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diff --git a/doc/context/sources/general/manuals/fonts/fonts-tricks.tex b/doc/context/sources/general/manuals/fonts/fonts-tricks.tex new file mode 100644 index 000000000..65b210e2c --- /dev/null +++ b/doc/context/sources/general/manuals/fonts/fonts-tricks.tex @@ -0,0 +1,390 @@ +% language=uk + +\startcomponent fonts-tricks + +\environment fonts-environment + +\startchapter[title=Tricks][color=middleorange] + +\startsection[title=Introduction] + +In this chapter topics that don't fit in the previous chapters are +collected. + +\stopsection + +\startsection[title=Extra characters] + +In one of our projects we need a small (high) minus and here we discuss +one way of achieving this. An option is to define a new character +and use a font feature to add it, as in: + +\starttyping +\startluacode + local function addextraminus(tfmdata) + fonts.helpers.addprivate(tfmdata, "smallminus", ... ) -- see below + fonts.helpers.addprivate(tfmdata, "highminus", ... ) -- see below + end + fonts.constructors.newfeatures.otf.register { + name = "extraminus", + description = "extra minus symbols", + default = true, + manipulators = { + base = addextraminus, + node = addextraminus, + } + } +\stopluacode +\stoptyping + +However, why make it an option when we can just add it to any font. So, +we can end up with just: + +\typebuffer[extraminus] % already defined before loading fonts + +It is important to do this before fonts get loaded. Next we need to decide how to +access these characters. A straightforward way is: + +\startbuffer +\def\smallminus{\privatechar{smallminus}} +\def\highminus {\privatechar{highminus}} +\stopbuffer + +\typebuffer \getbuffer + +An alternative is: + +\starttyping +\definemathcommand [smallminus] [ord] {\privatechar{smallminus}} +\definemathcommand [highminus] [ord] {\privatechar{highminus}} +\stoptyping + +but that fails in text mode. So, we can consider: + +\starttyping +\def\smallminus{\mathortext{\mathord{\privatechar{smallminus}}}{\privatechar{smallminus}}} +\def\highminus {\mathortext{\mathord{\privatechar {highminus}}}{\privatechar {highminus}}} +\stoptyping + +or more compact + +\starttyping +\def\smallminus{\mathortext\mathord\firstofoneargument{\privatechar{smallminus}}} +\def\highminus {\mathortext\mathord\firstofoneargument{\privatechar {highminus}}} +\stoptyping + +What method you choose depends on usage. With the first, simple definitions we +get this: + +\startbuffer +[\getprivateslot{smallminus}] [\getprivatechar{smallminus}] [\smallminus] $[\smallminus]$\par +[\getprivateslot {highminus}] [\getprivatechar {highminus}] [\highminus ] $[\highminus ]$\par +\stopbuffer + +\typebuffer \getbuffer + +Because we are fully expandable we can even use this in: + +\startbuffer +\bTABLE[aligncharacter=yes,alignmentcharacter={text->\smallminus}] + \bTR \bTD \mathminus100\smallminus00+ \eTD \eTR + \bTR \bTD 100\smallminus00 \eTD \eTR + \bTR \bTD \mathminus 99\smallminus00+ \eTD \eTR + \bTR \bTD \mathminus 99\smallminus00 \eTD \eTR + \bTR \bTD 100\highminus \eTD \eTR +\eTABLE +\stopbuffer + +\typebuffer + +\startlinecorrection +\getbuffer +\stoplinecorrection + +With the other definitions the alignment would not work. If you need both then +you can define different commands for text and math. + +\stopsection + +\startsection[title=Tabular numbers] + +Some font features are meant to be used in controlled situations. An example is +the \type {tnum} feature that triggers so called \quote {tabular figures} meaning +numbers that have equal widths. Its opposite feature is \type {lnum} or lining +figures. We have two predefined \CONTEXT\ font features for this: + +\starttyping +\definefontfeature [inlinenumbers] [lnum=yes,tnum=no] +\definefontfeature [tabularnumbers] [tnum=yes,lnum=no] +\stoptyping + +Some mechanisms in \CONTEXT\ had better be aware of this and one of them is the +alignment mechanism in tables. + +\startbuffer[demo] +\startcombination[before=,after=] + \startcontent + \switchtobodyfont[pagella]\showglyphs% + \disabledirectives[typesetters.characteralign.autofont]% + \bTABLE[alignmentcharacter=.,aligncharacter=yes] + \bTR \bTD 11.111 \eTD \eTR + \bTR \bTD 2.2 \eTD \eTR + \bTR \bTD 444.444 \eTD \eTR + \eTABLE + \enabledirectives[typesetters.characteralign.autofont]% + \stopcontent + \startcaption + \small manual \type {tnum} + \stopcaption + \startcontent + \switchtobodyfont[pagella]\showglyphs% + \bTABLE[alignmentcharacter=.,aligncharacter=yes] + \bTR \bTD 11.111 \eTD \eTR + \bTR \bTD 2.2 \eTD \eTR + \bTR \bTD 444.444 \eTD \eTR + \eTABLE + \stopcontent + \startcaption + \small auto \type {tnum} + \stopcaption +\stopcombination +\stopbuffer + +In the following examples we demonstrate how the automatic font adaption makes +sure that tabular figures are used. The table is defined as: + +\typebuffer[demo] + +\startbuffer +\dontleavehmode\hbox to .3\textwidth \bgroup + \hss\getbuffer[demo]\hss +\egroup +\stopbuffer + +In \in {figure}[fig:tabularnumbers] we see what the features do. We use the \type +{\feature} or \type {\addfeature} macro for this. For the moment this trickery is +controlled by a directive (beware: enabling them is global). + +\startplacefigure[reference=fig:tabularnumbers,title={Tabular numbers}] + \startcombination[nx=3,ny=2] + {\getbuffer} {\tt\nohyphens default} + {\addfeature [inlinenumbers]\getbuffer} {\tt\nohyphens inlinenumbers} + {\addfeature [tabularnumbers]\getbuffer} {\tt\nohyphens tabularnumbers} + {\addfeature[oldstylenumbers]\getbuffer} {\tt\nohyphens oldstylenumbers} + {\addfeature[oldstylenumbers]% + \addfeature [inlinenumbers]\getbuffer} {\tt\nohyphens oldstylenumbers\par inlinenumbers} + {\addfeature[oldstylenumbers]% + \addfeature [tabularnumbers]\getbuffer} {\tt\nohyphens oldstylenumbers\par tabularnumbers} + \stopcombination +\stopplacefigure + +\stopsection + +\startsection[title=Symbols] + +You can access glyphs by name but you need to know that name, for example: + +\startbuffer +\definefontsynonym [bends] [file:manfnt.afm] + +\startsymbolset [Dangerous Bends] + \definesymbol [dbend] [\resolvedglyphdirect{bends}{n:char_7e}] + \definesymbol [lhdbend] [\resolvedglyphdirect{bends}{n:char_7f}] +\stopsymbolset + +\setupsymbolset [Dangerous Bends] + +Two dangerous bends: \symbol{dbend} and \symbol{lhdbend}. +\stopbuffer + +\typebuffer + +You can best save the fonts you use that way in a place that doesn't get +overwritten because names can change. + +\getbuffer + +\stopsection + +\startsection[title=Alternative styles] + +\startbuffer[demo] + \start + \getbuffer[setup] + \subject{[ {\myslanted myslanted} ] [ {\it it} ] [ {\slanted slanted} ] [ $x=1$ ]} + [ {\myslanted myslanted} ] [ {\it it} ] [ {\slanted slanted} ] [ $x=1$ ] + \typebuffer[setup] + \blackrule[width=\hsize,height=1pt,depth=0pt] + \stop +\stopbuffer + +In section heads we want a nested style (e.g.\ italic) to adapt to the main font. +The following definitions shows how you can influence that process. We use the +following \type {demo} buffer as sample: + +\typebuffer[demo] + +\startbuffer +\blackrule[width=\hsize,height=1pt,depth=0pt] + +\startbuffer[setup] +\setuphead[subject][style=\tfb,before=,after=] +\definealternativestyle [myslanted] [\it] [] +\stopbuffer + +\getbuffer[demo] + +\startbuffer[setup] +\setuphead[subject][style=\tfb,before=,after=] +\definealternativestyle [myslanted] [\it] [\bi] +\stopbuffer + +\getbuffer[demo] + +\startbuffer[setup] +\setuphead[subject][style=\tfb,before=,after=] +\definealternativestyle [myslanted] [\it] [\tf] +\stopbuffer + +\getbuffer[demo] + +\startbuffer[setup] +\definealternativestyle [myslanted] [\normalitalicface] +\setuphead[subject][style=bold,before=,after=] +\stopbuffer + +\getbuffer[demo] + +\startbuffer[setup] +\definealternativestyle [myslanted] [\normalitalicface] +\setuphead[subject][style=\bfd,before=,after=] +\stopbuffer + +\getbuffer[demo] + +\startbuffer[setup] +\definealternativestyle [myslanted] [\slantedface] +\setuphead[subject][style=boldface,before=,after=] +\stopbuffer + +\getbuffer[demo] +\stopbuffer + +You can influence the main method of operation with: + +\starttyping +\setupalternativestyles[method=normal] +\setupalternativestyles[method=auto] +\stoptyping + +\startplacefigure[title={Alternative style methods.},reference=fig:alternativestyle] + \startcombination + {\setupalternativestyles[method=normal]\scale[width=.45\textwidth]{\framed[width=.85\textwidth,align=normal,frame=off,offset=overlay]{\getbuffer}}} {\type{method=normal}} + {\setupalternativestyles [method=auto]\scale[width=.45\textwidth]{\framed[width=.85\textwidth,align=normal,frame=off,offset=overlay]{\getbuffer}}} {\type{method=auto}} + \stopcombination +\stopplacefigure + +The result is shown in \in {figure} [fig:alternativestyle]. Relevant commands are: + +\starttyping +\emphasistypeface +\emphasisboldface + +\normaltypeface \typeface +\normalboldface \boldface +\normalslantedface \slantedface +\normalitalicface \italicface +\swaptypeface \swapface +\stoptyping + +\stopsection + +\startsection[title={A virtual hack}] + +Here is some virtual trickery. A virtual font is just a font but instead of a +character being a reference to a slot in a font (often via an index) it +constructs a glyph from whatever characters, rules, displacements, inline \PDF\ +code, etc. We use them a lot deep down in \CONTEXT. The next example defines two +characters represented by rules. This definition is about as minimalistic as +reasonable and demonstrates how we can apply expansion (aka hz) to such a font. +\footnote {You need \LUATEX\ 1.08 or later for this.} We store the font id (a +number) in a macro. Watch how we don't refer to a glyph in a font. Because we +don't specify its type as \type {virtual} we can leave out the \type {font} +table. After all, we don't refer to real glyphs. + +\startbuffer +\startluacode +local d = 400000 -- just over 6pt +local a = font.define { + characters = { + [string.byte("A")] = + { + width = d, + depth = d, + commands = { { "down", d }, { "rule", d, d } }, + expansion_factor = 1000, + }, + [string.byte("B")] = + { + width = d, + height = d, + commands = { { "rule", d, d } }, + expansion_factor = 500, + }, + + }, + parameters = { + space = 2*d, + space_stretch = d, + space_shrink = d, + }, + stretch = 8, + shrink = 8, + step = 2, + name = "foo" +} + +tex.count.scratchcounter = a +\stopluacode + +\edef\MyFontID{\the\scratchcounter} +\stopbuffer + +\typebuffer \getbuffer + +% \enabletrackers[*expans*] + +\startbuffer +\startoverlay + {\vbox \bgroup + \setuptolerance[verytolerant,stretch] + \setfontid\MyFontID + \dorecurse{5}{ABABABABABABABABABABABABABABABABA } + \egroup} + {\vbox \bgroup + \normaladjustspacing2 + \middlegray + \setuptolerance[verytolerant,stretch] + \setfontid\MyFontID + \dorecurse{5}{ABABABABABABABABABABABABABABABABA } + \egroup} +\stopoverlay +\stopbuffer + +We test this with some rather low level code and show the result in \in {figure} +[fig:virtualhack]. Of course you will never define a font this way if only +because we don't set important parameters and this version is not generic in the +sense that it scales well. You can find better examples elsewhere in the manual +and in the distribution. + +\typebuffer + +\startplacefigure[title={A virtual hack.},reference=fig:virtualhack] + \getbuffer +\stopplacefigure + +\stopsection + +\stopchapter + +\stopcomponent |