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<a name="unilbrk_002eh"></a>
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<h1 class="chapter"> <a href="libunistring.html#TOC47">12. Line breaking <code><unilbrk.h></code></a> </h1>
<p>This include file declares functions for determining where in a string
line breaks could or should be introduced, in order to make the displayed
string fit into a column of given width.
</p>
<p>These functions are locale dependent. The <var>encoding</var> argument identifies
the encoding (e.g. <code>"ISO-8859-2"</code> for Polish).
</p>
<p>The following enumerated values indicate whether, at a given position, a line
break is possible or not. Given an string <var>s</var> as an array
<code><var>s</var>[0..<var>n</var>-1]</code> and a position <var>i</var>, the values have the
following meanings:
</p>
<dl>
<dt><u>Constant:</u> int <b>UC_BREAK_MANDATORY</b>
<a name="IDX754"></a>
</dt>
<dd><p>This value indicates that <code><var>s</var>[<var>i</var>]</code> is a line break character.
</p></dd></dl>
<dl>
<dt><u>Constant:</u> int <b>UC_BREAK_POSSIBLE</b>
<a name="IDX755"></a>
</dt>
<dd><p>This value indicates that a line break may be inserted between
<code><var>s</var>[<var>i</var>-1]</code> and <code><var>s</var>[<var>i</var>]</code>.
</p></dd></dl>
<dl>
<dt><u>Constant:</u> int <b>UC_BREAK_HYPHENATION</b>
<a name="IDX756"></a>
</dt>
<dd><p>This value indicates that a hyphen and a line break may be inserted between
<code><var>s</var>[<var>i</var>-1]</code> and <code><var>s</var>[<var>i</var>]</code>. But beware of language
dependent hyphenation rules.
</p></dd></dl>
<dl>
<dt><u>Constant:</u> int <b>UC_BREAK_PROHIBITED</b>
<a name="IDX757"></a>
</dt>
<dd><p>This value indicates that <code><var>s</var>[<var>i</var>-1]</code> and <code><var>s</var>[<var>i</var>]</code>
must not be separated.
</p></dd></dl>
<dl>
<dt><u>Constant:</u> int <b>UC_BREAK_UNDEFINED</b>
<a name="IDX758"></a>
</dt>
<dd><p>This value is not used as a return value; rather, in the overriding argument of
the <code>u*_width_linebreaks</code> functions, it indicates the absence of an
override.
</p></dd></dl>
<p>The following functions determine the positions at which line breaks are
possible.
</p>
<dl>
<dt><u>Function:</u> void <b>u8_possible_linebreaks</b><i> (const uint8_t *<var>s</var>, size_t <var>n</var>, const char *<var>encoding</var>, char *<var>p</var>)</i>
<a name="IDX759"></a>
</dt>
<dt><u>Function:</u> void <b>u16_possible_linebreaks</b><i> (const uint16_t *<var>s</var>, size_t <var>n</var>, const char *<var>encoding</var>, char *<var>p</var>)</i>
<a name="IDX760"></a>
</dt>
<dt><u>Function:</u> void <b>u32_possible_linebreaks</b><i> (const uint32_t *<var>s</var>, size_t <var>n</var>, const char *<var>encoding</var>, char *<var>p</var>)</i>
<a name="IDX761"></a>
</dt>
<dt><u>Function:</u> void <b>ulc_possible_linebreaks</b><i> (const char *<var>s</var>, size_t <var>n</var>, const char *<var>encoding</var>, char *<var>p</var>)</i>
<a name="IDX762"></a>
</dt>
<dd><p>Determines the line break points in <var>s</var>, and stores the result at
<code><var>p</var>[0..<var>n</var>-1]</code>. Every <code><var>p</var>[<var>i</var>]</code> is assigned one of
the values <code>UC_BREAK_MANDATORY</code>, <code>UC_BREAK_POSSIBLE</code>,
<code>UC_BREAK_HYPHENATION</code>, <code>UC_BREAK_PROHIBITED</code>.
</p></dd></dl>
<p>The following functions determine where line breaks should be inserted so that
each line fits in a given width, when output to a device that uses
non-proportional fonts.
</p>
<dl>
<dt><u>Function:</u> int <b>u8_width_linebreaks</b><i> (const uint8_t *<var>s</var>, size_t <var>n</var>, int <var>width</var>, int <var>start_column</var>, int <var>at_end_columns</var>, const char *<var>override</var>, const char *<var>encoding</var>, char *<var>p</var>)</i>
<a name="IDX763"></a>
</dt>
<dt><u>Function:</u> int <b>u16_width_linebreaks</b><i> (const uint16_t *<var>s</var>, size_t <var>n</var>, int <var>width</var>, int <var>start_column</var>, int <var>at_end_columns</var>, const char *<var>override</var>, const char *<var>encoding</var>, char *<var>p</var>)</i>
<a name="IDX764"></a>
</dt>
<dt><u>Function:</u> int <b>u32_width_linebreaks</b><i> (const uint32_t *<var>s</var>, size_t <var>n</var>, int <var>width</var>, int <var>start_column</var>, int <var>at_end_columns</var>, const char *<var>override</var>, const char *<var>encoding</var>, char *<var>p</var>)</i>
<a name="IDX765"></a>
</dt>
<dt><u>Function:</u> int <b>ulc_width_linebreaks</b><i> (const char *<var>s</var>, size_t <var>n</var>, int <var>width</var>, int <var>start_column</var>, int <var>at_end_columns</var>, const char *<var>override</var>, const char *<var>encoding</var>, char *<var>p</var>)</i>
<a name="IDX766"></a>
</dt>
<dd><p>Chooses the best line breaks, assuming that every character occupies a width
given by the <code>uc_width</code> function (see <a href="libunistring_9.html#SEC40">Display width <code><uniwidth.h></code></a>).
</p>
<p>The string is <code><var>s</var>[0..<var>n</var>-1]</code>.
</p>
<p>The maximum number of columns per line is given as <var>width</var>.
The starting column of the string is given as <var>start_column</var>.
If the algorithm shall keep room after the last piece, this amount of room can
be given as <var>at_end_columns</var>.
</p>
<p><var>override</var> is an optional override; if
<code><var>override</var>[<var>i</var>] != UC_BREAK_UNDEFINED</code>,
<code><var>override</var>[<var>i</var>]</code> takes precedence over <code><var>p</var>[<var>i</var>]</code>
as returned by the <code>u*_possible_linebreaks</code> function.
</p>
<p>The given <var>encoding</var> is used for disambiguating widths in <code>uc_width</code>.
</p>
<p>Returns the column after the end of the string, and stores the result at
<code><var>p</var>[0..<var>n</var>-1]</code>. Every <code><var>p</var>[<var>i</var>]</code> is assigned one of
the values <code>UC_BREAK_MANDATORY</code>, <code>UC_BREAK_POSSIBLE</code>,
<code>UC_BREAK_HYPHENATION</code>, <code>UC_BREAK_PROHIBITED</code>. Here the value
<code>UC_BREAK_POSSIBLE</code> indicates that a line break <em>should</em> be inserted.
</p></dd></dl>
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