<?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-cairo-t"> <refmeta> <refentrytitle role="top_of_page" id="cairo-cairo-t.top_of_page">cairo_t</refentrytitle> <manvolnum>3</manvolnum> <refmiscinfo> CAIRO Library </refmiscinfo> </refmeta> <refnamediv> <refname>cairo_t</refname> <refpurpose>The cairo drawing context</refpurpose> </refnamediv> <refsynopsisdiv id="cairo-cairo-t.synopsis" role="synopsis"> <title role="synopsis.title">Synopsis</title> <synopsis>typedef <link linkend="cairo-t">cairo_t</link>; <link linkend="cairo-t"><returnvalue>cairo_t</returnvalue></link> * <link linkend="cairo-create">cairo_create</link> (<parameter><link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> *target</parameter>); <link linkend="cairo-t"><returnvalue>cairo_t</returnvalue></link> * <link linkend="cairo-reference">cairo_reference</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-destroy">cairo_destroy</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-status">cairo_status</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-save">cairo_save</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-restore">cairo_restore</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="cairo-surface-t"><returnvalue>cairo_surface_t</returnvalue></link> * <link linkend="cairo-get-target">cairo_get_target</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-push-group">cairo_push_group</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-push-group-with-content">cairo_push_group_with_content</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-content-t"><type>cairo_content_t</type></link> content</parameter>); <link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * <link linkend="cairo-pop-group">cairo_pop_group</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-pop-group-to-source">cairo_pop_group_to_source</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="cairo-surface-t"><returnvalue>cairo_surface_t</returnvalue></link> * <link linkend="cairo-get-group-target">cairo_get_group_target</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-source-rgb">cairo_set_source_rgb</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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-set-source-rgba">cairo_set_source_rgba</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-source">cairo_set_source</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *source</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-source-surface">cairo_set_source_surface</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> *surface</parameter>, <parameter><link linkend="double"><type>double</type></link> x</parameter>, <parameter><link linkend="double"><type>double</type></link> y</parameter>); <link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * <link linkend="cairo-get-source">cairo_get_source</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); enum <link linkend="cairo-antialias-t">cairo_antialias_t</link>; <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-antialias">cairo_set_antialias</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-antialias-t"><type>cairo_antialias_t</type></link> antialias</parameter>); <link linkend="cairo-antialias-t"><returnvalue>cairo_antialias_t</returnvalue></link> <link linkend="cairo-get-antialias">cairo_get_antialias</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-dash">cairo_set_dash</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter>const <link linkend="double"><type>double</type></link> *dashes</parameter>, <parameter><link linkend="int"><type>int</type></link> num_dashes</parameter>, <parameter><link linkend="double"><type>double</type></link> offset</parameter>); <link linkend="int"><returnvalue>int</returnvalue></link> <link linkend="cairo-get-dash-count">cairo_get_dash_count</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-get-dash">cairo_get_dash</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> *dashes</parameter>, <parameter><link linkend="double"><type>double</type></link> *offset</parameter>); enum <link linkend="cairo-fill-rule-t">cairo_fill_rule_t</link>; <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-fill-rule">cairo_set_fill_rule</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-fill-rule-t"><type>cairo_fill_rule_t</type></link> fill_rule</parameter>); <link linkend="cairo-fill-rule-t"><returnvalue>cairo_fill_rule_t</returnvalue></link> <link linkend="cairo-get-fill-rule">cairo_get_fill_rule</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); enum <link linkend="cairo-line-cap-t">cairo_line_cap_t</link>; <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-line-cap">cairo_set_line_cap</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-line-cap-t"><type>cairo_line_cap_t</type></link> line_cap</parameter>); <link linkend="cairo-line-cap-t"><returnvalue>cairo_line_cap_t</returnvalue></link> <link linkend="cairo-get-line-cap">cairo_get_line_cap</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); enum <link linkend="cairo-line-join-t">cairo_line_join_t</link>; <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-line-join">cairo_set_line_join</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-line-join-t"><type>cairo_line_join_t</type></link> line_join</parameter>); <link linkend="cairo-line-join-t"><returnvalue>cairo_line_join_t</returnvalue></link> <link linkend="cairo-get-line-join">cairo_get_line_join</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-line-width">cairo_set_line_width</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> width</parameter>); <link linkend="double"><returnvalue>double</returnvalue></link> <link linkend="cairo-get-line-width">cairo_get_line_width</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-miter-limit">cairo_set_miter_limit</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> limit</parameter>); <link linkend="double"><returnvalue>double</returnvalue></link> <link linkend="cairo-get-miter-limit">cairo_get_miter_limit</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); enum <link linkend="cairo-operator-t">cairo_operator_t</link>; <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-operator">cairo_set_operator</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-operator-t"><type>cairo_operator_t</type></link> op</parameter>); <link linkend="cairo-operator-t"><returnvalue>cairo_operator_t</returnvalue></link> <link linkend="cairo-get-operator">cairo_get_operator</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-set-tolerance">cairo_set_tolerance</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> tolerance</parameter>); <link linkend="double"><returnvalue>double</returnvalue></link> <link linkend="cairo-get-tolerance">cairo_get_tolerance</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-clip">cairo_clip</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-clip-preserve">cairo_clip_preserve</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-clip-extents">cairo_clip_extents</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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> *x2</parameter>, <parameter><link linkend="double"><type>double</type></link> *y2</parameter>); <link linkend="cairo-bool-t"><returnvalue>cairo_bool_t</returnvalue></link> <link linkend="cairo-in-clip">cairo_in_clip</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> x</parameter>, <parameter><link linkend="double"><type>double</type></link> y</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-reset-clip">cairo_reset_clip</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="cairo-rectangle-t">cairo_rectangle_t</link>; <link linkend="cairo-rectangle-list-t">cairo_rectangle_list_t</link>; <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-rectangle-list-destroy">cairo_rectangle_list_destroy</link> (<parameter><link linkend="cairo-rectangle-list-t"><type>cairo_rectangle_list_t</type></link> *rectangle_list</parameter>); <link linkend="cairo-rectangle-list-t"><returnvalue>cairo_rectangle_list_t</returnvalue></link> * <link linkend="cairo-copy-clip-rectangle-list">cairo_copy_clip_rectangle_list</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-fill">cairo_fill</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-fill-preserve">cairo_fill_preserve</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-fill-extents">cairo_fill_extents</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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> *x2</parameter>, <parameter><link linkend="double"><type>double</type></link> *y2</parameter>); <link linkend="cairo-bool-t"><returnvalue>cairo_bool_t</returnvalue></link> <link linkend="cairo-in-fill">cairo_in_fill</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> x</parameter>, <parameter><link linkend="double"><type>double</type></link> y</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-mask">cairo_mask</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-mask-surface">cairo_mask_surface</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> *surface</parameter>, <parameter><link linkend="double"><type>double</type></link> surface_x</parameter>, <parameter><link linkend="double"><type>double</type></link> surface_y</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-paint">cairo_paint</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-paint-with-alpha">cairo_paint_with_alpha</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> alpha</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-stroke">cairo_stroke</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-stroke-preserve">cairo_stroke_preserve</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-stroke-extents">cairo_stroke_extents</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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> *x2</parameter>, <parameter><link linkend="double"><type>double</type></link> *y2</parameter>); <link linkend="cairo-bool-t"><returnvalue>cairo_bool_t</returnvalue></link> <link linkend="cairo-in-stroke">cairo_in_stroke</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> x</parameter>, <parameter><link linkend="double"><type>double</type></link> y</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-copy-page">cairo_copy_page</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-show-page">cairo_show_page</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); unsigned <link linkend="int"><returnvalue>int</returnvalue></link> <link linkend="cairo-get-reference-count">cairo_get_reference_count</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>); <link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> <link linkend="cairo-set-user-data">cairo_set_user_data</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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-get-user-data">cairo_get_user_data</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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-t.description" role="desc"> <title role="desc.title">Description</title> <para> <link linkend="cairo-t"><type>cairo_t</type></link> is the main object used when drawing with cairo. To draw with cairo, you create a <link linkend="cairo-t"><type>cairo_t</type></link>, set the target surface, and drawing options for the <link linkend="cairo-t"><type>cairo_t</type></link>, create shapes with functions like <link linkend="cairo-move-to"><function>cairo_move_to()</function></link> and <link linkend="cairo-line-to"><function>cairo_line_to()</function></link>, and then draw shapes with <link linkend="cairo-stroke"><function>cairo_stroke()</function></link> or <link linkend="cairo-fill"><function>cairo_fill()</function></link>. </para> <para> <link linkend="cairo-t"><type>cairo_t</type></link><!-- -->'s can be pushed to a stack via <link linkend="cairo-save"><function>cairo_save()</function></link>. They may then safely be changed, without loosing the current state. Use <link linkend="cairo-restore"><function>cairo_restore()</function></link> to restore to the saved state. </para> </refsect1> <refsect1 id="cairo-cairo-t.details" role="details"> <title role="details.title">Details</title> <refsect2 id="cairo-t" role="typedef"> <title>cairo_t</title> <indexterm zone="cairo-t"><primary sortas="t">cairo_t</primary></indexterm> <programlisting>typedef struct _cairo cairo_t; </programlisting> <para> A <link linkend="cairo-t"><type>cairo_t</type></link> contains the current state of the rendering device, including coordinates of yet to be drawn shapes. </para> <para> Cairo contexts, as <link linkend="cairo-t"><type>cairo_t</type></link> objects are named, are central to cairo and all drawing with cairo is always done to a <link linkend="cairo-t"><type>cairo_t</type></link> object. </para> <para> Memory management of <link linkend="cairo-t"><type>cairo_t</type></link> is done with <link linkend="cairo-reference"><function>cairo_reference()</function></link> and <link linkend="cairo-destroy"><function>cairo_destroy()</function></link>. </para></refsect2> <refsect2 id="cairo-create" role="function"> <title>cairo_create ()</title> <indexterm zone="cairo-create"><primary sortas="create">cairo_create</primary></indexterm> <programlisting><link linkend="cairo-t"><returnvalue>cairo_t</returnvalue></link> * cairo_create (<parameter><link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> *target</parameter>);</programlisting> <para> Creates a new <link linkend="cairo-t"><type>cairo_t</type></link> with all graphics state parameters set to default values and with <parameter>target</parameter> as a target surface. The target surface should be constructed with a backend-specific function such as <link linkend="cairo-image-surface-create"><function>cairo_image_surface_create()</function></link> (or any other cairo_<emphasis>backend</emphasis><link linkend="surface-create"><function>_surface_create()</function></link> variant). </para> <para> This function references <parameter>target</parameter>, so you can immediately call <link linkend="cairo-surface-destroy"><function>cairo_surface_destroy()</function></link> on it if you don't need to maintain a separate reference to it. </para><variablelist role="params"> <varlistentry><term><parameter>target</parameter> :</term> <listitem><simpara>target surface for the context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> a newly allocated <link linkend="cairo-t"><type>cairo_t</type></link> with a reference count of 1. The initial reference count should be released with <link linkend="cairo-destroy"><function>cairo_destroy()</function></link> when you are done using the <link linkend="cairo-t"><type>cairo_t</type></link>. This function never returns <link linkend="NULL:CAPS"><literal>NULL</literal></link>. If memory cannot be allocated, a special <link linkend="cairo-t"><type>cairo_t</type></link> object will be returned on which <link linkend="cairo-status"><function>cairo_status()</function></link> returns <link linkend="CAIRO-STATUS-NO-MEMORY:CAPS"><literal>CAIRO_STATUS_NO_MEMORY</literal></link>. You can use this object normally, but no drawing will be done. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-reference" role="function"> <title>cairo_reference ()</title> <indexterm zone="cairo-reference"><primary sortas="reference">cairo_reference</primary></indexterm> <programlisting><link linkend="cairo-t"><returnvalue>cairo_t</returnvalue></link> * cairo_reference (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Increases the reference count on <parameter>cr</parameter> by one. This prevents <parameter>cr</parameter> from being destroyed until a matching call to <link linkend="cairo-destroy"><function>cairo_destroy()</function></link> is made. </para> <para> The number of references to a <link linkend="cairo-t"><type>cairo_t</type></link> can be get using <link linkend="cairo-get-reference-count"><function>cairo_get_reference_count()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the referenced <link linkend="cairo-t"><type>cairo_t</type></link>. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-destroy" role="function"> <title>cairo_destroy ()</title> <indexterm zone="cairo-destroy"><primary sortas="destroy">cairo_destroy</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_destroy (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Decreases the reference count on <parameter>cr</parameter> by one. If the result is zero, then <parameter>cr</parameter> and all associated resources are freed. See <link linkend="cairo-reference"><function>cairo_reference()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-status" role="function"> <title>cairo_status ()</title> <indexterm zone="cairo-status"><primary sortas="status">cairo_status</primary></indexterm> <programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_status (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Checks whether an error has previously occurred for this context. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current status of this context, see <link linkend="cairo-status-t"><type>cairo_status_t</type></link> </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-save" role="function"> <title>cairo_save ()</title> <indexterm zone="cairo-save"><primary sortas="save">cairo_save</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_save (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Makes a copy of the current state of <parameter>cr</parameter> and saves it on an internal stack of saved states for <parameter>cr</parameter>. When <link linkend="cairo-restore"><function>cairo_restore()</function></link> is called, <parameter>cr</parameter> will be restored to the saved state. Multiple calls to <link linkend="cairo-save"><function>cairo_save()</function></link> and <link linkend="cairo-restore"><function>cairo_restore()</function></link> can be nested; each call to <link linkend="cairo-restore"><function>cairo_restore()</function></link> restores the state from the matching paired <link linkend="cairo-save"><function>cairo_save()</function></link>. </para> <para> It isn't necessary to clear all saved states before a <link linkend="cairo-t"><type>cairo_t</type></link> is freed. If the reference count of a <link linkend="cairo-t"><type>cairo_t</type></link> drops to zero in response to a call to <link linkend="cairo-destroy"><function>cairo_destroy()</function></link>, any saved states will be freed along with the <link linkend="cairo-t"><type>cairo_t</type></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-restore" role="function"> <title>cairo_restore ()</title> <indexterm zone="cairo-restore"><primary sortas="restore">cairo_restore</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_restore (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Restores <parameter>cr</parameter> to the state saved by a preceding call to <link linkend="cairo-save"><function>cairo_save()</function></link> and removes that state from the stack of saved states. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-target" role="function"> <title>cairo_get_target ()</title> <indexterm zone="cairo-get-target"><primary sortas="get_target">cairo_get_target</primary></indexterm> <programlisting><link linkend="cairo-surface-t"><returnvalue>cairo_surface_t</returnvalue></link> * cairo_get_target (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Gets the target surface for the cairo context as passed to <link linkend="cairo-create"><function>cairo_create()</function></link>. </para> <para> This function will always return a valid pointer, but the result can be a "nil" surface if <parameter>cr</parameter> is already in an error state, (ie. <link linkend="cairo-status"><function>cairo_status()</function></link> <literal>!=</literal> <link linkend="CAIRO-STATUS-SUCCESS:CAPS"><literal>CAIRO_STATUS_SUCCESS</literal></link>). A nil surface is indicated by <link linkend="cairo-surface-status"><function>cairo_surface_status()</function></link> <literal>!=</literal> <link linkend="CAIRO-STATUS-SUCCESS:CAPS"><literal>CAIRO_STATUS_SUCCESS</literal></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the target surface. This object is owned by cairo. To keep a reference to it, you must call <link linkend="cairo-surface-reference"><function>cairo_surface_reference()</function></link>. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-push-group" role="function" condition="since:1.2"> <title>cairo_push_group ()</title> <indexterm zone="cairo-push-group" role="1.2"><primary sortas="push_group">cairo_push_group</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_push_group (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Temporarily redirects drawing to an intermediate surface known as a group. The redirection lasts until the group is completed by a call to <link linkend="cairo-pop-group"><function>cairo_pop_group()</function></link> or <link linkend="cairo-pop-group-to-source"><function>cairo_pop_group_to_source()</function></link>. These calls provide the result of any drawing to the group as a pattern, (either as an explicit object, or set as the source pattern). </para> <para> This group functionality can be convenient for performing intermediate compositing. One common use of a group is to render objects as opaque within the group, (so that they occlude each other), and then blend the result with translucence onto the destination. </para> <para> Groups can be nested arbitrarily deep by making balanced calls to <link linkend="cairo-push-group"><function>cairo_push_group()</function></link>/<link linkend="cairo-pop-group"><function>cairo_pop_group()</function></link>. Each call pushes/pops the new target group onto/from a stack. </para> <para> The <link linkend="cairo-push-group"><function>cairo_push_group()</function></link> function calls <link linkend="cairo-save"><function>cairo_save()</function></link> so that any changes to the graphics state will not be visible outside the group, (the pop_group functions call <link linkend="cairo-restore"><function>cairo_restore()</function></link>). </para> <para> By default the intermediate group will have a content type of <link linkend="CAIRO-CONTENT-COLOR-ALPHA:CAPS"><literal>CAIRO_CONTENT_COLOR_ALPHA</literal></link>. Other content types can be chosen for the group by using <link linkend="cairo-push-group-with-content"><function>cairo_push_group_with_content()</function></link> instead. </para> <para> As an example, here is how one might fill and stroke a path with translucence, but without any portion of the fill being visible under the stroke: </para> <para> <informalexample><programlisting> cairo_push_group (cr); cairo_set_source (cr, fill_pattern); cairo_fill_preserve (cr); cairo_set_source (cr, stroke_pattern); cairo_stroke (cr); cairo_pop_group_to_source (cr); cairo_paint_with_alpha (cr, alpha); </programlisting></informalexample> </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist><para role="since">Since 1.2</para></refsect2> <refsect2 id="cairo-push-group-with-content" role="function" condition="since:1.2"> <title>cairo_push_group_with_content ()</title> <indexterm zone="cairo-push-group-with-content" role="1.2"><primary sortas="push_group_with_content">cairo_push_group_with_content</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_push_group_with_content (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-content-t"><type>cairo_content_t</type></link> content</parameter>);</programlisting> <para> Temporarily redirects drawing to an intermediate surface known as a group. The redirection lasts until the group is completed by a call to <link linkend="cairo-pop-group"><function>cairo_pop_group()</function></link> or <link linkend="cairo-pop-group-to-source"><function>cairo_pop_group_to_source()</function></link>. These calls provide the result of any drawing to the group as a pattern, (either as an explicit object, or set as the source pattern). </para> <para> The group will have a content type of <parameter>content</parameter>. The ability to control this content type is the only distinction between this function and <link linkend="cairo-push-group"><function>cairo_push_group()</function></link> which you should see for a more detailed description of group rendering. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>content</parameter> :</term> <listitem><simpara>a <link linkend="cairo-content-t"><type>cairo_content_t</type></link> indicating the type of group that will be created </simpara></listitem></varlistentry> </variablelist><para role="since">Since 1.2</para></refsect2> <refsect2 id="cairo-pop-group" role="function" condition="since:1.2"> <title>cairo_pop_group ()</title> <indexterm zone="cairo-pop-group" role="1.2"><primary sortas="pop_group">cairo_pop_group</primary></indexterm> <programlisting><link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * cairo_pop_group (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Terminates the redirection begun by a call to <link linkend="cairo-push-group"><function>cairo_push_group()</function></link> or <link linkend="cairo-push-group-with-content"><function>cairo_push_group_with_content()</function></link> and returns a new pattern containing the results of all drawing operations performed to the group. </para> <para> The <link linkend="cairo-pop-group"><function>cairo_pop_group()</function></link> function calls <link linkend="cairo-restore"><function>cairo_restore()</function></link>, (balancing a call to <link linkend="cairo-save"><function>cairo_save()</function></link> by the push_group function), so that any changes to the graphics state will not be visible outside the group. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> a newly created (surface) pattern containing the results of all drawing operations performed to the group. The caller owns the returned object and should call <link linkend="cairo-pattern-destroy"><function>cairo_pattern_destroy()</function></link> when finished with it. </simpara></listitem></varlistentry> </variablelist><para role="since">Since 1.2</para></refsect2> <refsect2 id="cairo-pop-group-to-source" role="function" condition="since:1.2"> <title>cairo_pop_group_to_source ()</title> <indexterm zone="cairo-pop-group-to-source" role="1.2"><primary sortas="pop_group_to_source">cairo_pop_group_to_source</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_pop_group_to_source (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Terminates the redirection begun by a call to <link linkend="cairo-push-group"><function>cairo_push_group()</function></link> or <link linkend="cairo-push-group-with-content"><function>cairo_push_group_with_content()</function></link> and installs the resulting pattern as the source pattern in the given cairo context. </para> <para> The behavior of this function is equivalent to the sequence of operations: </para> <para> <informalexample><programlisting> <link linkend="cairo-pattern-t">cairo_pattern_t</link> *group = cairo_pop_group (cr); cairo_set_source (cr, group); cairo_pattern_destroy (group); </programlisting></informalexample> </para> <para> but is more convenient as their is no need for a variable to store the short-lived pointer to the pattern. </para> <para> The <link linkend="cairo-pop-group"><function>cairo_pop_group()</function></link> function calls <link linkend="cairo-restore"><function>cairo_restore()</function></link>, (balancing a call to <link linkend="cairo-save"><function>cairo_save()</function></link> by the push_group function), so that any changes to the graphics state will not be visible outside the group. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist><para role="since">Since 1.2</para></refsect2> <refsect2 id="cairo-get-group-target" role="function" condition="since:1.2"> <title>cairo_get_group_target ()</title> <indexterm zone="cairo-get-group-target" role="1.2"><primary sortas="get_group_target">cairo_get_group_target</primary></indexterm> <programlisting><link linkend="cairo-surface-t"><returnvalue>cairo_surface_t</returnvalue></link> * cairo_get_group_target (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Gets the current destination surface for the context. This is either the original target surface as passed to <link linkend="cairo-create"><function>cairo_create()</function></link> or the target surface for the current group as started by the most recent call to <link linkend="cairo-push-group"><function>cairo_push_group()</function></link> or <link linkend="cairo-push-group-with-content"><function>cairo_push_group_with_content()</function></link>. </para> <para> This function will always return a valid pointer, but the result can be a "nil" surface if <parameter>cr</parameter> is already in an error state, (ie. <link linkend="cairo-status"><function>cairo_status()</function></link> <literal>!=</literal> <link linkend="CAIRO-STATUS-SUCCESS:CAPS"><literal>CAIRO_STATUS_SUCCESS</literal></link>). A nil surface is indicated by <link linkend="cairo-surface-status"><function>cairo_surface_status()</function></link> <literal>!=</literal> <link linkend="CAIRO-STATUS-SUCCESS:CAPS"><literal>CAIRO_STATUS_SUCCESS</literal></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the target surface. This object is owned by cairo. To keep a reference to it, you must call <link linkend="cairo-surface-reference"><function>cairo_surface_reference()</function></link>. </simpara></listitem></varlistentry> </variablelist><para role="since">Since 1.2</para></refsect2> <refsect2 id="cairo-set-source-rgb" role="function"> <title>cairo_set_source_rgb ()</title> <indexterm zone="cairo-set-source-rgb"><primary sortas="set_source_rgb">cairo_set_source_rgb</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_source_rgb (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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> Sets the source pattern within <parameter>cr</parameter> to an opaque color. This opaque color will then be used for any subsequent drawing operation until a new source pattern is set. </para> <para> 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> <para> The default source pattern is opaque black, (that is, it is equivalent to cairo_set_source_rgb(cr, 0.0, 0.0, 0.0)). </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </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-set-source-rgba" role="function"> <title>cairo_set_source_rgba ()</title> <indexterm zone="cairo-set-source-rgba"><primary sortas="set_source_rgba">cairo_set_source_rgba</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_source_rgba (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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> Sets the source pattern within <parameter>cr</parameter> to a translucent color. This color will then be used for any subsequent drawing operation until a new source pattern is set. </para> <para> The color and alpha 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> <para> The default source pattern is opaque black, (that is, it is equivalent to cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, 1.0)). </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </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-set-source" role="function"> <title>cairo_set_source ()</title> <indexterm zone="cairo-set-source"><primary sortas="set_source">cairo_set_source</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_source (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *source</parameter>);</programlisting> <para> Sets the source pattern within <parameter>cr</parameter> to <parameter>source</parameter>. This pattern will then be used for any subsequent drawing operation until a new source pattern is set. </para> <para> Note: The pattern's transformation matrix will be locked to the user space in effect at the time of <link linkend="cairo-set-source"><function>cairo_set_source()</function></link>. This means that further modifications of the current transformation matrix will not affect the source pattern. See <link linkend="cairo-pattern-set-matrix"><function>cairo_pattern_set_matrix()</function></link>. </para> <para> The default source pattern is a solid pattern that is opaque black, (that is, it is equivalent to cairo_set_source_rgb(cr, 0.0, 0.0, 0.0)). </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>source</parameter> :</term> <listitem><simpara>a <link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> to be used as the source for subsequent drawing operations. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-set-source-surface" role="function"> <title>cairo_set_source_surface ()</title> <indexterm zone="cairo-set-source-surface"><primary sortas="set_source_surface">cairo_set_source_surface</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_source_surface (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> *surface</parameter>, <parameter><link linkend="double"><type>double</type></link> x</parameter>, <parameter><link linkend="double"><type>double</type></link> y</parameter>);</programlisting> <para> This is a convenience function for creating a pattern from <parameter>surface</parameter> and setting it as the source in <parameter>cr</parameter> with <link linkend="cairo-set-source"><function>cairo_set_source()</function></link>. </para> <para> The <parameter>x</parameter> and <parameter>y</parameter> parameters give the user-space coordinate at which the surface origin should appear. (The surface origin is its upper-left corner before any transformation has been applied.) The <parameter>x</parameter> and <parameter>y</parameter> parameters are negated and then set as translation values in the pattern matrix. </para> <para> Other than the initial translation pattern matrix, as described above, all other pattern attributes, (such as its extend mode), are set to the default values as in <link linkend="cairo-pattern-create-for-surface"><function>cairo_pattern_create_for_surface()</function></link>. The resulting pattern can be queried with <link linkend="cairo-get-source"><function>cairo_get_source()</function></link> so that these attributes can be modified if desired, (eg. to create a repeating pattern with <link linkend="cairo-pattern-set-extend"><function>cairo_pattern_set_extend()</function></link>). </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>surface</parameter> :</term> <listitem><simpara>a surface to be used to set the source pattern </simpara></listitem></varlistentry> <varlistentry><term><parameter>x</parameter> :</term> <listitem><simpara>User-space X coordinate for surface origin </simpara></listitem></varlistentry> <varlistentry><term><parameter>y</parameter> :</term> <listitem><simpara>User-space Y coordinate for surface origin </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-source" role="function"> <title>cairo_get_source ()</title> <indexterm zone="cairo-get-source"><primary sortas="get_source">cairo_get_source</primary></indexterm> <programlisting><link linkend="cairo-pattern-t"><returnvalue>cairo_pattern_t</returnvalue></link> * cairo_get_source (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Gets the current source pattern for <parameter>cr</parameter>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current source pattern. This object is owned by cairo. To keep a reference to it, you must call <link linkend="cairo-pattern-reference"><function>cairo_pattern_reference()</function></link>. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-antialias-t" role="enum"> <title>enum cairo_antialias_t</title> <indexterm zone="cairo-antialias-t"><primary sortas="antialias_t">cairo_antialias_t</primary></indexterm> <programlisting>typedef enum _cairo_antialias { CAIRO_ANTIALIAS_DEFAULT, CAIRO_ANTIALIAS_NONE, CAIRO_ANTIALIAS_GRAY, CAIRO_ANTIALIAS_SUBPIXEL } cairo_antialias_t; </programlisting> <para> Specifies the type of antialiasing to do when rendering text or shapes. </para><variablelist role="enum"> <varlistentry id="CAIRO-ANTIALIAS-DEFAULT:CAPS" role="constant"> <term><literal>CAIRO_ANTIALIAS_DEFAULT</literal></term> <listitem><simpara>Use the default antialiasing for the subsystem and target device </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-ANTIALIAS-NONE:CAPS" role="constant"> <term><literal>CAIRO_ANTIALIAS_NONE</literal></term> <listitem><simpara>Use a bilevel alpha mask </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-ANTIALIAS-GRAY:CAPS" role="constant"> <term><literal>CAIRO_ANTIALIAS_GRAY</literal></term> <listitem><simpara>Perform single-color antialiasing (using shades of gray for black text on a white background, for example). </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-ANTIALIAS-SUBPIXEL:CAPS" role="constant"> <term><literal>CAIRO_ANTIALIAS_SUBPIXEL</literal></term> <listitem><simpara>Perform antialiasing by taking advantage of the order of subpixel elements on devices such as LCD panels </simpara></listitem> </varlistentry> </variablelist></refsect2> <refsect2 id="cairo-set-antialias" role="function"> <title>cairo_set_antialias ()</title> <indexterm zone="cairo-set-antialias"><primary sortas="set_antialias">cairo_set_antialias</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_antialias (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-antialias-t"><type>cairo_antialias_t</type></link> antialias</parameter>);</programlisting> <para> Set the antialiasing mode of the rasterizer used for drawing shapes. This value is a hint, and a particular backend may or may not support a particular value. At the current time, no backend supports <link linkend="CAIRO-ANTIALIAS-SUBPIXEL:CAPS"><literal>CAIRO_ANTIALIAS_SUBPIXEL</literal></link> when drawing shapes. </para> <para> Note that this option does not affect text rendering, instead see <link linkend="cairo-font-options-set-antialias"><function>cairo_font_options_set_antialias()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> <varlistentry><term><parameter>antialias</parameter> :</term> <listitem><simpara>the new antialiasing mode </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-antialias" role="function"> <title>cairo_get_antialias ()</title> <indexterm zone="cairo-get-antialias"><primary sortas="get_antialias">cairo_get_antialias</primary></indexterm> <programlisting><link linkend="cairo-antialias-t"><returnvalue>cairo_antialias_t</returnvalue></link> cairo_get_antialias (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Gets the current shape antialiasing mode, as set by <link linkend="cairo-set-shape-antialias"><function>cairo_set_shape_antialias()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current shape antialiasing mode. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-set-dash" role="function"> <title>cairo_set_dash ()</title> <indexterm zone="cairo-set-dash"><primary sortas="set_dash">cairo_set_dash</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_dash (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter>const <link linkend="double"><type>double</type></link> *dashes</parameter>, <parameter><link linkend="int"><type>int</type></link> num_dashes</parameter>, <parameter><link linkend="double"><type>double</type></link> offset</parameter>);</programlisting> <para> Sets the dash pattern to be used by <link linkend="cairo-stroke"><function>cairo_stroke()</function></link>. A dash pattern is specified by <parameter>dashes</parameter>, an array of positive values. Each value provides the length of alternate "on" and "off" portions of the stroke. The <parameter>offset</parameter> specifies an offset into the pattern at which the stroke begins. </para> <para> Each "on" segment will have caps applied as if the segment were a separate sub-path. In particular, it is valid to use an "on" length of 0.0 with <link linkend="CAIRO-LINE-CAP-ROUND:CAPS"><literal>CAIRO_LINE_CAP_ROUND</literal></link> or <link linkend="CAIRO-LINE-CAP-SQUARE:CAPS"><literal>CAIRO_LINE_CAP_SQUARE</literal></link> in order to distributed dots or squares along a path. </para> <para> Note: The length values are in user-space units as evaluated at the time of stroking. This is not necessarily the same as the user space at the time of <link linkend="cairo-set-dash"><function>cairo_set_dash()</function></link>. </para> <para> If <parameter>num_dashes</parameter> is 0 dashing is disabled. </para> <para> If <parameter>num_dashes</parameter> is 1 a symmetric pattern is assumed with alternating on and off portions of the size specified by the single value in <parameter>dashes</parameter>. </para> <para> If any value in <parameter>dashes</parameter> is negative, or if all values are 0, then <parameter>cr</parameter> will be put into an error state with a status of <link linkend="CAIRO-STATUS-INVALID-DASH:CAPS"><literal>CAIRO_STATUS_INVALID_DASH</literal></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>dashes</parameter> :</term> <listitem><simpara>an array specifying alternate lengths of on and off stroke portions </simpara></listitem></varlistentry> <varlistentry><term><parameter>num_dashes</parameter> :</term> <listitem><simpara>the length of the dashes array </simpara></listitem></varlistentry> <varlistentry><term><parameter>offset</parameter> :</term> <listitem><simpara>an offset into the dash pattern at which the stroke should start </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-dash-count" role="function" condition="since:1.4"> <title>cairo_get_dash_count ()</title> <indexterm zone="cairo-get-dash-count" role="1.4"><primary sortas="get_dash_count">cairo_get_dash_count</primary></indexterm> <programlisting><link linkend="int"><returnvalue>int</returnvalue></link> cairo_get_dash_count (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> This function returns the length of the dash array in <parameter>cr</parameter> (0 if dashing is not currently in effect). </para> <para> See also <link linkend="cairo-set-dash"><function>cairo_set_dash()</function></link> and <link linkend="cairo-get-dash"><function>cairo_get_dash()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the length of the dash array, or 0 if no dash array set. </simpara></listitem></varlistentry> </variablelist><para role="since">Since 1.4</para></refsect2> <refsect2 id="cairo-get-dash" role="function" condition="since:1.4"> <title>cairo_get_dash ()</title> <indexterm zone="cairo-get-dash" role="1.4"><primary sortas="get_dash">cairo_get_dash</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_get_dash (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> *dashes</parameter>, <parameter><link linkend="double"><type>double</type></link> *offset</parameter>);</programlisting> <para> Gets the current dash array. If not <link linkend="NULL:CAPS"><literal>NULL</literal></link>, <parameter>dashes</parameter> should be big enough to hold at least the number of values returned by <link linkend="cairo-get-dash-count"><function>cairo_get_dash_count()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> <varlistentry><term><parameter>dashes</parameter> :</term> <listitem><simpara>return value for the dash array, or <link linkend="NULL:CAPS"><literal>NULL</literal></link> </simpara></listitem></varlistentry> <varlistentry><term><parameter>offset</parameter> :</term> <listitem><simpara>return value for the current dash offset, or <link linkend="NULL:CAPS"><literal>NULL</literal></link> </simpara></listitem></varlistentry> </variablelist><para role="since">Since 1.4</para></refsect2> <refsect2 id="cairo-fill-rule-t" role="enum"> <title>enum cairo_fill_rule_t</title> <indexterm zone="cairo-fill-rule-t"><primary sortas="fill_rule_t">cairo_fill_rule_t</primary></indexterm> <programlisting>typedef enum _cairo_fill_rule { CAIRO_FILL_RULE_WINDING, CAIRO_FILL_RULE_EVEN_ODD } cairo_fill_rule_t; </programlisting> <para> <link linkend="cairo-fill-rule-t"><type>cairo_fill_rule_t</type></link> is used to select how paths are filled. For both fill rules, whether or not a point is included in the fill is determined by taking a ray from that point to infinity and looking at intersections with the path. The ray can be in any direction, as long as it doesn't pass through the end point of a segment or have a tricky intersection such as intersecting tangent to the path. (Note that filling is not actually implemented in this way. This is just a description of the rule that is applied.) </para> <para> The default fill rule is <link linkend="CAIRO-FILL-RULE-WINDING:CAPS"><literal>CAIRO_FILL_RULE_WINDING</literal></link>. </para> <para> New entries may be added in future versions. </para><variablelist role="enum"> <varlistentry id="CAIRO-FILL-RULE-WINDING:CAPS" role="constant"> <term><literal>CAIRO_FILL_RULE_WINDING</literal></term> <listitem><simpara>If the path crosses the ray from left-to-right, counts +1. If the path crosses the ray from right to left, counts -1. (Left and right are determined from the perspective of looking along the ray from the starting point.) If the total count is non-zero, the point will be filled. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-FILL-RULE-EVEN-ODD:CAPS" role="constant"> <term><literal>CAIRO_FILL_RULE_EVEN_ODD</literal></term> <listitem><simpara>Counts the total number of intersections, without regard to the orientation of the contour. If the total number of intersections is odd, the point will be filled. </simpara></listitem> </varlistentry> </variablelist></refsect2> <refsect2 id="cairo-set-fill-rule" role="function"> <title>cairo_set_fill_rule ()</title> <indexterm zone="cairo-set-fill-rule"><primary sortas="set_fill_rule">cairo_set_fill_rule</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_fill_rule (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-fill-rule-t"><type>cairo_fill_rule_t</type></link> fill_rule</parameter>);</programlisting> <para> Set the current fill rule within the cairo context. The fill rule is used to determine which regions are inside or outside a complex (potentially self-intersecting) path. The current fill rule affects both <link linkend="cairo-fill"><function>cairo_fill()</function></link> and <link linkend="cairo-clip"><function>cairo_clip()</function></link>. See <link linkend="cairo-fill-rule-t"><type>cairo_fill_rule_t</type></link> for details on the semantics of each available fill rule. </para> <para> The default fill rule is <link linkend="CAIRO-FILL-RULE-WINDING:CAPS"><literal>CAIRO_FILL_RULE_WINDING</literal></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> <varlistentry><term><parameter>fill_rule</parameter> :</term> <listitem><simpara>a fill rule, specified as a <link linkend="cairo-fill-rule-t"><type>cairo_fill_rule_t</type></link> </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-fill-rule" role="function"> <title>cairo_get_fill_rule ()</title> <indexterm zone="cairo-get-fill-rule"><primary sortas="get_fill_rule">cairo_get_fill_rule</primary></indexterm> <programlisting><link linkend="cairo-fill-rule-t"><returnvalue>cairo_fill_rule_t</returnvalue></link> cairo_get_fill_rule (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Gets the current fill rule, as set by <link linkend="cairo-set-fill-rule"><function>cairo_set_fill_rule()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current fill rule. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-line-cap-t" role="enum"> <title>enum cairo_line_cap_t</title> <indexterm zone="cairo-line-cap-t"><primary sortas="line_cap_t">cairo_line_cap_t</primary></indexterm> <programlisting>typedef enum _cairo_line_cap { CAIRO_LINE_CAP_BUTT, CAIRO_LINE_CAP_ROUND, CAIRO_LINE_CAP_SQUARE } cairo_line_cap_t; </programlisting> <para> Specifies how to render the endpoints of the path when stroking. </para> <para> The default line cap style is <link linkend="CAIRO-LINE-CAP-BUTT:CAPS"><literal>CAIRO_LINE_CAP_BUTT</literal></link>. </para><variablelist role="enum"> <varlistentry id="CAIRO-LINE-CAP-BUTT:CAPS" role="constant"> <term><literal>CAIRO_LINE_CAP_BUTT</literal></term> <listitem><simpara>start(stop) the line exactly at the start(end) point </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-LINE-CAP-ROUND:CAPS" role="constant"> <term><literal>CAIRO_LINE_CAP_ROUND</literal></term> <listitem><simpara>use a round ending, the center of the circle is the end point </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-LINE-CAP-SQUARE:CAPS" role="constant"> <term><literal>CAIRO_LINE_CAP_SQUARE</literal></term> <listitem><simpara>use squared ending, the center of the square is the end point </simpara></listitem> </varlistentry> </variablelist></refsect2> <refsect2 id="cairo-set-line-cap" role="function"> <title>cairo_set_line_cap ()</title> <indexterm zone="cairo-set-line-cap"><primary sortas="set_line_cap">cairo_set_line_cap</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_line_cap (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-line-cap-t"><type>cairo_line_cap_t</type></link> line_cap</parameter>);</programlisting> <para> Sets the current line cap style within the cairo context. See <link linkend="cairo-line-cap-t"><type>cairo_line_cap_t</type></link> for details about how the available line cap styles are drawn. </para> <para> As with the other stroke parameters, the current line cap style is examined by <link linkend="cairo-stroke"><function>cairo_stroke()</function></link>, <link linkend="cairo-stroke-extents"><function>cairo_stroke_extents()</function></link>, and <link linkend="cairo-stroke-to-path"><function>cairo_stroke_to_path()</function></link>, but does not have any effect during path construction. </para> <para> The default line cap style is <link linkend="CAIRO-LINE-CAP-BUTT:CAPS"><literal>CAIRO_LINE_CAP_BUTT</literal></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>line_cap</parameter> :</term> <listitem><simpara>a line cap style </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-line-cap" role="function"> <title>cairo_get_line_cap ()</title> <indexterm zone="cairo-get-line-cap"><primary sortas="get_line_cap">cairo_get_line_cap</primary></indexterm> <programlisting><link linkend="cairo-line-cap-t"><returnvalue>cairo_line_cap_t</returnvalue></link> cairo_get_line_cap (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Gets the current line cap style, as set by <link linkend="cairo-set-line-cap"><function>cairo_set_line_cap()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current line cap style. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-line-join-t" role="enum"> <title>enum cairo_line_join_t</title> <indexterm zone="cairo-line-join-t"><primary sortas="line_join_t">cairo_line_join_t</primary></indexterm> <programlisting>typedef enum _cairo_line_join { CAIRO_LINE_JOIN_MITER, CAIRO_LINE_JOIN_ROUND, CAIRO_LINE_JOIN_BEVEL } cairo_line_join_t; </programlisting> <para> Specifies how to render the junction of two lines when stroking. </para> <para> The default line join style is <link linkend="CAIRO-LINE-JOIN-MITER:CAPS"><literal>CAIRO_LINE_JOIN_MITER</literal></link>. </para><variablelist role="enum"> <varlistentry id="CAIRO-LINE-JOIN-MITER:CAPS" role="constant"> <term><literal>CAIRO_LINE_JOIN_MITER</literal></term> <listitem><simpara>use a sharp (angled) corner, see <link linkend="cairo-set-miter-limit"><function>cairo_set_miter_limit()</function></link> </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-LINE-JOIN-ROUND:CAPS" role="constant"> <term><literal>CAIRO_LINE_JOIN_ROUND</literal></term> <listitem><simpara>use a rounded join, the center of the circle is the joint point </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-LINE-JOIN-BEVEL:CAPS" role="constant"> <term><literal>CAIRO_LINE_JOIN_BEVEL</literal></term> <listitem><simpara>use a cut-off join, the join is cut off at half the line width from the joint point </simpara></listitem> </varlistentry> </variablelist></refsect2> <refsect2 id="cairo-set-line-join" role="function"> <title>cairo_set_line_join ()</title> <indexterm zone="cairo-set-line-join"><primary sortas="set_line_join">cairo_set_line_join</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_line_join (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-line-join-t"><type>cairo_line_join_t</type></link> line_join</parameter>);</programlisting> <para> Sets the current line join style within the cairo context. See <link linkend="cairo-line-join-t"><type>cairo_line_join_t</type></link> for details about how the available line join styles are drawn. </para> <para> As with the other stroke parameters, the current line join style is examined by <link linkend="cairo-stroke"><function>cairo_stroke()</function></link>, <link linkend="cairo-stroke-extents"><function>cairo_stroke_extents()</function></link>, and <link linkend="cairo-stroke-to-path"><function>cairo_stroke_to_path()</function></link>, but does not have any effect during path construction. </para> <para> The default line join style is <link linkend="CAIRO-LINE-JOIN-MITER:CAPS"><literal>CAIRO_LINE_JOIN_MITER</literal></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>line_join</parameter> :</term> <listitem><simpara>a line join style </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-line-join" role="function"> <title>cairo_get_line_join ()</title> <indexterm zone="cairo-get-line-join"><primary sortas="get_line_join">cairo_get_line_join</primary></indexterm> <programlisting><link linkend="cairo-line-join-t"><returnvalue>cairo_line_join_t</returnvalue></link> cairo_get_line_join (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Gets the current line join style, as set by <link linkend="cairo-set-line-join"><function>cairo_set_line_join()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current line join style. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-set-line-width" role="function"> <title>cairo_set_line_width ()</title> <indexterm zone="cairo-set-line-width"><primary sortas="set_line_width">cairo_set_line_width</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_line_width (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> width</parameter>);</programlisting> <para> Sets the current line width within the cairo context. The line width value specifies the diameter of a pen that is circular in user space, (though device-space pen may be an ellipse in general due to scaling/shear/rotation of the CTM). </para> <para> Note: When the description above refers to user space and CTM it refers to the user space and CTM in effect at the time of the stroking operation, not the user space and CTM in effect at the time of the call to <link linkend="cairo-set-line-width"><function>cairo_set_line_width()</function></link>. The simplest usage makes both of these spaces identical. That is, if there is no change to the CTM between a call to <link linkend="cairo-set-line-width"><function>cairo_set_line_width()</function></link> and the stroking operation, then one can just pass user-space values to <link linkend="cairo-set-line-width"><function>cairo_set_line_width()</function></link> and ignore this note. </para> <para> As with the other stroke parameters, the current line width is examined by <link linkend="cairo-stroke"><function>cairo_stroke()</function></link>, <link linkend="cairo-stroke-extents"><function>cairo_stroke_extents()</function></link>, and <link linkend="cairo-stroke-to-path"><function>cairo_stroke_to_path()</function></link>, but does not have any effect during path construction. </para> <para> The default line width value is 2.0. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> <varlistentry><term><parameter>width</parameter> :</term> <listitem><simpara>a line width </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-line-width" role="function"> <title>cairo_get_line_width ()</title> <indexterm zone="cairo-get-line-width"><primary sortas="get_line_width">cairo_get_line_width</primary></indexterm> <programlisting><link linkend="double"><returnvalue>double</returnvalue></link> cairo_get_line_width (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> This function returns the current line width value exactly as set by <link linkend="cairo-set-line-width"><function>cairo_set_line_width()</function></link>. Note that the value is unchanged even if the CTM has changed between the calls to <link linkend="cairo-set-line-width"><function>cairo_set_line_width()</function></link> and <link linkend="cairo-get-line-width"><function>cairo_get_line_width()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current line width. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-set-miter-limit" role="function"> <title>cairo_set_miter_limit ()</title> <indexterm zone="cairo-set-miter-limit"><primary sortas="set_miter_limit">cairo_set_miter_limit</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_miter_limit (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> limit</parameter>);</programlisting> <para> Sets the current miter limit within the cairo context. </para> <para> If the current line join style is set to <link linkend="CAIRO-LINE-JOIN-MITER:CAPS"><literal>CAIRO_LINE_JOIN_MITER</literal></link> (see <link linkend="cairo-set-line-join"><function>cairo_set_line_join()</function></link>), the miter limit is used to determine whether the lines should be joined with a bevel instead of a miter. Cairo divides the length of the miter by the line width. If the result is greater than the miter limit, the style is converted to a bevel. </para> <para> As with the other stroke parameters, the current line miter limit is examined by <link linkend="cairo-stroke"><function>cairo_stroke()</function></link>, <link linkend="cairo-stroke-extents"><function>cairo_stroke_extents()</function></link>, and <link linkend="cairo-stroke-to-path"><function>cairo_stroke_to_path()</function></link>, but does not have any effect during path construction. </para> <para> The default miter limit value is 10.0, which will convert joins with interior angles less than 11 degrees to bevels instead of miters. For reference, a miter limit of 2.0 makes the miter cutoff at 60 degrees, and a miter limit of 1.414 makes the cutoff at 90 degrees. </para> <para> A miter limit for a desired angle can be computed as: miter limit = 1/sin(angle/2) </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>limit</parameter> :</term> <listitem><simpara>miter limit to set </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-miter-limit" role="function"> <title>cairo_get_miter_limit ()</title> <indexterm zone="cairo-get-miter-limit"><primary sortas="get_miter_limit">cairo_get_miter_limit</primary></indexterm> <programlisting><link linkend="double"><returnvalue>double</returnvalue></link> cairo_get_miter_limit (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Gets the current miter limit, as set by <link linkend="cairo-set-miter-limit"><function>cairo_set_miter_limit()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current miter limit. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-operator-t" role="enum"> <title>enum cairo_operator_t</title> <indexterm zone="cairo-operator-t"><primary sortas="operator_t">cairo_operator_t</primary></indexterm> <programlisting>typedef enum _cairo_operator { CAIRO_OPERATOR_CLEAR, CAIRO_OPERATOR_SOURCE, CAIRO_OPERATOR_OVER, CAIRO_OPERATOR_IN, CAIRO_OPERATOR_OUT, CAIRO_OPERATOR_ATOP, CAIRO_OPERATOR_DEST, CAIRO_OPERATOR_DEST_OVER, CAIRO_OPERATOR_DEST_IN, CAIRO_OPERATOR_DEST_OUT, CAIRO_OPERATOR_DEST_ATOP, CAIRO_OPERATOR_XOR, CAIRO_OPERATOR_ADD, CAIRO_OPERATOR_SATURATE, CAIRO_OPERATOR_MULTIPLY, CAIRO_OPERATOR_SCREEN, CAIRO_OPERATOR_OVERLAY, CAIRO_OPERATOR_DARKEN, CAIRO_OPERATOR_LIGHTEN, CAIRO_OPERATOR_COLOR_DODGE, CAIRO_OPERATOR_COLOR_BURN, CAIRO_OPERATOR_HARD_LIGHT, CAIRO_OPERATOR_SOFT_LIGHT, CAIRO_OPERATOR_DIFFERENCE, CAIRO_OPERATOR_EXCLUSION, CAIRO_OPERATOR_HSL_HUE, CAIRO_OPERATOR_HSL_SATURATION, CAIRO_OPERATOR_HSL_COLOR, CAIRO_OPERATOR_HSL_LUMINOSITY } cairo_operator_t; </programlisting> <para> <link linkend="cairo-operator-t"><type>cairo_operator_t</type></link> is used to set the compositing operator for all cairo drawing operations. </para> <para> The default operator is <link linkend="CAIRO-OPERATOR-OVER:CAPS"><literal>CAIRO_OPERATOR_OVER</literal></link>. </para> <para> The operators marked as <firstterm>unbounded</firstterm> modify their destination even outside of the mask layer (that is, their effect is not bound by the mask layer). However, their effect can still be limited by way of clipping. </para> <para> To keep things simple, the operator descriptions here document the behavior for when both source and destination are either fully transparent or fully opaque. The actual implementation works for translucent layers too. For a more detailed explanation of the effects of each operator, including the mathematical definitions, see <ulink url="http://cairographics.org/operators/">http://cairographics.org/operators/</ulink>. </para><variablelist role="enum"> <varlistentry id="CAIRO-OPERATOR-CLEAR:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_CLEAR</literal></term> <listitem><simpara>clear destination layer (bounded) </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-SOURCE:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_SOURCE</literal></term> <listitem><simpara>replace destination layer (bounded) </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-OVER:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_OVER</literal></term> <listitem><simpara>draw source layer on top of destination layer (bounded) </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-IN:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_IN</literal></term> <listitem><simpara>draw source where there was destination content (unbounded) </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-OUT:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_OUT</literal></term> <listitem><simpara>draw source where there was no destination content (unbounded) </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-ATOP:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_ATOP</literal></term> <listitem><simpara>draw source on top of destination content and only there </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-DEST:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_DEST</literal></term> <listitem><simpara>ignore the source </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-DEST-OVER:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_DEST_OVER</literal></term> <listitem><simpara>draw destination on top of source </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-DEST-IN:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_DEST_IN</literal></term> <listitem><simpara>leave destination only where there was source content (unbounded) </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-DEST-OUT:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_DEST_OUT</literal></term> <listitem><simpara>leave destination only where there was no source content </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-DEST-ATOP:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_DEST_ATOP</literal></term> <listitem><simpara>leave destination on top of source content and only there (unbounded) </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-XOR:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_XOR</literal></term> <listitem><simpara>source and destination are shown where there is only one of them </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-ADD:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_ADD</literal></term> <listitem><simpara>source and destination layers are accumulated </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-SATURATE:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_SATURATE</literal></term> <listitem><simpara>like over, but assuming source and dest are disjoint geometries </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-MULTIPLY:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_MULTIPLY</literal></term> <listitem><simpara>source and destination layers are multiplied. This causes the result to be at least as dark as the darker inputs. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-SCREEN:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_SCREEN</literal></term> <listitem><simpara>source and destination are complemented and multiplied. This causes the result to be at least as light as the lighter inputs. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-OVERLAY:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_OVERLAY</literal></term> <listitem><simpara>multiplies or screens, depending on the lightness of the destination color. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-DARKEN:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_DARKEN</literal></term> <listitem><simpara>replaces the destination with the source if it is darker, otherwise keeps the source. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-LIGHTEN:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_LIGHTEN</literal></term> <listitem><simpara>replaces the destination with the source if it is lighter, otherwise keeps the source. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-COLOR-DODGE:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_COLOR_DODGE</literal></term> <listitem><simpara>brightens the destination color to reflect the source color. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-COLOR-BURN:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_COLOR_BURN</literal></term> <listitem><simpara>darkens the destination color to reflect the source color. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-HARD-LIGHT:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_HARD_LIGHT</literal></term> <listitem><simpara>Multiplies or screens, dependant on source color. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-SOFT-LIGHT:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_SOFT_LIGHT</literal></term> <listitem><simpara>Darkens or lightens, dependant on source color. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-DIFFERENCE:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_DIFFERENCE</literal></term> <listitem><simpara>Takes the difference of the source and destination color. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-EXCLUSION:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_EXCLUSION</literal></term> <listitem><simpara>Produces an effect similar to difference, but with lower contrast. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-HSL-HUE:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_HSL_HUE</literal></term> <listitem><simpara>Creates a color with the hue of the source and the saturation and luminosity of the target. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-HSL-SATURATION:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_HSL_SATURATION</literal></term> <listitem><simpara>Creates a color with the saturation of the source and the hue and luminosity of the target. Painting with this mode onto a gray area prduces no change. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-HSL-COLOR:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_HSL_COLOR</literal></term> <listitem><simpara>Creates a color with the hue and saturation of the source and the luminosity of the target. This preserves the gray levels of the target and is useful for coloring monochrome images or tinting color images. </simpara></listitem> </varlistentry> <varlistentry id="CAIRO-OPERATOR-HSL-LUMINOSITY:CAPS" role="constant"> <term><literal>CAIRO_OPERATOR_HSL_LUMINOSITY</literal></term> <listitem><simpara>Creates a color with the luminosity of the source and the hue and saturation of the target. This produces an inverse effect to <parameter>CAIRO_OPERATOR_HSL_COLOR</parameter>. </simpara></listitem> </varlistentry> </variablelist></refsect2> <refsect2 id="cairo-set-operator" role="function"> <title>cairo_set_operator ()</title> <indexterm zone="cairo-set-operator"><primary sortas="set_operator">cairo_set_operator</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_operator (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-operator-t"><type>cairo_operator_t</type></link> op</parameter>);</programlisting> <para> Sets the compositing operator to be used for all drawing operations. See <link linkend="cairo-operator-t"><type>cairo_operator_t</type></link> for details on the semantics of each available compositing operator. </para> <para> The default operator is <link linkend="CAIRO-OPERATOR-OVER:CAPS"><literal>CAIRO_OPERATOR_OVER</literal></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> <varlistentry><term><parameter>op</parameter> :</term> <listitem><simpara>a compositing operator, specified as a <link linkend="cairo-operator-t"><type>cairo_operator_t</type></link> </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-operator" role="function"> <title>cairo_get_operator ()</title> <indexterm zone="cairo-get-operator"><primary sortas="get_operator">cairo_get_operator</primary></indexterm> <programlisting><link linkend="cairo-operator-t"><returnvalue>cairo_operator_t</returnvalue></link> cairo_get_operator (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Gets the current compositing operator for a cairo context. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current compositing operator. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-set-tolerance" role="function"> <title>cairo_set_tolerance ()</title> <indexterm zone="cairo-set-tolerance"><primary sortas="set_tolerance">cairo_set_tolerance</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_set_tolerance (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> tolerance</parameter>);</programlisting> <para> Sets the tolerance used when converting paths into trapezoids. Curved segments of the path will be subdivided until the maximum deviation between the original path and the polygonal approximation is less than <parameter>tolerance</parameter>. The default value is 0.1. A larger value will give better performance, a smaller value, better appearance. (Reducing the value from the default value of 0.1 is unlikely to improve appearance significantly.) The accuracy of paths within Cairo is limited by the precision of its internal arithmetic, and the prescribed <parameter>tolerance</parameter> is restricted to the smallest representable internal value. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> <varlistentry><term><parameter>tolerance</parameter> :</term> <listitem><simpara>the tolerance, in device units (typically pixels) </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-tolerance" role="function"> <title>cairo_get_tolerance ()</title> <indexterm zone="cairo-get-tolerance"><primary sortas="get_tolerance">cairo_get_tolerance</primary></indexterm> <programlisting><link linkend="double"><returnvalue>double</returnvalue></link> cairo_get_tolerance (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Gets the current tolerance value, as set by <link linkend="cairo-set-tolerance"><function>cairo_set_tolerance()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current tolerance value. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-clip" role="function"> <title>cairo_clip ()</title> <indexterm zone="cairo-clip"><primary sortas="clip">cairo_clip</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_clip (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Establishes a new clip region by intersecting the current clip region with the current path as it would be filled by <link linkend="cairo-fill"><function>cairo_fill()</function></link> and according to the current fill rule (see <link linkend="cairo-set-fill-rule"><function>cairo_set_fill_rule()</function></link>). </para> <para> After <link linkend="cairo-clip"><function>cairo_clip()</function></link>, the current path will be cleared from the cairo context. </para> <para> The current clip region affects all drawing operations by effectively masking out any changes to the surface that are outside the current clip region. </para> <para> Calling <link linkend="cairo-clip"><function>cairo_clip()</function></link> can only make the clip region smaller, never larger. But the current clip is part of the graphics state, so a temporary restriction of the clip region can be achieved by calling <link linkend="cairo-clip"><function>cairo_clip()</function></link> within a <link linkend="cairo-save"><function>cairo_save()</function></link>/<link linkend="cairo-restore"><function>cairo_restore()</function></link> pair. The only other means of increasing the size of the clip region is <link linkend="cairo-reset-clip"><function>cairo_reset_clip()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-clip-preserve" role="function"> <title>cairo_clip_preserve ()</title> <indexterm zone="cairo-clip-preserve"><primary sortas="clip_preserve">cairo_clip_preserve</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_clip_preserve (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Establishes a new clip region by intersecting the current clip region with the current path as it would be filled by <link linkend="cairo-fill"><function>cairo_fill()</function></link> and according to the current fill rule (see <link linkend="cairo-set-fill-rule"><function>cairo_set_fill_rule()</function></link>). </para> <para> Unlike <link linkend="cairo-clip"><function>cairo_clip()</function></link>, <link linkend="cairo-clip-preserve"><function>cairo_clip_preserve()</function></link> preserves the path within the cairo context. </para> <para> The current clip region affects all drawing operations by effectively masking out any changes to the surface that are outside the current clip region. </para> <para> Calling <link linkend="cairo-clip-preserve"><function>cairo_clip_preserve()</function></link> can only make the clip region smaller, never larger. But the current clip is part of the graphics state, so a temporary restriction of the clip region can be achieved by calling <link linkend="cairo-clip-preserve"><function>cairo_clip_preserve()</function></link> within a <link linkend="cairo-save"><function>cairo_save()</function></link>/<link linkend="cairo-restore"><function>cairo_restore()</function></link> pair. The only other means of increasing the size of the clip region is <link linkend="cairo-reset-clip"><function>cairo_reset_clip()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-clip-extents" role="function" condition="since:1.4"> <title>cairo_clip_extents ()</title> <indexterm zone="cairo-clip-extents" role="1.4"><primary sortas="clip_extents">cairo_clip_extents</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_clip_extents (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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> *x2</parameter>, <parameter><link linkend="double"><type>double</type></link> *y2</parameter>);</programlisting> <para> Computes a bounding box in user coordinates covering the area inside the current clip. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>x1</parameter> :</term> <listitem><simpara>left of the resulting extents </simpara></listitem></varlistentry> <varlistentry><term><parameter>y1</parameter> :</term> <listitem><simpara>top of the resulting extents </simpara></listitem></varlistentry> <varlistentry><term><parameter>x2</parameter> :</term> <listitem><simpara>right of the resulting extents </simpara></listitem></varlistentry> <varlistentry><term><parameter>y2</parameter> :</term> <listitem><simpara>bottom of the resulting extents </simpara></listitem></varlistentry> </variablelist><para role="since">Since 1.4</para></refsect2> <refsect2 id="cairo-in-clip" role="function" condition="since:1.10"> <title>cairo_in_clip ()</title> <indexterm zone="cairo-in-clip" role="1.10"><primary sortas="in_clip">cairo_in_clip</primary></indexterm> <programlisting><link linkend="cairo-bool-t"><returnvalue>cairo_bool_t</returnvalue></link> cairo_in_clip (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> x</parameter>, <parameter><link linkend="double"><type>double</type></link> y</parameter>);</programlisting> <para> Tests whether the given point is inside the area that would be visible through the current clip, i.e. the area that would be filled by a <link linkend="cairo-paint"><function>cairo_paint()</function></link> operation. </para> <para> See <link linkend="cairo-clip"><function>cairo_clip()</function></link>, and <link linkend="cairo-clip-preserve"><function>cairo_clip_preserve()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>x</parameter> :</term> <listitem><simpara>X coordinate of the point to test </simpara></listitem></varlistentry> <varlistentry><term><parameter>y</parameter> :</term> <listitem><simpara>Y coordinate of the point to test </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> A non-zero value if the point is inside, or zero if outside. </simpara></listitem></varlistentry> </variablelist><para role="since">Since 1.10</para></refsect2> <refsect2 id="cairo-reset-clip" role="function"> <title>cairo_reset_clip ()</title> <indexterm zone="cairo-reset-clip"><primary sortas="reset_clip">cairo_reset_clip</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_reset_clip (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Reset the current clip region to its original, unrestricted state. That is, set the clip region to an infinitely large shape containing the target surface. Equivalently, if infinity is too hard to grasp, one can imagine the clip region being reset to the exact bounds of the target surface. </para> <para> Note that code meant to be reusable should not call <link linkend="cairo-reset-clip"><function>cairo_reset_clip()</function></link> as it will cause results unexpected by higher-level code which calls <link linkend="cairo-clip"><function>cairo_clip()</function></link>. Consider using <link linkend="cairo-save"><function>cairo_save()</function></link> and <link linkend="cairo-restore"><function>cairo_restore()</function></link> around <link linkend="cairo-clip"><function>cairo_clip()</function></link> as a more robust means of temporarily restricting the clip region. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-rectangle-t" role="struct" condition="since:1.4"> <title>cairo_rectangle_t</title> <indexterm zone="cairo-rectangle-t" role="1.4"><primary sortas="rectangle_t">cairo_rectangle_t</primary></indexterm> <programlisting>typedef struct { double x, y, width, height; } cairo_rectangle_t; </programlisting> <para> A data structure for holding a rectangle. </para><variablelist role="struct"> <varlistentry><term><link linkend="double"><type>double</type></link> <structfield id="cairo-rectangle-t.x">x</structfield>;</term> <listitem><simpara>X coordinate of the left side of the rectangle </simpara></listitem> </varlistentry> <varlistentry><term><link linkend="double"><type>double</type></link> <structfield id="cairo-rectangle-t.y">y</structfield>;</term> <listitem><simpara>Y coordinate of the the top side of the rectangle </simpara></listitem> </varlistentry> <varlistentry><term><link linkend="double"><type>double</type></link> <structfield id="cairo-rectangle-t.width">width</structfield>;</term> <listitem><simpara>width of the rectangle </simpara></listitem> </varlistentry> <varlistentry><term><link linkend="double"><type>double</type></link> <structfield id="cairo-rectangle-t.height">height</structfield>;</term> <listitem><simpara>height of the rectangle </simpara></listitem> </varlistentry> </variablelist><para role="since">Since 1.4</para></refsect2> <refsect2 id="cairo-rectangle-list-t" role="struct" condition="since:1.4"> <title>cairo_rectangle_list_t</title> <indexterm zone="cairo-rectangle-list-t" role="1.4"><primary sortas="rectangle_list_t">cairo_rectangle_list_t</primary></indexterm> <programlisting>typedef struct { cairo_status_t status; cairo_rectangle_t *rectangles; int num_rectangles; } cairo_rectangle_list_t; </programlisting> <para> A data structure for holding a dynamically allocated array of rectangles. </para><variablelist role="struct"> <varlistentry><term><link linkend="cairo-status-t"><type>cairo_status_t</type></link> <structfield id="cairo-rectangle-list-t.status">status</structfield>;</term> <listitem><simpara>Error status of the rectangle list </simpara></listitem> </varlistentry> <varlistentry><term><link linkend="cairo-rectangle-t"><type>cairo_rectangle_t</type></link> *<structfield id="cairo-rectangle-list-t.rectangles">rectangles</structfield>;</term> <listitem><simpara>Array containing the rectangles </simpara></listitem> </varlistentry> <varlistentry><term><link linkend="int"><type>int</type></link> <structfield id="cairo-rectangle-list-t.num-rectangles">num_rectangles</structfield>;</term> <listitem><simpara>Number of rectangles in this list </simpara></listitem> </varlistentry> </variablelist><para role="since">Since 1.4</para></refsect2> <refsect2 id="cairo-rectangle-list-destroy" role="function" condition="since:1.4"> <title>cairo_rectangle_list_destroy ()</title> <indexterm zone="cairo-rectangle-list-destroy" role="1.4"><primary sortas="rectangle_list_destroy">cairo_rectangle_list_destroy</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_rectangle_list_destroy (<parameter><link linkend="cairo-rectangle-list-t"><type>cairo_rectangle_list_t</type></link> *rectangle_list</parameter>);</programlisting> <para> Unconditionally frees <parameter>rectangle_list</parameter> and all associated references. After this call, the <parameter>rectangle_list</parameter> pointer must not be dereferenced. </para><variablelist role="params"> <varlistentry><term><parameter>rectangle_list</parameter> :</term> <listitem><simpara>a rectangle list, as obtained from <link linkend="cairo-copy-clip-rectangles"><function>cairo_copy_clip_rectangles()</function></link> </simpara></listitem></varlistentry> </variablelist><para role="since">Since 1.4</para></refsect2> <refsect2 id="cairo-copy-clip-rectangle-list" role="function" condition="since:1.4"> <title>cairo_copy_clip_rectangle_list ()</title> <indexterm zone="cairo-copy-clip-rectangle-list" role="1.4"><primary sortas="copy_clip_rectangle_list">cairo_copy_clip_rectangle_list</primary></indexterm> <programlisting><link linkend="cairo-rectangle-list-t"><returnvalue>cairo_rectangle_list_t</returnvalue></link> * cairo_copy_clip_rectangle_list (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Gets the current clip region as a list of rectangles in user coordinates. Never returns <link linkend="NULL:CAPS"><literal>NULL</literal></link>. </para> <para> The status in the list may be <link linkend="CAIRO-STATUS-CLIP-NOT-REPRESENTABLE:CAPS"><literal>CAIRO_STATUS_CLIP_NOT_REPRESENTABLE</literal></link> to indicate that the clip region cannot be represented as a list of user-space rectangles. The status may have other values to indicate other errors. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current clip region as a list of rectangles in user coordinates, which should be destroyed using <link linkend="cairo-rectangle-list-destroy"><function>cairo_rectangle_list_destroy()</function></link>. </simpara></listitem></varlistentry> </variablelist><para role="since">Since 1.4</para></refsect2> <refsect2 id="cairo-fill" role="function"> <title>cairo_fill ()</title> <indexterm zone="cairo-fill"><primary sortas="fill">cairo_fill</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_fill (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> A drawing operator that fills the current path according to the current fill rule, (each sub-path is implicitly closed before being filled). After <link linkend="cairo-fill"><function>cairo_fill()</function></link>, the current path will be cleared from the cairo context. See <link linkend="cairo-set-fill-rule"><function>cairo_set_fill_rule()</function></link> and <link linkend="cairo-fill-preserve"><function>cairo_fill_preserve()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-fill-preserve" role="function"> <title>cairo_fill_preserve ()</title> <indexterm zone="cairo-fill-preserve"><primary sortas="fill_preserve">cairo_fill_preserve</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_fill_preserve (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> A drawing operator that fills the current path according to the current fill rule, (each sub-path is implicitly closed before being filled). Unlike <link linkend="cairo-fill"><function>cairo_fill()</function></link>, <link linkend="cairo-fill-preserve"><function>cairo_fill_preserve()</function></link> preserves the path within the cairo context. </para> <para> See <link linkend="cairo-set-fill-rule"><function>cairo_set_fill_rule()</function></link> and <link linkend="cairo-fill"><function>cairo_fill()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-fill-extents" role="function"> <title>cairo_fill_extents ()</title> <indexterm zone="cairo-fill-extents"><primary sortas="fill_extents">cairo_fill_extents</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_fill_extents (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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> *x2</parameter>, <parameter><link linkend="double"><type>double</type></link> *y2</parameter>);</programlisting> <para> Computes a bounding box in user coordinates covering the area that would be affected, (the "inked" area), by a <link linkend="cairo-fill"><function>cairo_fill()</function></link> operation given the current path and fill parameters. If the current path is empty, returns an empty rectangle ((0,0), (0,0)). Surface dimensions and clipping are not taken into account. </para> <para> Contrast with <link linkend="cairo-path-extents"><function>cairo_path_extents()</function></link>, which is similar, but returns non-zero extents for some paths with no inked area, (such as a simple line segment). </para> <para> Note that <link linkend="cairo-fill-extents"><function>cairo_fill_extents()</function></link> must necessarily do more work to compute the precise inked areas in light of the fill rule, so <link linkend="cairo-path-extents"><function>cairo_path_extents()</function></link> may be more desirable for sake of performance if the non-inked path extents are desired. </para> <para> See <link linkend="cairo-fill"><function>cairo_fill()</function></link>, <link linkend="cairo-set-fill-rule"><function>cairo_set_fill_rule()</function></link> and <link linkend="cairo-fill-preserve"><function>cairo_fill_preserve()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>x1</parameter> :</term> <listitem><simpara>left of the resulting extents </simpara></listitem></varlistentry> <varlistentry><term><parameter>y1</parameter> :</term> <listitem><simpara>top of the resulting extents </simpara></listitem></varlistentry> <varlistentry><term><parameter>x2</parameter> :</term> <listitem><simpara>right of the resulting extents </simpara></listitem></varlistentry> <varlistentry><term><parameter>y2</parameter> :</term> <listitem><simpara>bottom of the resulting extents </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-in-fill" role="function"> <title>cairo_in_fill ()</title> <indexterm zone="cairo-in-fill"><primary sortas="in_fill">cairo_in_fill</primary></indexterm> <programlisting><link linkend="cairo-bool-t"><returnvalue>cairo_bool_t</returnvalue></link> cairo_in_fill (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> x</parameter>, <parameter><link linkend="double"><type>double</type></link> y</parameter>);</programlisting> <para> Tests whether the given point is inside the area that would be affected by a <link linkend="cairo-fill"><function>cairo_fill()</function></link> operation given the current path and filling parameters. Surface dimensions and clipping are not taken into account. </para> <para> See <link linkend="cairo-fill"><function>cairo_fill()</function></link>, <link linkend="cairo-set-fill-rule"><function>cairo_set_fill_rule()</function></link> and <link linkend="cairo-fill-preserve"><function>cairo_fill_preserve()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>x</parameter> :</term> <listitem><simpara>X coordinate of the point to test </simpara></listitem></varlistentry> <varlistentry><term><parameter>y</parameter> :</term> <listitem><simpara>Y coordinate of the point to test </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> A non-zero value if the point is inside, or zero if outside. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-mask" role="function"> <title>cairo_mask ()</title> <indexterm zone="cairo-mask"><primary sortas="mask">cairo_mask</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_mask (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-pattern-t"><type>cairo_pattern_t</type></link> *pattern</parameter>);</programlisting> <para> A drawing operator that paints the current source using the alpha channel of <parameter>pattern</parameter> as a mask. (Opaque areas of <parameter>pattern</parameter> are painted with the source, transparent areas are not painted.) </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <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-mask-surface" role="function"> <title>cairo_mask_surface ()</title> <indexterm zone="cairo-mask-surface"><primary sortas="mask_surface">cairo_mask_surface</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_mask_surface (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> *surface</parameter>, <parameter><link linkend="double"><type>double</type></link> surface_x</parameter>, <parameter><link linkend="double"><type>double</type></link> surface_y</parameter>);</programlisting> <para> A drawing operator that paints the current source using the alpha channel of <parameter>surface</parameter> as a mask. (Opaque areas of <parameter>surface</parameter> are painted with the source, transparent areas are not painted.) </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>surface</parameter> :</term> <listitem><simpara>a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> </simpara></listitem></varlistentry> <varlistentry><term><parameter>surface_x</parameter> :</term> <listitem><simpara>X coordinate at which to place the origin of <parameter>surface</parameter> </simpara></listitem></varlistentry> <varlistentry><term><parameter>surface_y</parameter> :</term> <listitem><simpara>Y coordinate at which to place the origin of <parameter>surface</parameter> </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-paint" role="function"> <title>cairo_paint ()</title> <indexterm zone="cairo-paint"><primary sortas="paint">cairo_paint</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_paint (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> A drawing operator that paints the current source everywhere within the current clip region. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-paint-with-alpha" role="function"> <title>cairo_paint_with_alpha ()</title> <indexterm zone="cairo-paint-with-alpha"><primary sortas="paint_with_alpha">cairo_paint_with_alpha</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_paint_with_alpha (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> alpha</parameter>);</programlisting> <para> A drawing operator that paints the current source everywhere within the current clip region using a mask of constant alpha value <parameter>alpha</parameter>. The effect is similar to <link linkend="cairo-paint"><function>cairo_paint()</function></link>, but the drawing is faded out using the alpha value. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>alpha</parameter> :</term> <listitem><simpara>alpha value, between 0 (transparent) and 1 (opaque) </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-stroke" role="function"> <title>cairo_stroke ()</title> <indexterm zone="cairo-stroke"><primary sortas="stroke">cairo_stroke</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_stroke (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> A drawing operator that strokes the current path according to the current line width, line join, line cap, and dash settings. After <link linkend="cairo-stroke"><function>cairo_stroke()</function></link>, the current path will be cleared from the cairo context. See <link linkend="cairo-set-line-width"><function>cairo_set_line_width()</function></link>, <link linkend="cairo-set-line-join"><function>cairo_set_line_join()</function></link>, <link linkend="cairo-set-line-cap"><function>cairo_set_line_cap()</function></link>, <link linkend="cairo-set-dash"><function>cairo_set_dash()</function></link>, and <link linkend="cairo-stroke-preserve"><function>cairo_stroke_preserve()</function></link>. </para> <para> Note: Degenerate segments and sub-paths are treated specially and provide a useful result. These can result in two different situations: </para> <para> 1. Zero-length "on" segments set in <link linkend="cairo-set-dash"><function>cairo_set_dash()</function></link>. If the cap style is <link linkend="CAIRO-LINE-CAP-ROUND:CAPS"><literal>CAIRO_LINE_CAP_ROUND</literal></link> or <link linkend="CAIRO-LINE-CAP-SQUARE:CAPS"><literal>CAIRO_LINE_CAP_SQUARE</literal></link> then these segments will be drawn as circular dots or squares respectively. In the case of <link linkend="CAIRO-LINE-CAP-SQUARE:CAPS"><literal>CAIRO_LINE_CAP_SQUARE</literal></link>, the orientation of the squares is determined by the direction of the underlying path. </para> <para> 2. A sub-path created by <link linkend="cairo-move-to"><function>cairo_move_to()</function></link> followed by either a <link linkend="cairo-close-path"><function>cairo_close_path()</function></link> or one or more calls to <link linkend="cairo-line-to"><function>cairo_line_to()</function></link> to the same coordinate as the <link linkend="cairo-move-to"><function>cairo_move_to()</function></link>. If the cap style is <link linkend="CAIRO-LINE-CAP-ROUND:CAPS"><literal>CAIRO_LINE_CAP_ROUND</literal></link> then these sub-paths will be drawn as circular dots. Note that in the case of <link linkend="CAIRO-LINE-CAP-SQUARE:CAPS"><literal>CAIRO_LINE_CAP_SQUARE</literal></link> a degenerate sub-path will not be drawn at all, (since the correct orientation is indeterminate). </para> <para> In no case will a cap style of <link linkend="CAIRO-LINE-CAP-BUTT:CAPS"><literal>CAIRO_LINE_CAP_BUTT</literal></link> cause anything to be drawn in the case of either degenerate segments or sub-paths. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-stroke-preserve" role="function"> <title>cairo_stroke_preserve ()</title> <indexterm zone="cairo-stroke-preserve"><primary sortas="stroke_preserve">cairo_stroke_preserve</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_stroke_preserve (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> A drawing operator that strokes the current path according to the current line width, line join, line cap, and dash settings. Unlike <link linkend="cairo-stroke"><function>cairo_stroke()</function></link>, <link linkend="cairo-stroke-preserve"><function>cairo_stroke_preserve()</function></link> preserves the path within the cairo context. </para> <para> See <link linkend="cairo-set-line-width"><function>cairo_set_line_width()</function></link>, <link linkend="cairo-set-line-join"><function>cairo_set_line_join()</function></link>, <link linkend="cairo-set-line-cap"><function>cairo_set_line_cap()</function></link>, <link linkend="cairo-set-dash"><function>cairo_set_dash()</function></link>, and <link linkend="cairo-stroke-preserve"><function>cairo_stroke_preserve()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-stroke-extents" role="function"> <title>cairo_stroke_extents ()</title> <indexterm zone="cairo-stroke-extents"><primary sortas="stroke_extents">cairo_stroke_extents</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_stroke_extents (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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> *x2</parameter>, <parameter><link linkend="double"><type>double</type></link> *y2</parameter>);</programlisting> <para> Computes a bounding box in user coordinates covering the area that would be affected, (the "inked" area), by a <link linkend="cairo-stroke"><function>cairo_stroke()</function></link> operation given the current path and stroke parameters. If the current path is empty, returns an empty rectangle ((0,0), (0,0)). Surface dimensions and clipping are not taken into account. </para> <para> Note that if the line width is set to exactly zero, then <link linkend="cairo-stroke-extents"><function>cairo_stroke_extents()</function></link> will return an empty rectangle. Contrast with <link linkend="cairo-path-extents"><function>cairo_path_extents()</function></link> which can be used to compute the non-empty bounds as the line width approaches zero. </para> <para> Note that <link linkend="cairo-stroke-extents"><function>cairo_stroke_extents()</function></link> must necessarily do more work to compute the precise inked areas in light of the stroke parameters, so <link linkend="cairo-path-extents"><function>cairo_path_extents()</function></link> may be more desirable for sake of performance if non-inked path extents are desired. </para> <para> See <link linkend="cairo-stroke"><function>cairo_stroke()</function></link>, <link linkend="cairo-set-line-width"><function>cairo_set_line_width()</function></link>, <link linkend="cairo-set-line-join"><function>cairo_set_line_join()</function></link>, <link linkend="cairo-set-line-cap"><function>cairo_set_line_cap()</function></link>, <link linkend="cairo-set-dash"><function>cairo_set_dash()</function></link>, and <link linkend="cairo-stroke-preserve"><function>cairo_stroke_preserve()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>x1</parameter> :</term> <listitem><simpara>left of the resulting extents </simpara></listitem></varlistentry> <varlistentry><term><parameter>y1</parameter> :</term> <listitem><simpara>top of the resulting extents </simpara></listitem></varlistentry> <varlistentry><term><parameter>x2</parameter> :</term> <listitem><simpara>right of the resulting extents </simpara></listitem></varlistentry> <varlistentry><term><parameter>y2</parameter> :</term> <listitem><simpara>bottom of the resulting extents </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-in-stroke" role="function"> <title>cairo_in_stroke ()</title> <indexterm zone="cairo-in-stroke"><primary sortas="in_stroke">cairo_in_stroke</primary></indexterm> <programlisting><link linkend="cairo-bool-t"><returnvalue>cairo_bool_t</returnvalue></link> cairo_in_stroke (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>, <parameter><link linkend="double"><type>double</type></link> x</parameter>, <parameter><link linkend="double"><type>double</type></link> y</parameter>);</programlisting> <para> Tests whether the given point is inside the area that would be affected by a <link linkend="cairo-stroke"><function>cairo_stroke()</function></link> operation given the current path and stroking parameters. Surface dimensions and clipping are not taken into account. </para> <para> See <link linkend="cairo-stroke"><function>cairo_stroke()</function></link>, <link linkend="cairo-set-line-width"><function>cairo_set_line_width()</function></link>, <link linkend="cairo-set-line-join"><function>cairo_set_line_join()</function></link>, <link linkend="cairo-set-line-cap"><function>cairo_set_line_cap()</function></link>, <link linkend="cairo-set-dash"><function>cairo_set_dash()</function></link>, and <link linkend="cairo-stroke-preserve"><function>cairo_stroke_preserve()</function></link>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> <varlistentry><term><parameter>x</parameter> :</term> <listitem><simpara>X coordinate of the point to test </simpara></listitem></varlistentry> <varlistentry><term><parameter>y</parameter> :</term> <listitem><simpara>Y coordinate of the point to test </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> A non-zero value if the point is inside, or zero if outside. </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-copy-page" role="function"> <title>cairo_copy_page ()</title> <indexterm zone="cairo-copy-page"><primary sortas="copy_page">cairo_copy_page</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_copy_page (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Emits the current page for backends that support multiple pages, but doesn't clear it, so, the contents of the current page will be retained for the next page too. Use <link linkend="cairo-show-page"><function>cairo_show_page()</function></link> if you want to get an empty page after the emission. </para> <para> This is a convenience function that simply calls <link linkend="cairo-surface-copy-page"><function>cairo_surface_copy_page()</function></link> on <parameter>cr</parameter>'s target. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-show-page" role="function"> <title>cairo_show_page ()</title> <indexterm zone="cairo-show-page"><primary sortas="show_page">cairo_show_page</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_show_page (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Emits and clears the current page for backends that support multiple pages. Use <link linkend="cairo-copy-page"><function>cairo_copy_page()</function></link> if you don't want to clear the page. </para> <para> This is a convenience function that simply calls <link linkend="cairo-surface-show-page"><function>cairo_surface_show_page()</function></link> on <parameter>cr</parameter>'s target. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a cairo context </simpara></listitem></varlistentry> </variablelist></refsect2> <refsect2 id="cairo-get-reference-count" role="function" condition="since:1.4"> <title>cairo_get_reference_count ()</title> <indexterm zone="cairo-get-reference-count" role="1.4"><primary sortas="get_reference_count">cairo_get_reference_count</primary></indexterm> <programlisting>unsigned <link linkend="int"><returnvalue>int</returnvalue></link> cairo_get_reference_count (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting> <para> Returns the current reference count of <parameter>cr</parameter>. </para><variablelist role="params"> <varlistentry><term><parameter>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_t</type></link> </simpara></listitem></varlistentry> <varlistentry><term><emphasis>Returns</emphasis> :</term><listitem><simpara> the current reference count of <parameter>cr</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-set-user-data" role="function" condition="since:1.4"> <title>cairo_set_user_data ()</title> <indexterm zone="cairo-set-user-data" role="1.4"><primary sortas="set_user_data">cairo_set_user_data</primary></indexterm> <programlisting><link linkend="cairo-status-t"><returnvalue>cairo_status_t</returnvalue></link> cairo_set_user_data (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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>cr</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>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_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-t"><type>cairo_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-get-user-data" role="function" condition="since:1.4"> <title>cairo_get_user_data ()</title> <indexterm zone="cairo-get-user-data" role="1.4"><primary sortas="get_user_data">cairo_get_user_data</primary></indexterm> <programlisting><link linkend="void"><returnvalue>void</returnvalue></link> * cairo_get_user_data (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</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>cr</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>cr</parameter> :</term> <listitem><simpara>a <link linkend="cairo-t"><type>cairo_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-t.see-also"> <title>See Also</title> <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> </refsect1> </refentry>