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<refentry id="cairo-cairo-pattern-t">
<refmeta>
<refentrytitle role="top_of_page" id="cairo-cairo-pattern-t.top_of_page">cairo_pattern_t</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>
CAIRO Library
</refmiscinfo>
</refmeta>
<refnamediv>
<refname>cairo_pattern_t</refname>
<refpurpose>Sources for drawing</refpurpose>
</refnamediv>
<refsynopsisdiv id="cairo-cairo-pattern-t.synopsis" role="synopsis">
<title role="synopsis.title">Synopsis</title>
<synopsis>typedef <link linkend="cairo-pattern-t">cairo_pattern_t</link>;
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-pattern-add-color-stop-rgb">cairo_pattern_add_color_stop_rgb</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="double"><type>double</type></link> offset</parameter>,
<parameter><link linkend="double"><type>double</type></link> red</parameter>,
<parameter><link linkend="double"><type>double</type></link> green</parameter>,
<parameter><link linkend="double"><type>double</type></link> blue</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-pattern-add-color-stop-rgba">cairo_pattern_add_color_stop_rgba</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="double"><type>double</type></link> offset</parameter>,
<parameter><link linkend="double"><type>double</type></link> red</parameter>,
<parameter><link linkend="double"><type>double</type></link> green</parameter>,
<parameter><link linkend="double"><type>double</type></link> blue</parameter>,
<parameter><link linkend="double"><type>double</type></link> alpha</parameter>);
<link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-pattern-get-color-stop-count">cairo_pattern_get_color_stop_count</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="int"><type>int</type></link> *count</parameter>);
<link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-pattern-get-color-stop-rgba">cairo_pattern_get_color_stop_rgba</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="int"><type>int</type></link> index</parameter>,
<parameter><link linkend="double"><type>double</type></link> *offset</parameter>,
<parameter><link linkend="double"><type>double</type></link> *red</parameter>,
<parameter><link linkend="double"><type>double</type></link> *green</parameter>,
<parameter><link linkend="double"><type>double</type></link> *blue</parameter>,
<parameter><link linkend="double"><type>double</type></link> *alpha</parameter>);
<link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * <link linkend="cairo-pattern-create-rgb">cairo_pattern_create_rgb</link> (<parameter><link linkend="double"><type>double</type></link> red</parameter>,
<parameter><link linkend="double"><type>double</type></link> green</parameter>,
<parameter><link linkend="double"><type>double</type></link> blue</parameter>);
<link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * <link linkend="cairo-pattern-create-rgba">cairo_pattern_create_rgba</link> (<parameter><link linkend="double"><type>double</type></link> red</parameter>,
<parameter><link linkend="double"><type>double</type></link> green</parameter>,
<parameter><link linkend="double"><type>double</type></link> blue</parameter>,
<parameter><link linkend="double"><type>double</type></link> alpha</parameter>);
<link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-pattern-get-rgba">cairo_pattern_get_rgba</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="double"><type>double</type></link> *red</parameter>,
<parameter><link linkend="double"><type>double</type></link> *green</parameter>,
<parameter><link linkend="double"><type>double</type></link> *blue</parameter>,
<parameter><link linkend="double"><type>double</type></link> *alpha</parameter>);
<link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * <link linkend="cairo-pattern-create-for-surface">cairo_pattern_create_for_surface</link> (<parameter><link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> *surface</parameter>);
<link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-pattern-get-surface">cairo_pattern_get_surface</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> **surface</parameter>);
<link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * <link linkend="cairo-pattern-create-linear">cairo_pattern_create_linear</link> (<parameter><link linkend="double"><type>double</type></link> x0</parameter>,
<parameter><link linkend="double"><type>double</type></link> y0</parameter>,
<parameter><link linkend="double"><type>double</type></link> x1</parameter>,
<parameter><link linkend="double"><type>double</type></link> y1</parameter>);
<link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-pattern-get-linear-points">cairo_pattern_get_linear_points</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="double"><type>double</type></link> *x0</parameter>,
<parameter><link linkend="double"><type>double</type></link> *y0</parameter>,
<parameter><link linkend="double"><type>double</type></link> *x1</parameter>,
<parameter><link linkend="double"><type>double</type></link> *y1</parameter>);
<link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * <link linkend="cairo-pattern-create-radial">cairo_pattern_create_radial</link> (<parameter><link linkend="double"><type>double</type></link> cx0</parameter>,
<parameter><link linkend="double"><type>double</type></link> cy0</parameter>,
<parameter><link linkend="double"><type>double</type></link> radius0</parameter>,
<parameter><link linkend="double"><type>double</type></link> cx1</parameter>,
<parameter><link linkend="double"><type>double</type></link> cy1</parameter>,
<parameter><link linkend="double"><type>double</type></link> radius1</parameter>);
<link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-pattern-get-radial-circles">cairo_pattern_get_radial_circles</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="double"><type>double</type></link> *x0</parameter>,
<parameter><link linkend="double"><type>double</type></link> *y0</parameter>,
<parameter><link linkend="double"><type>double</type></link> *r0</parameter>,
<parameter><link linkend="double"><type>double</type></link> *x1</parameter>,
<parameter><link linkend="double"><type>double</type></link> *y1</parameter>,
<parameter><link linkend="double"><type>double</type></link> *r1</parameter>);
<link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * <link linkend="cairo-pattern-reference">cairo_pattern_reference</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-pattern-destroy">cairo_pattern_destroy</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);
<link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-pattern-status">cairo_pattern_status</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);
enum <link linkend="cairo-extend-t">cairo_extend_t</link>;
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-pattern-set-extend">cairo_pattern_set_extend</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="cairo-extend-t"><type>cairo_extend_t</type></link> extend</parameter>);
<link linkend="cairo-extend-t"><returnvalue>cairo_extend_t</returnvalue></link> <link linkend="cairo-pattern-get-extend">cairo_pattern_get_extend</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);
enum <link linkend="cairo-filter-t">cairo_filter_t</link>;
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-pattern-set-filter">cairo_pattern_set_filter</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="cairo-filter-t"><type>cairo_filter_t</type></link> filter</parameter>);
<link linkend="cairo-filter-t"><returnvalue>cairo_filter_t</returnvalue></link> <link linkend="cairo-pattern-get-filter">cairo_pattern_get_filter</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-pattern-set-matrix">cairo_pattern_set_matrix</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter>const <link linkend="cairo-matrix-t"><type>cairo_matrix_t</type></link> *matrix</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-pattern-get-matrix">cairo_pattern_get_matrix</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="cairo-matrix-t"><type>cairo_matrix_t</type></link> *matrix</parameter>);
enum <link linkend="cairo-pattern-type-t">cairo_pattern_type_t</link>;
<link linkend="cairo-pattern-type-t"><returnvalue>cairo_pattern_type_t</returnvalue></link> <link linkend="cairo-pattern-get-type">cairo_pattern_get_type</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);
unsigned <link linkend="int"><returnvalue>int</returnvalue></link> <link linkend="cairo-pattern-get-reference-count">cairo_pattern_get_reference_count</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);
<link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-pattern-set-user-data">cairo_pattern_set_user_data</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</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-pattern-get-user-data">cairo_pattern_get_user_data</link> (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</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-pattern-t.description" role="desc">
<title role="desc.title">Description</title>
<para>
<link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> is the paint with which cairo draws.
The primary use of patterns is as the source for all cairo drawing
operations, although they can also be used as masks, that is, as the
brush too.
</para>
<para>
A cairo pattern is created by using one of the many constructors,
of the form cairo_pattern_create_<emphasis>type</emphasis>()
or implicitly through
cairo_set_source_<emphasis>type</emphasis>() functions.
</para>
</refsect1>
<refsect1 id="cairo-cairo-pattern-t.details" role="details">
<title role="details.title">Details</title>
<refsect2 id="cairo-pattern-t" role="typedef">
<title>cairo_pattern_t</title>
<indexterm zone="cairo-pattern-t"><primary sortas="pattern_t">cairo_pattern_t</primary></indexterm>
<programlisting>typedef struct _cairo_pattern cairo_pattern_t;
</programlisting>
<para>
A <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> represents a source when drawing onto a
surface. There are different subtypes of <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>,
for different types of sources; for example,
<link linkend="cairo-pattern-create-rgb"><function>cairo_pattern_create_rgb()</function></link> creates a pattern for a solid
opaque color.
</para>
<para>
Other than various cairo_pattern_create_<emphasis>type</emphasis>()
functions, some of the pattern types can be implicitly created
using various cairo_set_source_<emphasis>type</emphasis>() functions;
for example <link linkend="cairo-set-source-rgb"><function>cairo_set_source_rgb()</function></link>.
</para>
<para>
The type of a pattern can be queried with <link linkend="cairo-pattern-get-type"><function>cairo_pattern_get_type()</function></link>.
</para>
<para>
Memory management of <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> is done with
<link linkend="cairo-pattern-reference"><function>cairo_pattern_reference()</function></link> and <link linkend="cairo-pattern-destroy"><function>cairo_pattern_destroy()</function></link>.
</para></refsect2>
<refsect2 id="cairo-pattern-add-color-stop-rgb" role="function">
<title>cairo_pattern_add_color_stop_rgb ()</title>
<indexterm zone="cairo-pattern-add-color-stop-rgb"><primary sortas="pattern_add_color_stop_rgb">cairo_pattern_add_color_stop_rgb</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_pattern_add_color_stop_rgb (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="double"><type>double</type></link> offset</parameter>,
<parameter><link linkend="double"><type>double</type></link> red</parameter>,
<parameter><link linkend="double"><type>double</type></link> green</parameter>,
<parameter><link linkend="double"><type>double</type></link> blue</parameter>);</programlisting>
<para>
Adds an opaque color stop to a gradient pattern. The offset
specifies the location along the gradient's control vector. For
example, a linear gradient's control vector is from (x0,y0) to
(x1,y1) while a radial gradient's control vector is from any point
on the start circle to the corresponding point on the end circle.
</para>
<para>
The color is specified in the same way as in <link linkend="cairo-set-source-rgb"><function>cairo_set_source_rgb()</function></link>.
</para>
<para>
If two (or more) stops are specified with identical offset values,
they will be sorted according to the order in which the stops are
added, (stops added earlier will compare less than stops added
later). This can be useful for reliably making sharp color
transitions instead of the typical blend.
</para>
<para>
Note: If the pattern is not a gradient pattern, (eg. a linear or
radial pattern), then the pattern will be put into an error status
with a status of <link linkend="CAIRO-STATUS-PATTERN-TYPE-MISMATCH:CAPS"><literal>CAIRO_STATUS_PATTERN_TYPE_MISMATCH</literal></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>offset</parameter> :</term>
<listitem><simpara>an offset in the range [0.0 .. 1.0]
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>red</parameter> :</term>
<listitem><simpara>red component of color
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>green</parameter> :</term>
<listitem><simpara>green component of color
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>blue</parameter> :</term>
<listitem><simpara>blue component of color
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-add-color-stop-rgba" role="function">
<title>cairo_pattern_add_color_stop_rgba ()</title>
<indexterm zone="cairo-pattern-add-color-stop-rgba"><primary sortas="pattern_add_color_stop_rgba">cairo_pattern_add_color_stop_rgba</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_pattern_add_color_stop_rgba (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="double"><type>double</type></link> offset</parameter>,
<parameter><link linkend="double"><type>double</type></link> red</parameter>,
<parameter><link linkend="double"><type>double</type></link> green</parameter>,
<parameter><link linkend="double"><type>double</type></link> blue</parameter>,
<parameter><link linkend="double"><type>double</type></link> alpha</parameter>);</programlisting>
<para>
Adds a translucent color stop to a gradient pattern. The offset
specifies the location along the gradient's control vector. For
example, a linear gradient's control vector is from (x0,y0) to
(x1,y1) while a radial gradient's control vector is from any point
on the start circle to the corresponding point on the end circle.
</para>
<para>
The color is specified in the same way as in <link linkend="cairo-set-source-rgba"><function>cairo_set_source_rgba()</function></link>.
</para>
<para>
If two (or more) stops are specified with identical offset values,
they will be sorted according to the order in which the stops are
added, (stops added earlier will compare less than stops added
later). This can be useful for reliably making sharp color
transitions instead of the typical blend.
</para>
<para>
Note: If the pattern is not a gradient pattern, (eg. a linear or
radial pattern), then the pattern will be put into an error status
with a status of <link linkend="CAIRO-STATUS-PATTERN-TYPE-MISMATCH:CAPS"><literal>CAIRO_STATUS_PATTERN_TYPE_MISMATCH</literal></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>offset</parameter> :</term>
<listitem><simpara>an offset in the range [0.0 .. 1.0]
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>red</parameter> :</term>
<listitem><simpara>red component of color
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>green</parameter> :</term>
<listitem><simpara>green component of color
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>blue</parameter> :</term>
<listitem><simpara>blue component of color
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>alpha</parameter> :</term>
<listitem><simpara>alpha component of color
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-get-color-stop-count" role="function" condition="since:1.4">
<title>cairo_pattern_get_color_stop_count ()</title>
<indexterm zone="cairo-pattern-get-color-stop-count" role="1.4"><primary sortas="pattern_get_color_stop_count">cairo_pattern_get_color_stop_count</primary></indexterm>
<programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_pattern_get_color_stop_count (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="int"><type>int</type></link> *count</parameter>);</programlisting>
<para>
Gets the number of color stops specified in the given gradient
pattern.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>count</parameter> :</term>
<listitem><simpara>return value for the number of color stops, or <link linkend="NULL:CAPS"><literal>NULL</literal></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
<link linkend="CAIRO-STATUS-PATTERN-TYPE-MISMATCH:CAPS"><literal>CAIRO_STATUS_PATTERN_TYPE_MISMATCH</literal></link> if <parameter>pattern</parameter> is not a gradient
pattern.
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since 1.4</para></refsect2>
<refsect2 id="cairo-pattern-get-color-stop-rgba" role="function" condition="since:1.4">
<title>cairo_pattern_get_color_stop_rgba ()</title>
<indexterm zone="cairo-pattern-get-color-stop-rgba" role="1.4"><primary sortas="pattern_get_color_stop_rgba">cairo_pattern_get_color_stop_rgba</primary></indexterm>
<programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_pattern_get_color_stop_rgba (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="int"><type>int</type></link> index</parameter>,
<parameter><link linkend="double"><type>double</type></link> *offset</parameter>,
<parameter><link linkend="double"><type>double</type></link> *red</parameter>,
<parameter><link linkend="double"><type>double</type></link> *green</parameter>,
<parameter><link linkend="double"><type>double</type></link> *blue</parameter>,
<parameter><link linkend="double"><type>double</type></link> *alpha</parameter>);</programlisting>
<para>
Gets the color and offset information at the given <parameter>index</parameter> for a
gradient pattern. Values of <parameter>index</parameter> are 0 to 1 less than the number
returned by <link linkend="cairo-pattern-get-color-stop-count"><function>cairo_pattern_get_color_stop_count()</function></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>index</parameter> :</term>
<listitem><simpara>index of the stop to return data for
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>offset</parameter> :</term>
<listitem><simpara>return value for the offset of the stop, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>red</parameter> :</term>
<listitem><simpara>return value for red component of color, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>green</parameter> :</term>
<listitem><simpara>return value for green component of color, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>blue</parameter> :</term>
<listitem><simpara>return value for blue component of color, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>alpha</parameter> :</term>
<listitem><simpara>return value for alpha component of color, or <link linkend="NULL:CAPS"><literal>NULL</literal></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 <link linkend="CAIRO-STATUS-INVALID-INDEX:CAPS"><literal>CAIRO_STATUS_INVALID_INDEX</literal></link>
if <parameter>index</parameter> is not valid for the given pattern. If the pattern is
not a gradient pattern, <link linkend="CAIRO-STATUS-PATTERN-TYPE-MISMATCH:CAPS"><literal>CAIRO_STATUS_PATTERN_TYPE_MISMATCH</literal></link> is
returned.
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since 1.4</para></refsect2>
<refsect2 id="cairo-pattern-create-rgb" role="function">
<title>cairo_pattern_create_rgb ()</title>
<indexterm zone="cairo-pattern-create-rgb"><primary sortas="pattern_create_rgb">cairo_pattern_create_rgb</primary></indexterm>
<programlisting><link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * cairo_pattern_create_rgb (<parameter><link linkend="double"><type>double</type></link> red</parameter>,
<parameter><link linkend="double"><type>double</type></link> green</parameter>,
<parameter><link linkend="double"><type>double</type></link> blue</parameter>);</programlisting>
<para>
Creates a new <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> corresponding to an opaque color. The
color components are floating point numbers in the range 0 to 1.
If the values passed in are outside that range, they will be
clamped.
</para><variablelist role="params">
<varlistentry><term><parameter>red</parameter> :</term>
<listitem><simpara>red component of the color
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>green</parameter> :</term>
<listitem><simpara>green component of the color
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>blue</parameter> :</term>
<listitem><simpara>blue component of the color
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the newly created <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> if successful, or
an error pattern in case of no memory. The caller owns the
returned object and should call <link linkend="cairo-pattern-destroy"><function>cairo_pattern_destroy()</function></link> when
finished with it.
This function will always return a valid pointer, but if an error
occurred the pattern status will be set to an error. To inspect
the status of a pattern use <link linkend="cairo-pattern-status"><function>cairo_pattern_status()</function></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-create-rgba" role="function">
<title>cairo_pattern_create_rgba ()</title>
<indexterm zone="cairo-pattern-create-rgba"><primary sortas="pattern_create_rgba">cairo_pattern_create_rgba</primary></indexterm>
<programlisting><link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * cairo_pattern_create_rgba (<parameter><link linkend="double"><type>double</type></link> red</parameter>,
<parameter><link linkend="double"><type>double</type></link> green</parameter>,
<parameter><link linkend="double"><type>double</type></link> blue</parameter>,
<parameter><link linkend="double"><type>double</type></link> alpha</parameter>);</programlisting>
<para>
Creates a new <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> corresponding to a translucent color.
The color components are floating point numbers in the range 0 to
1. If the values passed in are outside that range, they will be
clamped.
</para><variablelist role="params">
<varlistentry><term><parameter>red</parameter> :</term>
<listitem><simpara>red component of the color
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>green</parameter> :</term>
<listitem><simpara>green component of the color
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>blue</parameter> :</term>
<listitem><simpara>blue component of the color
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>alpha</parameter> :</term>
<listitem><simpara>alpha component of the color
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the newly created <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> if successful, or
an error pattern in case of no memory. The caller owns the
returned object and should call <link linkend="cairo-pattern-destroy"><function>cairo_pattern_destroy()</function></link> when
finished with it.
This function will always return a valid pointer, but if an error
occurred the pattern status will be set to an error. To inspect
the status of a pattern use <link linkend="cairo-pattern-status"><function>cairo_pattern_status()</function></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-get-rgba" role="function" condition="since:1.4">
<title>cairo_pattern_get_rgba ()</title>
<indexterm zone="cairo-pattern-get-rgba" role="1.4"><primary sortas="pattern_get_rgba">cairo_pattern_get_rgba</primary></indexterm>
<programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_pattern_get_rgba (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="double"><type>double</type></link> *red</parameter>,
<parameter><link linkend="double"><type>double</type></link> *green</parameter>,
<parameter><link linkend="double"><type>double</type></link> *blue</parameter>,
<parameter><link linkend="double"><type>double</type></link> *alpha</parameter>);</programlisting>
<para>
Gets the solid color for a solid color pattern.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>red</parameter> :</term>
<listitem><simpara>return value for red component of color, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>green</parameter> :</term>
<listitem><simpara>return value for green component of color, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>blue</parameter> :</term>
<listitem><simpara>return value for blue component of color, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>alpha</parameter> :</term>
<listitem><simpara>return value for alpha component of color, or <link linkend="NULL:CAPS"><literal>NULL</literal></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
<link linkend="CAIRO-STATUS-PATTERN-TYPE-MISMATCH:CAPS"><literal>CAIRO_STATUS_PATTERN_TYPE_MISMATCH</literal></link> if the pattern is not a solid
color pattern.
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since 1.4</para></refsect2>
<refsect2 id="cairo-pattern-create-for-surface" role="function">
<title>cairo_pattern_create_for_surface ()</title>
<indexterm zone="cairo-pattern-create-for-surface"><primary sortas="pattern_create_for_surface">cairo_pattern_create_for_surface</primary></indexterm>
<programlisting><link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * cairo_pattern_create_for_surface (<parameter><link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> *surface</parameter>);</programlisting>
<para>
Create a new <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> for the given surface.
</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter> :</term>
<listitem><simpara>the surface
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the newly created <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> if successful, or
an error pattern in case of no memory. The caller owns the
returned object and should call <link linkend="cairo-pattern-destroy"><function>cairo_pattern_destroy()</function></link> when
finished with it.
This function will always return a valid pointer, but if an error
occurred the pattern status will be set to an error. To inspect
the status of a pattern use <link linkend="cairo-pattern-status"><function>cairo_pattern_status()</function></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-get-surface" role="function" condition="since:1.4">
<title>cairo_pattern_get_surface ()</title>
<indexterm zone="cairo-pattern-get-surface" role="1.4"><primary sortas="pattern_get_surface">cairo_pattern_get_surface</primary></indexterm>
<programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_pattern_get_surface (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> **surface</parameter>);</programlisting>
<para>
Gets the surface of a surface pattern. The reference returned in
<parameter>surface</parameter> is owned by the pattern; the caller should call
<link linkend="cairo-surface-reference"><function>cairo_surface_reference()</function></link> if the surface is to be retained.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>surface</parameter> :</term>
<listitem><simpara>return value for surface of pattern, or <link linkend="NULL:CAPS"><literal>NULL</literal></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
<link linkend="CAIRO-STATUS-PATTERN-TYPE-MISMATCH:CAPS"><literal>CAIRO_STATUS_PATTERN_TYPE_MISMATCH</literal></link> if the pattern is not a surface
pattern.
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since 1.4</para></refsect2>
<refsect2 id="cairo-pattern-create-linear" role="function">
<title>cairo_pattern_create_linear ()</title>
<indexterm zone="cairo-pattern-create-linear"><primary sortas="pattern_create_linear">cairo_pattern_create_linear</primary></indexterm>
<programlisting><link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * cairo_pattern_create_linear (<parameter><link linkend="double"><type>double</type></link> x0</parameter>,
<parameter><link linkend="double"><type>double</type></link> y0</parameter>,
<parameter><link linkend="double"><type>double</type></link> x1</parameter>,
<parameter><link linkend="double"><type>double</type></link> y1</parameter>);</programlisting>
<para>
Create a new linear gradient <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> along the line defined
by (x0, y0) and (x1, y1). Before using the gradient pattern, a
number of color stops should be defined using
<link linkend="cairo-pattern-add-color-stop-rgb"><function>cairo_pattern_add_color_stop_rgb()</function></link> or
<link linkend="cairo-pattern-add-color-stop-rgba"><function>cairo_pattern_add_color_stop_rgba()</function></link>.
</para>
<para>
Note: The coordinates here are in pattern space. For a new pattern,
pattern space is identical to user space, but the relationship
between the spaces can be changed with <link linkend="cairo-pattern-set-matrix"><function>cairo_pattern_set_matrix()</function></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>x0</parameter> :</term>
<listitem><simpara>x coordinate of the start point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y0</parameter> :</term>
<listitem><simpara>y coordinate of the start point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>x1</parameter> :</term>
<listitem><simpara>x coordinate of the end point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y1</parameter> :</term>
<listitem><simpara>y coordinate of the end point
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the newly created <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> if successful, or
an error pattern in case of no memory. The caller owns the
returned object and should call <link linkend="cairo-pattern-destroy"><function>cairo_pattern_destroy()</function></link> when
finished with it.
This function will always return a valid pointer, but if an error
occurred the pattern status will be set to an error. To inspect
the status of a pattern use <link linkend="cairo-pattern-status"><function>cairo_pattern_status()</function></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-get-linear-points" role="function" condition="since:1.4">
<title>cairo_pattern_get_linear_points ()</title>
<indexterm zone="cairo-pattern-get-linear-points" role="1.4"><primary sortas="pattern_get_linear_points">cairo_pattern_get_linear_points</primary></indexterm>
<programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_pattern_get_linear_points (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="double"><type>double</type></link> *x0</parameter>,
<parameter><link linkend="double"><type>double</type></link> *y0</parameter>,
<parameter><link linkend="double"><type>double</type></link> *x1</parameter>,
<parameter><link linkend="double"><type>double</type></link> *y1</parameter>);</programlisting>
<para>
Gets the gradient endpoints for a linear gradient.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>x0</parameter> :</term>
<listitem><simpara>return value for the x coordinate of the first point, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y0</parameter> :</term>
<listitem><simpara>return value for the y coordinate of the first point, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>x1</parameter> :</term>
<listitem><simpara>return value for the x coordinate of the second point, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y1</parameter> :</term>
<listitem><simpara>return value for the y coordinate of the second point, or <link linkend="NULL:CAPS"><literal>NULL</literal></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
<link linkend="CAIRO-STATUS-PATTERN-TYPE-MISMATCH:CAPS"><literal>CAIRO_STATUS_PATTERN_TYPE_MISMATCH</literal></link> if <parameter>pattern</parameter> is not a linear
gradient pattern.
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since 1.4</para></refsect2>
<refsect2 id="cairo-pattern-create-radial" role="function">
<title>cairo_pattern_create_radial ()</title>
<indexterm zone="cairo-pattern-create-radial"><primary sortas="pattern_create_radial">cairo_pattern_create_radial</primary></indexterm>
<programlisting><link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * cairo_pattern_create_radial (<parameter><link linkend="double"><type>double</type></link> cx0</parameter>,
<parameter><link linkend="double"><type>double</type></link> cy0</parameter>,
<parameter><link linkend="double"><type>double</type></link> radius0</parameter>,
<parameter><link linkend="double"><type>double</type></link> cx1</parameter>,
<parameter><link linkend="double"><type>double</type></link> cy1</parameter>,
<parameter><link linkend="double"><type>double</type></link> radius1</parameter>);</programlisting>
<para>
Creates a new radial gradient <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> between the two
circles defined by (cx0, cy0, radius0) and (cx1, cy1, radius1). Before using the
gradient pattern, a number of color stops should be defined using
<link linkend="cairo-pattern-add-color-stop-rgb"><function>cairo_pattern_add_color_stop_rgb()</function></link> or
<link linkend="cairo-pattern-add-color-stop-rgba"><function>cairo_pattern_add_color_stop_rgba()</function></link>.
</para>
<para>
Note: The coordinates here are in pattern space. For a new pattern,
pattern space is identical to user space, but the relationship
between the spaces can be changed with <link linkend="cairo-pattern-set-matrix"><function>cairo_pattern_set_matrix()</function></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>cx0</parameter> :</term>
<listitem><simpara>x coordinate for the center of the start circle
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>cy0</parameter> :</term>
<listitem><simpara>y coordinate for the center of the start circle
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>radius0</parameter> :</term>
<listitem><simpara>radius of the start circle
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>cx1</parameter> :</term>
<listitem><simpara>x coordinate for the center of the end circle
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>cy1</parameter> :</term>
<listitem><simpara>y coordinate for the center of the end circle
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>radius1</parameter> :</term>
<listitem><simpara>radius of the end circle
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the newly created <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> if successful, or
an error pattern in case of no memory. The caller owns the
returned object and should call <link linkend="cairo-pattern-destroy"><function>cairo_pattern_destroy()</function></link> when
finished with it.
This function will always return a valid pointer, but if an error
occurred the pattern status will be set to an error. To inspect
the status of a pattern use <link linkend="cairo-pattern-status"><function>cairo_pattern_status()</function></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-get-radial-circles" role="function" condition="since:1.4">
<title>cairo_pattern_get_radial_circles ()</title>
<indexterm zone="cairo-pattern-get-radial-circles" role="1.4"><primary sortas="pattern_get_radial_circles">cairo_pattern_get_radial_circles</primary></indexterm>
<programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_pattern_get_radial_circles (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="double"><type>double</type></link> *x0</parameter>,
<parameter><link linkend="double"><type>double</type></link> *y0</parameter>,
<parameter><link linkend="double"><type>double</type></link> *r0</parameter>,
<parameter><link linkend="double"><type>double</type></link> *x1</parameter>,
<parameter><link linkend="double"><type>double</type></link> *y1</parameter>,
<parameter><link linkend="double"><type>double</type></link> *r1</parameter>);</programlisting>
<para>
Gets the gradient endpoint circles for a radial gradient, each
specified as a center coordinate and a radius.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>x0</parameter> :</term>
<listitem><simpara>return value for the x coordinate of the center of the first circle, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y0</parameter> :</term>
<listitem><simpara>return value for the y coordinate of the center of the first circle, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>r0</parameter> :</term>
<listitem><simpara>return value for the radius of the first circle, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>x1</parameter> :</term>
<listitem><simpara>return value for the x coordinate of the center of the second circle, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y1</parameter> :</term>
<listitem><simpara>return value for the y coordinate of the center of the second circle, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>r1</parameter> :</term>
<listitem><simpara>return value for the radius of the second circle, or <link linkend="NULL:CAPS"><literal>NULL</literal></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
<link linkend="CAIRO-STATUS-PATTERN-TYPE-MISMATCH:CAPS"><literal>CAIRO_STATUS_PATTERN_TYPE_MISMATCH</literal></link> if <parameter>pattern</parameter> is not a radial
gradient pattern.
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since 1.4</para></refsect2>
<refsect2 id="cairo-pattern-reference" role="function">
<title>cairo_pattern_reference ()</title>
<indexterm zone="cairo-pattern-reference"><primary sortas="pattern_reference">cairo_pattern_reference</primary></indexterm>
<programlisting><link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * cairo_pattern_reference (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);</programlisting>
<para>
Increases the reference count on <parameter>pattern</parameter> by one. This prevents
<parameter>pattern</parameter> from being destroyed until a matching call to
<link linkend="cairo-pattern-destroy"><function>cairo_pattern_destroy()</function></link> is made.
</para>
<para>
The number of references to a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> can be get using
<link linkend="cairo-pattern-get-reference-count"><function>cairo_pattern_get_reference_count()</function></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the referenced <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-destroy" role="function">
<title>cairo_pattern_destroy ()</title>
<indexterm zone="cairo-pattern-destroy"><primary sortas="pattern_destroy">cairo_pattern_destroy</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_pattern_destroy (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);</programlisting>
<para>
Decreases the reference count on <parameter>pattern</parameter> by one. If the result is
zero, then <parameter>pattern</parameter> and all associated resources are freed. See
<link linkend="cairo-pattern-reference"><function>cairo_pattern_reference()</function></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-status" role="function">
<title>cairo_pattern_status ()</title>
<indexterm zone="cairo-pattern-status"><primary sortas="pattern_status">cairo_pattern_status</primary></indexterm>
<programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_pattern_status (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);</programlisting>
<para>
Checks whether an error has previously occurred for this
pattern.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_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>, <link linkend="CAIRO-STATUS-NO-MEMORY:CAPS"><literal>CAIRO_STATUS_NO_MEMORY</literal></link>, or
<link linkend="CAIRO-STATUS-PATTERN-TYPE-MISMATCH:CAPS"><literal>CAIRO_STATUS_PATTERN_TYPE_MISMATCH</literal></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-extend-t" role="enum">
<title>enum cairo_extend_t</title>
<indexterm zone="cairo-extend-t"><primary sortas="extend_t">cairo_extend_t</primary></indexterm>
<programlisting>typedef enum _cairo_extend {
CAIRO_EXTEND_NONE,
CAIRO_EXTEND_REPEAT,
CAIRO_EXTEND_REFLECT,
CAIRO_EXTEND_PAD
} cairo_extend_t;
</programlisting>
<para>
<link linkend="cairo-extend-t"><type>cairo_extend_t</type></link> is used to describe how pattern color/alpha will be
determined for areas "outside" the pattern's natural area, (for
example, outside the surface bounds or outside the gradient
geometry).
</para>
<para>
The default extend mode is <link linkend="CAIRO-EXTEND-NONE:CAPS"><literal>CAIRO_EXTEND_NONE</literal></link> for surface patterns
and <link linkend="CAIRO-EXTEND-PAD:CAPS"><literal>CAIRO_EXTEND_PAD</literal></link> for gradient patterns.
</para>
<para>
New entries may be added in future versions.
</para><variablelist role="enum">
<varlistentry id="CAIRO-EXTEND-NONE:CAPS" role="constant">
<term><literal>CAIRO_EXTEND_NONE</literal></term>
<listitem><simpara>pixels outside of the source pattern
are fully transparent
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-EXTEND-REPEAT:CAPS" role="constant">
<term><literal>CAIRO_EXTEND_REPEAT</literal></term>
<listitem><simpara>the pattern is tiled by repeating
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-EXTEND-REFLECT:CAPS" role="constant">
<term><literal>CAIRO_EXTEND_REFLECT</literal></term>
<listitem><simpara>the pattern is tiled by reflecting
at the edges (Implemented for surface patterns since 1.6)
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-EXTEND-PAD:CAPS" role="constant">
<term><literal>CAIRO_EXTEND_PAD</literal></term>
<listitem><simpara>pixels outside of the pattern copy
the closest pixel from the source (Since 1.2; but only
implemented for surface patterns since 1.6)
</simpara></listitem>
</varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-set-extend" role="function">
<title>cairo_pattern_set_extend ()</title>
<indexterm zone="cairo-pattern-set-extend"><primary sortas="pattern_set_extend">cairo_pattern_set_extend</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_pattern_set_extend (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="cairo-extend-t"><type>cairo_extend_t</type></link> extend</parameter>);</programlisting>
<para>
Sets the mode to be used for drawing outside the area of a pattern.
See <link linkend="cairo-extend-t"><type>cairo_extend_t</type></link> for details on the semantics of each extend
strategy.
</para>
<para>
The default extend mode is <link linkend="CAIRO-EXTEND-NONE:CAPS"><literal>CAIRO_EXTEND_NONE</literal></link> for surface patterns
and <link linkend="CAIRO-EXTEND-PAD:CAPS"><literal>CAIRO_EXTEND_PAD</literal></link> for gradient patterns.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>extend</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-extend-t"><type>cairo_extend_t</type></link> describing how the area outside of the
pattern will be drawn
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-get-extend" role="function">
<title>cairo_pattern_get_extend ()</title>
<indexterm zone="cairo-pattern-get-extend"><primary sortas="pattern_get_extend">cairo_pattern_get_extend</primary></indexterm>
<programlisting><link linkend="cairo-extend-t"><returnvalue>cairo_extend_t</returnvalue></link> cairo_pattern_get_extend (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);</programlisting>
<para>
Gets the current extend mode for a pattern. See <link linkend="cairo-extend-t"><type>cairo_extend_t</type></link>
for details on the semantics of each extend strategy.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current extend strategy used for drawing the
pattern.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-filter-t" role="enum">
<title>enum cairo_filter_t</title>
<indexterm zone="cairo-filter-t"><primary sortas="filter_t">cairo_filter_t</primary></indexterm>
<programlisting>typedef enum _cairo_filter {
CAIRO_FILTER_FAST,
CAIRO_FILTER_GOOD,
CAIRO_FILTER_BEST,
CAIRO_FILTER_NEAREST,
CAIRO_FILTER_BILINEAR,
CAIRO_FILTER_GAUSSIAN
} cairo_filter_t;
</programlisting>
<para>
<link linkend="cairo-filter-t"><type>cairo_filter_t</type></link> is used to indicate what filtering should be
applied when reading pixel values from patterns. See
<link linkend="cairo-pattern-set-source"><function>cairo_pattern_set_source()</function></link> for indicating the desired filter to be
used with a particular pattern.
</para><variablelist role="enum">
<varlistentry id="CAIRO-FILTER-FAST:CAPS" role="constant">
<term><literal>CAIRO_FILTER_FAST</literal></term>
<listitem><simpara>A high-performance filter, with quality similar
to <link linkend="CAIRO-FILTER-NEAREST:CAPS"><literal>CAIRO_FILTER_NEAREST</literal></link>
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-FILTER-GOOD:CAPS" role="constant">
<term><literal>CAIRO_FILTER_GOOD</literal></term>
<listitem><simpara>A reasonable-performance filter, with quality
similar to <link linkend="CAIRO-FILTER-BILINEAR:CAPS"><literal>CAIRO_FILTER_BILINEAR</literal></link>
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-FILTER-BEST:CAPS" role="constant">
<term><literal>CAIRO_FILTER_BEST</literal></term>
<listitem><simpara>The highest-quality available, performance may
not be suitable for interactive use.
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-FILTER-NEAREST:CAPS" role="constant">
<term><literal>CAIRO_FILTER_NEAREST</literal></term>
<listitem><simpara>Nearest-neighbor filtering
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-FILTER-BILINEAR:CAPS" role="constant">
<term><literal>CAIRO_FILTER_BILINEAR</literal></term>
<listitem><simpara>Linear interpolation in two dimensions
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-FILTER-GAUSSIAN:CAPS" role="constant">
<term><literal>CAIRO_FILTER_GAUSSIAN</literal></term>
<listitem><simpara>This filter value is currently
unimplemented, and should not be used in current code.
</simpara></listitem>
</varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-set-filter" role="function">
<title>cairo_pattern_set_filter ()</title>
<indexterm zone="cairo-pattern-set-filter"><primary sortas="pattern_set_filter">cairo_pattern_set_filter</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_pattern_set_filter (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="cairo-filter-t"><type>cairo_filter_t</type></link> filter</parameter>);</programlisting>
<para>
Sets the filter to be used for resizing when using this pattern.
See <link linkend="cairo-filter-t"><type>cairo_filter_t</type></link> for details on each filter.
</para>
<para>
* Note that you might want to control filtering even when you do not
have an explicit <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> object, (for example when using
<link linkend="cairo-set-source-surface"><function>cairo_set_source_surface()</function></link>). In these cases, it is convenient to
use <link linkend="cairo-get-source"><function>cairo_get_source()</function></link> to get access to the pattern that cairo
creates implicitly. For example:
</para>
<para>
<informalexample><programlisting>
cairo_set_source_surface (cr, image, x, y);
cairo_pattern_set_filter (cairo_get_source (cr), CAIRO_FILTER_NEAREST);
</programlisting></informalexample>
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>filter</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-filter-t"><type>cairo_filter_t</type></link> describing the filter to use for resizing
the pattern
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-get-filter" role="function">
<title>cairo_pattern_get_filter ()</title>
<indexterm zone="cairo-pattern-get-filter"><primary sortas="pattern_get_filter">cairo_pattern_get_filter</primary></indexterm>
<programlisting><link linkend="cairo-filter-t"><returnvalue>cairo_filter_t</returnvalue></link> cairo_pattern_get_filter (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);</programlisting>
<para>
Gets the current filter for a pattern. See <link linkend="cairo-filter-t"><type>cairo_filter_t</type></link>
for details on each filter.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current filter used for resizing the pattern.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-set-matrix" role="function">
<title>cairo_pattern_set_matrix ()</title>
<indexterm zone="cairo-pattern-set-matrix"><primary sortas="pattern_set_matrix">cairo_pattern_set_matrix</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_pattern_set_matrix (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter>const <link linkend="cairo-matrix-t"><type>cairo_matrix_t</type></link> *matrix</parameter>);</programlisting>
<para>
Sets the pattern's transformation matrix to <parameter>matrix</parameter>. This matrix is
a transformation from user space to pattern space.
</para>
<para>
When a pattern is first created it always has the identity matrix
for its transformation matrix, which means that pattern space is
initially identical to user space.
</para>
<para>
Important: Please note that the direction of this transformation
matrix is from user space to pattern space. This means that if you
imagine the flow from a pattern to user space (and on to device
space), then coordinates in that flow will be transformed by the
inverse of the pattern matrix.
</para>
<para>
For example, if you want to make a pattern appear twice as large as
it does by default the correct code to use is:
</para>
<para>
<informalexample><programlisting>
cairo_matrix_init_scale (&matrix, 0.5, 0.5);
cairo_pattern_set_matrix (pattern, &matrix);
</programlisting></informalexample>
</para>
<para>
Meanwhile, using values of 2.0 rather than 0.5 in the code above
would cause the pattern to appear at half of its default size.
</para>
<para>
Also, please note the discussion of the user-space locking
semantics of <link linkend="cairo-set-source"><function>cairo_set_source()</function></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>matrix</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-matrix-t"><type>cairo_matrix_t</type></link>
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-get-matrix" role="function">
<title>cairo_pattern_get_matrix ()</title>
<indexterm zone="cairo-pattern-get-matrix"><primary sortas="pattern_get_matrix">cairo_pattern_get_matrix</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_pattern_get_matrix (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>,
<parameter><link linkend="cairo-matrix-t"><type>cairo_matrix_t</type></link> *matrix</parameter>);</programlisting>
<para>
Stores the pattern's transformation matrix into <parameter>matrix</parameter>.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>matrix</parameter> :</term>
<listitem><simpara>return value for the matrix
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-pattern-type-t" role="enum" condition="since:1.2">
<title>enum cairo_pattern_type_t</title>
<indexterm zone="cairo-pattern-type-t" role="1.2"><primary sortas="pattern_type_t">cairo_pattern_type_t</primary></indexterm>
<programlisting>typedef enum _cairo_pattern_type {
CAIRO_PATTERN_TYPE_SOLID,
CAIRO_PATTERN_TYPE_SURFACE,
CAIRO_PATTERN_TYPE_LINEAR,
CAIRO_PATTERN_TYPE_RADIAL
} cairo_pattern_type_t;
</programlisting>
<para>
<link linkend="cairo-pattern-type-t"><type>cairo_pattern_type_t</type></link> is used to describe the type of a given pattern.
</para>
<para>
The type of a pattern is determined by the function used to create
it. The <link linkend="cairo-pattern-create-rgb"><function>cairo_pattern_create_rgb()</function></link> and <link linkend="cairo-pattern-create-rgba"><function>cairo_pattern_create_rgba()</function></link>
functions create SOLID patterns. The remaining
cairo_pattern_create<!-- --> functions map to pattern types in obvious
ways.
</para>
<para>
The pattern type can be queried with <link linkend="cairo-pattern-get-type"><function>cairo_pattern_get_type()</function></link>
</para>
<para>
Most <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> functions can be called with a pattern of any
type, (though trying to change the extend or filter for a solid
pattern will have no effect). A notable exception is
<link linkend="cairo-pattern-add-color-stop-rgb"><function>cairo_pattern_add_color_stop_rgb()</function></link> and
<link linkend="cairo-pattern-add-color-stop-rgba"><function>cairo_pattern_add_color_stop_rgba()</function></link> which must only be called with
gradient patterns (either LINEAR or RADIAL). Otherwise the pattern
will be shutdown and put into an error state.
</para>
<para>
New entries may be added in future versions.
</para><variablelist role="enum">
<varlistentry id="CAIRO-PATTERN-TYPE-SOLID:CAPS" role="constant">
<term><literal>CAIRO_PATTERN_TYPE_SOLID</literal></term>
<listitem><simpara>The pattern is a solid (uniform)
color. It may be opaque or translucent.
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-PATTERN-TYPE-SURFACE:CAPS" role="constant">
<term><literal>CAIRO_PATTERN_TYPE_SURFACE</literal></term>
<listitem><simpara>The pattern is a based on a surface (an image).
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-PATTERN-TYPE-LINEAR:CAPS" role="constant">
<term><literal>CAIRO_PATTERN_TYPE_LINEAR</literal></term>
<listitem><simpara>The pattern is a linear gradient.
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-PATTERN-TYPE-RADIAL:CAPS" role="constant">
<term><literal>CAIRO_PATTERN_TYPE_RADIAL</literal></term>
<listitem><simpara>The pattern is a radial gradient.
</simpara></listitem>
</varlistentry>
</variablelist><para role="since">Since 1.2</para></refsect2>
<refsect2 id="cairo-pattern-get-type" role="function" condition="since:1.2">
<title>cairo_pattern_get_type ()</title>
<indexterm zone="cairo-pattern-get-type" role="1.2"><primary sortas="pattern_get_type">cairo_pattern_get_type</primary></indexterm>
<programlisting><link linkend="cairo-pattern-type-t"><returnvalue>cairo_pattern_type_t</returnvalue></link> cairo_pattern_get_type (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);</programlisting>
<para>
This function returns the type a pattern.
See <link linkend="cairo-pattern-type-t"><type>cairo_pattern_type_t</type></link> for available types.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> The type of <parameter>pattern</parameter>.
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since 1.2</para></refsect2>
<refsect2 id="cairo-pattern-get-reference-count" role="function" condition="since:1.4">
<title>cairo_pattern_get_reference_count ()</title>
<indexterm zone="cairo-pattern-get-reference-count" role="1.4"><primary sortas="pattern_get_reference_count">cairo_pattern_get_reference_count</primary></indexterm>
<programlisting>unsigned <link linkend="int"><returnvalue>int</returnvalue></link> cairo_pattern_get_reference_count (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);</programlisting>
<para>
Returns the current reference count of <parameter>pattern</parameter>.
</para><variablelist role="params">
<varlistentry><term><parameter>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current reference count of <parameter>pattern</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-pattern-set-user-data" role="function" condition="since:1.4">
<title>cairo_pattern_set_user_data ()</title>
<indexterm zone="cairo-pattern-set-user-data" role="1.4"><primary sortas="pattern_set_user_data">cairo_pattern_set_user_data</primary></indexterm>
<programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_pattern_set_user_data (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</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>pattern</parameter>. To remove user data from a surface,
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>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_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 <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link>
</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
<link linkend="cairo-t"><type>cairo_t</type></link> 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><para role="since">Since 1.4</para></refsect2>
<refsect2 id="cairo-pattern-get-user-data" role="function" condition="since:1.4">
<title>cairo_pattern_get_user_data ()</title>
<indexterm zone="cairo-pattern-get-user-data" role="1.4"><primary sortas="pattern_get_user_data">cairo_pattern_get_user_data</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> * cairo_pattern_get_user_data (<parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</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>pattern</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>pattern</parameter> :</term>
<listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_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><para role="since">Since 1.4</para></refsect2>
</refsect1>
<refsect1 id="cairo-cairo-pattern-t.see-also">
<title>See Also</title>
<link linkend="cairo-t"><type>cairo_t</type></link>, <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</refsect1>
</refentry>