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<refentry id="cairo-cairo-surface-t">
<refmeta>
<refentrytitle role="top_of_page">cairo_surface_t</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>CAIRO Library</refmiscinfo>
</refmeta>

<refnamediv>
<refname>cairo_surface_t</refname>
<refpurpose>Base class for surfaces</refpurpose>
<!--[<xref linkend="desc" endterm="desc.title"/>]-->
</refnamediv>

<refsynopsisdiv role="synopsis">
<title role="synopsis.title">Synopsis</title>

<synopsis>



typedef             <link linkend="cairo-surface-t">cairo_surface_t</link>;
enum                <link linkend="cairo-content-t">cairo_content_t</link>;
<link linkend="cairo-surface-t">cairo_surface_t</link>*    <link linkend="cairo-surface-create-similar">cairo_surface_create_similar</link>        (<link linkend="cairo-surface-t">cairo_surface_t</link> *other,
                                                         <link linkend="cairo-content-t">cairo_content_t</link> content,
                                                         <link linkend="int">int</link> width,
                                                         <link linkend="int">int</link> height);
<link linkend="cairo-surface-t">cairo_surface_t</link>*    <link linkend="cairo-surface-reference">cairo_surface_reference</link>             (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);
<link linkend="void">void</link>                <link linkend="cairo-surface-destroy">cairo_surface_destroy</link>               (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);
<link linkend="cairo-status-t">cairo_status_t</link>      <link linkend="cairo-surface-status">cairo_surface_status</link>                (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);
<link linkend="void">void</link>                <link linkend="cairo-surface-finish">cairo_surface_finish</link>                (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);
<link linkend="void">void</link>                <link linkend="cairo-surface-flush">cairo_surface_flush</link>                 (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);
<link linkend="void">void</link>                <link linkend="cairo-surface-get-font-options">cairo_surface_get_font_options</link>      (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         <link linkend="cairo-font-options-t">cairo_font_options_t</link> *options);
<link linkend="cairo-content-t">cairo_content_t</link>     <link linkend="cairo-surface-get-content">cairo_surface_get_content</link>           (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);
<link linkend="void">void</link>                <link linkend="cairo-surface-mark-dirty">cairo_surface_mark_dirty</link>            (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);
<link linkend="void">void</link>                <link linkend="cairo-surface-mark-dirty-rectangle">cairo_surface_mark_dirty_rectangle</link>  (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         <link linkend="int">int</link> x,
                                                         <link linkend="int">int</link> y,
                                                         <link linkend="int">int</link> width,
                                                         <link linkend="int">int</link> height);
<link linkend="void">void</link>                <link linkend="cairo-surface-set-device-offset">cairo_surface_set_device_offset</link>     (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         <link linkend="double">double</link> x_offset,
                                                         <link linkend="double">double</link> y_offset);
<link linkend="void">void</link>                <link linkend="cairo-surface-get-device-offset">cairo_surface_get_device_offset</link>     (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         <link linkend="double">double</link> *x_offset,
                                                         <link linkend="double">double</link> *y_offset);
<link linkend="void">void</link>                <link linkend="cairo-surface-set-fallback-resolution">cairo_surface_set_fallback_resolution</link>
                                                        (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         <link linkend="double">double</link> x_pixels_per_inch,
                                                         <link linkend="double">double</link> y_pixels_per_inch);
enum                <link linkend="cairo-surface-type-t">cairo_surface_type_t</link>;
<link linkend="cairo-surface-type-t">cairo_surface_type_t</link> <link linkend="cairo-surface-get-type">cairo_surface_get_type</link>             (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);
unsigned <link linkend="int">int</link>        <link linkend="cairo-surface-get-reference-count">cairo_surface_get_reference_count</link>   (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);
<link linkend="cairo-status-t">cairo_status_t</link>      <link linkend="cairo-surface-set-user-data">cairo_surface_set_user_data</link>         (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         const <link linkend="cairo-user-data-key-t">cairo_user_data_key_t</link> *key,
                                                         <link linkend="void">void</link> *user_data,
                                                         <link linkend="cairo-destroy-func-t">cairo_destroy_func_t</link> destroy);
<link linkend="void">void</link>*               <link linkend="cairo-surface-get-user-data">cairo_surface_get_user_data</link>         (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         const <link linkend="cairo-user-data-key-t">cairo_user_data_key_t</link> *key);
<link linkend="void">void</link>                <link linkend="cairo-surface-copy-page">cairo_surface_copy_page</link>             (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);
<link linkend="void">void</link>                <link linkend="cairo-surface-show-page">cairo_surface_show_page</link>             (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);
</synopsis>
</refsynopsisdiv>









<refsect1 role="desc">
<title role="desc.title">Description</title>
<para>
<link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> is the abstract type representing all different drawing
targets that cairo can render to.  The actual drawings are
performed using a cairo <firstterm>context</firstterm>.
</para>
<para>
A cairo surface is created by using <firstterm>backend</firstterm>-specific
constructors, typically of the form
cairo_<emphasis>backend</emphasis><link linkend="surface-create"><function>_surface_create()</function></link>.
</para>
</refsect1>

<refsect1 role="details">
<title role="details.title">Details</title>
<refsect2>
<title><anchor id="cairo-surface-t" role="typedef"/>cairo_surface_t</title>
<indexterm><primary>cairo_surface_t</primary></indexterm><programlisting>typedef struct _cairo_surface cairo_surface_t;
</programlisting>
<para>
A <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> represents an image, either as the destination
of a drawing operation or as source when drawing onto another
surface.  To draw to a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>, create a cairo context
with the surface as the target, using <link linkend="cairo-create"><function>cairo_create()</function></link>.
</para>
<para>
There are different subtypes of <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> for
different drawing backends; for example, <link linkend="cairo-image-surface-create"><function>cairo_image_surface_create()</function></link>
creates a bitmap image in memory.
The type of a surface can be queried with <link linkend="cairo-surface-get-type"><function>cairo_surface_get_type()</function></link>.
</para>
<para>
Memory management of <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> is done with
<link linkend="cairo-surface-reference"><function>cairo_surface_reference()</function></link> and <link linkend="cairo-surface-destroy"><function>cairo_surface_destroy()</function></link>.</para>
<para>

</para></refsect2>
<refsect2>
<title><anchor id="cairo-content-t" role="enum"/>enum cairo_content_t</title>
<indexterm><primary>cairo_content_t</primary></indexterm><programlisting>typedef enum _cairo_content {
    CAIRO_CONTENT_COLOR		= 0x1000,
    CAIRO_CONTENT_ALPHA		= 0x2000,
    CAIRO_CONTENT_COLOR_ALPHA	= 0x3000
} cairo_content_t;
</programlisting>
<para>
<link linkend="cairo-content-t"><type>cairo_content_t</type></link> is used to describe the content that a surface will
contain, whether color information, alpha information (translucence
vs. opacity), or both.
</para>
<para>
Note: The large values here are designed to keep <link linkend="cairo-content-t"><type>cairo_content_t</type></link>
values distinct from <link linkend="cairo-format-t"><type>cairo_format_t</type></link> values so that the
implementation can detect the error if users confuse the two types.</para>
<para>

</para><variablelist role="enum">
<varlistentry>
<term><anchor id="CAIRO-CONTENT-COLOR:CAPS" role="constant"/><literal>CAIRO_CONTENT_COLOR</literal></term>
<listitem><simpara> The surface will hold color content only.
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-CONTENT-ALPHA:CAPS" role="constant"/><literal>CAIRO_CONTENT_ALPHA</literal></term>
<listitem><simpara> The surface will hold alpha content only.
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-CONTENT-COLOR-ALPHA:CAPS" role="constant"/><literal>CAIRO_CONTENT_COLOR_ALPHA</literal></term>
<listitem><simpara> The surface will hold color and alpha content.
</simpara></listitem>
</varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-create-similar" role="function"/>cairo_surface_create_similar ()</title>
<indexterm><primary>cairo_surface_create_similar</primary></indexterm><programlisting><link linkend="cairo-surface-t">cairo_surface_t</link>*    cairo_surface_create_similar        (<link linkend="cairo-surface-t">cairo_surface_t</link> *other,
                                                         <link linkend="cairo-content-t">cairo_content_t</link> content,
                                                         <link linkend="int">int</link> width,
                                                         <link linkend="int">int</link> height);</programlisting>
<para>
Create a new surface that is as compatible as possible with an
existing surface. For example the new surface will have the same
fallback resolution and font options as <parameter>other</parameter>. Generally, the new
surface will also use the same backend as <parameter>other</parameter>, unless that is
not possible for some reason. The type of the returned surface may
be examined with <link linkend="cairo-surface-get-type"><function>cairo_surface_get_type()</function></link>.
</para>
<para>
Initially the surface contents are all 0 (transparent if contents
have transparency, black otherwise.)</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>other</parameter>&nbsp;:</term>
<listitem><simpara> an existing surface used to select the backend of the new surface
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>content</parameter>&nbsp;:</term>
<listitem><simpara> the content for the new surface
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>width</parameter>&nbsp;:</term>
<listitem><simpara> width of the new surface, (in device-space units)
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>height</parameter>&nbsp;:</term>
<listitem><simpara> height of the new surface (in device-space units)
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis>&nbsp;:</term><listitem><simpara> a pointer to the newly allocated surface. The caller
owns the surface and should call <link linkend="cairo-surface-destroy"><function>cairo_surface_destroy()</function></link> when done
with it.

This function always returns a valid pointer, but it will return a
pointer to a "nil" surface if <parameter>other</parameter> is already in an error state
or any other error occurs.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-reference" role="function"/>cairo_surface_reference ()</title>
<indexterm><primary>cairo_surface_reference</primary></indexterm><programlisting><link linkend="cairo-surface-t">cairo_surface_t</link>*    cairo_surface_reference             (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);</programlisting>
<para>
Increases the reference count on <parameter>surface</parameter> by one. This prevents
<parameter>surface</parameter> from being destroyed until a matching call to
<link linkend="cairo-surface-destroy"><function>cairo_surface_destroy()</function></link> is made.
</para>
<para>
The number of references to a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> can be get using
<link linkend="cairo-surface-get-reference-count"><function>cairo_surface_get_reference_count()</function></link>.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis>&nbsp;:</term><listitem><simpara> the referenced <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-destroy" role="function"/>cairo_surface_destroy ()</title>
<indexterm><primary>cairo_surface_destroy</primary></indexterm><programlisting><link linkend="void">void</link>                cairo_surface_destroy               (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);</programlisting>
<para>
Decreases the reference count on <parameter>surface</parameter> by one. If the result is
zero, then <parameter>surface</parameter> and all associated resources are freed.  See
<link linkend="cairo-surface-reference"><function>cairo_surface_reference()</function></link>.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-status" role="function"/>cairo_surface_status ()</title>
<indexterm><primary>cairo_surface_status</primary></indexterm><programlisting><link linkend="cairo-status-t">cairo_status_t</link>      cairo_surface_status                (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);</programlisting>
<para>
Checks whether an error has previously occurred for this
surface.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis>&nbsp;:</term><listitem><simpara> <link linkend="CAIRO-STATUS-SUCCESS:CAPS"><literal>CAIRO_STATUS_SUCCESS</literal></link>, <link linkend="CAIRO-STATUS-NULL-POINTER:CAPS"><literal>CAIRO_STATUS_NULL_POINTER</literal></link>,
<link linkend="CAIRO-STATUS-NO-MEMORY:CAPS"><literal>CAIRO_STATUS_NO_MEMORY</literal></link>, <link linkend="CAIRO-STATUS-READ-ERROR:CAPS"><literal>CAIRO_STATUS_READ_ERROR</literal></link>,
<link linkend="CAIRO-STATUS-INVALID-CONTENT:CAPS"><literal>CAIRO_STATUS_INVALID_CONTENT</literal></link>, <link linkend="CAIRO-STATUS-INVALID-FORMAT:CAPS"><literal>CAIRO_STATUS_INVALID_FORMAT</literal></link>, or
<link linkend="CAIRO-STATUS-INVALID-VISUAL:CAPS"><literal>CAIRO_STATUS_INVALID_VISUAL</literal></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-finish" role="function"/>cairo_surface_finish ()</title>
<indexterm><primary>cairo_surface_finish</primary></indexterm><programlisting><link linkend="void">void</link>                cairo_surface_finish                (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);</programlisting>
<para>
This function finishes the surface and drops all references to
external resources.  For example, for the Xlib backend it means
that cairo will no longer access the drawable, which can be freed.
After calling <link linkend="cairo-surface-finish"><function>cairo_surface_finish()</function></link> the only valid operations on a
surface are getting and setting user data and referencing and
destroying it.  Further drawing to the surface will not affect the
surface but will instead trigger a CAIRO_STATUS_SURFACE_FINISHED
error.
</para>
<para>
When the last call to <link linkend="cairo-surface-destroy"><function>cairo_surface_destroy()</function></link> decreases the
reference count to zero, cairo will call <link linkend="cairo-surface-finish"><function>cairo_surface_finish()</function></link> if
it hasn't been called already, before freeing the resources
associated with the surface.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> the <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> to finish
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-flush" role="function"/>cairo_surface_flush ()</title>
<indexterm><primary>cairo_surface_flush</primary></indexterm><programlisting><link linkend="void">void</link>                cairo_surface_flush                 (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);</programlisting>
<para>
Do any pending drawing for the surface and also restore any
temporary modification's cairo has made to the surface's
state. This function must be called before switching from
drawing on the surface with cairo to drawing on it directly
with native APIs. If the surface doesn't support direct access,
then this function does nothing.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-get-font-options" role="function"/>cairo_surface_get_font_options ()</title>
<indexterm><primary>cairo_surface_get_font_options</primary></indexterm><programlisting><link linkend="void">void</link>                cairo_surface_get_font_options      (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         <link linkend="cairo-font-options-t">cairo_font_options_t</link> *options);</programlisting>
<para>
Retrieves the default font rendering options for the surface.
This allows display surfaces to report the correct subpixel order
for rendering on them, print surfaces to disable hinting of
metrics and so forth. The result can then be used with
<link linkend="cairo-scaled-font-create"><function>cairo_scaled_font_create()</function></link>.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>options</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-font-options-t"><type>cairo_font_options_t</type></link> object into which to store
  the retrieved options. All existing values are overwritten
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-get-content" role="function" condition="since:1.2"/>cairo_surface_get_content ()</title>
<indexterm role="1.2"><primary>cairo_surface_get_content</primary></indexterm><programlisting><link linkend="cairo-content-t">cairo_content_t</link>     cairo_surface_get_content           (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);</programlisting>
<para>
This function returns the content type of <parameter>surface</parameter> which indicates
whether the surface contains color and/or alpha information. See
<link linkend="cairo-content-t"><type>cairo_content_t</type></link>.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis>&nbsp;:</term><listitem><simpara> The content type of <parameter>surface</parameter>.

</simpara></listitem></varlistentry>
</variablelist><para role="since">Since  1.2
</para></refsect2>
<refsect2>
<title><anchor id="cairo-surface-mark-dirty" role="function"/>cairo_surface_mark_dirty ()</title>
<indexterm><primary>cairo_surface_mark_dirty</primary></indexterm><programlisting><link linkend="void">void</link>                cairo_surface_mark_dirty            (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);</programlisting>
<para>
Tells cairo that drawing has been done to surface using means other
than cairo, and that cairo should reread any cached areas. Note
that you must call <link linkend="cairo-surface-flush"><function>cairo_surface_flush()</function></link> before doing such drawing.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-mark-dirty-rectangle" role="function"/>cairo_surface_mark_dirty_rectangle ()</title>
<indexterm><primary>cairo_surface_mark_dirty_rectangle</primary></indexterm><programlisting><link linkend="void">void</link>                cairo_surface_mark_dirty_rectangle  (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         <link linkend="int">int</link> x,
                                                         <link linkend="int">int</link> y,
                                                         <link linkend="int">int</link> width,
                                                         <link linkend="int">int</link> height);</programlisting>
<para>
Like <link linkend="cairo-surface-mark-dirty"><function>cairo_surface_mark_dirty()</function></link>, but drawing has been done only to
the specified rectangle, so that cairo can retain cached contents
for other parts of the surface.
</para>
<para>
Any cached clip set on the surface will be reset by this function,
to make sure that future cairo calls have the clip set that they
expect.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>x</parameter>&nbsp;:</term>
<listitem><simpara> X coordinate of dirty rectangle
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y</parameter>&nbsp;:</term>
<listitem><simpara> Y coordinate of dirty rectangle
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>width</parameter>&nbsp;:</term>
<listitem><simpara> width of dirty rectangle
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>height</parameter>&nbsp;:</term>
<listitem><simpara> height of dirty rectangle
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-set-device-offset" role="function"/>cairo_surface_set_device_offset ()</title>
<indexterm><primary>cairo_surface_set_device_offset</primary></indexterm><programlisting><link linkend="void">void</link>                cairo_surface_set_device_offset     (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         <link linkend="double">double</link> x_offset,
                                                         <link linkend="double">double</link> y_offset);</programlisting>
<para>
Sets an offset that is added to the device coordinates determined
by the CTM when drawing to <parameter>surface</parameter>. One use case for this function
is when we want to create a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> that redirects drawing
for a portion of an onscreen surface to an offscreen surface in a
way that is completely invisible to the user of the cairo
API. Setting a transformation via <link linkend="cairo-translate"><function>cairo_translate()</function></link> isn't
sufficient to do this, since functions like
<link linkend="cairo-device-to-user"><function>cairo_device_to_user()</function></link> will expose the hidden offset.
</para>
<para>
Note that the offset affects drawing to the surface as well as
using the surface in a source pattern.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>x_offset</parameter>&nbsp;:</term>
<listitem><simpara> the offset in the X direction, in device units
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y_offset</parameter>&nbsp;:</term>
<listitem><simpara> the offset in the Y direction, in device units
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-get-device-offset" role="function" condition="since:1.2"/>cairo_surface_get_device_offset ()</title>
<indexterm role="1.2"><primary>cairo_surface_get_device_offset</primary></indexterm><programlisting><link linkend="void">void</link>                cairo_surface_get_device_offset     (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         <link linkend="double">double</link> *x_offset,
                                                         <link linkend="double">double</link> *y_offset);</programlisting>
<para>
This function returns the previous device offset set by
<link linkend="cairo-surface-set-device-offset"><function>cairo_surface_set_device_offset()</function></link>.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>x_offset</parameter>&nbsp;:</term>
<listitem><simpara> the offset in the X direction, in device units
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y_offset</parameter>&nbsp;:</term>
<listitem><simpara> the offset in the Y direction, in device units
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since  1.2
</para></refsect2>
<refsect2>
<title><anchor id="cairo-surface-set-fallback-resolution" role="function" condition="since:1.2"/>cairo_surface_set_fallback_resolution ()</title>
<indexterm role="1.2"><primary>cairo_surface_set_fallback_resolution</primary></indexterm><programlisting><link linkend="void">void</link>                cairo_surface_set_fallback_resolution
                                                        (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         <link linkend="double">double</link> x_pixels_per_inch,
                                                         <link linkend="double">double</link> y_pixels_per_inch);</programlisting>
<para>
Set the horizontal and vertical resolution for image fallbacks.
</para>
<para>
When certain operations aren't supported natively by a backend,
cairo will fallback by rendering operations to an image and then
overlaying that image onto the output. For backends that are
natively vector-oriented, this function can be used to set the
resolution used for these image fallbacks, (larger values will
result in more detailed images, but also larger file sizes).
</para>
<para>
Some examples of natively vector-oriented backends are the ps, pdf,
and svg backends.
</para>
<para>
For backends that are natively raster-oriented, image fallbacks are
still possible, but they are always performed at the native
device resolution. So this function has no effect on those
backends.
</para>
<para>
Note: The fallback resolution only takes effect at the time of
completing a page (with <link linkend="cairo-show-page"><function>cairo_show_page()</function></link> or <link linkend="cairo-copy-page"><function>cairo_copy_page()</function></link>) so
there is currently no way to have more than one fallback resolution
in effect on a single page.
</para>
<para>
The default fallback resoultion is 300 pixels per inch in both
dimensions.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>x_pixels_per_inch</parameter>&nbsp;:</term>
<listitem><simpara> horizontal setting for pixels per inch
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>y_pixels_per_inch</parameter>&nbsp;:</term>
<listitem><simpara> vertical setting for pixels per inch
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since  1.2
</para></refsect2>
<refsect2>
<title><anchor id="cairo-surface-type-t" role="enum" condition="since:1.2"/>enum cairo_surface_type_t</title>
<indexterm role="1.2"><primary>cairo_surface_type_t</primary></indexterm><programlisting>typedef enum _cairo_surface_type {
    CAIRO_SURFACE_TYPE_IMAGE,
    CAIRO_SURFACE_TYPE_PDF,
    CAIRO_SURFACE_TYPE_PS,
    CAIRO_SURFACE_TYPE_XLIB,
    CAIRO_SURFACE_TYPE_XCB,
    CAIRO_SURFACE_TYPE_GLITZ,
    CAIRO_SURFACE_TYPE_QUARTZ,
    CAIRO_SURFACE_TYPE_WIN32,
    CAIRO_SURFACE_TYPE_BEOS,
    CAIRO_SURFACE_TYPE_DIRECTFB,
    CAIRO_SURFACE_TYPE_SVG,
    CAIRO_SURFACE_TYPE_OS2,
    CAIRO_SURFACE_TYPE_WIN32_PRINTING,
    CAIRO_SURFACE_TYPE_QUARTZ_IMAGE
} cairo_surface_type_t;
</programlisting>
<para>
<link linkend="cairo-surface-type-t"><type>cairo_surface_type_t</type></link> is used to describe the type of a given
surface. The surface types are also known as "backends" or "surface
backends" within cairo.
</para>
<para>
The type of a surface is determined by the function used to create
it, which will generally be of the form cairo_<emphasis>type</emphasis><link linkend="surface-create"><function>_surface_create()</function></link>,
(though see <link linkend="cairo-surface-create-similar"><function>cairo_surface_create_similar()</function></link> as well).
</para>
<para>
The surface type can be queried with <link linkend="cairo-surface-get-type"><function>cairo_surface_get_type()</function></link>
</para>
<para>
The various <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link> functions can be used with surfaces of
any type, but some backends also provide type-specific functions
that must only be called with a surface of the appropriate
type. These functions have names that begin with
cairo_<emphasis>type</emphasis>_surface such as <link linkend="cairo-image-surface-get-width"><function>cairo_image_surface_get_width()</function></link>.
</para>
<para>
The behavior of calling a type-specific function with a surface of
the wrong type is undefined.
</para>
<para>
New entries may be added in future versions.</para>
<para>

</para><variablelist role="enum">
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-IMAGE:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_IMAGE</literal></term>
<listitem><simpara> The surface is of type image
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-PDF:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_PDF</literal></term>
<listitem><simpara> The surface is of type pdf
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-PS:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_PS</literal></term>
<listitem><simpara> The surface is of type ps
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-XLIB:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_XLIB</literal></term>
<listitem><simpara> The surface is of type xlib
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-XCB:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_XCB</literal></term>
<listitem><simpara> The surface is of type xcb
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-GLITZ:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_GLITZ</literal></term>
<listitem><simpara> The surface is of type glitz
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-QUARTZ:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_QUARTZ</literal></term>
<listitem><simpara> The surface is of type quartz
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-WIN32:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_WIN32</literal></term>
<listitem><simpara> The surface is of type win32
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-BEOS:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_BEOS</literal></term>
<listitem><simpara> The surface is of type beos
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-DIRECTFB:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_DIRECTFB</literal></term>
<listitem><simpara> The surface is of type directfb
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-SVG:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_SVG</literal></term>
<listitem><simpara> The surface is of type svg
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-OS2:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_OS2</literal></term>
<listitem><simpara> The surface is of type os2
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-WIN32-PRINTING:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_WIN32_PRINTING</literal></term>
<listitem><simpara> The surface is a win32 printing surface
</simpara></listitem>
</varlistentry>
<varlistentry>
<term><anchor id="CAIRO-SURFACE-TYPE-QUARTZ-IMAGE:CAPS" role="constant"/><literal>CAIRO_SURFACE_TYPE_QUARTZ_IMAGE</literal></term>
<listitem><simpara> The surface is of type quartz_image
</simpara></listitem>
</varlistentry>
</variablelist><para role="since">Since  1.2
</para></refsect2>
<refsect2>
<title><anchor id="cairo-surface-get-type" role="function" condition="since:1.2"/>cairo_surface_get_type ()</title>
<indexterm role="1.2"><primary>cairo_surface_get_type</primary></indexterm><programlisting><link linkend="cairo-surface-type-t">cairo_surface_type_t</link> cairo_surface_get_type             (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);</programlisting>
<para>
This function returns the type of the backend used to create
a surface. See <link linkend="cairo-surface-type-t"><type>cairo_surface_type_t</type></link> for available types.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis>&nbsp;:</term><listitem><simpara> The type of <parameter>surface</parameter>.

</simpara></listitem></varlistentry>
</variablelist><para role="since">Since  1.2
</para></refsect2>
<refsect2>
<title><anchor id="cairo-surface-get-reference-count" role="function" condition="since:1.4"/>cairo_surface_get_reference_count ()</title>
<indexterm role="1.4"><primary>cairo_surface_get_reference_count</primary></indexterm><programlisting>unsigned <link linkend="int">int</link>        cairo_surface_get_reference_count   (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);</programlisting>
<para>
Returns the current reference count of <parameter>surface</parameter>.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis>&nbsp;:</term><listitem><simpara> the current reference count of <parameter>surface</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>
<title><anchor id="cairo-surface-set-user-data" role="function"/>cairo_surface_set_user_data ()</title>
<indexterm><primary>cairo_surface_set_user_data</primary></indexterm><programlisting><link linkend="cairo-status-t">cairo_status_t</link>      cairo_surface_set_user_data         (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         const <link linkend="cairo-user-data-key-t">cairo_user_data_key_t</link> *key,
                                                         <link linkend="void">void</link> *user_data,
                                                         <link linkend="cairo-destroy-func-t">cairo_destroy_func_t</link> destroy);</programlisting>
<para>
Attach user data to <parameter>surface</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>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>key</parameter>&nbsp;:</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>&nbsp;:</term>
<listitem><simpara> the user data to attach to the surface
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>destroy</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-destroy-func-t"><type>cairo_destroy_func_t</type></link> which will be called when the
surface is destroyed or when new user data is attached using the
same key.
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis>&nbsp;:</term><listitem><simpara> <link linkend="CAIRO-STATUS-SUCCESS:CAPS"><literal>CAIRO_STATUS_SUCCESS</literal></link> or <link linkend="CAIRO-STATUS-NO-MEMORY:CAPS"><literal>CAIRO_STATUS_NO_MEMORY</literal></link> if a
slot could not be allocated for the user data.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-get-user-data" role="function"/>cairo_surface_get_user_data ()</title>
<indexterm><primary>cairo_surface_get_user_data</primary></indexterm><programlisting><link linkend="void">void</link>*               cairo_surface_get_user_data         (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                                         const <link linkend="cairo-user-data-key-t">cairo_user_data_key_t</link> *key);</programlisting>
<para>
Return user data previously attached to <parameter>surface</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>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>key</parameter>&nbsp;:</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>&nbsp;:</term><listitem><simpara> the user data previously attached or <link linkend="NULL:CAPS"><literal>NULL</literal></link>.
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-copy-page" role="function" condition="since:1.6"/>cairo_surface_copy_page ()</title>
<indexterm role="1.6"><primary>cairo_surface_copy_page</primary></indexterm><programlisting><link linkend="void">void</link>                cairo_surface_copy_page             (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);</programlisting>
<para>
Emits the current page for backends that support multiple pages,
but doesn't clear it, so that the contents of the current page will
be retained for the next page.  Use <link linkend="cairo-surface-show-page"><function>cairo_surface_show_page()</function></link> if you
want to get an empty page after the emission.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-surface-t"><type>cairo_surface_t</type></link>
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since  1.6
</para></refsect2>
<refsect2>
<title><anchor id="cairo-surface-show-page" role="function" condition="since:1.6"/>cairo_surface_show_page ()</title>
<indexterm role="1.6"><primary>cairo_surface_show_page</primary></indexterm><programlisting><link linkend="void">void</link>                cairo_surface_show_page             (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface);</programlisting>
<para>
Emits and clears the current page for backends that support multiple
pages.  Use <link linkend="cairo-surface-copy-page"><function>cairo_surface_copy_page()</function></link> if you don't want to clear the page.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>surface</parameter>&nbsp;:</term>
<listitem><simpara> a <link linkend="cairo-Surface-t"><type>cairo_Surface_t</type></link>
</simpara></listitem></varlistentry>
</variablelist><para role="since">Since  1.6
</para></refsect2>

</refsect1>



<refsect1>
<title>See Also</title>
<para>
<itemizedlist>
<listitem>#<link linkend="cairo-t"><function>cairo_t()</function></link></listitem>
<listitem>#<link linkend="cairo-pattern-t"><function>cairo_pattern_t()</function></link></listitem>
</itemizedlist>
</para>
</refsect1>


<refsect1><refsect2 /><refsect2 /></refsect1>
</refentry>
