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<refentry id="cairo-Paths">
<refmeta>
<refentrytitle role="top_of_page" id="cairo-Paths.top_of_page">Paths</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>
CAIRO Library
</refmiscinfo>
</refmeta>
<refnamediv>
<refname>Paths</refname>
<refpurpose>Creating paths and manipulating path data</refpurpose>
</refnamediv>
<refsynopsisdiv id="cairo-Paths.synopsis" role="synopsis">
<title role="synopsis.title">Synopsis</title>
<synopsis> <link linkend="cairo-path-t">cairo_path_t</link>;
union <link linkend="cairo-path-data-t">cairo_path_data_t</link>;
enum <link linkend="cairo-path-data-type-t">cairo_path_data_type_t</link>;
<link linkend="cairo-path-t"><returnvalue>cairo_path_t</returnvalue></link> * <link linkend="cairo-copy-path">cairo_copy_path</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);
<link linkend="cairo-path-t"><returnvalue>cairo_path_t</returnvalue></link> * <link linkend="cairo-copy-path-flat">cairo_copy_path_flat</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-path-destroy">cairo_path_destroy</link> (<parameter><link linkend="cairo-path-t"><type>cairo_path_t</type></link> *path</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-append-path">cairo_append_path</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter>const <link linkend="cairo-path-t"><type>cairo_path_t</type></link> *path</parameter>);
<link linkend="cairo-bool-t"><returnvalue>cairo_bool_t</returnvalue></link> <link linkend="cairo-has-current-point">cairo_has_current_point</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-get-current-point">cairo_get_current_point</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-new-path">cairo_new_path</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-new-sub-path">cairo_new_sub_path</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-close-path">cairo_close_path</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-arc">cairo_arc</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter><link linkend="double"><type>double</type></link> xc</parameter>,
<parameter><link linkend="double"><type>double</type></link> yc</parameter>,
<parameter><link linkend="double"><type>double</type></link> radius</parameter>,
<parameter><link linkend="double"><type>double</type></link> angle1</parameter>,
<parameter><link linkend="double"><type>double</type></link> angle2</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-arc-negative">cairo_arc_negative</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter><link linkend="double"><type>double</type></link> xc</parameter>,
<parameter><link linkend="double"><type>double</type></link> yc</parameter>,
<parameter><link linkend="double"><type>double</type></link> radius</parameter>,
<parameter><link linkend="double"><type>double</type></link> angle1</parameter>,
<parameter><link linkend="double"><type>double</type></link> angle2</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-curve-to">cairo_curve_to</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>,
<parameter><link linkend="double"><type>double</type></link> x3</parameter>,
<parameter><link linkend="double"><type>double</type></link> y3</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-line-to">cairo_line_to</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-move-to">cairo_move_to</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-rectangle">cairo_rectangle</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>,
<parameter><link linkend="double"><type>double</type></link> width</parameter>,
<parameter><link linkend="double"><type>double</type></link> height</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-glyph-path">cairo_glyph_path</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter>const <link linkend="cairo-glyph-t"><type>cairo_glyph_t</type></link> *glyphs</parameter>,
<parameter><link linkend="int"><type>int</type></link> num_glyphs</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-text-path">cairo_text_path</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter>const <link linkend="char"><type>char</type></link> *utf8</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-rel-curve-to">cairo_rel_curve_to</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter><link linkend="double"><type>double</type></link> dx1</parameter>,
<parameter><link linkend="double"><type>double</type></link> dy1</parameter>,
<parameter><link linkend="double"><type>double</type></link> dx2</parameter>,
<parameter><link linkend="double"><type>double</type></link> dy2</parameter>,
<parameter><link linkend="double"><type>double</type></link> dx3</parameter>,
<parameter><link linkend="double"><type>double</type></link> dy3</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-rel-line-to">cairo_rel_line_to</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter><link linkend="double"><type>double</type></link> dx</parameter>,
<parameter><link linkend="double"><type>double</type></link> dy</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-rel-move-to">cairo_rel_move_to</link> (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter><link linkend="double"><type>double</type></link> dx</parameter>,
<parameter><link linkend="double"><type>double</type></link> dy</parameter>);
<link linkend="void"><returnvalue>void</returnvalue></link> <link linkend="cairo-path-extents">cairo_path_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>);
</synopsis>
</refsynopsisdiv>
<refsect1 id="cairo-Paths.description" role="desc">
<title role="desc.title">Description</title>
<para>
Paths are the most basic drawing tools and are primarily used to implicitly
generate simple masks.
</para>
</refsect1>
<refsect1 id="cairo-Paths.details" role="details">
<title role="details.title">Details</title>
<refsect2 id="cairo-path-t" role="struct">
<title>cairo_path_t</title>
<indexterm zone="cairo-path-t"><primary sortas="path_t">cairo_path_t</primary></indexterm>
<programlisting>typedef struct {
cairo_status_t status;
cairo_path_data_t *data;
int num_data;
} cairo_path_t;
</programlisting>
<para>
A data structure for holding a path. This data structure serves as
the return value for <link linkend="cairo-copy-path"><function>cairo_copy_path()</function></link> and
<link linkend="cairo-copy-path-flat"><function>cairo_copy_path_flat()</function></link> as well the input value for
<link linkend="cairo-append-path"><function>cairo_append_path()</function></link>.
</para>
<para>
See <link linkend="cairo-path-data-t"><type>cairo_path_data_t</type></link> for hints on how to iterate over the
actual data within the path.
</para>
<para>
The num_data member gives the number of elements in the data
array. This number is larger than the number of independent path
portions (defined in <link linkend="cairo-path-data-type-t"><type>cairo_path_data_type_t</type></link>), since the data
includes both headers and coordinates for each portion.
</para><variablelist role="struct">
<varlistentry><term><link linkend="cairo-status-t"><type>cairo_status_t</type></link> <structfield id="cairo-path-t.status">status</structfield>;</term>
<listitem><simpara>the current error status
</simpara></listitem>
</varlistentry>
<varlistentry><term><link linkend="cairo-path-data-t"><type>cairo_path_data_t</type></link> *<structfield id="cairo-path-t.data">data</structfield>;</term>
<listitem><simpara>the elements in the path
</simpara></listitem>
</varlistentry>
<varlistentry><term><link linkend="int"><type>int</type></link> <structfield id="cairo-path-t.num-data">num_data</structfield>;</term>
<listitem><simpara>the number of elements in the data array
</simpara></listitem>
</varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-path-data-t" role="union">
<title>union cairo_path_data_t</title>
<indexterm zone="cairo-path-data-t"><primary sortas="path_data_t">cairo_path_data_t</primary></indexterm>
<programlisting></programlisting>
<para>
<link linkend="cairo-path-data-t"><type>cairo_path_data_t</type></link> is used to represent the path data inside a
<link linkend="cairo-path-t"><type>cairo_path_t</type></link>.
</para>
<para>
The data structure is designed to try to balance the demands of
efficiency and ease-of-use. A path is represented as an array of
<link linkend="cairo-path-data-t"><type>cairo_path_data_t</type></link>, which is a union of headers and points.
</para>
<para>
Each portion of the path is represented by one or more elements in
the array, (one header followed by 0 or more points). The length
value of the header is the number of array elements for the current
portion including the header, (ie. length == 1 + # of points), and
where the number of points for each element type is as follows:
</para>
<para>
<programlisting>
%CAIRO_PATH_MOVE_TO: 1 point
%CAIRO_PATH_LINE_TO: 1 point
%CAIRO_PATH_CURVE_TO: 3 points
%CAIRO_PATH_CLOSE_PATH: 0 points
</programlisting>
</para>
<para>
The semantics and ordering of the coordinate values are consistent
with <link linkend="cairo-move-to"><function>cairo_move_to()</function></link>, <link linkend="cairo-line-to"><function>cairo_line_to()</function></link>, <link linkend="cairo-curve-to"><function>cairo_curve_to()</function></link>, and
<link linkend="cairo-close-path"><function>cairo_close_path()</function></link>.
</para>
<para>
Here is sample code for iterating through a <link linkend="cairo-path-t"><type>cairo_path_t</type></link>:
</para>
<para>
<informalexample><programlisting>
int i;
cairo_path_t *path;
cairo_path_data_t *data;
path = cairo_copy_path (cr);
for (i=0; i < path->num_data; i += path->data[i].header.length) {
data = &path->data[i];
switch (data->header.type) {
case CAIRO_PATH_MOVE_TO:
do_move_to_things (data[1].point.x, data[1].point.y);
break;
case CAIRO_PATH_LINE_TO:
do_line_to_things (data[1].point.x, data[1].point.y);
break;
case CAIRO_PATH_CURVE_TO:
do_curve_to_things (data[1].point.x, data[1].point.y,
data[2].point.x, data[2].point.y,
data[3].point.x, data[3].point.y);
break;
case CAIRO_PATH_CLOSE_PATH:
do_close_path_things ();
break;
}
}
cairo_path_destroy (path);
</programlisting></informalexample>
</para>
<para>
As of cairo 1.4, cairo does not mind if there are more elements in
a portion of the path than needed. Such elements can be used by
users of the cairo API to hold extra values in the path data
structure. For this reason, it is recommended that applications
always use <literal>data->header.length</literal> to
iterate over the path data, instead of hardcoding the number of
elements for each element type.
</para></refsect2>
<refsect2 id="cairo-path-data-type-t" role="enum">
<title>enum cairo_path_data_type_t</title>
<indexterm zone="cairo-path-data-type-t"><primary sortas="path_data_type_t">cairo_path_data_type_t</primary></indexterm>
<programlisting>typedef enum _cairo_path_data_type {
CAIRO_PATH_MOVE_TO,
CAIRO_PATH_LINE_TO,
CAIRO_PATH_CURVE_TO,
CAIRO_PATH_CLOSE_PATH
} cairo_path_data_type_t;
</programlisting>
<para>
<link linkend="cairo-path-data-t"><type>cairo_path_data_t</type></link> is used to describe the type of one portion
of a path when represented as a <link linkend="cairo-path-t"><type>cairo_path_t</type></link>.
See <link linkend="cairo-path-data-t"><type>cairo_path_data_t</type></link> for details.
</para><variablelist role="enum">
<varlistentry id="CAIRO-PATH-MOVE-TO:CAPS" role="constant">
<term><literal>CAIRO_PATH_MOVE_TO</literal></term>
<listitem><simpara>A move-to operation
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-PATH-LINE-TO:CAPS" role="constant">
<term><literal>CAIRO_PATH_LINE_TO</literal></term>
<listitem><simpara>A line-to operation
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-PATH-CURVE-TO:CAPS" role="constant">
<term><literal>CAIRO_PATH_CURVE_TO</literal></term>
<listitem><simpara>A curve-to operation
</simpara></listitem>
</varlistentry>
<varlistentry id="CAIRO-PATH-CLOSE-PATH:CAPS" role="constant">
<term><literal>CAIRO_PATH_CLOSE_PATH</literal></term>
<listitem><simpara>A close-path operation
</simpara></listitem>
</varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-copy-path" role="function">
<title>cairo_copy_path ()</title>
<indexterm zone="cairo-copy-path"><primary sortas="copy_path">cairo_copy_path</primary></indexterm>
<programlisting><link linkend="cairo-path-t"><returnvalue>cairo_path_t</returnvalue></link> * cairo_copy_path (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting>
<para>
Creates a copy of the current path and returns it to the user as a
<link linkend="cairo-path-t"><type>cairo_path_t</type></link>. See <link linkend="cairo-path-data-t"><type>cairo_path_data_t</type></link> for hints on how to iterate
over the returned data structure.
</para>
<para>
This function will always return a valid pointer, but the result
will have no data (<literal>data==<link linkend="NULL:CAPS"><literal>NULL</literal></link></literal> and
<literal>num_data==0</literal>), if either of the following
conditions hold:
</para>
<para>
<orderedlist>
<listitem>If there is insufficient memory to copy the path. In this
case <literal>path->status</literal> will be set to
<link linkend="CAIRO-STATUS-NO-MEMORY:CAPS"><literal>CAIRO_STATUS_NO_MEMORY</literal></link>.</listitem>
<listitem>If <parameter>cr</parameter> is already in an error state. In this case
<literal>path->status</literal> will contain the same status that
would be returned by <link linkend="cairo-status"><function>cairo_status()</function></link>.</listitem>
</orderedlist>
</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 copy of the current path. The caller owns the
returned object and should call <link linkend="cairo-path-destroy"><function>cairo_path_destroy()</function></link> when finished
with it.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-copy-path-flat" role="function">
<title>cairo_copy_path_flat ()</title>
<indexterm zone="cairo-copy-path-flat"><primary sortas="copy_path_flat">cairo_copy_path_flat</primary></indexterm>
<programlisting><link linkend="cairo-path-t"><returnvalue>cairo_path_t</returnvalue></link> * cairo_copy_path_flat (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting>
<para>
Gets a flattened copy of the current path and returns it to the
user as a <link linkend="cairo-path-t"><type>cairo_path_t</type></link>. See <link linkend="cairo-path-data-t"><type>cairo_path_data_t</type></link> for hints on
how to iterate over the returned data structure.
</para>
<para>
This function is like <link linkend="cairo-copy-path"><function>cairo_copy_path()</function></link> except that any curves
in the path will be approximated with piecewise-linear
approximations, (accurate to within the current tolerance
value). That is, the result is guaranteed to not have any elements
of type <link linkend="CAIRO-PATH-CURVE-TO:CAPS"><literal>CAIRO_PATH_CURVE_TO</literal></link> which will instead be replaced by a
series of <link linkend="CAIRO-PATH-LINE-TO:CAPS"><literal>CAIRO_PATH_LINE_TO</literal></link> elements.
</para>
<para>
This function will always return a valid pointer, but the result
will have no data (<literal>data==<link linkend="NULL:CAPS"><literal>NULL</literal></link></literal> and
<literal>num_data==0</literal>), if either of the following
conditions hold:
</para>
<para>
<orderedlist>
<listitem>If there is insufficient memory to copy the path. In this
case <literal>path->status</literal> will be set to
<link linkend="CAIRO-STATUS-NO-MEMORY:CAPS"><literal>CAIRO_STATUS_NO_MEMORY</literal></link>.</listitem>
<listitem>If <parameter>cr</parameter> is already in an error state. In this case
<literal>path->status</literal> will contain the same status that
would be returned by <link linkend="cairo-status"><function>cairo_status()</function></link>.</listitem>
</orderedlist>
</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 copy of the current path. The caller owns the
returned object and should call <link linkend="cairo-path-destroy"><function>cairo_path_destroy()</function></link> when finished
with it.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-path-destroy" role="function">
<title>cairo_path_destroy ()</title>
<indexterm zone="cairo-path-destroy"><primary sortas="path_destroy">cairo_path_destroy</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_path_destroy (<parameter><link linkend="cairo-path-t"><type>cairo_path_t</type></link> *path</parameter>);</programlisting>
<para>
Immediately releases all memory associated with <parameter>path</parameter>. After a call
to <link linkend="cairo-path-destroy"><function>cairo_path_destroy()</function></link> the <parameter>path</parameter> pointer is no longer valid and
should not be used further.
</para>
<para>
Note: <link linkend="cairo-path-destroy"><function>cairo_path_destroy()</function></link> should only be called with a
pointer to a <link linkend="cairo-path-t"><type>cairo_path_t</type></link> returned by a cairo function. Any path
that is created manually (ie. outside of cairo) should be destroyed
manually as well.
</para><variablelist role="params">
<varlistentry><term><parameter>path</parameter> :</term>
<listitem><simpara>a path previously returned by either <link linkend="cairo-copy-path"><function>cairo_copy_path()</function></link> or
<link linkend="cairo-copy-path-flat"><function>cairo_copy_path_flat()</function></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-append-path" role="function">
<title>cairo_append_path ()</title>
<indexterm zone="cairo-append-path"><primary sortas="append_path">cairo_append_path</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_append_path (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter>const <link linkend="cairo-path-t"><type>cairo_path_t</type></link> *path</parameter>);</programlisting>
<para>
Append the <parameter>path</parameter> onto the current path. The <parameter>path</parameter> may be either the
return value from one of <link linkend="cairo-copy-path"><function>cairo_copy_path()</function></link> or
<link linkend="cairo-copy-path-flat"><function>cairo_copy_path_flat()</function></link> or it may be constructed manually. See
<link linkend="cairo-path-t"><type>cairo_path_t</type></link> for details on how the path data structure should be
initialized, and note that <literal>path->status</literal> must be
initialized to <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><parameter>path</parameter> :</term>
<listitem><simpara>path to be appended
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-has-current-point" role="function" condition="since:1.6">
<title>cairo_has_current_point ()</title>
<indexterm zone="cairo-has-current-point" role="1.6"><primary sortas="has_current_point">cairo_has_current_point</primary></indexterm>
<programlisting><link linkend="cairo-bool-t"><returnvalue>cairo_bool_t</returnvalue></link> cairo_has_current_point (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting>
<para>
Returns whether a current point is defined on the current path.
See <link linkend="cairo-get-current-point"><function>cairo_get_current_point()</function></link> for details on the current point.
</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> whether a current point is defined.
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since 1.6</para></refsect2>
<refsect2 id="cairo-get-current-point" role="function">
<title>cairo_get_current_point ()</title>
<indexterm zone="cairo-get-current-point"><primary sortas="get_current_point">cairo_get_current_point</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_get_current_point (<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>
Gets the current point of the current path, which is
conceptually the final point reached by the path so far.
</para>
<para>
The current point is returned in the user-space coordinate
system. If there is no defined current point or if <parameter>cr</parameter> is in an
error status, <parameter>x</parameter> and <parameter>y</parameter> will both be set to 0.0. It is possible to
check this in advance with <link linkend="cairo-has-current-point"><function>cairo_has_current_point()</function></link>.
</para>
<para>
Most path construction functions alter the current point. See the
following for details on how they affect the current point:
<link linkend="cairo-new-path"><function>cairo_new_path()</function></link>, <link linkend="cairo-new-sub-path"><function>cairo_new_sub_path()</function></link>,
<link linkend="cairo-append-path"><function>cairo_append_path()</function></link>, <link linkend="cairo-close-path"><function>cairo_close_path()</function></link>,
<link linkend="cairo-move-to"><function>cairo_move_to()</function></link>, <link linkend="cairo-line-to"><function>cairo_line_to()</function></link>, <link linkend="cairo-curve-to"><function>cairo_curve_to()</function></link>,
<link linkend="cairo-rel-move-to"><function>cairo_rel_move_to()</function></link>, <link linkend="cairo-rel-line-to"><function>cairo_rel_line_to()</function></link>, <link linkend="cairo-rel-curve-to"><function>cairo_rel_curve_to()</function></link>,
<link linkend="cairo-arc"><function>cairo_arc()</function></link>, <link linkend="cairo-arc-negative"><function>cairo_arc_negative()</function></link>, <link linkend="cairo-rectangle"><function>cairo_rectangle()</function></link>,
<link linkend="cairo-text-path"><function>cairo_text_path()</function></link>, <link linkend="cairo-glyph-path"><function>cairo_glyph_path()</function></link>, <link linkend="cairo-stroke-to-path"><function>cairo_stroke_to_path()</function></link>.
</para>
<para>
Some functions use and alter the current point but do not
otherwise change current path:
<link linkend="cairo-show-text"><function>cairo_show_text()</function></link>.
</para>
<para>
Some functions unset the current path and as a result, current point:
<link linkend="cairo-fill"><function>cairo_fill()</function></link>, <link linkend="cairo-stroke"><function>cairo_stroke()</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>return value for X coordinate of the current point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y</parameter> :</term>
<listitem><simpara>return value for Y coordinate of the current point
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-new-path" role="function">
<title>cairo_new_path ()</title>
<indexterm zone="cairo-new-path"><primary sortas="new_path">cairo_new_path</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_new_path (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting>
<para>
Clears the current path. After this call there will be no path and
no current point.
</para><variablelist role="params">
<varlistentry><term><parameter>cr</parameter> :</term>
<listitem><simpara>a cairo context
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-new-sub-path" role="function" condition="since:1.2">
<title>cairo_new_sub_path ()</title>
<indexterm zone="cairo-new-sub-path" role="1.2"><primary sortas="new_sub_path">cairo_new_sub_path</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_new_sub_path (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting>
<para>
Begin a new sub-path. Note that the existing path is not
affected. After this call there will be no current point.
</para>
<para>
In many cases, this call is not needed since new sub-paths are
frequently started with <link linkend="cairo-move-to"><function>cairo_move_to()</function></link>.
</para>
<para>
A call to <link linkend="cairo-new-sub-path"><function>cairo_new_sub_path()</function></link> is particularly useful when
beginning a new sub-path with one of the <link linkend="cairo-arc"><function>cairo_arc()</function></link> calls. This
makes things easier as it is no longer necessary to manually
compute the arc's initial coordinates for a call to
<link linkend="cairo-move-to"><function>cairo_move_to()</function></link>.
</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-close-path" role="function">
<title>cairo_close_path ()</title>
<indexterm zone="cairo-close-path"><primary sortas="close_path">cairo_close_path</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_close_path (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>);</programlisting>
<para>
Adds a line segment to the path from the current point to the
beginning of the current sub-path, (the most recent point passed to
<link linkend="cairo-move-to"><function>cairo_move_to()</function></link>), and closes this sub-path. After this call the
current point will be at the joined endpoint of the sub-path.
</para>
<para>
The behavior of <link linkend="cairo-close-path"><function>cairo_close_path()</function></link> is distinct from simply calling
<link linkend="cairo-line-to"><function>cairo_line_to()</function></link> with the equivalent coordinate in the case of
stroking. When a closed sub-path is stroked, there are no caps on
the ends of the sub-path. Instead, there is a line join connecting
the final and initial segments of the sub-path.
</para>
<para>
If there is no current point before the call to <link linkend="cairo-close-path"><function>cairo_close_path()</function></link>,
this function will have no effect.
</para>
<para>
Note: As of cairo version 1.2.4 any call to <link linkend="cairo-close-path"><function>cairo_close_path()</function></link> will
place an explicit MOVE_TO element into the path immediately after
the CLOSE_PATH element, (which can be seen in <link linkend="cairo-copy-path"><function>cairo_copy_path()</function></link> for
example). This can simplify path processing in some cases as it may
not be necessary to save the "last move_to point" during processing
as the MOVE_TO immediately after the CLOSE_PATH will provide that
point.
</para><variablelist role="params">
<varlistentry><term><parameter>cr</parameter> :</term>
<listitem><simpara>a cairo context
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-arc" role="function">
<title>cairo_arc ()</title>
<indexterm zone="cairo-arc"><primary sortas="arc">cairo_arc</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_arc (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter><link linkend="double"><type>double</type></link> xc</parameter>,
<parameter><link linkend="double"><type>double</type></link> yc</parameter>,
<parameter><link linkend="double"><type>double</type></link> radius</parameter>,
<parameter><link linkend="double"><type>double</type></link> angle1</parameter>,
<parameter><link linkend="double"><type>double</type></link> angle2</parameter>);</programlisting>
<para>
Adds a circular arc of the given <parameter>radius</parameter> to the current path. The
arc is centered at (<parameter>xc</parameter>, <parameter>yc</parameter>), begins at <parameter>angle1</parameter> and proceeds in
the direction of increasing angles to end at <parameter>angle2</parameter>. If <parameter>angle2</parameter> is
less than <parameter>angle1</parameter> it will be progressively increased by 2*M_PI
until it is greater than <parameter>angle1</parameter>.
</para>
<para>
If there is a current point, an initial line segment will be added
to the path to connect the current point to the beginning of the
arc. If this initial line is undesired, it can be avoided by
calling <link linkend="cairo-new-sub-path"><function>cairo_new_sub_path()</function></link> before calling <link linkend="cairo-arc"><function>cairo_arc()</function></link>.
</para>
<para>
Angles are measured in radians. An angle of 0.0 is in the direction
of the positive X axis (in user space). An angle of <link linkend="M-PI:CAPS"><literal>M_PI</literal></link>/2.0 radians
(90 degrees) is in the direction of the positive Y axis (in
user space). Angles increase in the direction from the positive X
axis toward the positive Y axis. So with the default transformation
matrix, angles increase in a clockwise direction.
</para>
<para>
(To convert from degrees to radians, use <literal>degrees * (M_PI /
180.)</literal>.)
</para>
<para>
This function gives the arc in the direction of increasing angles;
see <link linkend="cairo-arc-negative"><function>cairo_arc_negative()</function></link> to get the arc in the direction of
decreasing angles.
</para>
<para>
The arc is circular in user space. To achieve an elliptical arc,
you can scale the current transformation matrix by different
amounts in the X and Y directions. For example, to draw an ellipse
in the box given by <parameter>x</parameter>, <parameter>y</parameter>, <parameter>width</parameter>, <parameter>height</parameter>:
</para>
<para>
<informalexample><programlisting>
cairo_save (cr);
cairo_translate (cr, x + width / 2., y + height / 2.);
cairo_scale (cr, width / 2., height / 2.);
cairo_arc (cr, 0., 0., 1., 0., 2 * M_PI);
cairo_restore (cr);
</programlisting></informalexample>
</para><variablelist role="params">
<varlistentry><term><parameter>cr</parameter> :</term>
<listitem><simpara>a cairo context
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>xc</parameter> :</term>
<listitem><simpara>X position of the center of the arc
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>yc</parameter> :</term>
<listitem><simpara>Y position of the center of the arc
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>radius</parameter> :</term>
<listitem><simpara>the radius of the arc
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>angle1</parameter> :</term>
<listitem><simpara>the start angle, in radians
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>angle2</parameter> :</term>
<listitem><simpara>the end angle, in radians
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-arc-negative" role="function">
<title>cairo_arc_negative ()</title>
<indexterm zone="cairo-arc-negative"><primary sortas="arc_negative">cairo_arc_negative</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_arc_negative (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter><link linkend="double"><type>double</type></link> xc</parameter>,
<parameter><link linkend="double"><type>double</type></link> yc</parameter>,
<parameter><link linkend="double"><type>double</type></link> radius</parameter>,
<parameter><link linkend="double"><type>double</type></link> angle1</parameter>,
<parameter><link linkend="double"><type>double</type></link> angle2</parameter>);</programlisting>
<para>
Adds a circular arc of the given <parameter>radius</parameter> to the current path. The
arc is centered at (<parameter>xc</parameter>, <parameter>yc</parameter>), begins at <parameter>angle1</parameter> and proceeds in
the direction of decreasing angles to end at <parameter>angle2</parameter>. If <parameter>angle2</parameter> is
greater than <parameter>angle1</parameter> it will be progressively decreased by 2*M_PI
until it is less than <parameter>angle1</parameter>.
</para>
<para>
See <link linkend="cairo-arc"><function>cairo_arc()</function></link> for more details. This function differs only in the
direction of the arc between the two angles.
</para><variablelist role="params">
<varlistentry><term><parameter>cr</parameter> :</term>
<listitem><simpara>a cairo context
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>xc</parameter> :</term>
<listitem><simpara>X position of the center of the arc
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>yc</parameter> :</term>
<listitem><simpara>Y position of the center of the arc
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>radius</parameter> :</term>
<listitem><simpara>the radius of the arc
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>angle1</parameter> :</term>
<listitem><simpara>the start angle, in radians
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>angle2</parameter> :</term>
<listitem><simpara>the end angle, in radians
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-curve-to" role="function">
<title>cairo_curve_to ()</title>
<indexterm zone="cairo-curve-to"><primary sortas="curve_to">cairo_curve_to</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_curve_to (<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>,
<parameter><link linkend="double"><type>double</type></link> x3</parameter>,
<parameter><link linkend="double"><type>double</type></link> y3</parameter>);</programlisting>
<para>
Adds a cubic Bézier spline to the path from the current point to
position (<parameter>x3</parameter>, <parameter>y3</parameter>) in user-space coordinates, using (<parameter>x1</parameter>, <parameter>y1</parameter>) and
(<parameter>x2</parameter>, <parameter>y2</parameter>) as the control points. After this call the current point
will be (<parameter>x3</parameter>, <parameter>y3</parameter>).
</para>
<para>
If there is no current point before the call to <link linkend="cairo-curve-to"><function>cairo_curve_to()</function></link>
this function will behave as if preceded by a call to
cairo_move_to(<parameter>cr</parameter>, <parameter>x1</parameter>, <parameter>y1</parameter>).
</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>the X coordinate of the first control point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y1</parameter> :</term>
<listitem><simpara>the Y coordinate of the first control point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>x2</parameter> :</term>
<listitem><simpara>the X coordinate of the second control point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y2</parameter> :</term>
<listitem><simpara>the Y coordinate of the second control point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>x3</parameter> :</term>
<listitem><simpara>the X coordinate of the end of the curve
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y3</parameter> :</term>
<listitem><simpara>the Y coordinate of the end of the curve
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-line-to" role="function">
<title>cairo_line_to ()</title>
<indexterm zone="cairo-line-to"><primary sortas="line_to">cairo_line_to</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_line_to (<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>
Adds a line to the path from the current point to position (<parameter>x</parameter>, <parameter>y</parameter>)
in user-space coordinates. After this call the current point
will be (<parameter>x</parameter>, <parameter>y</parameter>).
</para>
<para>
If there is no current point before the call to <link linkend="cairo-line-to"><function>cairo_line_to()</function></link>
this function will behave as cairo_move_to(<parameter>cr</parameter>, <parameter>x</parameter>, <parameter>y</parameter>).
</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>the X coordinate of the end of the new line
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y</parameter> :</term>
<listitem><simpara>the Y coordinate of the end of the new line
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-move-to" role="function">
<title>cairo_move_to ()</title>
<indexterm zone="cairo-move-to"><primary sortas="move_to">cairo_move_to</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_move_to (<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>
Begin a new sub-path. After this call the current point will be (<parameter>x</parameter>,
<parameter>y</parameter>).
</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>the X coordinate of the new position
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y</parameter> :</term>
<listitem><simpara>the Y coordinate of the new position
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-rectangle" role="function">
<title>cairo_rectangle ()</title>
<indexterm zone="cairo-rectangle"><primary sortas="rectangle">cairo_rectangle</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_rectangle (<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>,
<parameter><link linkend="double"><type>double</type></link> width</parameter>,
<parameter><link linkend="double"><type>double</type></link> height</parameter>);</programlisting>
<para>
Adds a closed sub-path rectangle of the given size to the current
path at position (<parameter>x</parameter>, <parameter>y</parameter>) in user-space coordinates.
</para>
<para>
This function is logically equivalent to:
<informalexample><programlisting>
cairo_move_to (cr, x, y);
cairo_rel_line_to (cr, width, 0);
cairo_rel_line_to (cr, 0, height);
cairo_rel_line_to (cr, -width, 0);
cairo_close_path (cr);
</programlisting></informalexample>
</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>the X coordinate of the top left corner of the rectangle
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y</parameter> :</term>
<listitem><simpara>the Y coordinate to the top left corner of the rectangle
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>width</parameter> :</term>
<listitem><simpara>the width of the rectangle
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>height</parameter> :</term>
<listitem><simpara>the height of the rectangle
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-glyph-path" role="function">
<title>cairo_glyph_path ()</title>
<indexterm zone="cairo-glyph-path"><primary sortas="glyph_path">cairo_glyph_path</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_glyph_path (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter>const <link linkend="cairo-glyph-t"><type>cairo_glyph_t</type></link> *glyphs</parameter>,
<parameter><link linkend="int"><type>int</type></link> num_glyphs</parameter>);</programlisting>
<para>
Adds closed paths for the glyphs to the current path. The generated
path if filled, achieves an effect similar to that of
<link linkend="cairo-show-glyphs"><function>cairo_show_glyphs()</function></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>cr</parameter> :</term>
<listitem><simpara>a cairo context
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>glyphs</parameter> :</term>
<listitem><simpara>array of glyphs to show
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>num_glyphs</parameter> :</term>
<listitem><simpara>number of glyphs to show
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-text-path" role="function">
<title>cairo_text_path ()</title>
<indexterm zone="cairo-text-path"><primary sortas="text_path">cairo_text_path</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_text_path (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter>const <link linkend="char"><type>char</type></link> *utf8</parameter>);</programlisting>
<para>
Adds closed paths for text to the current path. The generated
path if filled, achieves an effect similar to that of
<link linkend="cairo-show-text"><function>cairo_show_text()</function></link>.
</para>
<para>
Text conversion and positioning is done similar to <link linkend="cairo-show-text"><function>cairo_show_text()</function></link>.
</para>
<para>
Like <link linkend="cairo-show-text"><function>cairo_show_text()</function></link>, After this call the current point is
moved to the origin of where the next glyph would be placed in
this same progression. That is, the current point will be at
the origin of the final glyph offset by its advance values.
This allows for chaining multiple calls to to <link linkend="cairo-text-path"><function>cairo_text_path()</function></link>
without having to set current point in between.
</para>
<para>
Note: The <link linkend="cairo-text-path"><function>cairo_text_path()</function></link> function call is part of what the cairo
designers call the "toy" text API. It is convenient for short demos
and simple programs, but it is not expected to be adequate for
serious text-using applications. See <link linkend="cairo-glyph-path"><function>cairo_glyph_path()</function></link> for the
"real" text path API in cairo.
</para><variablelist role="params">
<varlistentry><term><parameter>cr</parameter> :</term>
<listitem><simpara>a cairo context
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>utf8</parameter> :</term>
<listitem><simpara>a NUL-terminated string of text encoded in UTF-8, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-rel-curve-to" role="function">
<title>cairo_rel_curve_to ()</title>
<indexterm zone="cairo-rel-curve-to"><primary sortas="rel_curve_to">cairo_rel_curve_to</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_rel_curve_to (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter><link linkend="double"><type>double</type></link> dx1</parameter>,
<parameter><link linkend="double"><type>double</type></link> dy1</parameter>,
<parameter><link linkend="double"><type>double</type></link> dx2</parameter>,
<parameter><link linkend="double"><type>double</type></link> dy2</parameter>,
<parameter><link linkend="double"><type>double</type></link> dx3</parameter>,
<parameter><link linkend="double"><type>double</type></link> dy3</parameter>);</programlisting>
<para>
Relative-coordinate version of <link linkend="cairo-curve-to"><function>cairo_curve_to()</function></link>. All offsets are
relative to the current point. Adds a cubic Bézier spline to the
path from the current point to a point offset from the current
point by (<parameter>dx3</parameter>, <parameter>dy3</parameter>), using points offset by (<parameter>dx1</parameter>, <parameter>dy1</parameter>) and
(<parameter>dx2</parameter>, <parameter>dy2</parameter>) as the control points. After this call the current
point will be offset by (<parameter>dx3</parameter>, <parameter>dy3</parameter>).
</para>
<para>
Given a current point of (x, y), cairo_rel_curve_to(<parameter>cr</parameter>, <parameter>dx1</parameter>,
<parameter>dy1</parameter>, <parameter>dx2</parameter>, <parameter>dy2</parameter>, <parameter>dx3</parameter>, <parameter>dy3</parameter>) is logically equivalent to
cairo_curve_to(<parameter>cr</parameter>, x+<parameter>dx1</parameter>, y+<parameter>dy1</parameter>, x+<parameter>dx2</parameter>, y+<parameter>dy2</parameter>, x+<parameter>dx3</parameter>, y+<parameter>dy3</parameter>).
</para>
<para>
It is an error to call this function with no current point. Doing
so will cause <parameter>cr</parameter> to shutdown with a status of
<link linkend="CAIRO-STATUS-NO-CURRENT-POINT:CAPS"><literal>CAIRO_STATUS_NO_CURRENT_POINT</literal></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>cr</parameter> :</term>
<listitem><simpara>a cairo context
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>dx1</parameter> :</term>
<listitem><simpara>the X offset to the first control point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>dy1</parameter> :</term>
<listitem><simpara>the Y offset to the first control point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>dx2</parameter> :</term>
<listitem><simpara>the X offset to the second control point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>dy2</parameter> :</term>
<listitem><simpara>the Y offset to the second control point
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>dx3</parameter> :</term>
<listitem><simpara>the X offset to the end of the curve
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>dy3</parameter> :</term>
<listitem><simpara>the Y offset to the end of the curve
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-rel-line-to" role="function">
<title>cairo_rel_line_to ()</title>
<indexterm zone="cairo-rel-line-to"><primary sortas="rel_line_to">cairo_rel_line_to</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_rel_line_to (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter><link linkend="double"><type>double</type></link> dx</parameter>,
<parameter><link linkend="double"><type>double</type></link> dy</parameter>);</programlisting>
<para>
Relative-coordinate version of <link linkend="cairo-line-to"><function>cairo_line_to()</function></link>. Adds a line to the
path from the current point to a point that is offset from the
current point by (<parameter>dx</parameter>, <parameter>dy</parameter>) in user space. After this call the
current point will be offset by (<parameter>dx</parameter>, <parameter>dy</parameter>).
</para>
<para>
Given a current point of (x, y), cairo_rel_line_to(<parameter>cr</parameter>, <parameter>dx</parameter>, <parameter>dy</parameter>)
is logically equivalent to cairo_line_to(<parameter>cr</parameter>, x + <parameter>dx</parameter>, y + <parameter>dy</parameter>).
</para>
<para>
It is an error to call this function with no current point. Doing
so will cause <parameter>cr</parameter> to shutdown with a status of
<link linkend="CAIRO-STATUS-NO-CURRENT-POINT:CAPS"><literal>CAIRO_STATUS_NO_CURRENT_POINT</literal></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>cr</parameter> :</term>
<listitem><simpara>a cairo context
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>dx</parameter> :</term>
<listitem><simpara>the X offset to the end of the new line
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>dy</parameter> :</term>
<listitem><simpara>the Y offset to the end of the new line
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-rel-move-to" role="function">
<title>cairo_rel_move_to ()</title>
<indexterm zone="cairo-rel-move-to"><primary sortas="rel_move_to">cairo_rel_move_to</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_rel_move_to (<parameter><link linkend="cairo-t"><type>cairo_t</type></link> *cr</parameter>,
<parameter><link linkend="double"><type>double</type></link> dx</parameter>,
<parameter><link linkend="double"><type>double</type></link> dy</parameter>);</programlisting>
<para>
Begin a new sub-path. After this call the current point will offset
by (<parameter>x</parameter>, <parameter>y</parameter>).
</para>
<para>
Given a current point of (x, y), cairo_rel_move_to(<parameter>cr</parameter>, <parameter>dx</parameter>, <parameter>dy</parameter>)
is logically equivalent to cairo_move_to(<parameter>cr</parameter>, x + <parameter>dx</parameter>, y + <parameter>dy</parameter>).
</para>
<para>
It is an error to call this function with no current point. Doing
so will cause <parameter>cr</parameter> to shutdown with a status of
<link linkend="CAIRO-STATUS-NO-CURRENT-POINT:CAPS"><literal>CAIRO_STATUS_NO_CURRENT_POINT</literal></link>.
</para><variablelist role="params">
<varlistentry><term><parameter>cr</parameter> :</term>
<listitem><simpara>a cairo context
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>dx</parameter> :</term>
<listitem><simpara>the X offset
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>dy</parameter> :</term>
<listitem><simpara>the Y offset
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2 id="cairo-path-extents" role="function" condition="since:1.6">
<title>cairo_path_extents ()</title>
<indexterm zone="cairo-path-extents" role="1.6"><primary sortas="path_extents">cairo_path_extents</primary></indexterm>
<programlisting><link linkend="void"><returnvalue>void</returnvalue></link> cairo_path_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-space coordinates covering the
points on the current path. If the current path is empty, returns
an empty rectangle ((0,0), (0,0)). Stroke parameters, fill rule,
surface dimensions and clipping are not taken into account.
</para>
<para>
Contrast with <link linkend="cairo-fill-extents"><function>cairo_fill_extents()</function></link> and <link linkend="cairo-stroke-extents"><function>cairo_stroke_extents()</function></link> which
return the extents of only the area that would be "inked" by
the corresponding drawing operations.
</para>
<para>
The result of <link linkend="cairo-path-extents"><function>cairo_path_extents()</function></link> is defined as equivalent to the
limit of <link linkend="cairo-stroke-extents"><function>cairo_stroke_extents()</function></link> with <link linkend="CAIRO-LINE-CAP-ROUND:CAPS"><literal>CAIRO_LINE_CAP_ROUND</literal></link> as the
line width approaches 0.0, (but never reaching the empty-rectangle
returned by <link linkend="cairo-stroke-extents"><function>cairo_stroke_extents()</function></link> for a line width of 0.0).
</para>
<para>
Specifically, this means that zero-area sub-paths such as
<link linkend="cairo-move-to"><function>cairo_move_to()</function></link>;<link linkend="cairo-line-to"><function>cairo_line_to()</function></link> segments, (even degenerate cases
where the coordinates to both calls are identical), will be
considered as contributing to the extents. However, a lone
<link linkend="cairo-move-to"><function>cairo_move_to()</function></link> will not contribute to the results of
<link linkend="cairo-path-extents"><function>cairo_path_extents()</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><para role="since">Since 1.6</para></refsect2>
</refsect1>
</refentry>