1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
% language=uk
% author : Hans Hagen
% copyright : PRAGMA ADE & ConTeXt Development Team
% license : Creative Commons Attribution ShareAlike 4.0 International
% reference : pragma-ade.nl | contextgarden.net | texlive (related) distributions
% origin : the ConTeXt distribution
%
% comment : Because this manual is distributed with TeX distributions it comes with a rather
% liberal license. We try to adapt these documents to upgrades in the (sub)systems
% that they describe. Using parts of the content otherwise can therefore conflict
% with existing functionality and we cannot be held responsible for that. Many of
% the manuals contain characteristic graphics and personal notes or examples that
% make no sense when used out-of-context.
%
% comment : Some chapters might have been published in TugBoat, the NTG Maps, the ConTeXt
% Group journal or otherwise. Thanks to the editors for corrections. Also thanks
% to users for testing, feedback and corrections.
\usemodule[art-01,abr-02]
\definecolor
[maincolor]
[r=.4]
\definecolor
[extracolor]
[g=.4]
\setupbodyfont
[11pt]
\setuptype
[color=maincolor]
\setuptyping
[color=maincolor]
\definefontsynonym
[TitlePageMono]
[file:lmmonoproplt10-bold*default]
\setuphead
[color=maincolor]
\usesymbols
[cc]
\setupinteraction
[hidden]
\loadfontgoodies[lm]
\startdocument
[metadata:author=Hans Hagen,
metadata:title=Libraries in ConTeXt,
author=Hans Hagen,
affiliation=PRAGMA ADE,
location=Hasselt NL,
title=Libraries in \ConTeXt,
support=www.contextgarden.net,
website=www.pragma-ade.nl]
\startluasetups[swiglib]
context.nohyphens()
for i=1,640 do
context.definedfont { string.formatters["TitlePageMono at %p"](65536*(10+math.random(5))) }
context("Libraries ")
end
context.removeunwantedspaces()
\stopluasetups
\startMPpage
StartPage ;
fill Page enlarged 1cm withcolor \MPcolor{extracolor} ;
draw textext("\framed[loffset=2pt,roffset=2pt,frame=off,width=\paperwidth,align={normal,paragraph,verytolerant,stretch}]{\luasetup{swiglib}}")
xysized (PaperWidth,PaperHeight)
shifted center Page
withcolor .8white ;
draw textext.ulft("\definedfont[TitlePageMono]basics")
xsized .75PaperWidth
shifted lrcorner Page
shifted (-1cm,2cm)
withcolor \MPcolor{maincolor} ;
% draw textext.ulft("\definedfont[TitlePageMono]in context mkiv")
% xsized .6PaperWidth
% shifted lrcorner Page
% shifted (-1cm,6cm)
% withcolor \MPcolor{maincolor} ;
StopPage ;
\stopMPpage
\dontcomplain
\startsubject[title=Contents]
\placelist[section][alternative=a]
\stopsubject
\startsection[title=Introduction]
Not long after we released \LUATEX\ 1.0, we started experimenting a bit more with
so called foreign function interface: \FFI. Originally that interface to external
libraries was only available in \LUAJITTEX, but a good and compatible alternative
is now also available in the normal engine too. For users it is not that relevant
to know how it works, as long as it works. It means that in addition to \SWIGLIB\
we have a method that doesn't demand compilation as it uses normal (public)
libraries.
Of course one needs to make sure that the right version of a library is used.
And, as there is the danger of the \API\ having been changed in an incompatible
way one can wonder if such a dependency is really what one wants. On the other
hand one can expect \CONTEXT\ to keep up.
Do you really need libraries? For instance does it really make sense to use curl,
ghostscript or graphicmagic libraries while the command line version is
(normally) just as efficient and avoids a dependency. This is even more true if
you realizes that for instance a fetch or conversion only needs to happen once
per run or in fact only when there is some change in the resource.
On the other hand, when accessing databases one can avoid the often slower
command line calls and save the hassle of intermediate files. Here efficiency
wins. Also, when \CONTEXT\ is used in a high performance database backend
application a distribution and the used libraries are not updated on a daily
basis.
\stopsection
\startsection[title=Supported]
Apart from some experiments we currently can use \FFI\ interfaced libraries in:
\starttabulate[|l|l|l|l|l|]
\FL
\BC module \BC library \BC windows \BC unix \NC \NR
\ML
\NC util-crl \NC curl \NC libcurl \NC libcurl \NC \NR % todo: client and ffi
\NC util-sql-imp-ffi \NC mysql \NC libmysql \NC libmysqlclient \NC \NR
\NC util-sql-imp-sqlite \NC sqlite \NC sqlite3 \NC sqlite3 \NC \NR
%NC font-phb-imp-library \NC harfbuzz \NC libharfbuzz \NC libharfbuzz \NC \NR % for testing uniscribe (idris fonts)
%NC \NC ghostscript \NC \NC \NC \NR % only a few experiments
%NC \NC graphicmagick \NC \NC \NC \NR % only a few experiments
\LL
\stoptabulate
The profiler that we occasionally use to identify bottlenecks in the engine (for
instance when we upgrade \LUA) uses \FFI\ to provide access to the high resolution
timers but this is typically different per platform.
One problem with libraries, especially on \WINDOWS\ is that the library is found on
some system path and it can happen that multiple programs ship the same library but in
different versions. You can try to play safe and put libraries in the \TEX\ tree, for
instance on my system they are in:
\starttyping
c:/data/tex-context/tex/texmf-win64/bin/lib/luatex/lua/whatever/libwhatever.dll
\stoptyping
You can trace where libraries are looked for with:
\starttyping
\enabletrackers[resolvers.ffilib]
\stoptyping
or in \LUA\ with:
\starttyping
trackers.enable("resolvers.ffilib")
\stoptyping
The library is first located on one of the valid \TDS\ paths (these are sort of
standardized in \TEX\ distributions) and then using the normal \FFI\ loader.
As this is all still experimental in \LUATEX\ there is not much more to say about
it now. Of course this kind of specialized support to a large degree depends on
the need to use it.
\stopsection
\startsection[title=Colofon]
\starttabulate[|B|p|]
\NC author \NC \getvariable{document}{author}, \getvariable{document}{affiliation}, \getvariable{document}{location} \NC \NR
\NC version \NC \currentdate \NC \NR
\NC website \NC \getvariable{document}{website} \endash\ \getvariable{document}{support} \NC \NR
\NC comment \NC many thanks to Luigi Scarso for taking care of ffi support in the engines \NC \NR
\stoptabulate
\stopsection
\stopdocument
|
