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< [[The ConTeXt Way]] | [[Inside ConTeXt]] | [[Project structure]] >
In this article I explain how to activate a mode and how to check if a mode is
active or not.
<code>texexec</code> or <code>context</code>. For example, another way to activate the <code>screen</code> and
texexec --mode=screen,solution ...
\doifnotmodeelse {mode1, mode2, ...} {Processed if any mode is disabled} {else this is processed}
In MkIV, the The state of any mode is accessible at the Lua end as <code>tex.modes</code> table. Specifically,
'''Note''': This table was added in 2010.10.14 beta and is not available in earlier releases.
Sometimes you want a macro to behave differently if it is part of a section head, a section number, a list, a marking, or a register. For section heads, you can check for modes <code>*chapter</code>, <code>*section</code>, <code>*subsection</code>, etc. Similarly, <code>*list<code> is enabled inside a list, <code>*marking</code> is enabled inside a marking, and <code>*register</code> is enabled inside a register.
→System modes
Very often, you want to generate multiple versions of the same document:
one version for printing and one for viewing on the screen, one version for
multiple modes can be simultaneously enabled or disabled, and the status of multiple
modes can be checked easily. Moreover, modes can be set from a command line
switch. As a result, multiple versions of a document can be generated without changingthe source file.
The name or identifier of a mode can be any combination of letters, digits, or
spaces. Names starting with <code>*</code> are reserved for system modes.
= Setting modes =
ConTeXt has three commands for setting modes:
* <code><{{cmd>|enablemode </cmd>}}[...]</code>* <code><{{cmd>|disablemode</cmd>}}[...]</code>* <code><{{cmd>|preventmode</cmd>}}[...]</code>
The names are self-descriptive. <{{cmd>|enablemode</cmd> }} activates a mode,<{{cmd>|disablemode</cmd> }} deactivates a mode, and <{{cmd>|preventmode</cmd> }} permanently
deactivates a mode. All three commands take a list of modes as an argument. For
example, you can activate to active modes named <code>screen</code> and <code>solution</code> withuse:
<texcode>
\enablemode[screen,solution]
Modes can also be activated by a command line switch <code>--modes</code> to
<code>solution</code> modes, to run ConTeXt using one of:
context --mode=screen,solution ...
== Pre-defining modes ==
Normally, the overhead for testing modes is negligible, but it can add up if
modes are tested multiple times in a document (for example, as part of a
macro). To speed up the processing, a mode can be ''define''d before being
used:
<texcode>
\definemode[...][...]
</texcode>
The first argument is a list of modes; the second argument may be `yes`, `no`, or `keep`. For example,
* <code>\definemode[screen][yes]</code> defines a mode and enables it;
* <code>\definemode[screen][no]</code> defines a mode and disables it;
* <code>\definemode[screen][keep]</code> defines a mode and keeps its previous status.
Typically, it is better to use <code>\definemode[...][keep]</code> so that the modes may be enabled or disabled from command line as well.
= Conditional processing based on modes =
4:3 aspect ratio and a width equal to the width of A4 paper.)
Alternatively, youcould set a default paper size for the screen and change it if screen mode isnot enabled:
<texcode>
\setuppapersize[S6][S6]
<texcode>
\doifmodeelse {mode1, mode2, ...} {Processed if any mode is enabled} {else this is processed}
\doifallmodeselse {mode1, mode2, ...} {Processed if all modes are enabled} {else this is processed}
\doifnotallmodeselse {mode1, mode2, ...} {Processed if all modes are disabled} {else this is processed}
</texcode>
Note that there is no command <code>\doifnotmodeelse</code> because there is no need for it; <code>\doifmodeelse</code> may be used for the same effect (with the <code>if</code> and <code>else</code> branches switched).
== Checking multiple modes in parallel (<code>case</code> statement for modes) ==
<texcode>
\startmodeset
% NOTE: Empty lines are not allowed here!
[mode1, mode2, ...] {Processed if either mode is enabled}
[mode3, mode4, ...] {Processed if either mode is enabled}
</texcode>
The same mode can be referenced multiple times, and '''all''' matching brances branches are executed. The <{{cmd>|startmodeset</cmd> }} ... <{{cmd>|stopmodeset</cmd> }} environments can be nested. So, you can use
<texcode>
== Checking modes in Lua ==
<texcode>
checks if both <code>mode1</code> and <code>mode2</code> are enabled.
= System modes =
| Enabled when running [[MkIV]]
|}
Perhaps the most useful system modes are <code>*mkii</code> and <code>*mkiv</code> which
Other modes are useful for very specific situations. Some of these are described
below.
{|cellpadding="5" style="border-collapse: collapse;border-width: 1px; border-style: solid;"
<code>*first</code> mode is handy—it is active only on the first run of the
document.
{|cellpadding="5" style="border-collapse: collapse;border-width: 1px; border-style: solid;"
| '''*export'''
| Enabled when <code>\setupbackend[export=yes]</code> is set
|}
You may want to use different images for XML [Export]. The <code>*export</code> mode is useful in such cases.
{|cellpadding="5" style="border-collapse: collapse;border-width: 1px; border-style: solid;"
encountered. Similarly, a mode <code>*text</code> is enabled when
<code>\starttext</code> is encountered, and likewise for the others.
{|cellpadding="5" style="border-collapse: collapse;border-width: 1px; border-style: solid;"
if you want macros that work differently in different section blocks, you can
check for modes <code>*frontpart</code>, <code>*bodypart</code>, and so on.
{|cellpadding="5" style="border-collapse: collapse;border-width: 1px; border-style: solid;"
| Enabled inside the corresponding section head.
|}
Sometimes you want a macro to behave differently if it is part of a section head, a section number, a list, a marking, or a register. For section heads, you can check for modes <code>*chapter</code>, <code>*section</code>, <code>*subsection</code>, etc. Similarly, <code>*list</code> is enabled inside a list, <code>*marking</code> is enabled inside a marking, and <code>*register</code> is enabled inside a register.
{|cellpadding="5" style="border-collapse: collapse;border-width: 1px; border-style: solid;"
English and the current language is Dutch, the modes <code>**en-us</code> and
<code>*nl</code> are set (notice the extra <code>*</code> in <code>**en-us</code>).
{|cellpadding="5" style="border-collapse: collapse;border-width: 1px; border-style: solid;"
|'''*grid'''
| Enabled when grid typesetting is enabled
|-
|'''*singlesided'''
| Enabled when singlesided layout is enabled
|-
|'''*doublesided'''
| Enabled when doublesided layout is enabled
|}
{|cellpadding="5" style="border-collapse: collapse;border-width: 1px; border-style: solid;"
\executesystemcommand{some_external_program ...}
% convert PS into PDF
\executesystemcommand{texmfstart pstopdf fig-1.ps}
\stopmode
</texcode>
[[Category:ConTeXt programmingTools]]
