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<div class="refentry" lang="en">
<a name="cairo-user-font"></a><div class="titlepage"></div>
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<h2><span class="refentrytitle"><a name="cairo-user-font.top_of_page"></a>User Fonts</span></h2>
<p>User Fonts — Font support with font data provided by the user</p>
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<div class="refsynopsisdiv">
<a name="cairo-user-font.synopsis"></a><h2>Synopsis</h2>
<pre class="synopsis">
#define <a class="link" href="cairo-user-font.html#CAIRO-HAS-USER-FONT--CAPS" title="CAIRO_HAS_USER_FONT">CAIRO_HAS_USER_FONT</a>
<a class="link" href="cairo-error-status.html#cairo-status-t" title="enum cairo_status_t">cairo_status_t</a> (<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-init-func-t" title="cairo_user_scaled_font_init_func_t ()">*cairo_user_scaled_font_init_func_t</a>)
(<a class="link" href="cairo-scaled-font.html#cairo-scaled-font-t" title="cairo_scaled_font_t">cairo_scaled_font_t</a> *scaled_font,
<a class="link" href="cairo-context.html#cairo-t" title="cairo_t">cairo_t</a> *cr,
<a class="link" href="cairo-scaled-font.html#cairo-font-extents-t" title="cairo_font_extents_t">cairo_font_extents_t</a> *extents);
<a class="link" href="cairo-error-status.html#cairo-status-t" title="enum cairo_status_t">cairo_status_t</a> (<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-render-glyph-func-t" title="cairo_user_scaled_font_render_glyph_func_t ()">*cairo_user_scaled_font_render_glyph_func_t</a>)
(<a class="link" href="cairo-scaled-font.html#cairo-scaled-font-t" title="cairo_scaled_font_t">cairo_scaled_font_t</a> *scaled_font,
unsigned long glyph,
<a class="link" href="cairo-context.html#cairo-t" title="cairo_t">cairo_t</a> *cr,
<a class="link" href="cairo-scaled-font.html#cairo-text-extents-t" title="cairo_text_extents_t">cairo_text_extents_t</a> *extents);
<a class="link" href="cairo-error-status.html#cairo-status-t" title="enum cairo_status_t">cairo_status_t</a> (<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-text-to-glyphs-func-t" title="cairo_user_scaled_font_text_to_glyphs_func_t ()">*cairo_user_scaled_font_text_to_glyphs_func_t</a>)
(<a class="link" href="cairo-scaled-font.html#cairo-scaled-font-t" title="cairo_scaled_font_t">cairo_scaled_font_t</a> *scaled_font,
const char *utf8,
int utf8_len,
<a class="link" href="cairo-text.html#cairo-glyph-t" title="cairo_glyph_t">cairo_glyph_t</a> **glyphs,
int *num_glyphs,
<a class="link" href="cairo-text.html#cairo-text-cluster-t" title="cairo_text_cluster_t">cairo_text_cluster_t</a> **clusters,
int *num_clusters,
<a class="link" href="cairo-text.html#cairo-text-cluster-flags-t" title="enum cairo_text_cluster_flags_t">cairo_text_cluster_flags_t</a> *cluster_flags);
<a class="link" href="cairo-error-status.html#cairo-status-t" title="enum cairo_status_t">cairo_status_t</a> (<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-unicode-to-glyph-func-t" title="cairo_user_scaled_font_unicode_to_glyph_func_t ()">*cairo_user_scaled_font_unicode_to_glyph_func_t</a>)
(<a class="link" href="cairo-scaled-font.html#cairo-scaled-font-t" title="cairo_scaled_font_t">cairo_scaled_font_t</a> *scaled_font,
unsigned long unicode,
unsigned long *glyph_index);
<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> * <a class="link" href="cairo-user-font.html#cairo-user-font-face-create" title="cairo_user_font_face_create ()">cairo_user_font_face_create</a> (void);
void <a class="link" href="cairo-user-font.html#cairo-user-font-face-set-init-func" title="cairo_user_font_face_set_init_func ()">cairo_user_font_face_set_init_func</a> (<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face,
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-init-func-t" title="cairo_user_scaled_font_init_func_t ()">cairo_user_scaled_font_init_func_t</a> init_func);
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-init-func-t" title="cairo_user_scaled_font_init_func_t ()">cairo_user_scaled_font_init_func_t</a> <a class="link" href="cairo-user-font.html#cairo-user-font-face-get-init-func" title="cairo_user_font_face_get_init_func ()">cairo_user_font_face_get_init_func</a>
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face);
void <a class="link" href="cairo-user-font.html#cairo-user-font-face-set-render-glyph-func" title="cairo_user_font_face_set_render_glyph_func ()">cairo_user_font_face_set_render_glyph_func</a>
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face,
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-render-glyph-func-t" title="cairo_user_scaled_font_render_glyph_func_t ()">cairo_user_scaled_font_render_glyph_func_t</a> render_glyph_func);
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-render-glyph-func-t" title="cairo_user_scaled_font_render_glyph_func_t ()">cairo_user_scaled_font_render_glyph_func_t</a> <a class="link" href="cairo-user-font.html#cairo-user-font-face-get-render-glyph-func" title="cairo_user_font_face_get_render_glyph_func ()">cairo_user_font_face_get_render_glyph_func</a>
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face);
void <a class="link" href="cairo-user-font.html#cairo-user-font-face-set-unicode-to-glyph-func" title="cairo_user_font_face_set_unicode_to_glyph_func ()">cairo_user_font_face_set_unicode_to_glyph_func</a>
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face,
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-unicode-to-glyph-func-t" title="cairo_user_scaled_font_unicode_to_glyph_func_t ()">cairo_user_scaled_font_unicode_to_glyph_func_t</a> unicode_to_glyph_func);
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-unicode-to-glyph-func-t" title="cairo_user_scaled_font_unicode_to_glyph_func_t ()">cairo_user_scaled_font_unicode_to_glyph_func_t</a> <a class="link" href="cairo-user-font.html#cairo-user-font-face-get-unicode-to-glyph-func" title="cairo_user_font_face_get_unicode_to_glyph_func ()">cairo_user_font_face_get_unicode_to_glyph_func</a>
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face);
void <a class="link" href="cairo-user-font.html#cairo-user-font-face-set-text-to-glyphs-func" title="cairo_user_font_face_set_text_to_glyphs_func ()">cairo_user_font_face_set_text_to_glyphs_func</a>
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face,
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-text-to-glyphs-func-t" title="cairo_user_scaled_font_text_to_glyphs_func_t ()">cairo_user_scaled_font_text_to_glyphs_func_t</a> text_to_glyphs_func);
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-text-to-glyphs-func-t" title="cairo_user_scaled_font_text_to_glyphs_func_t ()">cairo_user_scaled_font_text_to_glyphs_func_t</a> <a class="link" href="cairo-user-font.html#cairo-user-font-face-get-text-to-glyphs-func" title="cairo_user_font_face_get_text_to_glyphs_func ()">cairo_user_font_face_get_text_to_glyphs_func</a>
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face);
</pre>
</div>
<div class="refsect1" lang="en">
<a name="cairo-user-font.description"></a><h2>Description</h2>
<p>
The user-font feature allows the cairo user to provide drawings for glyphs
in a font. This is most useful in implementing fonts in non-standard
formats, like SVG fonts and Flash fonts, but can also be used by games and
other application to draw "funky" fonts.
</p>
</div>
<div class="refsect1" lang="en">
<a name="cairo-user-font.details"></a><h2>Details</h2>
<div class="refsect2" lang="en">
<a name="CAIRO-HAS-USER-FONT--CAPS"></a><h3>CAIRO_HAS_USER_FONT</h3>
<pre class="programlisting">#define CAIRO_HAS_USER_FONT 1
</pre>
<p>
Defined if the user font backend is available.
This macro can be used to conditionally compile backend-specific code.
The user font backend is always built in versions of cairo that support
this feature (1.8 and later).
</p>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-scaled-font-init-func-t"></a><h3>cairo_user_scaled_font_init_func_t ()</h3>
<pre class="programlisting"><a class="link" href="cairo-error-status.html#cairo-status-t" title="enum cairo_status_t">cairo_status_t</a> (*cairo_user_scaled_font_init_func_t)
(<a class="link" href="cairo-scaled-font.html#cairo-scaled-font-t" title="cairo_scaled_font_t">cairo_scaled_font_t</a> *scaled_font,
<a class="link" href="cairo-context.html#cairo-t" title="cairo_t">cairo_t</a> *cr,
<a class="link" href="cairo-scaled-font.html#cairo-font-extents-t" title="cairo_font_extents_t">cairo_font_extents_t</a> *extents);</pre>
<p>
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-init-func-t" title="cairo_user_scaled_font_init_func_t ()"><span class="type">cairo_user_scaled_font_init_func_t</span></a> is the type of function which is
called when a scaled-font needs to be created for a user font-face.
</p>
<p>
The cairo context <em class="parameter"><code>cr</code></em> is not used by the caller, but is prepared in font
space, similar to what the cairo contexts passed to the render_glyph
method will look like. The callback can use this context for extents
computation for example. After the callback is called, <em class="parameter"><code>cr</code></em> is checked
for any error status.
</p>
<p>
The <em class="parameter"><code>extents</code></em> argument is where the user font sets the font extents for
<em class="parameter"><code>scaled_font</code></em>. It is in font space, which means that for most cases its
ascent and descent members should add to 1.0. <em class="parameter"><code>extents</code></em> is preset to
hold a value of 1.0 for ascent, height, and max_x_advance, and 0.0 for
descent and max_y_advance members.
</p>
<p>
The callback is optional. If not set, default font extents as described
in the previous paragraph will be used.
</p>
<p>
Note that <em class="parameter"><code>scaled_font</code></em> is not fully initialized at this
point and trying to use it for text operations in the callback will result
in deadlock.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>scaled_font</code></em> :</span></p></td>
<td> the scaled-font being created
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>cr</code></em> :</span></p></td>
<td> a cairo context, in font space
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>extents</code></em> :</span></p></td>
<td> font extents to fill in, in font space
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a class="link" href="cairo-error-status.html#CAIRO-STATUS-SUCCESS--CAPS"><code class="literal">CAIRO_STATUS_SUCCESS</code></a> upon success, or
<a class="link" href="cairo-error-status.html#CAIRO-STATUS-USER-FONT-ERROR--CAPS"><code class="literal">CAIRO_STATUS_USER_FONT_ERROR</code></a> or any other error status on error.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-scaled-font-render-glyph-func-t"></a><h3>cairo_user_scaled_font_render_glyph_func_t ()</h3>
<pre class="programlisting"><a class="link" href="cairo-error-status.html#cairo-status-t" title="enum cairo_status_t">cairo_status_t</a> (*cairo_user_scaled_font_render_glyph_func_t)
(<a class="link" href="cairo-scaled-font.html#cairo-scaled-font-t" title="cairo_scaled_font_t">cairo_scaled_font_t</a> *scaled_font,
unsigned long glyph,
<a class="link" href="cairo-context.html#cairo-t" title="cairo_t">cairo_t</a> *cr,
<a class="link" href="cairo-scaled-font.html#cairo-text-extents-t" title="cairo_text_extents_t">cairo_text_extents_t</a> *extents);</pre>
<p>
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-render-glyph-func-t" title="cairo_user_scaled_font_render_glyph_func_t ()"><span class="type">cairo_user_scaled_font_render_glyph_func_t</span></a> is the type of function which
is called when a user scaled-font needs to render a glyph.
</p>
<p>
The callback is mandatory, and expected to draw the glyph with code <em class="parameter"><code>glyph</code></em> to
the cairo context <em class="parameter"><code>cr</code></em>. <em class="parameter"><code>cr</code></em> is prepared such that the glyph drawing is done in
font space. That is, the matrix set on <em class="parameter"><code>cr</code></em> is the scale matrix of <em class="parameter"><code>scaled_font</code></em>,
The <em class="parameter"><code>extents</code></em> argument is where the user font sets the font extents for
<em class="parameter"><code>scaled_font</code></em>. However, if user prefers to draw in user space, they can
achieve that by changing the matrix on <em class="parameter"><code>cr</code></em>. All cairo rendering operations
to <em class="parameter"><code>cr</code></em> are permitted, however, the result is undefined if any source other
than the default source on <em class="parameter"><code>cr</code></em> is used. That means, glyph bitmaps should
be rendered using <a class="link" href="cairo-context.html#cairo-mask" title="cairo_mask ()"><code class="function">cairo_mask()</code></a> instead of <a class="link" href="cairo-context.html#cairo-paint" title="cairo_paint ()"><code class="function">cairo_paint()</code></a>.
</p>
<p>
Other non-default settings on <em class="parameter"><code>cr</code></em> include a font size of 1.0 (given that
it is set up to be in font space), and font options corresponding to
<em class="parameter"><code>scaled_font</code></em>.
</p>
<p>
The <em class="parameter"><code>extents</code></em> argument is preset to have <code class="literal">x_bearing</code>,
<code class="literal">width</code>, and <code class="literal">y_advance</code> of zero,
<code class="literal">y_bearing</code> set to <code class="literal">-font_extents.ascent</code>,
<code class="literal">height</code> to <code class="literal">font_extents.ascent+font_extents.descent</code>,
and <code class="literal">x_advance</code> to <code class="literal">font_extents.max_x_advance</code>.
The only field user needs to set in majority of cases is
<code class="literal">x_advance</code>.
If the <code class="literal">width</code> field is zero upon the callback returning
(which is its preset value), the glyph extents are automatically computed
based on the drawings done to <em class="parameter"><code>cr</code></em>. This is in most cases exactly what the
desired behavior is. However, if for any reason the callback sets the
extents, it must be ink extents, and include the extents of all drawing
done to <em class="parameter"><code>cr</code></em> in the callback.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>scaled_font</code></em> :</span></p></td>
<td> user scaled-font
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>glyph</code></em> :</span></p></td>
<td> glyph code to render
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>cr</code></em> :</span></p></td>
<td> cairo context to draw to, in font space
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>extents</code></em> :</span></p></td>
<td> glyph extents to fill in, in font space
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a class="link" href="cairo-error-status.html#CAIRO-STATUS-SUCCESS--CAPS"><code class="literal">CAIRO_STATUS_SUCCESS</code></a> upon success, or
<a class="link" href="cairo-error-status.html#CAIRO-STATUS-USER-FONT-ERROR--CAPS"><code class="literal">CAIRO_STATUS_USER_FONT_ERROR</code></a> or any other error status on error.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-scaled-font-text-to-glyphs-func-t"></a><h3>cairo_user_scaled_font_text_to_glyphs_func_t ()</h3>
<pre class="programlisting"><a class="link" href="cairo-error-status.html#cairo-status-t" title="enum cairo_status_t">cairo_status_t</a> (*cairo_user_scaled_font_text_to_glyphs_func_t)
(<a class="link" href="cairo-scaled-font.html#cairo-scaled-font-t" title="cairo_scaled_font_t">cairo_scaled_font_t</a> *scaled_font,
const char *utf8,
int utf8_len,
<a class="link" href="cairo-text.html#cairo-glyph-t" title="cairo_glyph_t">cairo_glyph_t</a> **glyphs,
int *num_glyphs,
<a class="link" href="cairo-text.html#cairo-text-cluster-t" title="cairo_text_cluster_t">cairo_text_cluster_t</a> **clusters,
int *num_clusters,
<a class="link" href="cairo-text.html#cairo-text-cluster-flags-t" title="enum cairo_text_cluster_flags_t">cairo_text_cluster_flags_t</a> *cluster_flags);</pre>
<p>
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-text-to-glyphs-func-t" title="cairo_user_scaled_font_text_to_glyphs_func_t ()"><span class="type">cairo_user_scaled_font_text_to_glyphs_func_t</span></a> is the type of function which
is called to convert input text to an array of glyphs. This is used by the
<a class="link" href="cairo-text.html#cairo-show-text" title="cairo_show_text ()"><code class="function">cairo_show_text()</code></a> operation.
</p>
<p>
Using this callback the user-font has full control on glyphs and their
positions. That means, it allows for features like ligatures and kerning,
as well as complex <em class="firstterm">shaping</em> required for scripts like
Arabic and Indic.
</p>
<p>
The <em class="parameter"><code>num_glyphs</code></em> argument is preset to the number of glyph entries available
in the <em class="parameter"><code>glyphs</code></em> buffer. If the <em class="parameter"><code>glyphs</code></em> buffer is <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a>, the value of
<em class="parameter"><code>num_glyphs</code></em> will be zero. If the provided glyph array is too short for
the conversion (or for convenience), a new glyph array may be allocated
using <a class="link" href="cairo-text.html#cairo-glyph-allocate" title="cairo_glyph_allocate ()"><code class="function">cairo_glyph_allocate()</code></a> and placed in <em class="parameter"><code>glyphs</code></em>. Upon return,
<em class="parameter"><code>num_glyphs</code></em> should contain the number of generated glyphs. If the value
<em class="parameter"><code>glyphs</code></em> points at has changed after the call, the caller will free the
allocated glyph array using <a class="link" href="cairo-text.html#cairo-glyph-free" title="cairo_glyph_free ()"><code class="function">cairo_glyph_free()</code></a>.
The callback should populate the glyph indices and positions (in font space)
assuming that the text is to be shown at the origin.
</p>
<p>
If <em class="parameter"><code>clusters</code></em> is not <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a>, <em class="parameter"><code>num_clusters</code></em> and <em class="parameter"><code>cluster_flags</code></em> are also
non-<a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a>, and cluster mapping should be computed. The semantics of how
cluster array allocation works is similar to the glyph array. That is,
if <em class="parameter"><code>clusters</code></em> initially points to a non-<a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a> value, that array may be used
as a cluster buffer, and <em class="parameter"><code>num_clusters</code></em> points to the number of cluster
entries available there. If the provided cluster array is too short for
the conversion (or for convenience), a new cluster array may be allocated
using <a class="link" href="cairo-text.html#cairo-text-cluster-allocate" title="cairo_text_cluster_allocate ()"><code class="function">cairo_text_cluster_allocate()</code></a> and placed in <em class="parameter"><code>clusters</code></em>. Upon return,
<em class="parameter"><code>num_clusters</code></em> should contain the number of generated clusters.
If the value <em class="parameter"><code>clusters</code></em> points at has changed after the call, the caller
will free the allocated cluster array using <a class="link" href="cairo-text.html#cairo-text-cluster-free" title="cairo_text_cluster_free ()"><code class="function">cairo_text_cluster_free()</code></a>.
</p>
<p>
The callback is optional. If <em class="parameter"><code>num_glyphs</code></em> is negative upon
the callback returning, the unicode_to_glyph callback
is tried. See <a class="link" href="cairo-user-font.html#cairo-user-scaled-font-unicode-to-glyph-func-t" title="cairo_user_scaled_font_unicode_to_glyph_func_t ()"><span class="type">cairo_user_scaled_font_unicode_to_glyph_func_t</span></a>.
</p>
<p>
Note: While cairo does not impose any limitation on glyph indices,
some applications may assume that a glyph index fits in a 16-bit
unsigned integer. As such, it is advised that user-fonts keep their
glyphs in the 0 to 65535 range. Furthermore, some applications may
assume that glyph 0 is a special glyph-not-found glyph. User-fonts
are advised to use glyph 0 for such purposes and do not use that
glyph value for other purposes.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>scaled_font</code></em> :</span></p></td>
<td> the scaled-font being created
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>utf8</code></em> :</span></p></td>
<td> a string of text encoded in UTF-8
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>utf8_len</code></em> :</span></p></td>
<td> length of <em class="parameter"><code>utf8</code></em> in bytes
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>glyphs</code></em> :</span></p></td>
<td> pointer to array of glyphs to fill, in font space
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>num_glyphs</code></em> :</span></p></td>
<td> pointer to number of glyphs
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>clusters</code></em> :</span></p></td>
<td> pointer to array of cluster mapping information to fill, or <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>num_clusters</code></em> :</span></p></td>
<td> pointer to number of clusters
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>cluster_flags</code></em> :</span></p></td>
<td> pointer to location to store cluster flags corresponding to the
output <em class="parameter"><code>clusters</code></em>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a class="link" href="cairo-error-status.html#CAIRO-STATUS-SUCCESS--CAPS"><code class="literal">CAIRO_STATUS_SUCCESS</code></a> upon success, or
<a class="link" href="cairo-error-status.html#CAIRO-STATUS-USER-FONT-ERROR--CAPS"><code class="literal">CAIRO_STATUS_USER_FONT_ERROR</code></a> or any other error status on error.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-scaled-font-unicode-to-glyph-func-t"></a><h3>cairo_user_scaled_font_unicode_to_glyph_func_t ()</h3>
<pre class="programlisting"><a class="link" href="cairo-error-status.html#cairo-status-t" title="enum cairo_status_t">cairo_status_t</a> (*cairo_user_scaled_font_unicode_to_glyph_func_t)
(<a class="link" href="cairo-scaled-font.html#cairo-scaled-font-t" title="cairo_scaled_font_t">cairo_scaled_font_t</a> *scaled_font,
unsigned long unicode,
unsigned long *glyph_index);</pre>
<p>
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-unicode-to-glyph-func-t" title="cairo_user_scaled_font_unicode_to_glyph_func_t ()"><span class="type">cairo_user_scaled_font_unicode_to_glyph_func_t</span></a> is the type of function which
is called to convert an input Unicode character to a single glyph.
This is used by the <a class="link" href="cairo-text.html#cairo-show-text" title="cairo_show_text ()"><code class="function">cairo_show_text()</code></a> operation.
</p>
<p>
This callback is used to provide the same functionality as the
text_to_glyphs callback does (see <a class="link" href="cairo-user-font.html#cairo-user-scaled-font-text-to-glyphs-func-t" title="cairo_user_scaled_font_text_to_glyphs_func_t ()"><span class="type">cairo_user_scaled_font_text_to_glyphs_func_t</span></a>)
but has much less control on the output,
in exchange for increased ease of use. The inherent assumption to using
this callback is that each character maps to one glyph, and that the
mapping is context independent. It also assumes that glyphs are positioned
according to their advance width. These mean no ligatures, kerning, or
complex scripts can be implemented using this callback.
</p>
<p>
The callback is optional, and only used if text_to_glyphs callback is not
set or fails to return glyphs. If this callback is not set, an identity
mapping from Unicode code-points to glyph indices is assumed.
</p>
<p>
Note: While cairo does not impose any limitation on glyph indices,
some applications may assume that a glyph index fits in a 16-bit
unsigned integer. As such, it is advised that user-fonts keep their
glyphs in the 0 to 65535 range. Furthermore, some applications may
assume that glyph 0 is a special glyph-not-found glyph. User-fonts
are advised to use glyph 0 for such purposes and do not use that
glyph value for other purposes.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>scaled_font</code></em> :</span></p></td>
<td> the scaled-font being created
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>unicode</code></em> :</span></p></td>
<td> input unicode character code-point
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>glyph_index</code></em> :</span></p></td>
<td> output glyph index
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a class="link" href="cairo-error-status.html#CAIRO-STATUS-SUCCESS--CAPS"><code class="literal">CAIRO_STATUS_SUCCESS</code></a> upon success, or
<a class="link" href="cairo-error-status.html#CAIRO-STATUS-USER-FONT-ERROR--CAPS"><code class="literal">CAIRO_STATUS_USER_FONT_ERROR</code></a> or any other error status on error.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-font-face-create"></a><h3>cairo_user_font_face_create ()</h3>
<pre class="programlisting"><a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> * cairo_user_font_face_create (void);</pre>
<p>
Creates a new user font-face.
</p>
<p>
Use the setter functions to associate callbacks with the returned
user font. The only mandatory callback is render_glyph.
</p>
<p>
After the font-face is created, the user can attach arbitrary data
(the actual font data) to it using <a class="link" href="cairo-font-face.html#cairo-font-face-set-user-data" title="cairo_font_face_set_user_data ()"><code class="function">cairo_font_face_set_user_data()</code></a>
and access it from the user-font callbacks by using
<a class="link" href="cairo-scaled-font.html#cairo-scaled-font-get-font-face" title="cairo_scaled_font_get_font_face ()"><code class="function">cairo_scaled_font_get_font_face()</code></a> followed by
<a class="link" href="cairo-font-face.html#cairo-font-face-get-user-data" title="cairo_font_face_get_user_data ()"><code class="function">cairo_font_face_get_user_data()</code></a>.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> a newly created <a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t"><span class="type">cairo_font_face_t</span></a>. Free with
<a class="link" href="cairo-font-face.html#cairo-font-face-destroy" title="cairo_font_face_destroy ()"><code class="function">cairo_font_face_destroy()</code></a> when you are done using it.
</td>
</tr></tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-font-face-set-init-func"></a><h3>cairo_user_font_face_set_init_func ()</h3>
<pre class="programlisting">void cairo_user_font_face_set_init_func (<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face,
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-init-func-t" title="cairo_user_scaled_font_init_func_t ()">cairo_user_scaled_font_init_func_t</a> init_func);</pre>
<p>
Sets the scaled-font initialization function of a user-font.
See <a class="link" href="cairo-user-font.html#cairo-user-scaled-font-init-func-t" title="cairo_user_scaled_font_init_func_t ()"><span class="type">cairo_user_scaled_font_init_func_t</span></a> for details of how the callback
works.
</p>
<p>
The font-face should not be immutable or a <a class="link" href="cairo-error-status.html#CAIRO-STATUS-USER-FONT-IMMUTABLE--CAPS"><code class="literal">CAIRO_STATUS_USER_FONT_IMMUTABLE</code></a>
error will occur. A user font-face is immutable as soon as a scaled-font
is created from it.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>font_face</code></em> :</span></p></td>
<td> A user font face
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>init_func</code></em> :</span></p></td>
<td> The init callback, or <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a>
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-font-face-get-init-func"></a><h3>cairo_user_font_face_get_init_func ()</h3>
<pre class="programlisting"><a class="link" href="cairo-user-font.html#cairo-user-scaled-font-init-func-t" title="cairo_user_scaled_font_init_func_t ()">cairo_user_scaled_font_init_func_t</a> cairo_user_font_face_get_init_func
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face);</pre>
<p>
Gets the scaled-font initialization function of a user-font.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>font_face</code></em> :</span></p></td>
<td> A user font face
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The init callback of <em class="parameter"><code>font_face</code></em>
or <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a> if none set or an error has occurred.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-font-face-set-render-glyph-func"></a><h3>cairo_user_font_face_set_render_glyph_func ()</h3>
<pre class="programlisting">void cairo_user_font_face_set_render_glyph_func
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face,
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-render-glyph-func-t" title="cairo_user_scaled_font_render_glyph_func_t ()">cairo_user_scaled_font_render_glyph_func_t</a> render_glyph_func);</pre>
<p>
Sets the glyph rendering function of a user-font.
See <a class="link" href="cairo-user-font.html#cairo-user-scaled-font-render-glyph-func-t" title="cairo_user_scaled_font_render_glyph_func_t ()"><span class="type">cairo_user_scaled_font_render_glyph_func_t</span></a> for details of how the callback
works.
</p>
<p>
The font-face should not be immutable or a <a class="link" href="cairo-error-status.html#CAIRO-STATUS-USER-FONT-IMMUTABLE--CAPS"><code class="literal">CAIRO_STATUS_USER_FONT_IMMUTABLE</code></a>
error will occur. A user font-face is immutable as soon as a scaled-font
is created from it.
</p>
<p>
The render_glyph callback is the only mandatory callback of a user-font.
If the callback is <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a> and a glyph is tried to be rendered using
<em class="parameter"><code>font_face</code></em>, a <a class="link" href="cairo-error-status.html#CAIRO-STATUS-USER-FONT-ERROR--CAPS"><code class="literal">CAIRO_STATUS_USER_FONT_ERROR</code></a> will occur.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>font_face</code></em> :</span></p></td>
<td> A user font face
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>render_glyph_func</code></em> :</span></p></td>
<td> The render_glyph callback, or <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a>
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-font-face-get-render-glyph-func"></a><h3>cairo_user_font_face_get_render_glyph_func ()</h3>
<pre class="programlisting"><a class="link" href="cairo-user-font.html#cairo-user-scaled-font-render-glyph-func-t" title="cairo_user_scaled_font_render_glyph_func_t ()">cairo_user_scaled_font_render_glyph_func_t</a> cairo_user_font_face_get_render_glyph_func
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face);</pre>
<p>
Gets the glyph rendering function of a user-font.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>font_face</code></em> :</span></p></td>
<td> A user font face
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The render_glyph callback of <em class="parameter"><code>font_face</code></em>
or <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a> if none set or an error has occurred.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-font-face-set-unicode-to-glyph-func"></a><h3>cairo_user_font_face_set_unicode_to_glyph_func ()</h3>
<pre class="programlisting">void cairo_user_font_face_set_unicode_to_glyph_func
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face,
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-unicode-to-glyph-func-t" title="cairo_user_scaled_font_unicode_to_glyph_func_t ()">cairo_user_scaled_font_unicode_to_glyph_func_t</a> unicode_to_glyph_func);</pre>
<p>
Sets the unicode-to-glyph conversion function of a user-font.
See <a class="link" href="cairo-user-font.html#cairo-user-scaled-font-unicode-to-glyph-func-t" title="cairo_user_scaled_font_unicode_to_glyph_func_t ()"><span class="type">cairo_user_scaled_font_unicode_to_glyph_func_t</span></a> for details of how the callback
works.
</p>
<p>
The font-face should not be immutable or a <a class="link" href="cairo-error-status.html#CAIRO-STATUS-USER-FONT-IMMUTABLE--CAPS"><code class="literal">CAIRO_STATUS_USER_FONT_IMMUTABLE</code></a>
error will occur. A user font-face is immutable as soon as a scaled-font
is created from it.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>font_face</code></em> :</span></p></td>
<td> A user font face
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>unicode_to_glyph_func</code></em> :</span></p></td>
<td> The unicode_to_glyph callback, or <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a>
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-font-face-get-unicode-to-glyph-func"></a><h3>cairo_user_font_face_get_unicode_to_glyph_func ()</h3>
<pre class="programlisting"><a class="link" href="cairo-user-font.html#cairo-user-scaled-font-unicode-to-glyph-func-t" title="cairo_user_scaled_font_unicode_to_glyph_func_t ()">cairo_user_scaled_font_unicode_to_glyph_func_t</a> cairo_user_font_face_get_unicode_to_glyph_func
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face);</pre>
<p>
Gets the unicode-to-glyph conversion function of a user-font.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>font_face</code></em> :</span></p></td>
<td> A user font face
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The unicode_to_glyph callback of <em class="parameter"><code>font_face</code></em>
or <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a> if none set or an error occurred.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-font-face-set-text-to-glyphs-func"></a><h3>cairo_user_font_face_set_text_to_glyphs_func ()</h3>
<pre class="programlisting">void cairo_user_font_face_set_text_to_glyphs_func
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face,
<a class="link" href="cairo-user-font.html#cairo-user-scaled-font-text-to-glyphs-func-t" title="cairo_user_scaled_font_text_to_glyphs_func_t ()">cairo_user_scaled_font_text_to_glyphs_func_t</a> text_to_glyphs_func);</pre>
<p>
Sets th text-to-glyphs conversion function of a user-font.
See <a class="link" href="cairo-user-font.html#cairo-user-scaled-font-text-to-glyphs-func-t" title="cairo_user_scaled_font_text_to_glyphs_func_t ()"><span class="type">cairo_user_scaled_font_text_to_glyphs_func_t</span></a> for details of how the callback
works.
</p>
<p>
The font-face should not be immutable or a <a class="link" href="cairo-error-status.html#CAIRO-STATUS-USER-FONT-IMMUTABLE--CAPS"><code class="literal">CAIRO_STATUS_USER_FONT_IMMUTABLE</code></a>
error will occur. A user font-face is immutable as soon as a scaled-font
is created from it.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>font_face</code></em> :</span></p></td>
<td> A user font face
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>text_to_glyphs_func</code></em> :</span></p></td>
<td> The text_to_glyphs callback, or <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a>
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="cairo-user-font-face-get-text-to-glyphs-func"></a><h3>cairo_user_font_face_get_text_to_glyphs_func ()</h3>
<pre class="programlisting"><a class="link" href="cairo-user-font.html#cairo-user-scaled-font-text-to-glyphs-func-t" title="cairo_user_scaled_font_text_to_glyphs_func_t ()">cairo_user_scaled_font_text_to_glyphs_func_t</a> cairo_user_font_face_get_text_to_glyphs_func
(<a class="link" href="cairo-font-face.html#cairo-font-face-t" title="cairo_font_face_t">cairo_font_face_t</a> *font_face);</pre>
<p>
Gets the text-to-glyphs conversion function of a user-font.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>font_face</code></em> :</span></p></td>
<td> A user font face
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The text_to_glyphs callback of <em class="parameter"><code>font_face</code></em>
or <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#NULL--CAPS"
><code class="literal">NULL</code></a> if none set or an error occurred.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
</div>
</div>
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