<?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [ <!ENTITY version SYSTEM "version.xml"> ]> <refentry id="cairo-FreeType-Fonts"> <refmeta> <refentrytitle role="top_of_page" id="cairo-FreeType-Fonts.top_of_page">FreeType Fonts</refentrytitle> <manvolnum>3</manvolnum> <refmiscinfo> CAIRO Library </refmiscinfo> </refmeta> <refnamediv> <refname>FreeType Fonts</refname> <refpurpose>Font support for FreeType</refpurpose> </refnamediv> <refsynopsisdiv id="cairo-FreeType-Fonts.synopsis" role="synopsis"> <title role="synopsis.title">Synopsis</title> <synopsis>#define <link linkend="CAIRO-HAS-FT-FONT:CAPS">CAIRO_HAS_FT_FONT</link> #define <link linkend="CAIRO-HAS-FC-FONT:CAPS">CAIRO_HAS_FC_FONT</link> <link linkend="cairo-font-face-t"><returnvalue>cairo_font_face_t</returnvalue></link> * <link linkend="cairo-ft-font-face-create-for-ft-face">cairo_ft_font_face_create_for_ft_face</link> (<parameter><link linkend="FT-Face"><type>FT_Face</type></link> face</parameter>, <parameter><link linkend="int"><type>int</type></link> load_flags</parameter>); <link linkend="cairo-font-face-t"><returnvalue>cairo_font_face_t</returnvalue></link> * <link linkend="cairo-ft-font-face-create-for-pattern">cairo_ft_font_face_create_for_pattern</link> (<parameter><link linkend="FcPattern"><type>FcPattern</type></link> *pattern</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-ft-font-options-substitute">cairo_ft_font_options_substitute</link> (<parameter>const <link linkend="cairo-font-options-t"><type>cairo_font_options_t</type></link> *options</parameter>, <parameter><link linkend="FcPattern"><type>FcPattern</type></link> *pattern</parameter>); <link linkend="FT-Face"><returnvalue>FT_Face</returnvalue></link> <link linkend="cairo-ft-scaled-font-lock-face">cairo_ft_scaled_font_lock_face</link> (<parameter><link linkend="cairo-scaled-font-t"><type>cairo_scaled_font_t</type></link> *scaled_font</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-ft-scaled-font-unlock-face">cairo_ft_scaled_font_unlock_face</link> (<parameter><link linkend="cairo-scaled-font-t"><type>cairo_scaled_font_t</type></link> *scaled_font</parameter>); </synopsis> </refsynopsisdiv> <refsect1 id="cairo-FreeType-Fonts.description" role="desc"> <title role="desc.title">Description</title> <para> The FreeType font backend is primarily used to render text on GNU/Linux systems, but can be used on other platforms too. </para> </refsect1> <refsect1 id="cairo-FreeType-Fonts.details" role="details"> <title role="details.title">Details</title> <refsect2 id="CAIRO-HAS-FT-FONT:CAPS" role="macro"> <title>CAIRO_HAS_FT_FONT</title> <indexterm zone="CAIRO-HAS-FT-FONT:CAPS"><primary sortas="HAS_FT_FONT">CAIRO_HAS_FT_FONT</primary></indexterm> <programlisting>#define CAIRO_HAS_FT_FONT 1 </programlisting> <para> Defined if the FreeType font backend is available. This macro can be used to conditionally compile backend-specific code. </para></refsect2> <refsect2 id="CAIRO-HAS-FC-FONT:CAPS" role="macro"> <title>CAIRO_HAS_FC_FONT</title> <indexterm zone="CAIRO-HAS-FC-FONT:CAPS"><primary sortas="HAS_FC_FONT">CAIRO_HAS_FC_FONT</primary></indexterm> <programlisting>#define CAIRO_HAS_FC_FONT 1 </programlisting> <para> Defined if the Fontconfig-specific functions of the FreeType font backend are available. This macro can be used to conditionally compile backend-specific code. </para></refsect2> <refsect2 id="cairo-ft-font-face-create-for-ft-face" role="function"> <title>cairo_ft_font_face_create_for_ft_face ()</title> <indexterm zone="cairo-ft-font-face-create-for-ft-face"><primary sortas="ft_font_face_create_for_ft_face">cairo_ft_font_face_create_for_ft_face</primary></indexterm> <programlisting><link linkend="cairo-font-face-t"><returnvalue>cairo_font_face_t</returnvalue></link> * cairo_ft_font_face_create_for_ft_face (<parameter><link linkend="FT-Face"><type>FT_Face</type></link> face</parameter>, <parameter><link linkend="int"><type>int</type></link> load_flags</parameter>);</programlisting> <para> Creates a new font face for the FreeType font backend from a pre-opened FreeType face. This font can then be used with <link linkend="cairo-set-font-face"><function>cairo_set_font_face()</function></link> or <link linkend="cairo-scaled-font-create"><function>cairo_scaled_font_create()</function></link>. The <link linkend="cairo-scaled-font-t"><type>cairo_scaled_font_t</type></link> returned from <link linkend="cairo-scaled-font-create"><function>cairo_scaled_font_create()</function></link> is also for the FreeType backend and can be used with functions such as <link linkend="cairo-ft-scaled-font-lock-face"><function>cairo_ft_scaled_font_lock_face()</function></link>. Note that Cairo may keep a reference to the FT_Face alive in a font-cache and the exact lifetime of the reference depends highly upon the exact usage pattern and is subject to external factors. You must not call <link linkend="FT-Done-Face"><function>FT_Done_Face()</function></link> before the last reference to the <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> has been dropped. </para> <para> As an example, below is how one might correctly couple the lifetime of the FreeType face object to the <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link>. </para> <para> <informalexample><programlisting> static const cairo_user_data_key_t key; font_face = cairo_ft_font_face_create_for_ft_face (ft_face, 0); status = cairo_font_face_set_user_data (font_face, &key, ft_face, (cairo_destroy_func_t) FT_Done_Face); if (status) { cairo_font_face_destroy (font_face); FT_Done_Face (ft_face); return ERROR; } </programlisting></informalexample> </para><variablelist role="params"> <varlistentry><term><parameter>face</parameter> :</term> <listitem><simpara>A FreeType face object, already opened. This must be kept around until the face's ref_count drops to zero and it is freed. Since the face may be referenced internally to Cairo, the best way to determine when it is safe to free the face is to pass a <link linkend="cairo-destroy-func-t"><type>cairo_destroy_func_t</type></link> to <link linkend="cairo-font-face-set-user-data"><function>cairo_font_face_set_user_data()</function></link> </simpara></listitem></varlistentry> <varlistentry><term><parameter>load_flags</parameter> :</term> <listitem><simpara>flags to pass to FT_Load_Glyph when loading glyphs from the font. These flags are OR'ed together with the flags derived from the <link linkend="cairo-font-options-t"><type>cairo_font_options_t</type></link> passed to <link linkend="cairo-scaled-font-create"><function>cairo_scaled_font_create()</function></link>, so only a few values such as <link linkend="FT-LOAD-VERTICAL-LAYOUT:CAPS"><literal>FT_LOAD_VERTICAL_LAYOUT</literal></link>, and <link linkend="FT-LOAD-FORCE-AUTOHINT:CAPS"><literal>FT_LOAD_FORCE_AUTOHINT</literal></link> are useful. You should not pass any of the flags affecting the load target, such as <link linkend="FT-LOAD-TARGET-LIGHT:CAPS"><literal>FT_LOAD_TARGET_LIGHT</literal></link>. </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> a newly created <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link>. Free with <link linkend="cairo-font-face-destroy"><function>cairo_font_face_destroy()</function></link> when you are done using it. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-ft-font-face-create-for-pattern" role="function"> <title>cairo_ft_font_face_create_for_pattern ()</title> <indexterm zone="cairo-ft-font-face-create-for-pattern"><primary sortas="ft_font_face_create_for_pattern">cairo_ft_font_face_create_for_pattern</primary></indexterm> <programlisting><link linkend="cairo-font-face-t"><returnvalue>cairo_font_face_t</returnvalue></link> * cairo_ft_font_face_create_for_pattern (<parameter><link linkend="FcPattern"><type>FcPattern</type></link> *pattern</parameter>);</programlisting> <para> Creates a new font face for the FreeType font backend based on a fontconfig pattern. This font can then be used with <link linkend="cairo-set-font-face"><function>cairo_set_font_face()</function></link> or <link linkend="cairo-scaled-font-create"><function>cairo_scaled_font_create()</function></link>. The <link linkend="cairo-scaled-font-t"><type>cairo_scaled_font_t</type></link> returned from <link linkend="cairo-scaled-font-create"><function>cairo_scaled_font_create()</function></link> is also for the FreeType backend and can be used with functions such as <link linkend="cairo-ft-scaled-font-lock-face"><function>cairo_ft_scaled_font_lock_face()</function></link>. </para> <para> Font rendering options are represented both here and when you call <link linkend="cairo-scaled-font-create"><function>cairo_scaled_font_create()</function></link>. Font options that have a representation in a <link linkend="FcPattern"><type>FcPattern</type></link> must be passed in here; to modify <link linkend="FcPattern"><type>FcPattern</type></link> appropriately to reflect the options in a <link linkend="cairo-font-options-t"><type>cairo_font_options_t</type></link>, call <link linkend="cairo-ft-font-options-substitute"><function>cairo_ft_font_options_substitute()</function></link>. </para> <para> The pattern's FC_FT_FACE element is inspected first and if that is set, that will be the FreeType font face associated with the returned cairo font face. Otherwise the FC_FILE element is checked. If it's set, that and the value of the FC_INDEX element (defaults to zero) of <parameter>pattern</parameter> are used to load a font face from file. </para> <para> If both steps from the previous paragraph fails, <parameter>pattern</parameter> will be passed to FcConfigSubstitute, FcDefaultSubstitute, and finally FcFontMatch, and the resulting font pattern is used. </para> <para> If the FC_FT_FACE element of <parameter>pattern</parameter> is set, the user is responsible for making sure that the referenced FT_Face remains valid for the life time of the returned <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link>. See <link linkend="cairo-ft-font-face-create-for-ft-face"><function>cairo_ft_font_face_create_for_ft_face()</function></link> for an exmaple of how to couple the life time of the FT_Face to that of the cairo font-face. </para><variablelist role="params"> <varlistentry><term><parameter>pattern</parameter> :</term> <listitem><simpara>A fontconfig pattern. Cairo makes a copy of the pattern if it needs to. You are free to modify or free <parameter>pattern</parameter> after this call. </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> a newly created <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link>. Free with <link linkend="cairo-font-face-destroy"><function>cairo_font_face_destroy()</function></link> when you are done using it. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-ft-font-options-substitute" role="function"> <title>cairo_ft_font_options_substitute ()</title> <indexterm zone="cairo-ft-font-options-substitute"><primary sortas="ft_font_options_substitute">cairo_ft_font_options_substitute</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_ft_font_options_substitute (<parameter>const <link linkend="cairo-font-options-t"><type>cairo_font_options_t</type></link> *options</parameter>, <parameter><link linkend="FcPattern"><type>FcPattern</type></link> *pattern</parameter>);</programlisting> <para> Add options to a <link linkend="FcPattern"><type>FcPattern</type></link> based on a <link linkend="cairo-font-options-t"><type>cairo_font_options_t</type></link> font options object. Options that are already in the pattern, are not overridden, so you should call this function after calling <link linkend="FcConfigSubstitute"><function>FcConfigSubstitute()</function></link> (the user's settings should override options based on the surface type), but before calling <link linkend="FcDefaultSubstitute"><function>FcDefaultSubstitute()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>options</parameter> :</term> <listitem><simpara>a <link linkend="cairo-font-options-t"><type>cairo_font_options_t</type></link> object </simpara></listitem></varlistentry> <varlistentry><term><parameter>pattern</parameter> :</term> <listitem><simpara>an existing <link linkend="FcPattern"><type>FcPattern</type></link> </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-ft-scaled-font-lock-face" role="function"> <title>cairo_ft_scaled_font_lock_face ()</title> <indexterm zone="cairo-ft-scaled-font-lock-face"><primary sortas="ft_scaled_font_lock_face">cairo_ft_scaled_font_lock_face</primary></indexterm> <programlisting><link linkend="FT-Face"><returnvalue>FT_Face</returnvalue></link> cairo_ft_scaled_font_lock_face (<parameter><link linkend="cairo-scaled-font-t"><type>cairo_scaled_font_t</type></link> *scaled_font</parameter>);</programlisting> <para> <link linkend="cairo-ft-scaled-font-lock-face"><function>cairo_ft_scaled_font_lock_face()</function></link> gets the <link linkend="FT-Face"><type>FT_Face</type></link> object from a FreeType backend font and scales it appropriately for the font. You must release the face with <link linkend="cairo-ft-scaled-font-unlock-face"><function>cairo_ft_scaled_font_unlock_face()</function></link> when you are done using it. Since the <link linkend="FT-Face"><type>FT_Face</type></link> object can be shared between multiple <link linkend="cairo-scaled-font-t"><type>cairo_scaled_font_t</type></link> objects, you must not lock any other font objects until you unlock this one. A count is kept of the number of times <link linkend="cairo-ft-scaled-font-lock-face"><function>cairo_ft_scaled_font_lock_face()</function></link> is called. <link linkend="cairo-ft-scaled-font-unlock-face"><function>cairo_ft_scaled_font_unlock_face()</function></link> must be called the same number of times. </para> <para> You must be careful when using this function in a library or in a threaded application, because freetype's design makes it unsafe to call freetype functions simultaneously from multiple threads, (even if using distinct FT_Face objects). Because of this, application code that acquires an FT_Face object with this call must add its own locking to protect any use of that object, (and which also must protect any other calls into cairo as almost any cairo function might result in a call into the freetype library). </para><variablelist role="params"> <varlistentry><term><parameter>scaled_font</parameter> :</term> <listitem><simpara>A <link linkend="cairo-scaled-font-t"><type>cairo_scaled_font_t</type></link> from the FreeType font backend. Such an object can be created by calling <link linkend="cairo-scaled-font-create"><function>cairo_scaled_font_create()</function></link> on a FreeType backend font face (see <link linkend="cairo-ft-font-face-create-for-pattern"><function>cairo_ft_font_face_create_for_pattern()</function></link>, <link linkend="cairo-ft-font-face-create-for-ft-face"><function>cairo_ft_font_face_create_for_ft_face()</function></link>). </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> The <link linkend="FT-Face"><type>FT_Face</type></link> object for <parameter>font</parameter>, scaled appropriately, or <link linkend="NULL:CAPS"><literal>NULL</literal></link> if <parameter>scaled_font</parameter> is in an error state (see <link linkend="cairo-scaled-font-status"><function>cairo_scaled_font_status()</function></link>) or there is insufficient memory. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-ft-scaled-font-unlock-face" role="function"> <title>cairo_ft_scaled_font_unlock_face ()</title> <indexterm zone="cairo-ft-scaled-font-unlock-face"><primary sortas="ft_scaled_font_unlock_face">cairo_ft_scaled_font_unlock_face</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_ft_scaled_font_unlock_face (<parameter><link linkend="cairo-scaled-font-t"><type>cairo_scaled_font_t</type></link> *scaled_font</parameter>);</programlisting> <para> Releases a face obtained with <link linkend="cairo-ft-scaled-font-lock-face"><function>cairo_ft_scaled_font_lock_face()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>scaled_font</parameter> :</term> <listitem><simpara>A <link linkend="cairo-scaled-font-t"><type>cairo_scaled_font_t</type></link> from the FreeType font backend. Such an object can be created by calling <link linkend="cairo-scaled-font-create"><function>cairo_scaled_font_create()</function></link> on a FreeType backend font face (see <link linkend="cairo-ft-font-face-create-for-pattern"><function>cairo_ft_font_face_create_for_pattern()</function></link>, <link linkend="cairo-ft-font-face-create-for-ft-face"><function>cairo_ft_font_face_create_for_ft_face()</function></link>). </simpara></listitem></varlistentry> </variablelist></refsect2> </refsect1> <refsect1 id="cairo-FreeType-Fonts.see-also"> <title>See Also</title> <link linkend="cairo-font-face-t"><type>cairo_font_face_t</type></link> </refsect1> </refentry>