2021-11-24 15:18:00

8 files changed, 477 insertions, 10 deletions

diff --git a/doc/context/sources/general/manuals/math/math-fonts-accents-001.tex b/doc/context/sources/general/manuals/math/math-fonts-accents-001.tex
new file mode 100644
index 000000000..4c9737fa7
--- /dev/null
+++ b/doc/context/sources/general/manuals/math/math-fonts-accents-001.tex
@@ -0,0 +1,23 @@
+\environment math-fonts-helpers
+
+\startbuffer[accents]
+    $+\bar{u}\bar{f}\bar{\Omega}$
+    $\overbar{u}\overbar{f}\overbar{\Omega}$
+    $\overline{u}\overline{f}\overline{\Omega}$
+    \blank
+    $\dot{u}\dot{f}\dot{\Omega}$
+    $\hat{u}\hat{f}\hat{\Omega}$
+    $\tilde{u}\tilde{f}\tilde{\Omega}$
+    \blank
+    $\ddot{u}\ddot{f}\ddot{\Omega}$
+    $\widehat{u}\widehat{f}\widehat{\Omega}$
+    $\widetilde{u}\widetilde{f}\widetilde{\Omega}$
+\stopbuffer
+
+\starttext
+    \MathSamples [
+    ] [
+        accents
+    ]
+
+\stoptext
diff --git a/doc/context/sources/general/manuals/math/math-fonts-helpers.tex b/doc/context/sources/general/manuals/math/math-fonts-helpers.tex
new file mode 100644
index 000000000..7d52c2a7f
--- /dev/null
+++ b/doc/context/sources/general/manuals/math/math-fonts-helpers.tex
@@ -0,0 +1,83 @@
+\starttexdefinition OneMathSample #1#2
+    \startcontent
+        \switchtobodyfont[#1]
+        \framed[align=middle,offset=2ex,corner=round,rulethickness=1pt,framecolor=darkred] \bgroup
+            \getbuffer[#2]%
+            \blank[back]
+        \egroup
+    \stopcontent
+    \startcaption
+        \tt\tfb\color[darkred]{#1}
+    \stopcaption
+\stoptexdefinition
+
+\startluacode
+    local default = {
+        "cambria",
+        "modern",
+     -- "modernlatin",
+        "dejavu",
+        "pagella",
+        "termes",
+        "bonum",
+        "schola",
+        "lucidadk",
+     -- "xits",
+        "stixtwo",
+        "libertinus",
+        "ebgaramond",
+        "kpfonts",
+     -- "minion",
+     -- "asana"
+    }
+
+    function document.MathSamples(list,samples)
+        list    = string.strip(list)
+        samples = string.strip(samples)
+        local s = list ~= "" and utilities.parsers.settings_to_array(list) or default
+        local n = #s
+        if s[n] == "" then
+            n = n - 1
+        end
+        local m = n % 4
+        local x = 4
+        local y = n // 4
+        if m > 0 then
+            x = x + 1
+        end
+     -- for i=1,n do
+     --     context.usebodyfont { s[i] }
+     -- end
+--        context.startTEXpage { offset = "2ex" }
+            context.startcombination { nx = x, ny = y, location = "top", distance = "2ex", after = "\\blank[2*big]" }
+                for i=1,n do
+                    context.OneMathSample(s[i],samples)
+                end
+            context.stopcombination()
+--        context.stopTEXpage()
+    end
+\stopluacode
+
+\protected\def\MathSamples[#1]#*[#2]%
+  {\ctxlua{document.MathSamples("#1","#2")}}
+
+\def\DoShowNextBox
+  {\begingroup
+   \dowithnextbox
+     {\showboxinbuffer{mathbox}\nextbox\plusone
+      \midaligned{\framed{\box\nextbox}}%
+      \switchtobodyfont[4pt]
+      \typebuffer[mathbox][option=TEX]%
+      \endgroup
+      \endgroup}%
+    \hbox}
+
+\protected\def\StartShowBox
+  {\begingroup
+   \protected\def\StopShowBox{\removeunwantedspaces\egroup}%
+   \DoShowNextBox
+   \bgroup\ignorespaces}
+
+\protected\def\ShowBox
+  {\begingroup
+   \DoShowNextBox}
diff --git a/doc/context/sources/general/manuals/math/math-fonts-italics-002.tex b/doc/context/sources/general/manuals/math/math-fonts-italics-002.tex
new file mode 100644
index 000000000..89d93deb3
--- /dev/null
+++ b/doc/context/sources/general/manuals/math/math-fonts-italics-002.tex
@@ -0,0 +1,28 @@
+\environment math-fonts-helpers
+
+\startbuffer[italic-1]
+    $\showglyphs \showfontitalics V^1_2 + V^1 + V_2$
+    \blank
+    $\showglyphs \showfontitalics f^1_2 + g^1_2 + v^1_2 + w^1_2$
+    \blank
+    $\showglyphs \showfontitalics A^1_2 + B^1_2 + V^1_2 + W^1_2$
+    \blank
+\stopbuffer
+
+\startbuffer[italic-2]
+    \mathfontcontrol \italicshapekernmathcontrolcode
+    \mathcontrolmode \plusone
+    \getbuffer[italic-1]%
+\stopbuffer
+
+% \continueifinputfile{italics-002}
+
+\starttext
+
+    \MathSamples [
+    ] [
+        italic-1,
+        italic-2
+    ]
+
+\stoptext
diff --git a/doc/context/sources/general/manuals/math/math-fonts-primes-001.tex b/doc/context/sources/general/manuals/math/math-fonts-primes-001.tex
new file mode 100644
index 000000000..a93934def
--- /dev/null
+++ b/doc/context/sources/general/manuals/math/math-fonts-primes-001.tex
@@ -0,0 +1,28 @@
+% \enableexperiments[fonts.compact]
+% \enabletrackers[fonts.defining]
+
+\environment math-fonts-helpers
+
+\startbuffer[primes]
+    $\textstyle f' f'(x) $
+    $\textstyle f'' f''(x) $
+    $\textstyle f''' f'''(x) $
+    \blank
+    $\scriptstyle f' f'(x) $
+    $\scriptstyle f'' f''(x) $
+    $\scriptstyle f''' f'''(x) $
+    \blank
+    $\scriptscriptstyle f' f'(x) $
+    $\scriptscriptstyle f'' f''(x) $
+    $\scriptscriptstyle f''' f'''(x) $
+\stopbuffer
+
+\setupmathematics[stylealternative={calligraphic}]
+
+\starttext
+    \MathSamples [
+    ] [
+        primes
+    ]
+
+\stoptext
diff --git a/doc/context/sources/general/manuals/math/math-fonts-radicals-001.tex b/doc/context/sources/general/manuals/math/math-fonts-radicals-001.tex
new file mode 100644
index 000000000..a88378b98
--- /dev/null
+++ b/doc/context/sources/general/manuals/math/math-fonts-radicals-001.tex
@@ -0,0 +1,18 @@
+\environment math-fonts-helpers
+
+\startbuffer[scripts]
+    \ruledhbox{$\textstyle         \char"221A \sqrt{x} \sqrt[3]{x} \sqrt{\frac{1}{x}}$}
+    \blank
+    \ruledhbox{$\scriptstyle       \char"221A \sqrt{x} \sqrt[3]{x} \sqrt{\frac{1}{x}}$}
+    \blank
+    \ruledhbox{$\scriptscriptstyle \char"221A \sqrt{x} \sqrt[3]{x} \sqrt{\frac{1}{x}}$}
+\stopbuffer
+
+\starttext
+
+    \MathSamples [
+    ] [
+        scripts
+    ]
+
+\stoptext
diff --git a/doc/context/sources/general/manuals/math/math-fonts-scripts-001.tex b/doc/context/sources/general/manuals/math/math-fonts-scripts-001.tex
new file mode 100644
index 000000000..b0af35e6c
--- /dev/null
+++ b/doc/context/sources/general/manuals/math/math-fonts-scripts-001.tex
@@ -0,0 +1,18 @@
+\environment math-fonts-helpers
+
+\startbuffer[scripts]
+    \ruledhbox{$\textstyle         x\char"207A x\char"207B x\char"208A x\char"208B$}
+    \blank
+    \ruledhbox{$\scriptstyle       x\char"207A x\char"207B x\char"208A x\char"208B$}
+    \blank
+    \ruledhbox{$\scriptscriptstyle x\char"207A x\char"207B x\char"208A x\char"208B$}
+\stopbuffer
+
+\starttext
+
+    \MathSamples [
+    ] [
+        scripts
+    ]
+
+\stoptext
diff --git a/doc/context/sources/general/manuals/math/math-fonts.tex b/doc/context/sources/general/manuals/math/math-fonts.tex
new file mode 100644
index 000000000..421dfe43e
--- /dev/null
+++ b/doc/context/sources/general/manuals/math/math-fonts.tex
@@ -0,0 +1,263 @@
+% language=us runpath=texruns:manuals/math
+
+\environment math-layout
+\environment math-fonts-helpers
+
+% todo: use "keep-latin-modern-math.otf" and "keep-texgyre-pagella-math.otf"
+
+\startcomponent math-fonts
+
+\startchapter[title=Fonts]
+
+\startsection[title=Introduction]
+
+In this document we will discuss how we deal with \OPENTYPE\ math fonts. There is
+a set of samples that are used for testing. One problem is that these fonts
+evolve so what we discuss and fix today might not be applicable tomorrow in which
+case this document can also be seen from a historic perspective. We will mostly
+use \CONTEXT\ speak.
+
+The examples that we show use test files and normally they should render okay. If
+not, we need to fix something. They are part of a set of test files by Mikael
+Sundqvist and Hans Hagen made in the perspective of defining proper goodie files
+and this chapter summarizes our journey.
+
+{\em This chapter is uncorrected work in progress.}
+
+\stopsection
+
+\startsection[title=Italics]
+
+First of all we need to mention some fundamental differences between a
+traditional setup and one for \OPENTYPE\ \UNICODE\ fonts. When \TEX\ showed up,
+fonts had at most 256 characters. Sets of characters are organized in so called
+families of which there are 16: family zero is the one used for what is called
+roman (upright), family one for so called math italic characters, family two for
+all kind of symbols and family three for extensible characters. The \TEX\
+distribution comes with matching fonts. Now, when one enters a formula like this:
+
+\starttyping
+y = \sqrt{x^2 + 4}
+\stoptyping
+
+the \type {x} and \type {y} are math italics (family 1), \type {1} and \type {2}
+are upright (family 0), the \type {+} is a symbol (family 2) and the radical
+comes from family 3 as it can differ in size. The letters are actually from the
+math {\it italic} alphabet and there can be other alphabets: bold, bold italic,
+blackboard, script, etc. For these one defines additional families or when one
+runs out of families symbolic names can be used to map to the non alphabetic
+\ASCII\ slots.
+
+In \CONTEXT\ right from when we started with \LUATEX\ the multiple families were
+dropped in favor of just one. \footnote {This is not entirely true because we
+also have one for bold, and two for r2l regular and bold, but these are dealt
+with in a special way: all definitions use family zero.} Because \UNICODE\ has a
+concept of math alphabets (unfortunately with holes) we use \UNICODE\ \OPENTYPE\
+fonts as well as (certainly before there was anything else than Cambria) virtual
+(runtime) assemblies of traditional \TYPEONE\ fonts.
+
+In this and following chapters we only discuss the \OPENTYPE\ fonts because that
+is what we normally deal with. One complication there is that, although Cambria
+set a clear standard, the fonts that evolved in the \TEX\ ecosystem are to a
+large extend modelled after the traditional \TEX\ fonts. Fonts that originate
+from elsewhere are a mix of both models. And it is this curious mix of approaches
+that forces us to adapt the machinery and|/|or the fonts to our needs. For a long
+time \CONTEXT\ assumed some consistency and although there were mechanisms in
+place to deal with these (often not) subtle differences, in the long run that was
+not what we wanted. So, when these fonts became more and more frozen we decided
+to go for a more individual long term \quote {fix them runtime} solution.
+
+A result is that in \LMTX\ we use a similar approach as in \MKIV\ but instead of
+trying to fix the fonts automatically (driven by pseudo features), we now
+delegate that to the font goodie mechanism where we can also fine tune more
+easily per font: runtime tweaks. The basics are the same but it is a bit easier
+that way, also because in the worst case one can program a specific tweak without
+side effects for the rest.
+
+\startplacefigure[title={Italics Sample 2}]
+    \externalfigure
+        [math-fonts-italics-002.tex]
+        [width=\textwidth]
+\stopplacefigure
+
+The tweak that deals with italics (and other shapes) is:
+
+\starttabulate[|T|||]
+\NC tweak \NC \type {dimensions} \NC \NC \NR
+\NC list  \NC table \NC a hash with treatments \NC \NR
+\stoptabulate
+
+\stopsection
+
+\startsection[title={Primes}]
+
+% \ctxlua{nodes.tasks.disableaction("math","noads.handlers.fixscripts")}
+% \ctxlua{nodes.tasks.enableaction("math","noads.handlers.fixscripts")}
+
+Primes are implemented in a curious way. In traditional \TEX\ they are treated as
+superscripts which is often achieved by making the single quote into an active
+character (in math mode) that takes care of this. The dimensions of a prime are
+such that it comes at the right spot (according to the designers wish). However,
+in \UNICODE\ the same symbol is used for minutes in text mode and because there
+are no duplicates in \UNICODE, it is that already superscripted symbol that we
+see show up in fonts. There is (for some reason) no dedicated single prime slot
+(and one can argue that minutes and primes are really different things and if
+not, why then does greek and latin don't share more).
+
+In \CONTEXT\ we don't want to mess with active characters and even more, we want
+proper symbols for the multiple primes. At the same time we need to handle
+following superscripts as well as cases where a subscript is used as index to a
+nucleus where the whole is then primed. This is implemented in a combination of
+\TEX, \LUA\ and normalized prime symbols.
+
+\startplacefigure[title={Primes Sample 1}]
+    \externalfigure
+        [math-fonts-primes-001.tex]
+        [width=\textwidth]
+\stopplacefigure
+
+Fixing primes boils down to fixing dimensions and repositioning the shape.
+Optionally the multiples can be emulated and a smaller size can be chosen. It's
+also a matter of taste and primes are often not the best designed symbols.
+
+The specification is:
+
+\starttabulate[|T|||]
+\NC tweak   \NC \type {fixprimes} \NC \NC \NR
+\NC factor  \NC number  \NC fraction of the accent base height that the prime shifts up \NC \NR
+\NC smaller \NC boolean \NC when \type {true}, replace multiples \NC \NR
+\NC scale   \NC number  \NC the glyph scale \NC \NR
+\NC fake    \NC number  \NC when set, fake multiples and use this width 0.75 \NC \NR
+\NC keep    \NC boolean \NC keep text size prime as it is \NC \NR
+\stoptabulate
+
+In \MKIV\ we remap primes but in \LMTX\ we adapt the regular slots. As a
+consequence we sacrifice the text size minutes. The \type {keep} option will
+leave the text size variant as it is.
+
+Keep in mind that primes are processed depending on what precedes and follows so
+you cannot really test a character by just calling it: when there is something in
+front it will become a superscripted prime.
+
+\stopsection
+
+\startsection[title={Scripts}]
+
+This tweak will add superscript characters for plus and minus. The main reason
+for them being supplied is that we need them to indicate an explicit (minus)
+sign in calculator math examples.
+
+\startplacefigure[title={Scripts Sample 1}]
+    \externalfigure
+        [math-fonts-scripts-001.tex]
+        [width=\textwidth]
+\stopplacefigure
+
+The specification is:
+
+\starttabulate[|T|||]
+\NC tweak \NC \type {addscripts} \NC \NC \NR
+\NC scale \NC number \NC the scale of the scripted character \NC \NR
+\stoptabulate
+
+Keep in mind that these scripts are processed depending on what precedes so you
+cannot really test a character by just calling it.
+
+\stopsection
+
+\startsection[title={Radicals}]
+
+The traditional \TEX\ engine is made in conjunction with the Computer Modern
+Fonts and there the radical symbol sits below the baseline so that the height
+indicates the rule thickness. In \OPENTYPE\ fonts this is a variable. The Latin
+Modern Math font inherits this somewhat strange position property but we can fix
+that with this tweak:
+
+\startplacefigure[title={Radicals Sample 1}]
+    \externalfigure
+        [math-fonts-radicals-001.tex]
+        [width=\textwidth]
+\stopplacefigure
+
+There are no options:
+
+\starttabulate[|T|||]
+\NC tweak \NC \type {fixradicals} \NC \NC \NR
+\stoptabulate
+
+\stopsection
+
+\startsection[title={Accents}]
+
+We cannot yet tweak accents, but here is an example:
+
+\startplacefigure[title={Accents Sample 1}]
+    \externalfigure
+        [math-fonts-accents-001.tex]
+        [width=\textwidth]
+\stopplacefigure
+
+\stopsection
+
+\startsection[title={Spacing}]
+
+There are \UNICODE\ characters for various spaces and this option defines them
+when they are not present. It is up to the macro package to make sure that the
+non breakable spaces are treated as such. In this document we get:
+
+\def\ShowSpacing#1#2%
+  {\NC \ruledhbox{\showmakeup[glue]\showstruts\strut\char"#1\strut}\NC#2\NC\NR}
+
+\starttabulate[|w(1.5em)|T|]
+    \ShowSpacing{00A0}{nbsp}
+    \ShowSpacing{2000}{enquad}
+    \ShowSpacing{2001}{emquad}
+    \ShowSpacing{2002}{enspace}
+    \ShowSpacing{2003}{emspace}
+    \ShowSpacing{2004}{threeperemspace}
+    \ShowSpacing{2005}{fourperemspace}
+    \ShowSpacing{2006}{sixperemspace}
+    \ShowSpacing{2007}{figurespace}
+    \ShowSpacing{2008}{punctuationspace}
+    \ShowSpacing{2009}{breakablethinspace}
+    \ShowSpacing{200A}{hairspace}
+    \ShowSpacing{200B}{zerowidthspace}
+    \ShowSpacing{202F}{narrownobreakspace}
+    \ShowSpacing{205F}{maththinspace}
+\stoptabulate
+
+There are no options:
+
+\starttabulate[|T|||]
+\NC tweak \NC \type {checkspacing} \NC \NC \NR
+\stoptabulate
+
+\stopsection
+
+\startsection[title=Parameters]
+
+An \OPENTYPE\ math fonts has a lot of parameters and because the engine let you
+set them for every style (regular and cramped) you can exercise a lot of control.
+A difference with traditional math is that we only have one cramped parameter:
+\typ {SuperscriptShiftUpCramped}.
+
+\startbuffer
+\startoverlay
+    {\ruledhbox{$\strut \red  \displaystyle        x^2_1 x^2 x_1$}}
+    {\ruledhbox{$\strut \blue \crampeddisplaystyle x^2_1 x^2 x_1$}}
+\stopoverlay
+\stopbuffer
+
+\typebuffer
+
+Only the superscript is affected (in some miraculous way):
+
+\startlinecorrection
+    \scale[height=3cm]{\switchtobodyfont[pagella]\getbuffer}
+\stoplinecorrection
+
+\stopsection
+
+\stopchapter
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/math/math-layout.tex b/doc/context/sources/general/manuals/math/math-layout.tex
index 3695f9b56..d2ab22196 100644
--- a/doc/context/sources/general/manuals/math/math-layout.tex
+++ b/doc/context/sources/general/manuals/math/math-layout.tex
@@ -4,16 +4,22 @@
 
 \enabledirectives[fontgoodies.mathkerning]
 
-\usebodyfont   [modern]
-\usebodyfont  [cambria]
-\usebodyfont [lucidaot]
-\usebodyfont     [xits]
-\usebodyfont  [stixtwo]
-\usebodyfont   [dejavu]
-\usebodyfont  [pagella]
-\usebodyfont   [termes]
-\usebodyfont    [bonum]
-\usebodyfont   [schola]
+\usebodyfont       [modern]
+\usebodyfont  [modernlatin]
+\usebodyfont      [cambria]
+\usebodyfont     [lucidadk]
+\usebodyfont         [xits]
+\usebodyfont      [stixtwo]
+\usebodyfont       [dejavu]
+\usebodyfont      [pagella]
+\usebodyfont       [termes]
+\usebodyfont        [bonum]
+\usebodyfont       [schola]
+\usebodyfont   [libertinus]
+\usebodyfont   [ebgaramond]
+\usebodyfont      [kpfonts]
+%usebodyfont       [minion]
+%usebodyfont        [asana]
 
 \setupbodyfont % don't change this, it's assumed in examples
   [pagella]