cairo-font-face.xml [plain text]
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<refentry id="cairo-cairo-font-face-t">
<refmeta>
<refentrytitle role="top_of_page" id="cairo-cairo-font-face-t.top_of_page">cairo_font_face_t</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>
CAIRO Library
</refmiscinfo>
</refmeta>
<refnamediv>
<refname>cairo_font_face_t</refname>
<refpurpose>Base class for font faces</refpurpose>
</refnamediv>
<refsynopsisdiv id="cairo-cairo-font-face-t.synopsis" role="synopsis">
<title role="synopsis.title">Synopsis</title>
<synopsis>typedef <link linkend="cairo-font-face-t">cairo_font_face_t</link>;
<link linkend="cairo-font-face-t"><returnvalue>cairo_font_face_t</returnvalue></link> * <link linkend="cairo-font-face-reference">cairo_font_face_reference</link> (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-font-face-destroy">cairo_font_face_destroy</link> (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>);
<link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-font-face-status">cairo_font_face_status</link> (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>);
enum <link linkend="cairo-font-type-t">cairo_font_type_t</link>;
<link linkend="cairo-font-type-t"><returnvalue>cairo_font_type_t</returnvalue></link> <link linkend="cairo-font-face-get-type">cairo_font_face_get_type</link> (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>);
unsigned <link linkend="int"><returnvalue>int</returnvalue></link> <link linkend="cairo-font-face-get-reference-count">cairo_font_face_get_reference_count</link> (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>);
<link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-font-face-set-user-data">cairo_font_face_set_user_data</link> (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>,
<parameter>const <link linkend="cairo-user-data-key-t"><type>cairo_user_data_key_t</type></link> *key</parameter>,
<parameter><link linkend="void"><type>void</type></link> *user_data</parameter>,
<parameter><link linkend="cairo-destroy-func-t"><type>cairo_destroy_func_t</type></link> destroy</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> * <link linkend="cairo-font-face-get-user-data">cairo_font_face_get_user_data</link> (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>,
<parameter>const <link linkend="cairo-user-data-key-t"><type>cairo_user_data_key_t</type></link> *key</parameter>);
</synopsis>
</refsynopsisdiv>
<refsect1 id="cairo-cairo-font-face-t.description" role="desc">
<title role="desc.title">Description</title>
<para>
<link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> represents a particular font at a particular weight,
slant, and other characteristic but no size, transformation, or size.
</para>
<para>
Font faces are created using <firstterm>font-backend</firstterm>-specific
constructors, typically of the form
cairo_<emphasis>backend</emphasis><link linkend="font-face-create"><function>_font_face_create()</function></link>, or implicitly
using the <firstterm>toy</firstterm> text API by way of
<link linkend="cairo-select-font-face"><function>cairo_select_font_face()</function></link>. The resulting face can be accessed using
<link linkend="cairo-get-font-face"><function>cairo_get_font_face()</function></link>.
</para>
</refsect1>
<refsect1 id="cairo-cairo-font-face-t.details" role="details">
<title role="details.title">Details</title>
<refsect2 id="cairo-font-face-t" role="typedef">
<title>cairo_font_face_t</title>
<indexterm zone="cairo-font-face-t"><primary sortas="font_face_t">cairo_font_face_t</primary></indexterm>
<programlisting>typedef struct _cairo_font_face cairo_font_face_t;
</programlisting>
<para>
A <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> specifies all aspects of a font other
than the size or font matrix (a font matrix is used to distort
a font by sheering it or scaling it unequally in the two
directions) . A font face can be set on a <link linkend="cairo-t"><type>cairo_t</type></link> by using
<link linkend="cairo-set-font-face"><function>cairo_set_font_face()</function></link>; the size and font matrix are set with
<link linkend="cairo-set-font-size"><function>cairo_set_font_size()</function></link> and <link linkend="cairo-set-font-matrix"><function>cairo_set_font_matrix()</function></link>.
</para>
<para>
There are various types of font faces, depending on the
<firstterm>font backend</firstterm> they use. The type of a
font face can be queried using <link linkend="cairo-font-face-get-type"><function>cairo_font_face_get_type()</function></link>.
</para>
<para>
Memory management of <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> is done with
<link linkend="cairo-font-face-reference"><function>cairo_font_face_reference()</function></link> and <link linkend="cairo-font-face-destroy"><function>cairo_font_face_destroy()</function></link>.
</para></refsect2>
<refsect2 id="cairo-font-face-reference" role="function">
<title>cairo_font_face_reference ()</title>
<indexterm zone="cairo-font-face-reference"><primary sortas="font_face_reference">cairo_font_face_reference</primary></indexterm>
<programlisting><link linkend="cairo-font-face-t"><returnvalue>cairo_font_face_t</returnvalue></link> * cairo_font_face_reference (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>);</programlisting>
<para>
Increases the reference count on <parameter>font_face</parameter> by one. This prevents
<parameter>font_face</parameter> from being destroyed until a matching call to
<link linkend="cairo-font-face-destroy"><function>cairo_font_face_destroy()</function></link> is made.
</para>
<para>
The number of references to a <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> can be get using
<link linkend="cairo-font-face-get-reference-count"><function>cairo_font_face_get_reference_count()</function></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>font_face</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link>, (may be <link linkend="NULL:CAPS"><literal>NULL</literal></link> in which case this
function does nothing).
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the referenced <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-font-face-destroy" role="function">
<title>cairo_font_face_destroy ()</title>
<indexterm zone="cairo-font-face-destroy"><primary sortas="font_face_destroy">cairo_font_face_destroy</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_font_face_destroy (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>);</programlisting>
<para>
Decreases the reference count on <parameter>font_face</parameter> by one. If the result
is zero, then <parameter>font_face</parameter> and all associated resources are freed.
See <link linkend="cairo-font-face-reference"><function>cairo_font_face_reference()</function></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>font_face</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link>
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-font-face-status" role="function">
<title>cairo_font_face_status ()</title>
<indexterm zone="cairo-font-face-status"><primary sortas="font_face_status">cairo_font_face_status</primary></indexterm>
<programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_font_face_status (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>);</programlisting>
<para>
Checks whether an error has previously occurred for this
font face
</para><variablelist role="params">
<varlistentry><term><parameter>font_face</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> <link linkend="CAIRO-STATUS-SUCCESS:CAPS"><literal>CAIRO_STATUS_SUCCESS</literal></link> or another error such as
<link linkend="CAIRO-STATUS-NO-MEMORY:CAPS"><literal>CAIRO_STATUS_NO_MEMORY</literal></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-font-type-t" role="enum" condition="since:1.2">
<title>enum cairo_font_type_t</title>
<indexterm zone="cairo-font-type-t" role="1.2"><primary sortas="font_type_t">cairo_font_type_t</primary></indexterm>
<programlisting>typedef enum _cairo_font_type {
CAIRO_FONT_TYPE_TOY,
CAIRO_FONT_TYPE_FT,
CAIRO_FONT_TYPE_WIN32,
CAIRO_FONT_TYPE_QUARTZ,
CAIRO_FONT_TYPE_USER
} cairo_font_type_t;
</programlisting>
<para>
<link linkend="cairo-font-type-t"><type>cairo_font_type_t</type></link> is used to describe the type of a given font
face or scaled font. The font types are also known as "font
backends" within cairo.
</para>
<para>
The type of a font face is determined by the function used to
create it, which will generally be of the form
cairo_<emphasis>type</emphasis><link linkend="font-face-create"><function>_font_face_create()</function></link>. The font face type can be queried
with <link linkend="cairo-font-face-get-type"><function>cairo_font_face_get_type()</function></link>
</para>
<para>
The various <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> functions can be used with a font face
of any type.
</para>
<para>
The type of a scaled font is determined by the type of the font
face passed to <link linkend="cairo-scaled-font-create"><function>cairo_scaled_font_create()</function></link>. The scaled font type can
be queried with <link linkend="cairo-scaled-font-get-type"><function>cairo_scaled_font_get_type()</function></link>
</para>
<para>
The various <link linkend="cairo-scaled-font-t"><type>cairo_scaled_font_t</type></link> functions can be used with scaled
fonts of any type, but some font backends also provide
type-specific functions that must only be called with a scaled font
of the appropriate type. These functions have names that begin with
cairo_<emphasis>type</emphasis><link linkend="scaled-font"><function>_scaled_font()</function></link> such as <link linkend="cairo-ft-scaled-font-lock-face"><function>cairo_ft_scaled_font_lock_face()</function></link>.
</para>
<para>
The behavior of calling a type-specific function with a scaled font
of the wrong type is undefined.
</para>
<para>
New entries may be added in future versions.
</para><variablelist role="enum">
<varlistentry id="CAIRO-FONT-TYPE-TOY:CAPS" role="constant">
<term><literal>CAIRO_FONT_TYPE_TOY</literal></term>
<listitem><simpara>The font was created using cairo's toy font api
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-FONT-TYPE-FT:CAPS" role="constant">
<term><literal>CAIRO_FONT_TYPE_FT</literal></term>
<listitem><simpara>The font is of type FreeType
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-FONT-TYPE-WIN32:CAPS" role="constant">
<term><literal>CAIRO_FONT_TYPE_WIN32</literal></term>
<listitem><simpara>The font is of type Win32
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-FONT-TYPE-QUARTZ:CAPS" role="constant">
<term><literal>CAIRO_FONT_TYPE_QUARTZ</literal></term>
<listitem><simpara>The font is of type Quartz (Since: 1.6)
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-FONT-TYPE-USER:CAPS" role="constant">
<term><literal>CAIRO_FONT_TYPE_USER</literal></term>
<listitem><simpara>The font was create using cairo's user font api (Since: 1.8)
</simpara></listitem>
</varlistentry>
</variablelist><para role="since">Since 1.2</para></refsect2>
<refsect2 id="cairo-font-face-get-type" role="function" condition="since:1.2">
<title>cairo_font_face_get_type ()</title>
<indexterm zone="cairo-font-face-get-type" role="1.2"><primary sortas="font_face_get_type">cairo_font_face_get_type</primary></indexterm>
<programlisting><link linkend="cairo-font-type-t"><returnvalue>cairo_font_type_t</returnvalue></link> cairo_font_face_get_type (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>);</programlisting>
<para>
This function returns the type of the backend used to create
a font face. See <link linkend="cairo-font-type-t"><type>cairo_font_type_t</type></link> for available types.
</para><variablelist role="params">
<varlistentry><term><parameter>font_face</parameter> :</term>
<listitem><simpara>a font face
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> The type of <parameter>font_face</parameter>.
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since 1.2</para></refsect2>
<refsect2 id="cairo-font-face-get-reference-count" role="function" condition="since:1.4">
<title>cairo_font_face_get_reference_count ()</title>
<indexterm zone="cairo-font-face-get-reference-count" role="1.4"><primary sortas="font_face_get_reference_count">cairo_font_face_get_reference_count</primary></indexterm>
<programlisting>unsigned <link linkend="int"><returnvalue>int</returnvalue></link> cairo_font_face_get_reference_count (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>);</programlisting>
<para>
Returns the current reference count of <parameter>font_face</parameter>.
</para><variablelist role="params">
<varlistentry><term><parameter>font_face</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current reference count of <parameter>font_face</parameter>. If the
object is a nil object, 0 will be returned.
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since 1.4</para></refsect2>
<refsect2 id="cairo-font-face-set-user-data" role="function">
<title>cairo_font_face_set_user_data ()</title>
<indexterm zone="cairo-font-face-set-user-data"><primary sortas="font_face_set_user_data">cairo_font_face_set_user_data</primary></indexterm>
<programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_font_face_set_user_data (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>,
<parameter>const <link linkend="cairo-user-data-key-t"><type>cairo_user_data_key_t</type></link> *key</parameter>,
<parameter><link linkend="void"><type>void</type></link> *user_data</parameter>,
<parameter><link linkend="cairo-destroy-func-t"><type>cairo_destroy_func_t</type></link> destroy</parameter>);</programlisting>
<para>
Attach user data to <parameter>font_face</parameter>. To remove user data from a font face,
call this function with the key that was used to set it and <link linkend="NULL:CAPS"><literal>NULL</literal></link>
for <parameter>data</parameter>.
</para><variablelist role="params">
<varlistentry><term><parameter>font_face</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>key</parameter> :</term>
<listitem><simpara>the address of a <link linkend="cairo-user-data-key-t"><type>cairo_user_data_key_t</type></link> to attach the user data to
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>user_data</parameter> :</term>
<listitem><simpara>the user data to attach to the font face
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>destroy</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-destroy-func-t"><type>cairo_destroy_func_t</type></link> which will be called when the
font face is destroyed or when new user data is attached using the
same key.
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> <link linkend="CAIRO-STATUS-SUCCESS:CAPS"><literal>CAIRO_STATUS_SUCCESS</literal></link> or <link linkend="CAIRO-STATUS-NO-MEMORY:CAPS"><literal>CAIRO_STATUS_NO_MEMORY</literal></link> if a
slot could not be allocated for the user data.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-font-face-get-user-data" role="function">
<title>cairo_font_face_get_user_data ()</title>
<indexterm zone="cairo-font-face-get-user-data"><primary sortas="font_face_get_user_data">cairo_font_face_get_user_data</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> * cairo_font_face_get_user_data (<parameter><link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> *font_face</parameter>,
<parameter>const <link linkend="cairo-user-data-key-t"><type>cairo_user_data_key_t</type></link> *key</parameter>);</programlisting>
<para>
Return user data previously attached to <parameter>font_face</parameter> using the specified
key. If no user data has been attached with the given key this
function returns <link linkend="NULL:CAPS"><literal>NULL</literal></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>font_face</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>key</parameter> :</term>
<listitem><simpara>the address of the <link linkend="cairo-user-data-key-t"><type>cairo_user_data_key_t</type></link> the user data was
attached to
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the user data previously attached or <link linkend="NULL:CAPS"><literal>NULL</literal></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
</refsect1>
<refsect1 id="cairo-cairo-font-face-t.see-also">
<title>See Also</title>
<link linkend="cairo-scaled-font-t"><type>cairo_scaled_font_t</type></link>
</refsect1>
</refentry>