cairo-png.xml

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

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<refentry id="cairo-PNG-Support">
<refmeta>
<refentrytitle id="top_of_page">PNG Support</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>CAIRO Library</refmiscinfo>
</refmeta>

<refnamediv>
<refname>PNG Support</refname>
<refpurpose>Reading and writing PNG images</refpurpose>
<!--[<xref linkend="desc" endterm="desc.title"/>]-->
</refnamediv>

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

<synopsis>



<link linkend="cairo-surface-t">cairo_surface_t</link>* <link linkend="cairo-image-surface-create-from-png">cairo_image_surface_create_from_png</link>
                                            (const <link linkend="char">char</link> *filename);
<link linkend="cairo-status-t">cairo_status_t</link> (<link linkend="cairo-read-func-t">*cairo_read_func_t</link>)         (<link linkend="void">void</link> *closure,
                                             unsigned <link linkend="char">char</link> *data,
                                             unsigned <link linkend="int">int</link> length);
<link linkend="cairo-surface-t">cairo_surface_t</link>* <link linkend="cairo-image-surface-create-from-png-stream">cairo_image_surface_create_from_png_stream</link>
                                            (<link linkend="cairo-read-func-t">cairo_read_func_t</link> read_func,
                                             <link linkend="void">void</link> *closure);
<link linkend="cairo-status-t">cairo_status_t</link> <link linkend="cairo-surface-write-to-png">cairo_surface_write_to_png</link>   (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                             const <link linkend="char">char</link> *filename);
<link linkend="cairo-status-t">cairo_status_t</link> (<link linkend="cairo-write-func-t">*cairo_write_func_t</link>)        (<link linkend="void">void</link> *closure,
                                             unsigned <link linkend="char">char</link> *data,
                                             unsigned <link linkend="int">int</link> length);
<link linkend="cairo-status-t">cairo_status_t</link> <link linkend="cairo-surface-write-to-png-stream">cairo_surface_write_to_png_stream</link>
                                            (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                             <link linkend="cairo-write-func-t">cairo_write_func_t</link> write_func,
                                             <link linkend="void">void</link> *closure);
</synopsis>
</refsynopsisdiv>









<refsect1 id="desc">
<title id="desc.title">Description</title>
<para>

</para>
</refsect1>

<refsect1 id="details">
<title id="details.title">Details</title>
<refsect2>
<title><anchor id="cairo-image-surface-create-from-png" role="function"/>cairo_image_surface_create_from_png ()</title>
<indexterm><primary>cairo_image_surface_create_from_png</primary></indexterm><programlisting><link linkend="cairo-surface-t">cairo_surface_t</link>* cairo_image_surface_create_from_png
                                            (const <link linkend="char">char</link> *filename);</programlisting>
</refsect2>
<refsect2>
<title><anchor id="cairo-read-func-t" role="function"/>cairo_read_func_t ()</title>
<indexterm><primary>cairo_read_func_t</primary></indexterm><programlisting><link linkend="cairo-status-t">cairo_status_t</link> (*cairo_read_func_t)         (<link linkend="void">void</link> *closure,
                                             unsigned <link linkend="char">char</link> *data,
                                             unsigned <link linkend="int">int</link> length);</programlisting>
<para>
<link linkend="cairo-read-func-t"><type>cairo_read_func_t</type></link> is the type of function which is called when a
backend needs to read data from an intput stream.  It is passed the
closure which was specified by the user at the time the read
function was registered, the buffer to read the data into and the
length of the data in bytes.  The read function should return
CAIRO_STATUS_SUCCESS if all the data was successfully read,
CAIRO_STATUS_READ_ERROR otherwise.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>closure</parameter>&nbsp;:</term>
<listitem><simpara> the input closure
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>data</parameter>&nbsp;:</term>
<listitem><simpara> the buffer into which to read the data
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>length</parameter>&nbsp;:</term>
<listitem><simpara> the amount of data to read
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis>&nbsp;:</term><listitem><simpara> the status code of the read operation
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-image-surface-create-from-png-stream" role="function"/>cairo_image_surface_create_from_png_stream ()</title>
<indexterm><primary>cairo_image_surface_create_from_png_stream</primary></indexterm><programlisting><link linkend="cairo-surface-t">cairo_surface_t</link>* cairo_image_surface_create_from_png_stream
                                            (<link linkend="cairo-read-func-t">cairo_read_func_t</link> read_func,
                                             <link linkend="void">void</link> *closure);</programlisting>
</refsect2>
<refsect2>
<title><anchor id="cairo-surface-write-to-png" role="function"/>cairo_surface_write_to_png ()</title>
<indexterm><primary>cairo_surface_write_to_png</primary></indexterm><programlisting><link linkend="cairo-status-t">cairo_status_t</link> cairo_surface_write_to_png   (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                             const <link linkend="char">char</link> *filename);</programlisting>
</refsect2>
<refsect2>
<title><anchor id="cairo-write-func-t" role="function"/>cairo_write_func_t ()</title>
<indexterm><primary>cairo_write_func_t</primary></indexterm><programlisting><link linkend="cairo-status-t">cairo_status_t</link> (*cairo_write_func_t)        (<link linkend="void">void</link> *closure,
                                             unsigned <link linkend="char">char</link> *data,
                                             unsigned <link linkend="int">int</link> length);</programlisting>
<para>
<link linkend="cairo-write-func-t"><type>cairo_write_func_t</type></link> is the type of function which is called when a
backend needs to write data to an output stream.  It is passed the
closure which was specified by the user at the time the write
function was registered, the data to write and the length of the
data in bytes.  The write function should return
CAIRO_STATUS_SUCCESS if all the data was successfully written,
CAIRO_STATUS_WRITE_ERROR otherwise.</para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>closure</parameter>&nbsp;:</term>
<listitem><simpara> the output closure
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>data</parameter>&nbsp;:</term>
<listitem><simpara> the buffer containing the data to write
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>length</parameter>&nbsp;:</term>
<listitem><simpara> the amount of data to write
</simpara></listitem></varlistentry>
<varlistentry><term><emphasis>Returns</emphasis>&nbsp;:</term><listitem><simpara> the status code of the write operation
</simpara></listitem></varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="cairo-surface-write-to-png-stream" role="function"/>cairo_surface_write_to_png_stream ()</title>
<indexterm><primary>cairo_surface_write_to_png_stream</primary></indexterm><programlisting><link linkend="cairo-status-t">cairo_status_t</link> cairo_surface_write_to_png_stream
                                            (<link linkend="cairo-surface-t">cairo_surface_t</link> *surface,
                                             <link linkend="cairo-write-func-t">cairo_write_func_t</link> write_func,
                                             <link linkend="void">void</link> *closure);</programlisting>
</refsect2>

</refsect1>




</refentry>