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Diffstat (limited to 'doc/context/sources/general/manuals/luametatex/luametatex-fonts.tex')
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1 files changed, 142 insertions, 61 deletions
diff --git a/doc/context/sources/general/manuals/luametatex/luametatex-fonts.tex b/doc/context/sources/general/manuals/luametatex/luametatex-fonts.tex index 1bbdebb09..64eb06bc9 100644 --- a/doc/context/sources/general/manuals/luametatex/luametatex-fonts.tex +++ b/doc/context/sources/general/manuals/luametatex/luametatex-fonts.tex @@ -107,6 +107,11 @@ in combination with \LUA\ code that does this. In \CONTEXT\ we have base mode that uses the engine, and node mode that uses \LUA. A monospaced font normally has no ligatures and kerns and is normally not processed at all. +We can group the parameters. All characters have the following base set. It must +be noted here that \OPENTYPE\ doesn't have a italic property and that the height +and depth are also not part of the design: one can choose to derive them from the +bounding box. + \starttabulate[|l|l|pl|] \DB key \BC type \BC description \NC\NR \TB @@ -114,24 +119,87 @@ has no ligatures and kerns and is normally not processed at all. \NC \type {height} \NC number \NC height in sp (default 0) \NC\NR \NC \type {depth} \NC number \NC depth in sp (default 0) \NC\NR \NC \type {italic} \NC number \NC italic correction in sp (default 0) \NC\NR -\NC \type {topaccent} \NC number \NC top accent alignment place in sp (default zero) \NC\NR -\NC \type {bottomaccent} \NC number \NC bottom accent alignment place, in sp (default zero) \NC\NR +\stoptabulate + +Then there are three parameters that are more optional and relate to advanced +optical paragraph optimization: + +\starttabulate[|l|l|pl|] +\DB key \BC type \BC description \NC\NR +\TB \NC \type {leftprotruding} \NC number \NC left protruding factor (\prm {lpcode}) \NC\NR \NC \type {rightprotruding} \NC number \NC right protruding factor (\prm {rpcode}) \NC\NR \NC \type {expansion} \NC number \NC expansion factor (\prm {efcode}) \NC\NR -\NC \type {next} \NC number \NC \quote {next larger} character index \NC\NR -\NC \type {extensible} \NC table \NC constituent parts of an extensible (traditional) recipe \NC\NR -\NC \type {vparts} \NC table \NC constituent parts of a vertical (\OPENTYPE) recipe \NC \NR -\NC \type {hparts} \NC table \NC constituent parts of a horizontal (\OPENTYPE)recipe \NC \NR -\NC \type {kerns} \NC table \NC kerning information \NC\NR +\stoptabulate + +From \TEX\ we inherit the following tables. Ligatures are only used in so call +base mode, when the engine does the font magic. Kerns are used in text and +optionally in math: More details follow below. + +\starttabulate[|l|l|pl|] +\DB key \BC type \BC description \NC\NR +\TB \NC \type {ligatures} \NC table \NC ligaturing information \NC\NR -\NC \type {mathkern} \NC table \NC math cut-in specifications \NC\NR -\NC \type {smaller} \NC number \NC the next smaller math size character \NC\NR +\NC \type {kerns} \NC table \NC kerning information \NC\NR +\stoptabulate + +The next two fields control the engine and are a variant on \TEX's \TFM\ tag +property. In a future we might provide a bit more (local) control although +currently we see no need. Originally the tag and next field were combined into a +packed integer but in current \LUAMETATEX\ we have a 32 bit tag and the next +field moved to the math blob as it only is used as variant selector. + +\starttabulate[|l|l|pl|] +\DB key \BC type \BC description \NC\NR +\TB +\NC \type {tag} \NC number \NC a bitset, currently not really exposed \NC\NR +%NC \type {reserved} \NC number \NC note for myself \NC \NR +\stoptabulate + +In a math font characters have many more fields. + +\starttabulate[|l|l|pl|] +\DB key \BC type \BC description \NC\NR +\TB +\NC \type {smaller} \NC number \NC the next smaller math size character \NC\NR +\NC \type {mirror} \NC number \NC a right to left alternative \NC\NR +\NC \type {flataccent} \NC number \NC an accent alternative with less height (\OPENTYPE) \NC\NR +\NC \type {next} \NC number \NC \quote {next larger} character index \NC\NR +\HL +\NC \type {topleft} \NC number \NC alternative script kern \NC\NR +\NC \type {topright} \NC number \NC alternative script kern \NC\NR +\NC \type {bottomleft} \NC number \NC alternative script kern \NC\NR +\NC \type {bottomright} \NC number \NC alternative script kern \NC\NR +\HL +\NC \type {topmargin} \NC number \NC alternative accent calculation margin \NC\NR +\NC \type {bottomargin} \NC number \NC alternative accent calculation margin \NC\NR +\NC \type {leftmargin} \NC number \NC alternative accent calculation margin \NC\NR +\NC \type {rightmargin} \NC number \NC alternative accent calculation margin \NC\NR +\HL +\NC \type {topovershoot} \NC number \NC accent width tolerance \NC\NR +\NC \type {bottomovershoot} \NC number \NC accent width tolerance \NC\NR +\HL +\NC \type {topanchor} \NC number \NC horizontal top accent alignment position \NC\NR +\NC \type {bottomanchor} \NC number \NC horizontal bottom accent alignment position \NC\NR +\HL +\NC \type {innerlocation} \NC string \NC \type {left} or \type {right} \NC\NR +\NC \type {innerxoffset} \NC number \NC radical degree horizontal position \NC\NR +\NC \type {inneryoffset} \NC number \NC radical degree vertical position \NC\NR +\HL +\NC \type {parts} \NC table \NC constituent parts of an extensible \NC \NR +\NC \type {partsitalic} \NC number \NC the italic correction applied with the extensible \NC \NR +\NC \type {partsorientation} \NC number \NC \type {horizontal} or \type {vertical} \NC\NR +\HL +\NC \type {mathkerns} \NC table \NC math cut-in specifications \NC\NR +\HL +\NC \type {extensible} \NC table \NC stretch a fixed width accent to fit\NC\NR \LL \stoptabulate -For example, here is the character \quote {f} (decimal 102) in the font \type -{cmr10 at 10pt}. The numbers that represent dimensions are in scaled points. +Now some more details follow. For example, here is the character \quote {f} +(decimal 102) in the font \type {cmr10 at 10pt}. The numbers that represent +dimensions are in scaled points. Of course you will use Latin Modern \OPENTYPE\ +instead but the principles are the same: \starttyping [102] = { @@ -159,17 +227,23 @@ virtual character whose ligatures and kerns are used to handle word boundary processing. \type {rightboundary} is similar but not actually used for anything (yet). -The values of \type {topaccent}, \type {bottomaccent} and \type {mathkern} are +The values of \type {leftprotrusion} and \type {rightprotrusion} are used only +when \prm {protrudechars} is non-zero. Whether or not \type {expansion} is used +depends on the font's global expansion settings, as well as on the value of \prm +{adjustspacing}. + +The values of \type {topanchor}, \type {bottomanchor} and \type {mathkern} are used only for math accent and superscript placement, see \at {page} [math] in -this manual for details. The values of \type {leftprotrusion} and \type -{rightprotrusion} are used only when \prm {protrudechars} is non-zero. Whether or -not \type {expansion} is used depends on the font's global expansion settings, as -well as on the value of \prm {adjustspacing}. +this manual for details. The italic corrections are a story in themselves and +discussed in detail in other manuals. The additional parameters that deal with +kerns, margins, overshoots, inner anchoring, etc. are engine specific and not +part of \OPENTYPE. More information can be found in the \CONTEXT\ distribution; +they relate the upgraded math engine project by Mikael and Hans. A math character can have a \type {next} field that points to a next larger shape. However, the presence of \type {extensible} will overrule \type {next}, if that is also present. The \type {extensible} field in turn can be overruled by -\type {vparts}, the \OPENTYPE\ version. The \type {extensible} table is very +\type {parts}, the \OPENTYPE\ version. The \type {extensible} table is very simple: \starttabulate[|l|l|p|] @@ -182,8 +256,8 @@ simple: \LL \stoptabulate -The \type {hparts} and \type {vparts} are arrays of components. Each of -those components is itself a hash of up to five keys: +The \type {parts} entru is an arrays of components. Each of those components is +itself a hash of up to five keys: \starttabulate[|l|l|p|] \DB key \BC type \BC explanation \NC \NR @@ -198,15 +272,15 @@ those components is itself a hash of up to five keys: \LL \stoptabulate -The \type {kerns} table is a hash indexed by character index (and \quote -{character index} is defined as either a non|-|negative integer or the string -value \type {rightboundary}), with the values of the kerning to be applied, in -scaled points. +The traditional (text and math) \type {kerns} table is a hash indexed by +character index (and \quote {character index} is defined as either a +non|-|negative integer or the string value \type {rightboundary}), with the +values of the kerning to be applied, in scaled points. -The \type {ligatures} table is a hash indexed by character index (and \quote -{character index} is defined as either a non|-|negative integer or the string -value \type {rightboundary}), with the values being yet another small hash, with -two fields: +The traditional (text) \type {ligatures} table is a hash indexed by character +index (and \quote {character index} is defined as either a non|-|negative integer +or the string value \type {rightboundary}), with the values being yet another +small hash, with two fields: \starttabulate[|l|l|p|] \DB key \BC type \BC description \NC \NR @@ -243,46 +317,53 @@ The default value is~0, and can be left out. That signifies a \quote {normal} ligature where the ligature replaces both original glyphs. In this table the~\type {|} indicates the final insertion point. -The \type {mathcontrol} bitset is mostly there for experimental purposes. Because -there is inconsistency in the \OPENTYPE\ math fonts with respect to for instance -glyph dimensions, it is possible to force the traditional code path. We just mention -the possible flags: - -\startluacode - context.starttabulate { "|||" } - context.DB() context("value") context.BC() context("effect") context.NC() context.NR() - context.TB() - for k, v in table.sortedhash(tex.getmathcontrolvalues()) do - context.NC() context("0x%04X",k) context.NC() context(v) context.NC() context.NR() - end - context.LL() - context.stoptabulate() -\stopluacode +% The \type {mathcontrol} bitset is mostly there for experimental purposes. Because +% there is inconsistency in the \OPENTYPE\ math fonts with respect to for instance +% glyph dimensions, it is possible to force the traditional code path. We just mention +% the possible flags: +% +% \startluacode +% context.starttabulate { "|||" } +% context.DB() context("value") context.BC() context("effect") context.NC() context.NR() +% context.TB() +% for k, v in table.sortedhash(tex.getmathcontrolvalues()) do +% context.NC() context("0x%04X",k) context.NC() context(v) context.NC() context.NR() +% end +% context.LL() +% context.stoptabulate() +% \stopluacode Compact math is an experimental feature. The smaller field in a character definition of a text character can point to a script character that itself can point to a scriptscript one. When set the \type {textscale}, \type {scriptscale} and \type {scriptscriptscale} is applied to those. -The \type {textcontrol} field is used to control some aspects of text processing. -More options might be added in the future. - -\startluacode - context.starttabulate { "|||" } - context.DB() context("value") context.BC() context("effect") context.NC() context.NR() - context.TB() - for k, v in table.sortedhash(tex.gettextcontrolvalues()) do - context.NC() context("0x%04X",k) context.NC() context(v) context.NC() context.NR() - end - context.LL() - context.stoptabulate() -\stopluacode - -In \CONTEXT\ these are interfaced via pseudo features. The math control flags of -a font can be overloaded by \prm {mathcontrolmode} on the spot and the set -controls of a font can be queried by \prm {fontmathcontrol}. The text control -flags in a font always win over the ones set by other parameters, like \prm -{hyphenationmode}. They can be queried with \prm {fonttextcontrol}. +Bidirectional math is also experimental and driven by (in \CONTEXT\ speak) tweaks +which means that it has to be set up explicitly as it uses a combination of +fonts. In \CONTEXT\ is also uses specific features of the font subsystems that +hook into the backend where we have a more advanced virtual font subsystem than +in \LUATEX. Because this is macro package dependent it will not be discussed +here. + +% The \type {textcontrol} field is used to control some aspects of text processing. +% More options might be added in the future. + +% \startluacode +% context.starttabulate { "|||" } +% context.DB() context("value") context.BC() context("effect") context.NC() context.NR() +% context.TB() +% for k, v in table.sortedhash(tex.gettextcontrolvalues()) do +% context.NC() context("0x%04X",k) context.NC() context(v) context.NC() context.NR() +% end +% context.LL() +% context.stoptabulate() +% \stopluacode +% +% In \CONTEXT\ these are interfaced via pseudo features. The math control flags of +% a font can be overloaded by \prm {mathcontrolmode} on the spot and the set +% controls of a font can be queried by \prm {fontmathcontrol}. The text control +% flags in a font always win over the ones set by other parameters, like \prm +% {hyphenationmode}. They can be queried with \prm {fonttextcontrol}. \stopsection |