONTEXT. This time it was added as a side effect of a thread at the tenth \CONTEXT\ meeting. The ideas is to fill the rest of a line with some kind of (ornamental) rule. I'm not sure what sense it makes, even in legal documents. If it is to prevent additions then one should wonder if additions at the end of a (kind of arbitrary) broken line is what we should be afraid of most. So, for now, let's consider it an educational feature. \startbuffer \definelinefiller [filler-1] [height=.75\exheight, distance=.25\emwidth, rulethickness=.25\exheight, textcolor=darkyellow, before=\blank, after=\blank, color=darkred] \startlinefiller[filler-1] \input ward \stoplinefiller \stopbuffer \typebuffer Here we define a filler. As you can see, a rule gets added at the end of a paragraph. \getbuffer \startbuffer \startalign[flushleft,broad] \startlinefiller[filler-1] \input ward \stoplinefiller \stopalign \stopbuffer This time we don't justify: \typebuffer Now more lines get a rule appended: \getbuffer Before we continue it must be noted that the environment creates a paragraph. If you don't want that you need to use \type {\setlinefiller} instead. Next we show a \type {middle} alignment: \startbuffer \startalign[middle] \startlinefiller[filler-1] \input ward \stoplinefiller \stopalign \stopbuffer \getbuffer \startbuffer \startalign[middle] \startnarrower \startlinefiller[filler-1] \input ward \stoplinefiller \stopnarrower \stopalign \stopbuffer Let's add another level of complexity, left- and right skips: \typebuffer Here we get: \getbuffer The lines stay within the narrower boundaries but you can extend them to the margins if you like: \startbuffer \startalign[middle] \startnarrower \startlinefiller[filler-1][scope=global] \input ward \stoplinefiller \stopnarrower \stopalign \stopbuffer \typebuffer This looks like: \getbuffer You can also use a \type {left} or \type {right} scope, as in: \startbuffer \startalign[middle] \startnarrower \startlinefiller[filler-1][scope=right] \input ward \stoplinefiller \stopnarrower \stopalign \stopbuffer \typebuffer Only the right rules extend into the margins. \getbuffer \startbuffer \startalign[middle] \startnarrower \startlinefiller[filler-1][scope=right,location=right] \input ward \stoplinefiller \stopnarrower \stopalign \stopbuffer You can get rid of the left rules: \typebuffer So: \getbuffer Of course these rules are somewhat boring so let's now kick in some \METAPOST. \startbuffer[mp] \setuplinefiller [filler-1] [mp=rules:filler:demo, %threshold=.25\emwidth, color=darkred] \startuseMPgraphic{rules:filler:demo} drawarrow if RuleDirection == "TRT" : reverse fi ((0,RuleHeight) -- (RuleWidth,RuleHeight)) withpen pencircle scaled RuleThickness withcolor if RuleOption == "left" : complemented fi RuleColor ; setbounds currentpicture to unitsquare xysized(RuleWidth,RuleHeight) ; \stopuseMPgraphic \stopbuffer \typebuffer[mp] \getbuffer[mp] The previous example now looks like: \getbuffer \startbuffer \startalign[middle,r2l] \startnarrower[4*middle] \startlinefiller[filler-1] [scope=global] \input ward \stoplinefiller \stopnarrower \stopalign \stopbuffer This time we also change the direction and we can let the \METAPOST\ graphic adapt to that by reverting the arrows. \typebuffer The direction \type {TRT} is \TEX\ speak for a right|-|to|-|left direction. We use a latin script example for convenience. \getbuffer \startbuffer[mp] \startuseMPgraphic{rules:filler:demo} drawarrow if RuleDirection == "TRT" : reverse fi if RuleOption == "right" : reverse fi ((0,RuleHeight) -- (RuleWidth,RuleHeight)) withpen pencircle scaled RuleThickness withcolor if RuleOption == "left" : complemented fi RuleColor ; setbounds currentpicture to unitsquare xysized(RuleWidth,RuleHeight) ; \stopuseMPgraphic \stopbuffer % \startbuffer % \startnarrower[4*middle] % \startlinefiller[filler-1] [scope=global,align=middle] % \parindent 100pt % \parfillskip 100pt % \input ward % \stoplinefiller % \stopnarrower % \stopbuffer \startbuffer \startnarrower[4*middle] \startlinefiller[filler-1] [scope=global,align={middle,r2l}] \parindent 100pt \parfillskip 100pt \input ward \stoplinefiller \stopnarrower \stopbuffer The next rendering shows what happens when we set \type {\parindent} and \type {\parfillskip} to an excessive have a \type {100pt}. \getbuffer[mp] \getbuffer Here we have adapted the graphic a bit: \starttyping if RuleDirection == "TRT" : reverse fi if RuleOption == "right" : reverse fi ((0,RuleHeight) -- (RuleWidth,RuleHeight)) \stoptyping \showdefinition{definelinefiller} \showdefinition{setuplinefiller} \stopsubject % \startsubject[title=Backgrounds] % \stopsubject \startsubject[title=User rules] Characters and rules are the only graphical elements that \TEX\ really knows about. Even if you see images in a document, you should realize that they are just blobs with dimensions and that the backend replaces such blobs by real images. The primitive operations for rules are \type {\hrule} and \type {\vrule} and the main difference is to what way they adapt to their situation when no dimensions are given and the mode change they trigger. \startbuffer hrule{\darkred \hrule width 10cm height 3mm depth 2mm}\par vrule{\darkyellow\vrule width 10cm height 3mm depth 2mm}\par hrule{\darkred \hrule width 10cm }\par vrule{\darkyellow\vrule height 3mm depth 2mm}\par hrule{\darkred \leaders\hrule height 1mm\relax\hfill}hrule\par \stopbuffer \typebuffer When more text is to follow you should end a specification with \type {\relax} to make sure that the scanner stops looking for more arguments. With \type {\leaders} you can create flexible rules. \startlinecorrection \getbuffer \stoplinecorrection In \CONTEXT\ we also have so called frame rules: \startbuffer \color[darkred]{\frule width 10cm height 1cm line 1mm \relax} \stopbuffer \typebuffer This will produce a rectangle: \startlinecorrection \getbuffer \stoplinecorrection There are a few more keywords. Keep in mind that we actually have a new kind of primitive here, so we follow the \TEX\ conventions of keywords. \startbuffer \ruledhbox\bgroup \darkgray \frule width 100mm height 10mm depth 8mm radius 2mm line 2pt type fill\relax \hskip-100mm \darkred \frule width 100mm height 10mm depth 8mm radius 2mm line 2pt\relax \hskip-100mm \hbox to 100mm{\white \bold \hfill some handy word with frames\hfill} \egroup \stopbuffer \typebuffer Of course this is a rather low level way of doing frames and such, but when you like that kind of low level programming you get the possibility here. \startlinecorrection \getbuffer \stoplinecorrection You can combine this with existing mechanisms. Take the following: \startbuffer \defineoverlay[normalframe] [\frule width \overlaywidth height\overlayheight line \overlaylinewidth ] \defineoverlay[ovalframe] [\frule width \overlaywidth height \overlayheight line \overlaylinewidth radius \overlayradius ] \stopbuffer \typebuffer \getbuffer \startbuffer \hbox \bgroup \framed {test}\quad \framed[frame=off] {test}\quad \framed[background=normalframe,frame=off]{test}\quad \framed[background=normalframe,frame=off]{test}\quad \framed[corner=round] {test}\quad \framed[corner=round] {test}\quad \framed[background=ovalframe,frame=off] {test}\quad \framed[background=ovalframe,frame=off] {test}\quad \framed[background=ovalframe,frame=on] {test}\quad \framed[background=ovalframe,frame=on] {test}\quad \egroup \stopbuffer This is a variant on the already available round corners: \startlinecorrection \getbuffer \stoplinecorrection The above result is accomplished with: \typebuffer Given the examples in the previous sections it will be no surprise that we can also use \METAPOST. \startbuffer \startuseMPgraphic{demoshape:back} fill unitcircle xysized (RuleWidth,RuleHeight+RuleDepth) withcolor RuleColor ; \stopuseMPgraphic \startuseMPgraphic{demoshape:fore} draw unitcircle xysized (RuleWidth,RuleHeight+RuleDepth) withcolor RuleColor withpen pencircle scaled 4RuleThickness ; \stopuseMPgraphic \hbox\bgroup \darkgray \frule width 100mm height 10mm depth 8mm type mp line 2pt data {\includeMPgraphic{demoshape:back}} \relax \hskip-100mm \darkred \frule width 100mm height 10mm depth 8mm type mp line 2pt data {\includeMPgraphic{demoshape:fore}} \relax \hskip-100mm \hbox to 100mm{\white \bold \hfill some handy word with frames\hfill} \egroup \stopbuffer \typebuffer Or rendered: \startlinecorrection \getbuffer \stoplinecorrection The \type {\blackrule} command is the more high level way to inject a rule. \startbuffer \blackrule [width=10cm, height=1cm, depth=1cm, color=darkred] \stopbuffer \typebuffer This produces a boring rule: \startlinecorrection \getbuffer \stoplinecorrection Again we can revert to \METAPOST: \startbuffer \blackrule [width=10cm, height=1cm, depth=1cm, color=darkred, type=mp, mp=demoshape:back] \stopbuffer \typebuffer or: \startlinecorrection \getbuffer \stoplinecorrection The formal definition of this command is shown in \definition [setupblackrules, blackrule]. \showdefinition{setupblackrules} \showdefinition{blackrule} \stopsubject \startsubject[title=Hiding] In education a to be filled in text is often represented by a gap in the running text and the bar drawing mechanism supports this. THere is a predefined \type {\hiddenbar} command: \starttyping \definebar [hiddenbar] [underbar] [continue=yes,empty=yes, left=\zwj,right=\zwj] \stoptyping \startbuffer \input ward \hiddenbar {\color[red]{invisible}} \input ward \hiddenbar {\quad\color[red]{invisible}\quad} \input ward \hiddenbar{\quad\quad\quad\color[red]{invisible}\quad\quad\quad} \input ward \hiddenbar {\color[red]{invisible}\quad\quad\quad\quad\quad\quad} \input ward \stopbuffer \getbuffer The previous text is generated with: \typebuffer Here is a variant that inserts spacing at the left and right edges. In this case the spacing is kept at a linebreak: \startbuffer \definebar [widehiddenbar] [hiddenbar] [left={\quads[3]}, right={\quads[3]}] \widehiddenbar{invisible} \input weisman \widehiddenbar{invisible} \input weisman \widehiddenbar{invisible} \stopbuffer \typebuffer \getbuffer \stopsubject \stopdocument