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Added a hidden anchor because you can't link to a heading that has command names in it.
will cause ConTeXt to break the page.
Ordinarily this works as expected, unless, however, the heading
immediately follows a previous section heading with no text in between.
The rationale behind this is that consecutive headings are conceived of
collectively as one single structural element.
(For the curious, the explanation can be found in the definition of the
macro {{cmd|\strc_sectioning_handle_page_nop|link=no}} in {{src|strc-sec.mkiv}}).
as in the Plain format) and the more familiar {{cmd|dontleavehmode}}
({{src|syst-aux.mkiv}}).
Just use the chosen macro immediately before the <code>\framed</code> macro and
everything should be fine:
This is a [[Right_and_left|FAQ item]].
<span id="setupnotation v setupnote"></span>
== Footnotes: The Difference between {{cmd|setupnotation}} and {{cmd|setupnote}} ==
(For more definite answers concerning the ''notes'' mechanism, use the
source, Luke: {{src|strc-not.mkvi}}.)
== Float Insertion Issues ==
</texcode>
Another solution can be the less -known ''hangaround environment''
({{cmd|starthangaround}}, cf.
[[Using_Graphics#Flow_text_around_a_picture|Hangaround]]).
(If you desparately need separate captions please send a feature
request to one of the
[[ConTeXt_Mailing_Lists#Mailing ListsMailing_Lists]]).
<context source="yes" mode="mkii">
\stoptext
</context>
=== The “paragraph in a group” problem ===
Another common issue with sidefloats is starting a paragraph in a group.
<context source="yes" mode="mkiv">
\placefigure[right,none]{}{\externalfigure[cow][width=0.25\textwidth]}
Lorem ipsum dolor sit amet, consectetur adipiscing elit.
{\bf Oeps} \samplefile{lorem}
</context>
As you can see the paragraph starting with “Oeps” just overflows into the picture.
That is a well-known problem and there are posts about it on the mailing
list every once in a while. The sidefigure mechanism uses <code>\parshape</code> to
make the paragraph flow around the figure. The <code>\parshape</code> primitive only
applies to a single paragraph, so ConTeXt communicates the current
<code>\parshape</code> settings to the next paragraph using <code>\everypar</code>. However, when
a new paragraph starts in a group, i.e.
<texcode>
{\bf Oeps} ...
</texcode>
TeX inserts the <code>\everypar</code> tokens inside that group because only the
first letter starts the paragraph. That is to say is effectively looks
like this
<texcode>
% \everypar inserted inside the group
% ~~~v
{\bf \the\everypar Opes} ...
% ~~~~~~~~~~~~~~~~~~~~~^
% Setting of \everypar are discarded again when leaving the group and \parshape is lost.
</texcode>
You have to explicitly start a new paragraph before opening a group.
The easiest way to do this is
<texcode>
\dontleavehmode{\bf Oeps} ...
</texcode>
Now the <code>\everypar</code> tokens are inserted directly after {{cmd|dontleavehmode}}
outside the group and the problem goes away.
= Syntax =
== Assignments ==
Spaces before commas or before the closing <code>]</code> are '''''not''''' ignored in ConTeXt. That is a common pitfall and leads to errors that can be confusing for beginner, especially those coming from LaTeX, where this is the default behaviour. Formatting your keys like this might look nice but leads to spurious spaces:
<context source="yes" mode="mkiv">
\getparameters[test]
[ foo=bar
, hello=world
]
“\testfoo” “\testhello”
</context>
Instead it is recommended to adhere to the style that is used in the ConTeXt source to avoid problems with trailing spaces:
<context source="yes" mode="mkiv">
\getparameters[test]
[foo=bar,
hello=world]
“\testfoo” “\testhello”
</context>
In the most common form of key-value type arguments, ConTeXt will
What’s the status of this?
-->
== Disappearing Crop Marks Treacherous Dimensions ==Crop marksAt some places dimension-lookalikes are expected but they do not behaveexactly as in TEX per se because they are evaluated differently.A very common example is the command {{cmd|setupbodyfont}} that ispossibly called, albeit implicitly, in every production document.Its argument, the ''font size'', although it may look like an ordinarydimension expression, activated will not have the same result if it has zerosprepended or decimal places are specified. Suppose you want to set the main font to a very large size: <texcode>\setupbodyfont[42pt]\starttext foobar \stoptext</texcode> this works out well aslong as you do not mistake the expression''42pt'' to be a real dimension. In TEX dimensions (which are really just integers) are treated the sameirrespective of leading or trailing zeros used in the variableassignment.Thus the following are all equivalent: <texcode>\newdimen\fortytwo\fortytwo=42pt\newdimen\fortytoo\fortytoo=042pt\newdimen\fortytww\fortytww=42.00pt \starttext \the\fortytwo\ \ifnum\fortytwo=\fortytoo\m{\top}\else\m{\bot}\fi\par \the\fortytoo\ \ifnum\fortytwo=\fortytww\m{\top}\else\m{\bot}\fi\par \the\fortytww\ \ifnum\fortytoo=\fortytww\m{\top}\else\m{\bot}\fi\par\stoptext</texcode> However, this does not hold for the Context commands{{cmd|setupbodyfont}} and {{cmd|switchtobodyfont}}.With the latter macros, only the ''pure-integer'' specification(<code>42pt</code>) can be used reliably, everything else, even though itdenotates the same TEX dimension, will result in a warning: <pre>fonts > bodyfont 42.0pt is defined (can better be done global)</pre> Additionally, if the code in question relies on font switching a lot(e. g. Lua snippets that calculcate font sizes from floating pointnumbers), there will be a ''huge'' perfomance penalty because everytimea font switch occurs, the font will be reloaded entirely.The reason for this is that the process of defining a font for the maintext is accompanied by a myriad of secondary definitions for differentrelative font sizes ({{cmd|tfx|link=no}}, {{cmd|tfa|link=no}}[[Font_Switching#Font_sizes|and the likes]]) and shapes – thecreation of the ''body font environment''.If the “size” requested by {{cmd|setupbodyfont}} cannot be found in theinternal table, this environment will be rebuilt on the spot. ''It is also not possible to catch these cases by predefining the corresponding bodyfont environments''by placing {{cmd|definebodyfontenvironment}} statements in the preamble.So if you have, say: <texcode>\definebodyfontenvironment[42.0pt]\definebodyfontenvironment[042pt]\definebodyfontenvironment[042.0pt]\starttext \setupbodyfont[42.0pt] foo bar \setupbodyfont[042pt] foo bar \setupbodyfont[042.0pt] foo bar\stoptext</texcode> the warning and slowdown will occur regardless.The only real option is to serve {{cmd|setupbodyfont}} and the likesnatural integers only. Alternatively you can always employ raw font definitions, if thereisn’t any need for the environment in the first place:<texcode>\starttext \definedfont[file:iwona-regular.otf at 42.0pt] foo bar \definedfont[file:iwona-regular.otf at 042pt] foo bar \definedfont[file:iwona-regular.otf at 042.0pt] foo bar\stoptext</texcode>Here the dimensions are ''real''. For further information see[http://www.ntg.nl/pipermail/ntg-context/2012/067324.html this] and[http://www.ntg.nl/pipermail/ntg-context/2012/066940.html this]thread on the mailing list. = Multipass = In some circumstances, portions of code are evaluated two or moretimes.This can be disruptive in contexts where the order of actions isimportant. == Trialtypesetting == Often the size of elements must be calculated prior to determining theoptimal placements.Probably the most common example are tables:In order to align cells correctly the dimensions of later parts of thedocument must already be determined before anything is typeset.The stage during which this takes place is called *trial typesetting*. The system mode ''trialtypesetting'' allows fine-grained control overwhat code should be executed during what stage.For instance, the naive definition of a macro that increments andprints a counter register will behave erratically in tables: <context source="yes" mode="mkiv">\def \inccount {% \incrementnumber [somecount]% \getnumber [somecount]%}\definenumber [somecount]\setnumber [somecount] [42] \starttext before \inccount \startplacetable[location=here] \bTABLE \bTR \bTD \inccount \eTD \bTD \inccount \eTD \eTR \eTABLE \stopplacetable after \inccount \stoptext</context> To bypass the extra evaluation, wrap the incrementation part in an<code>\iftrialtypesetting</code> conditional. <context source="yes" mode="mkiv">\def \inccount {% \iftrialtypesetting \else \incrementnumber [somecount]% \fi \getnumber [somecount]%} \definenumber [somecount]\setnumber [somecount] [42] \starttext before \inccount \startplacetable[location=here] \bTABLE \bTR \bTD \inccount \eTD \bTD \inccount \eTD \eTR \eTABLE \stopplacetable after \inccount \stoptext</context> Note that annoying as it may appear, the trial typesetting phase isessential for certain features to work, so take extra care whenomitting it.In the example above the number itself must be present as placeholderduring the first pass even though it has not been updated at thispoint. <texcode>\def \inccount {% \iftrialtypesetting \else \incrementnumber [somecount]% \getnumber [somecount]% <= wrong! \fi}</texcode> <context mode="mkiv" source="no">\def \inccount {% \iftrialtypesetting \else \incrementnumber [somecount]% \getnumber [somecount]% \fi} \definenumber [somecount]\setnumber [somecount] [42] \starttext before \inccount \startplacetable[location=here] \bTABLE \bTR \bTD \inccount \eTD \bTD \inccount \eTD \eTR \eTABLE \stopplacetable after \inccount \stoptext</context> == Tables == In addition to trial typesetting Context also knows a ''table'' state: <context mode="mkiv" source="yes">\def \tablecheck {\ifintable In table. \else Outside table. \fi} \starttext \tablecheck \startplacetable[location=here] \bTABLE \bTR \bTD \tablecheck \eTD \bTD \tablecheck \eTD \eTR \eTABLE \stopplacetable \tablecheck %% decrement\stoptext</context> == Metapost == As with TeX, Metapost sometimes requires multiple passes,especially when processing text.In below snippet, the Metapost tracer reveals that the code is actuallyevaluated twice: <texcode>\enabletrackers[metapost.showlog]\starttext \startMPcode show "This gets printed twice."; label (btex Some label text etex, (0,0)); \stopMPcode\stoptext</texcode> NB removing the <code>label</code> statement will result in the secondpass being omitted. In [[MetaFun - MetaPost in ConTeXt]], the default Metapost format in Context, the booleans<code>mfun_first_run</code> and <code>mfun_trial_run</code> allowdetecting the individual stages: <texcode>\enabletrackers[metapost.showlog]\starttext \startMPcode if mfun_trial_run : show "This gets printed during the trial pass."; else : show "This gets printed during the final pass."; fi; label (btex Some label text etex, (0,0)); \stopMPcode\stoptext</texcode> [[Category:Basics]][[Category:Tools]]
