diff options
Diffstat (limited to 'luaotfload.dtx')
| -rw-r--r-- | luaotfload.dtx | 194 |
1 files changed, 191 insertions, 3 deletions
diff --git a/luaotfload.dtx b/luaotfload.dtx index 7ccd6e8..e576112 100644 --- a/luaotfload.dtx +++ b/luaotfload.dtx @@ -187,11 +187,14 @@ and the derived files {\normalsize\rmfamily\bfseries} {\movecountertomargin\thepart} \zeropoint {} \titleformat \section - {\normalsize\rmfamily\scshape}%% no \word; life is full of disappointments + {\normalsize\rmfamily\scshape} {\movecountertomargin\thesection} \zeropoint {} \titleformat \subsection {\small\rmfamily\itshape} {\movecountertomargin\thesubsection} \zeropoint {} +\titleformat \subsubsection + {\normalsize\rmfamily\upshape} + {\movecountertomargin\thesubsubsection} \zeropoint {} \usepackage{tocloft} \renewcommand \cftpartfont {\rmfamily\upshape} @@ -1178,6 +1181,174 @@ and the derived files % \label{file-graph} % \end{figure} % +% \section{Auxiliary Functions} +% +% With release version 2.2, \identifier{luaotfload} received +% additional functions for package authors to call from outside +% (see the file \fileent{luaotfload-auxiliary.lua} for details). +% The purpose of this addition twofold. +% Firstly, \identifier{luaotfload} failed to provide a stable interface +% to internals in the past which resulted in an unmanageable situation +% of different packages abusing the raw access to font objects by means +% of the \luafunction{patch_font} callback. +% When the structure of the font object changed due to an update, all +% of these imploded and several packages had to be fixed while +% simultaneously providing fallbacks for earlier versions. +% Now the patching is done on the \identifier{luaotfload} side and can +% be adapted with future modifications to font objects without touching +% the packages that depend on it. +% Second, some the capabilities of the font loader and the names +% database are not immediately relevant in \identifier{luaotfload} +% itself but might nevertheless be of great value to package authors or +% end users. +% +% Note that the current interface is not yet set in stone and the +% development team is open to suggestions for improvements or +% additions. +% +% \subsection{Callback Functions} +% +% The \luafunction{patch_font} callback is inserted in the wrapper +% \identifier{luaotfload} provides for the font definition callback +% (see below, page \pageref{define-font}). +% At this place it allows manipulating the font object immediately after +% the font loader is done creating it. +% For a short demonstration of its usefulness, here is a snippet that +% writes an entire font object to the file \fileent{fontdump.lua}: +% +% \begin{quote} +% \begin{verbatim} +% \input luaotfload.sty +% \directlua{ +% local dumpfile = "fontdump.lua" +% local dump_font = function (tfmdata) +% local data = table.serialize(tfmdata) +% io.savedata(dumpfile, data) +% end +% +% luatexbase.add_to_callback( +% "luaotfload.patch_font", +% dump_font, +% "my_private_callbacks.dump_font" +% ) +% } +% \font\dumpme=name:Iwona +% \bye +% \end{verbatim} +% \end{quote} +% +% \emphasis{Beware}: this creates a Lua file of around 150,000 lines of +% code, taking up 3~\abbrev{mb} of disk space. +% By inspecting the output you can get a first impression of how a font +% is structured in \LUATEX’s memory, what elements it is composed of, +% and in what ways it can be rearranged. +% +% \subsubsection{Compatibility with Earlier Versions} +% +% As has been touched on in the preface to this section, the structure +% of the object as returned by the fontloader underwent rather drastic +% changes during different stages of its development, and not all +% packages that made use of font patching have kept up with every one +% of it. +% To ensure compatibility with these as well as older versions of +% some packages, \identifier{luaotfload} sets up copies of or references +% to data in the font table where it used to be located. +% For instance, important parameters like the requested point size, the +% units factor, and the font name have again been made accessible from +% the toplevel of the table even though they were migrated to different +% subtables in the meantime. +% +% \subsubsection{Patches} +% +% These are mostly concerned with establishing compatibility with +% \XETEX. +% +% \begin{itemize} +% \let\normalitem=\item +% \def\ouritem#1{% +% \normalitem{\luafunction{#1}}% +% \hfill\break +% } +% +% \ouritem {set_sscale_dimens} +% Calculate \texmacro{fontdimen}s 10 and 11 to emulate \XETEX. +% +% \ouritem {set_capheight} +% Calculates \texmacro{fontdimen} 8 like \XETEX. +% +% \ouritem {patch_cambria_domh} +% Correct some values of the font \emphasis{Cambria Math}. +% +% \end{itemize} +% +% \subsection{Package Author’s Interface} +% +% As \LUATEX release 1.0 is nearing, the demand for a reliable interface +% for package authors increases. +% +% \subsubsection{Font Properties} +% +% Below functions mostly concern querying the different components of a +% font like for instance the glyphs it contains, or what font features +% are defined for which scripts. +% +% \begin{itemize} +% \let\normalitem=\item +% \def\ouritem#1{% +% \normalitem{\luafunction{#1}}% +% \hfill\break +% } +% +% \ouritem {aux.font_has_glyph (id : int, index : int)} +% Predicate that returns true if the font \luafunction{id} +% has glyph \luafunction{index}. +% +% \ouritem {aux.slot_of_name(name : string)} +% Translates an Adobe Glyph name to the corresponding glyph +% slot. +% +% \ouritem {aux.name_of_slot(slot : int)} +% The inverse of \luafunction{slot_of_name}; note that this +% might be incomplete as multiple glyph names may map to the +% same codepoint, only one of which is returned by +% \luafunction{name_of_slot}. +% +% \ouritem {aux.provides_script(id : int, script : string)} +% Test if a font supports \luafunction{script}. +% +% \ouritem {aux.provides_language(id : int, script : string, language : string)} +% Test if a font defines \luafunction{language} for a given +% \luafunction{script}. +% +% \ouritem {aux.provides_feature(id : int, script : string, +% language : string, feature : string)} +% Test if a font defines \luafunction{feature} for +% \luafunction{language} for a given \luafunction{script}. +% +% \ouritem {aux.get_math_dimension(id : int, dimension : string)} +% Get the dimension \luafunction{dimension} of font \luafunction{id}. +% +% \ouritem {aux.sprint_math_dimension(id : int, dimension : string)} +% Same as \luafunction{get_math_dimension()}, but output the value +% in scaled points at the \TEX end. +% +% \end{itemize} +% +% \subsubsection{Database} +% +% \begin{itemize} +% \let\normalitem=\item +% \def\ouritem#1{% +% \normalitem{\luafunction{#1}}% +% \hfill\break +% } +% +% \ouritem {aux.scan_external_dir(dir : string)} +% Include fonts in directory \luafunction{dir} in font lookups without +% adding them to the database. +% +% \end{itemize} +% % \section{Troubleshooting} % % If you encounter problems with some fonts, please first update to the latest @@ -1215,6 +1386,22 @@ and the derived files % \font\test=file:MyFont.otf:script=latn;+liga; % \end{verbatim} % +% Another strategy that helps avoiding problems is to not access raw \LUATEX +% internals directly. +% Some of them, even though they are dangerous to access, have not been +% overridden or disabled. +% Thus, whenever possible prefer the functions in the +% \luafunction{aux} namespace over direct manipulation of font objects. +% For example, raw access to the \luafunction{font.fonts} table like: +% +% \begin{verbatim} +% local somefont = font.fonts[2] +% \end{verbatim} +% +% can render already defined fonts unusable. +% Instead, the function \luafunction{font.getfont()} should be used because +% it has been replaced by a safe variant. +% % \part{Implementation} % % \section{\fileent{luaotfload.lua}} @@ -1592,8 +1779,8 @@ add_to_callback("hpack_filter", add_to_callback("find_vf_file", find_vf_file, "luaotfload.find_vf_file") -loadmodule"lib-dir.lua" --- required by luaofload-database.lua -loadmodule"override.lua" --- “luat-ovr” +loadmodule"lib-dir.lua" --- required by luaofload-database.lua +loadmodule"override.lua" --- “luat-ovr” logs.set_loglevel(config.luaotfload.loglevel) @@ -1723,6 +1910,7 @@ create_callback("luaotfload.patch_font", "simple", dummy_function) % \end{macrocode} % \subsection{\CONTEXT override} +% \label{define-font} % We provide a simplified version of the original font definition % callback. % |