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14 <title>GNU libunistring: 12. Line breaking <unilbrk.h></title>
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59 <a name="unilbrk_002eh"></a>
61 <h1 class="chapter"> <a href="libunistring.html#TOC47">12. Line breaking <code><unilbrk.h></code></a> </h1>
63 <p>This include file declares functions for determining where in a string
64 line breaks could or should be introduced, in order to make the displayed
65 string fit into a column of given width.
67 <p>These functions are locale dependent. The <var>encoding</var> argument identifies
68 the encoding (e.g. <code>"ISO-8859-2"</code> for Polish).
70 <p>The following enumerated values indicate whether, at a given position, a line
71 break is possible or not. Given an string <var>s</var> as an array
72 <code><var>s</var>[0..<var>n</var>-1]</code> and a position <var>i</var>, the values have the
76 <dt><u>Constant:</u> int <b>UC_BREAK_MANDATORY</b>
79 <dd><p>This value indicates that <code><var>s</var>[<var>i</var>]</code> is a line break character.
83 <dt><u>Constant:</u> int <b>UC_BREAK_POSSIBLE</b>
86 <dd><p>This value indicates that a line break may be inserted between
87 <code><var>s</var>[<var>i</var>-1]</code> and <code><var>s</var>[<var>i</var>]</code>.
91 <dt><u>Constant:</u> int <b>UC_BREAK_HYPHENATION</b>
94 <dd><p>This value indicates that a hyphen and a line break may be inserted between
95 <code><var>s</var>[<var>i</var>-1]</code> and <code><var>s</var>[<var>i</var>]</code>. But beware of language
96 dependent hyphenation rules.
100 <dt><u>Constant:</u> int <b>UC_BREAK_PROHIBITED</b>
101 <a name="IDX757"></a>
103 <dd><p>This value indicates that <code><var>s</var>[<var>i</var>-1]</code> and <code><var>s</var>[<var>i</var>]</code>
104 must not be separated.
108 <dt><u>Constant:</u> int <b>UC_BREAK_UNDEFINED</b>
109 <a name="IDX758"></a>
111 <dd><p>This value is not used as a return value; rather, in the overriding argument of
112 the <code>u*_width_linebreaks</code> functions, it indicates the absence of an
116 <p>The following functions determine the positions at which line breaks are
120 <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>
121 <a name="IDX759"></a>
123 <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>
124 <a name="IDX760"></a>
126 <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>
127 <a name="IDX761"></a>
129 <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>
130 <a name="IDX762"></a>
132 <dd><p>Determines the line break points in <var>s</var>, and stores the result at
133 <code><var>p</var>[0..<var>n</var>-1]</code>. Every <code><var>p</var>[<var>i</var>]</code> is assigned one of
134 the values <code>UC_BREAK_MANDATORY</code>, <code>UC_BREAK_POSSIBLE</code>,
135 <code>UC_BREAK_HYPHENATION</code>, <code>UC_BREAK_PROHIBITED</code>.
138 <p>The following functions determine where line breaks should be inserted so that
139 each line fits in a given width, when output to a device that uses
140 non-proportional fonts.
143 <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>
144 <a name="IDX763"></a>
146 <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>
147 <a name="IDX764"></a>
149 <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>
150 <a name="IDX765"></a>
152 <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>
153 <a name="IDX766"></a>
155 <dd><p>Chooses the best line breaks, assuming that every character occupies a width
156 given by the <code>uc_width</code> function (see <a href="libunistring_9.html#SEC40">Display width <code><uniwidth.h></code></a>).
158 <p>The string is <code><var>s</var>[0..<var>n</var>-1]</code>.
160 <p>The maximum number of columns per line is given as <var>width</var>.
161 The starting column of the string is given as <var>start_column</var>.
162 If the algorithm shall keep room after the last piece, this amount of room can
163 be given as <var>at_end_columns</var>.
165 <p><var>override</var> is an optional override; if
166 <code><var>override</var>[<var>i</var>] != UC_BREAK_UNDEFINED</code>,
167 <code><var>override</var>[<var>i</var>]</code> takes precedence over <code><var>p</var>[<var>i</var>]</code>
168 as returned by the <code>u*_possible_linebreaks</code> function.
170 <p>The given <var>encoding</var> is used for disambiguating widths in <code>uc_width</code>.
172 <p>Returns the column after the end of the string, and stores the result at
173 <code><var>p</var>[0..<var>n</var>-1]</code>. Every <code><var>p</var>[<var>i</var>]</code> is assigned one of
174 the values <code>UC_BREAK_MANDATORY</code>, <code>UC_BREAK_POSSIBLE</code>,
175 <code>UC_BREAK_HYPHENATION</code>, <code>UC_BREAK_PROHIBITED</code>. Here the value
176 <code>UC_BREAK_POSSIBLE</code> indicates that a line break <em>should</em> be inserted.
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