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diff --git a/Master/texmf-dist/doc/latex-dev/base/ltnews31.tex b/Master/texmf-dist/doc/latex-dev/base/ltnews31.tex index 69f8dd3cd1e..c365e527c00 100644 --- a/Master/texmf-dist/doc/latex-dev/base/ltnews31.tex +++ b/Master/texmf-dist/doc/latex-dev/base/ltnews31.tex @@ -1,6 +1,6 @@ % \iffalse meta-comment % -% Copyright 2019 +% Copyright 2019-2020 % The LaTeX3 Project and any individual authors listed elsewhere % in this file. % @@ -36,6 +36,7 @@ \usepackage{lmodern,url,hologo} \usepackage{csquotes} +\usepackage{multicol} \providecommand\acro[1]{\textsc{#1}} \providecommand\meta[1]{$\langle$\textit{#1}$\rangle$} @@ -136,72 +137,41 @@ This document is under construction \ldots -\section{Primitive requirements} +\section{Experiences with the \LaTeX\texttt{-dev} formats} -Since the finalisation of \eTeX{} in 1999, a number of additional `utility' -primitives have been added to \pdfTeX{}. Several of these are broadly useful -and have been requirements for \pkg{expl3} for some time, most notably -\cs{pdfstrcmp}. Over time, a common set of these `post-\eTeX{}' primitives have -been incorporated into \XeTeX{} and (u)p-\TeX{}; they were available in -\LuaTeX{} already. +As reported in the previous \emph{\LaTeX{} News}, we have made a pre-release +version of the \LaTeX{} kernel available as \LaTeX\texttt{-dev}. Overall, the +approach of having an explicit testing release has been positive: it is now +readily-available in \TeX{} systems and is getting real use beyond the team. -A number of the additional primitives are needed to support new or improved -functionality in \LaTeX{}. This is seen for example in improved UTF-8 handling, -which uses \cs{ifincsname}. The following primitive functionality (which in -\LuaTeX{} may be achieved using Lua code) will therefore be \emph{required} by -the \LaTeX{} kernel after [INSERT DATE HERE]: -\begin{itemize} - \item \cs{expanded} - \item \cs{ifincsname} - \item \cs{ifpdfprimitive} - \item \cs{pdfcreationdate} - \item \cs{pdfelapsedtime} - \item \cs{pdffiledump} - \item \cs{pdffilemoddate} - \item \cs{pdffilesize} - \item \cs{pdflastxpos} - \item \cs{pdflastypos} - \item \cs{pdfmdfivesum} - \item \cs{pdfnormaldeviate} - \item \cs{pdfpageheight} - \item \cs{pdfpagewidth} - \item \cs{pdfprimitive} - \item \cs{pdfrandomseed} - \item \cs{pdfresettimer} - \item \cs{pdfsavepos} - \item \cs{pdfsetrandomseed} - \item \cs{pdfshellescape} - \item \cs{pdfstrcmp} - \item \cs{pdfuniformdeviate} -\end{itemize} -For ease of reference, these primitives will be referred to as the -`\pdfTeX{} utilities'. +The current +release has been tested by a number of users, and we have had useful feedback +on a range of new ideas. This has allowed us to fix issues in several of the +new features described below. We thank the dedicated users who have been +trying out the development formats, and encourage others to do so. Pre-testing +in this way does mean that for the vast majority of users, problems are solved +before they even appear! -Engines which are fully Unicode-capable must all provide the following -primitives -\begin{itemize} - \item \cs{Uchar} - \item \cs{Ucharcat} - \item \cs{Umathcode} -\end{itemize} -In particular, note that \cs{Umathcode} is used as a marker primitive for -this capability. +\section{Concerning this pre-release \ldots} -\section{Experiences with the \LaTeX\texttt{-dev} formats} +In \TeX{}Live 2020 the Lua\LaTeX{} format will use the new LuaHB\TeX{} +engine, which is Lua\TeX{} with an embedded HarfBuzz library. +HarfBuzz can be used by setting a suitable renderer in the font +declaration. A basic interface for that is provided by \pkg{fontspec}. +This additional font renderer will greatly improve the shaping of +various scripts, which are currently handled correctly only by +\XeTeX{}. To simplify the testing of the new engine, binaries have +been already added to MiK\TeX{} and \TeX{}Live 2019 and both have changed +the Lua\LaTeX-dev format to use it. -\emph{write} -In TeXLive 2020 the Lua\LaTeX{} format will use the new LuaHB\TeX{} engine, which is Lua\TeX{} with an embedded HarfBuzz library. -HarfBuzz can be used by setting a suitable renderer in the font declaration. An interface for that is provided by \pkg{fontspec}. -This additional font renderer will greatly improve the shaping of various scripts, which are currently handled correctly only by \XeTeX{}. -To simplify the testing of the new engine, binaries have been added to MiKTeX and TeXLive 2019 and both have changed the Lua\LaTeX-dev format to use it. \section{Improved load-times for \pkg{expl3}} The \LaTeX3 programming layer, \pkg{expl3}, has over the past decade moved from being largely experimental to broadly stable. It is now used in a significant number of third-party packages, most notably \pkg{xparse} for defining -interfaces in cases where no \pkg{expl3} code is \enquote{visible}. Most +interfaces in cases where no \pkg{expl3} code is \enquote{visible}. In addition, most \LaTeX{} documents compiled using \XeTeX{} or \LuaTeX{} load \pkg{fontspec}, which is written using \pkg{expl3}. @@ -221,28 +191,482 @@ eventually, it will be possible to omit \end{verbatim} entirely, but to support older formats, this is still recommended at present. + + + + + +\section[Improvements to \LaTeX{}'s font selection\\ mechanism (NFSS)] + {Improvements to \LaTeX{}'s font selection\\ mechanism (NFSS)} + + +\subsection{Extending the shape management of NFSS} + +Over time more and more fonts have become available for use with +\LaTeX{}. Many such font families offer additional shapes, e.g., small +caps italics (\texttt{scit}), small caps slanted (\texttt{scsl} or +swash letters (\texttt{sw}). By using \cs{fontshape} those shapes can +be explicitly selected and for the swash letter shapes there is also +\cs{swshape} and \cs{textsw} available. + +In the original font selection implementation a request to select a new shape +always overrode the current shape. With the 2020 release of \LaTeX{} +this has changed and \cs{fontshape} can now be used to combine small +capitals with italics, slanted or swash letters, either by explicitly +asking for \texttt{scit}, etc., or by asking for italics when typesetting +already in small caps and so forth. + +Using \cs{upshape} will still change italics or slanted back to an +upright shape but will not any longer alter the small caps setting. To +change small capitals back to upper/lower case you can now use +\cs{ulcshape} (or \cs{textulc}) which in turn will not change the font +with respect to italics, slanted or swash. +% +There is one exception: for compatibility reasons \cs{upshape} will +change small capitals back to upright (\texttt{n} shape), if the +current shape is \texttt{sc}. This is done so that something like +\cs{scshape}\allowbreak\texttt{...}\allowbreak\cs{upshape} continues +to work, but we suggest that you don't use that deprecated method in +new documents. + +Finally, if you want to +reset the shape back to normal you can use \cs{normalshape} which is a +shorthand for \cs{upshape}\cs{ulcshape}. + +The way that shapes combine with each other is not hardwired but is +customizable and extensible if there is ever a need for it. The +mappings are defined through \cs{DeclareFontShapeChangeRule} and the +details for developers are documented in \texttt{source2e.pdf}. + +The ideas for this interface extension have been pioneered in +\pkg{fontspec} by Will Robertson for Unicode engines and in +\pkg{fontaxes} by Andreas Bühmann and Michael Ummels for \pdfTeX{} and +used in many font support packages. + + + +\subsection{Extending the series management of NFSS} + +Many of the the newer font families also come provided with additional +weights (thin, semi-bold, ultra-bold, etc.\@) or several running lengths +such a condensed or extra-condensed. In some cases the number of +different series values is really impressive, for example, Noto Sans +offers 36 fonts from ultra-light extra condensed to ultra-bold medium width. + +Already in its original design, NFSS supported 9 weight levels from +ultra-light (\texttt{ul}) to ultra-bold (\texttt{ub}) and also 9 width +levels from ultra-condensed (\texttt{uc}) to ultra-expanded +(\texttt{ux}) so more than enough even for a font family like Noto +Sans. Unfortunately, some font support packages nevertheless invented +their own names so in recent years you could find all kinds of +non-standard series names like \texttt{k}, \texttt{i}, \texttt{j} and +others making it impossible to combine different fonts successfully +using the standard NFSS mechanisms. + +Over the course of the last year a small number of individuals, +notably, Bob Tennent, Michael Sharpe and Marc Penninga worked hard to +bring this unsatisfying situation back under control and today we are +happy to report that the internal font support files for more than a +hundred font families are back to following the standard NFSS conventions +so that combining them is now again rather nice and easy (of course, +there is still the task of choosing combinations that visually work +well together, but from a technical perspective they can now easily +matched). + + +In the original font selection implementation, a request to select a new series +always overrode the current one. This was reasonable because there +were nearly no fonts available that offered anything other than a +medium or a bold series. Now that this has changed and families such +as Noto Sans are available, combining weight and width into a single +attribute is no longer appropriate. With the 2020 release of \LaTeX{} +the series management therefore changed to allow for independently +setting the weight and the width attribute of the series. + +For most users this change will be largely transparent as \LaTeX{} +offers only \cs{textbf} or \cs{bfseries} to select a bolder face (and +\cs{textmd} and \cs{mdseries} to return to a medium series) but no +high-level command for selecting a condensed face, etc. However, with +the NFSS low-level interface, it is now possible to ask for, say, +\verb=\fontseries{c}\selectfont= in a marginal note to get a condensed +face and that would still allow using \cs{textbf} inside. This then would +select a bold condensed face and not a rather odd-looking +bold-extended face in the middle of condensed type. + +The expectation is that this functionality is largely used by class and package +designers, but given that the low-level NFSS commands are usable on +the document level and not really difficult to apply, there are +probably also a number of users who will enjoy using the new +possibilities that bring \LaTeX{} back into the front league when it +comes to font usage. + +The way different series values combine with each other is not +hardwired but is again customizable and extensible. The mappings are +defined through \cs{DeclareFontSeriesChangeRule} and the details for +developers are documented in \texttt{source2e.pdf}. + + + +\subsection{Font series defaults per document family} + +With additional weights and widths available in many font families it +becomes more likely that somebody wants to match, say, a medium weight +serif family with a semi-light sans serif family or that with one +family one wants to use the bold-extend face when \cs{textbf} is used +while with another it should be bold (not extended) or semibold, etc. + +In the past this kind of extension was made available with the +\pkg{mweights} package by Bob Tennent which has been used in many font +support packages. + +With the 2020 release of \LaTeX{} this feature is now available out +of the box. In addition we also offer a document-level interface to adjust the +behavior of the high-level series commands \cs{textbf}, \cs{textmd} and their +declaration forms \cs{bfseries} and \cs{mdseries} so that they can +have different effects for the serif, sans serif and typewriter +families used in a document. + +For example, specifying +\begin{verbatim} + \DeclareFontSeriesDefault[rm]{bf}{sb} + \DeclareFontSeriesDefault[tt]{md}{lc} +\end{verbatim} +in the document preamble would result in \cs{textbf} producing +semi-bold (\texttt{sb}) when typesetting in roman typeface and +that typewriter is by default (medium series \texttt{md}) using +a light-condensed face. The optional argument here can be either +\texttt{rm}, \texttt{sf} or \texttt{tt} to indicate one of the three +main font families in a document; if omitted you will change the +overall document default instead. In the first mandatory argument you +specify either \texttt{md} or \texttt{bf} and the second mandatory +argument then gives the desired series value in NFSS nomenclature. + + +\subsection{Emphasis handling generalized} + +With previous releases of \LaTeX{} nested \cs{emph} commands +automatically alternated between italics and upright. This mechanism +has now been generalized and you can now specify for arbitrary nesting +levels how emphasis should be handled. + +The declaration \cs{DeclareEmphSequence} expects a comma separated +list of font declarations corresponding to increasing levels of +emphasis. For example, +\begin{verbatim} + \DeclareEmphSequence{\itshape,% + \upshape\scshape,\itshape} +\end{verbatim} +uses italics for the first, small capitals for the second, and italic +small capitals for the third level (provided you use a font that +supports these shapes). If there are a more nesting levels than +provided, \LaTeX{} uses the declarations stored in \cs{emreset} (by +default \cs{ulcshape}\cs{upshape}) for the next level and then +restarts the list. + +The mechanism tries to be \enquote{smart} and verifies that the given +declarations actually alter the current font. If not it continues and +tries the next level---the assumption being that there was already a +manual font change in the document to the font that is now supposed to +be used for emphasis. +% +Of course, this only works if the declarations in the list entries +actually change the font and not, for example, just the color. In such +a scenario one has to add \cs{emforce} to the entry which directs the +mechanism to use the level, even if the font attributes appear to be +unchanged. + + + +\subsection{Providing font family substitutions} + +Given that \pdfTeX{} can only handle fonts with up to 256 glyphs a +single font encoding can only support a few languages. The \texttt{T1} +encoding, for example, does support many of the Latin based scripts, +but if you want to write in Greek or Russian you need to switch +encodings to \texttt{LGR} or \texttt{T2A}. Given that not every font +family offers glyphs in such encodings, you may end up with some +default family (e.g., Computer Modern) that doesn’t blend in well +chosen document font. For such cases NFSS now offers +\cs{DeclareFontFamilySubstitution}, for example: +\begin{verbatim} + \DeclareFontFamilySubstitution{LGR} + {Montserrat-LF}{IBMPlexSans-TLF} +\end{verbatim} +tells \LaTeX{} that if you are typesetting in the sans serif font +\texttt{Montserrat-LF} and the Greek encoding \texttt{LGR} is asked +for, then \LaTeX{} should use \texttt{IBMPlexSans-TLF} to fulfill the +encoding request. + +The code is based on ideas from the \pkg{substitutefont} +package by Günter Milde, but implemented differently. + + +\subsection{Providing all text companion symbols by default} + +The text companion encoding \texttt{TS1} was originally not available +by default, but only when the \pkg{textcomp} package was loaded. The +main reason for this was limited availability in fonts other than +Computer Modern and memory restrictions back in the nineties. These +days neither limitation exists any more so with the 2020 release all +the symbols provided with the \pkg{textcomp} package are available out +of the box. + +Furthermore, an intelligent substitution mechanism has been +implemented so that missing glyphs are automatically substituted with +defaults that are sans serif if you typeset in \cs{textsf} and +monospaced if you typeset using \cs{texttt} and not always serifed. + + +\textsf{This is most noticeable with \cs{oldstylenums} which are now + taken from \texttt{TS1} so that you no longer get + \textrm{\oldstylenums{123}} but \oldstylenums{123} when typesetting + in sans serif fonts}\texttt{ and \oldstylenums{123} when using + typewriter fonts.} + +If there ever is a need to use the original (inferior) definition, +then that remains available as \cs{legacyoldstylenums} and to fully +revert to the old behavior there is also +\cs{UseLegacyTextSymbols}. That declaration reverts \cs{oldstylenums} +and also changes the footnote symbols, such as \cs{textdagger}, +\cs{textparagraph}, etc.\ pick up their glyphs again from the math +fonts instead of the current text font (this means they always keep +the same shape and do not nicely blend in with the text font). + +With the text companion symbols as part of the kernel it is normally +no longer necessary to load the \pkg{textcomp} package, but for +backwards compatibility this package will remain available. There is, +however, one use case where it remains useful: if you load the package +with the option \texttt{error} or \texttt{warn} then substitutions +will change their behavior and result in a \LaTeX{} error or a +\LaTeX{} warning (on the terminal), respectively. Without the package +the substitution information only appears in the \texttt{.log} +file. If you use the option \texttt{quit}, then even the information in +the transcript is suppressed (which is not really recommended). + \section{Other changes to the \LaTeX{} kernel} -\emph{fixed gh198} +\subsection{New \texttt{alias} size function for use in \texttt{.fd} files} +Most of the newer fonts supported in \TeX{} have been set up with the +\texttt{autoinst} tool by Marc Penninga. In the past this program did +set up the font faces using the face names chosen by its designer, +e.g., \enquote{\texttt{regular}}, \enquote{\texttt{bold}}, etc., and +then mapped those via substitution to the standard NFSS shape names, +i.e., \enquote{\texttt{m}} or \enquote{\texttt{b}}. As a result one +got unnecessary substitution warnings such as \enquote{\texttt{Font + T1/abc/bold/n not found using T1/abc/b/n instead}}. -\section{Changes to packages in the \pkg{tools} category} +We now provide a new NFSS \texttt{alias} size function that can and will be +used by \texttt{autoinst} in the future. It provides the same +functionality as the \texttt{subst} function but is less vocal about +its actions, such that only relevant font substitutions show up as +warnings. + + + + + +\subsection{UTF-8 characters in package descriptions} + +In 2018 we made UTF-8 the default input encoding for \LaTeX{} but we +overlooked the case of package descriptions in declarations such as +\cs{ProvidesPackage} which worked (sometimes) before but now died +always. This has been corrected. +\githubissue{52} + + +\subsection{Suppress unnecessary font substitution warnings} -\emph{fixed gh190} +Many sans serif fonts do not have real italics but usually only +oblique/slanted shapes, so the substitution of slanted for italics is +natural and in fact many designers talk about italic sans serif faces +even if in reality they are oblique. With nearly all sans serif font +family the \LaTeX{} support files therefore silently substitute +slanted if you ask for \cs{itshape} or \cs{textit}. This is also true +for Computer Modern in \texttt{T1} encoding but in \texttt{OT1} you +got a warning on the terminal even though there is nothing you can do +about it. This has now been changed to an information message only +written to the \texttt{.log} file. +% +\githubissue{172} + + +\subsection{Fix inconsistent hook setting when loading packages} + +When a package is loaded +\texttt{\textbackslash}\textit{package}\texttt{.sty-h@@k} is set, but +it was loaded several times it was unset again. Relevant only to +package developers. +% +\githubissue{198} +\subsection{Avoid spurious warning if \texttt{LY1} is made the default encoding} + +Making \texttt{LY1} the default encoding as done by some font support +packages gave a spurious warning even if \cs{rmdefault} was changed +first. This was corrected. +% +\githubissue{199} -\section{Changes to packages in the \pkg{amsmath} category} +\subsection{Ensure that \cs{\textbackslash} remains robust} +In the last release we made most document-level commands robust, but +\cs{\textbackslash} became fragile again if \cs{raggedright} +typesetting was used. +% +\githubissue{203} -\section{Documentation updates} +\subsection{Allow more write streams with \texttt{filecontents} in \LuaTeX} + +Most \TeX{} engines only support a maximum of sixteen concurrently +open write streams and if those have been used up, then +\texttt{filecontents} or any other code trying to open another one +will fail. In \LuaTeX{} more write streams are available and those can +now be utilized as well. +% +\githubissue{238} +\section{Changes to packages in the \pkg{graphics} category} + +\subsection[Make \pkg{color}/\pkg{graphics} user-level commands robust] + {Make \pkg{color} \& \pkg{graphics} user-level commands robust} + +Some of the user-level commands of \pkg{color}, \pkg{graphics} and +\pkg{graphicx} such as \cs{textcolor} or \cs{includegraphics} were +still fragile, so didn't work in moving arguments without extra +protection. All of them have now been made robust. +% +\githubissue{208} + + + + +\section{Changes to packages in the \pkg{tools} category} + +\subsection{Fixed column depth in boxed \texttt{multicols}} + +The \texttt{multicols} environment was setting \cs{maxdepth} when +splitting boxes but the way the internal interfaces of \LaTeX{} are +designed it should have used \cs{@maxdepth} instead. As a result +balanced boxed multicols sometimes ended up having different height +even if they had exactly the same content. +% +\githubissue{190} + + +\subsection{Ensure that \texttt{multicols} is not losing text} + +The \texttt{multicols} environment needs a set of consecutive boxes to +collect column material. The way those got allocated could result in +disaster if other packages allocated most boxes below box 255 (which +\TeX{} always uses for the output page). In the original +implementation that problem was identified because one could only +allocate boxes below 255, but nowadays the \LaTeX{} allocation routine +allows allocating boxes below and above 255. So the assumption that +asking for, say 20 boxes you get a consecutive sequence of box +registers was no longer true and so some of the column material could +end in box 255 and be overwritten. This has now been corrected by +allocating all necessary boxes above 255 if there aren't enough +registers available. +% +\githubissue{237} + +\subsection{Allow spaces in \cs{hhline} arguments} + +The verb \verb|\hhline| command which allows +specification of rule segments in \texttt{tabular} environments now +allows (and ignores) spaces between its tokens so +\verb|\hhline{: = : =}| is now allowed and equivalent to +\verb|\hhline{:=:=}|. This matches similar token arguments in \LaTeX{} +such as the \verb|[h t p]| argument on floats. A similar change has +been made to the extended \verb|\hhline| command in the +\texttt{colortbl} package. +% +\githubissue{242} + + + +\section{Primitive requirements} + +Since the finalization of \eTeX{} in 1999, a number of additional `utility' +primitives have been added to \pdfTeX{}. Several of these are broadly useful +and have been requirements for \pkg{expl3} for some time, most notably +\cs{pdfstrcmp}. Over time, a common set of these `post-\eTeX{}' primitives have +been incorporated into \XeTeX{} and (u)p-\TeX{}; they were available in +\LuaTeX{} already. + +A number of the additional primitives are needed to support new or improved +functionality in \LaTeX{}. This is seen for example in improved UTF-8 handling, +which uses \cs{ifincsname}. The following primitive functionality (which in +\LuaTeX{} may be achieved using Lua code) will therefore be \emph{required} by +the \LaTeX{} kernel from the start of 2021: +% +\begingroup\setlength\columnsep{0pt} +\begin{multicols}{2} +\begin{itemize} + \item \cs{expanded} + \item \cs{ifincsname} + \item \cs{ifpdfprimitive} + \item \cs{pdfcreationdate} + \item \cs{pdfelapsedtime} + \item \cs{pdffiledump} + \item \cs{pdffilemoddate} + \item \cs{pdffilesize} + \item \cs{pdflastxpos} + \item \cs{pdflastypos} + \item \cs{pdfmdfivesum} + \item \cs{pdfnormaldeviate} + \item \cs{pdfpageheight} + \item \cs{pdfpagewidth} + \item \cs{pdfprimitive} + \item \cs{pdfrandomseed} + \item \cs{pdfresettimer} + \item \cs{pdfsavepos} + \item \cs{pdfsetrandomseed} + \item \cs{pdfshellescape} + \item \cs{pdfstrcmp} + \item \cs{pdfuniformdeviate} +\end{itemize} +\end{multicols} +\endgroup +% +For ease of reference, these primitives will be referred to +as the `\pdfTeX{} utilities'. With the exception of \cs{expanded}, +these have been present in \pdfTeX{} since the release of version +1.40.0 in 2007; \cs{expanded} was added for \TeX{}~Live +2019. Similarly, the full set of utility primitives have been +available in \XeTeX{} from the 2019 \TeX{}~Live release, and have +always been available in \LuaTeX{} (some by Lua emulation). p\TeX{} +and up\TeX{} gained all of the above bar \cs{ifincsname} for +\TeX{}~Live 2019, and will have that primitive from the 2020 release. + +At the same time, engines which are fully Unicode-capable must all +provide the following primitives +% +\begingroup\setlength\columnsep{0pt} +\begin{multicols}{2} +\begin{itemize} + \item \cs{Uchar} + \item \cs{Ucharcat} + \item \cs{Umathcode} +\end{itemize} +\end{multicols} +\endgroup +% +Note that it has become standard practice to check for Unicode-aware +engines with the existence of the \cs{Umathcode} primitive. As such, +this is already a requirement: engines lacking these primitives cannot +access Unicode features of the \LaTeXe{} kernel or of +\pkg{expl3}. Note that up\TeX{} has facilities for handling Unicode +but is not classed as a Unicode engine by the base LaTeX code. + \begin{thebibliography}{9} %\fontsize{9.3}{11.3}\selectfont @@ -261,10 +685,6 @@ entirely, but to support older formats, this is still recommended at present. \emph{\LaTeX{} documentation on the \LaTeX{} Project Website}.\\ \url{https://latex-project.org/documentation/} -%\bibitem{31:site-pub} -% \emph{\LaTeX{} Project publications on the \LaTeX{} Project Website}.\\ -% \url{https://latex-project.org/publications/} - \end{thebibliography} \end{document} |