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Diffstat (limited to 'doc')
-rw-r--r-- | doc/context/sources/general/manuals/math/math-tweaks.tex | 108 |
1 files changed, 102 insertions, 6 deletions
diff --git a/doc/context/sources/general/manuals/math/math-tweaks.tex b/doc/context/sources/general/manuals/math/math-tweaks.tex index cf3ffaa0e..6a775688d 100644 --- a/doc/context/sources/general/manuals/math/math-tweaks.tex +++ b/doc/context/sources/general/manuals/math/math-tweaks.tex @@ -634,6 +634,104 @@ the loading. \stopchapter +\startchapter[title=Script parameters] + +Here we show the parameters that deal with script placement. This chapter was +added after we found that some values in Latin Modern were off. The tables show a +factor that relates the value to the x-height which is for some part of the +recommendation. + +\starttabulate[|c|l|c|l|] +\NC \NC SubscriptBaselineDropMin \NC .10 \NC harmless, seldom triggered \NC \NR +\NC \star \NC SubscriptShiftDown \NC .40 \NC by inspection in several files \NC \NR +\NC \star \NC SubscriptShiftDownWithSuperscript \NC .40 \NC as above \NC \NR +\NC \NC SubscriptTopMax \NC .80 \NC Microsoft recommendation \NC \NR +\NC \NC SuperscriptBaselineDropMax \NC .10 \NC see Subscript..Min variant \NC \NR +\NC \NC SuperscriptBottomMaxWithSubscript \NC .80 \NC Microsoft recommendation \NC \NR +\NC \NC SuperscriptBottomMin \NC .25 \NC Microsoft recommendation \NC \NR +\NC \star \NC SuperscriptShiftUp \NC .65 \NC by inspection, a gamble \NC \NR +\NC \star \NC SuperscriptShiftUpCramped \NC .65 \NC see above, non-\TEX \NC \NR +\stoptabulate + +In the end only the ones marked with a star are really important. The other ones +are often small and the drop ones between .5 and 1.5 points with (to us) no clear +logic. We decided to not enable a tweak but explicitly check and set the (four) +values in the goodie file. + +\starttexdefinition ShowScriptsValue #1#2#3 + \NC \csstring#2 + \NC \bgroup \switchtobodyfont[#1-nt]\normalexpanded{\egroup\fam0 \cldcontext{"\letterpercent0.3f",\number#2\textstyle/\number\exheight}} + \NC \bgroup \switchtobodyfont[#1-nt]\normalexpanded{\egroup\fam0 \the#2\textstyle} + \NC \bgroup \switchtobodyfont [#1]\normalexpanded{\egroup\fam0 \the#2\textstyle} + \NC \NR +\stoptexdefinition + +\starttexdefinition ShowScripts #1 + \testpage[4] + \starttabulate[|l|r|r|r|] + \FL + \NC \bf #1 + \NC factor + \NC original + \NC tweaked + \NC \NR + \ML + % \ShowScriptsValue{#1}{\Umathaxis} {MathAxis} + \ShowScriptsValue{#1}{\Umathsubshiftdown} {SubscriptShiftDown} + \ShowScriptsValue{#1}{\Umathsubshiftdrop} {SubscriptBaselineDropMin} + \ShowScriptsValue{#1}{\Umathsubsupshiftdown}{SubscriptShiftDownWithSuperscript} + % \ShowScriptsValue{#1}{\Umathsubsupvgap} {} + \ShowScriptsValue{#1}{\Umathsubtopmax} {SubscriptTopMax} + \ShowScriptsValue{#1}{\Umathsupbottommin} {SuperscriptBottomMin} + \ShowScriptsValue{#1}{\Umathsupshiftdrop} {SuperscriptBaselineDropMax} + \ShowScriptsValue{#1}{\Umathsupshiftup} {SuperscriptShiftUp} + \ShowScriptsValue{#1}{\Umathsupsubbottommax}{SuperscriptBaselineDropMax} + \LL + \stoptabulate +\stoptexdefinition + +\ShowSomething{ShowScripts} + +One of the pitfalls is that in \CONTEXT\ we actually set \type +{\Umathsubsupshiftdown} which the results in a bad parameter being used. This +also makes that we do need to fix the font. footnote {Other macro packages are +less likely to suffer from this as long as they don't set that parameter.} These +are issues that we easily spent days on checking, double checking and exploring +variants before settling on some approach. In this case we compared traditional +\PDFTEX\ output using Computer Modern with \OPENTYPE\ rendering using Latin +Modern which exposed the issue. + +\stopchapter + +\startchapter[title=primes] + +A few words on primes, a pain in the butt symbol. In traditional \TEX\ (fonts) a +prime is a special symbol. Macro packages are set up in such a way that single +quotes become primes. In practice that then boils down to putting the symbol in +the superscript which means that at the \TEX\ level the smaller size is used. + +This smaller size is somehow reflected in the \OPENTYPE\ math fonts: the script +and scriptscript sized (ssty variant 1 and 2) are basically meant to be +superscripted. The text size however often looks differently and is positioned +like an accent. Supposedly it is meant to be used without placement, as minute or +second indicator. This is one of the cases where a text, script and scriptscript +variant of the same glyphs looks pretty incompatible. + +Combined with up to four primes being combined as well as up to three reverse +primes being provided this a rather messy implementation. In \CONTEXT\ we always +tweaked the dimensions to consistently suit our purpose. + +When we experimented with primes as operator, implemented like we do with fourier +using right delimited radicals, we realized that hooking this into the text level +symbol gave inconsistent results so in the end we simplified the \type +{fixprimes} tweak in a way that suits both usage patterns: we just use the \type +{ssty}~1 variant (of course scaled to the right relative size) for all three +sizes: there is no need to be more granular and it safes us some trouble. We +thereby also sacrifice some detailed tweaking but also got rid of potential +visual incompatibilities as for instance in \STIX. + +\stopchapter + \startchapter[title=Tweak: dimensions] \ShowTweakUsage{dimensions} Usage of this tweak can best be observed (and experimented) in the goodie files @@ -1414,11 +1512,12 @@ You can substitute a character in a font by one from a substitution feature: \NC #1 \NC \showglyphs \switchtobodyfont[#1] $f'(x)+e^{g'(x)} - a''+ b''' + c''''$ \NC \showglyphs \switchtobodyfont[#1-nt] $f'(x)+e^{g'(x)} - a''+ b''' + c''''$ + \NC \showglyphs \switchtobodyfont[#1] $\primed{f}$ \NC \NR \stoptexdefinition -\starttabulate[|l|c|c|c|c|] - \NC \NC tweaked \NC original \NC \NR +\starttabulate[|l|c|c|c|] + \NC \NC tweaked \NC original \NC primed \NC \NR \ctxlua { for i=1,#document.usedfonts do if i > 1 then @@ -1617,16 +1716,13 @@ hand symbol. } \stoptabulate - - - \stopchapter \startchapter[title=Tweak: addmirrors] \ShowTweakUsage{addmirrors} This adds symbols for right|-|to|-|left math by simply mirroring existing ones. Deep down the engine doesn't really care about in what direction typesetting -happens (wrt spacing and building structures) , and it is the backend that does +happens (wrt spacing and building structures), and it is the backend that does the real work. However, symbols need to be flipped. \stopchapter |