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<chapter id="buffers-language-script-and-direction">
<title>Buffers, language, script and direction</title>
<para>
The input to Harfbuzz is a series of Unicode characters, stored in a
buffer. In this chapter, we'll look at how to set up a buffer with
the text that we want and then customize the properties of the
buffer.
</para>
<section id="creating-and-destroying-buffers">
<title>Creating and destroying buffers</title>
<para>
As we saw in our initial example, a buffer is created and
initialized with <literal>hb_buffer_create()</literal>. This
produces a new, empty buffer object, instantiated with some
default values and ready to accept your Unicode strings.
</para>
<para>
Harfbuzz manages the memory of objects that it creates (such as
buffers), so you don't have to. When you have finished working on
a buffer, you can call <literal>hb_buffer_destroy()</literal>:
</para>
<programlisting language="C">
hb_buffer_t *buffer = hb_buffer_create();
...
hb_buffer_destroy(buffer);
</programlisting>
<para>
This will destroy the object and free its associated memory -
unless some other part of the program holds a reference to this
buffer. If you acquire a Harfbuzz buffer from another subsystem
and want to ensure that it is not garbage collected by someone
else destroying it, you should increase its reference count:
</para>
<programlisting language="C">
void somefunc(hb_buffer_t *buffer) {
buffer = hb_buffer_reference(buffer);
...
</programlisting>
<para>
And then decrease it once you're done with it:
</para>
<programlisting language="C">
hb_buffer_destroy(buffer);
}
</programlisting>
<para>
To throw away all the data in your buffer and start from scratch,
call <literal>hb_buffer_reset(buffer)</literal>. If you want to
throw away the string in the buffer but keep the options, you can
instead call <literal>hb_buffer_clear_contents(buffer)</literal>.
</para>
</section>
<section id="adding-text-to-the-buffer">
<title>Adding text to the buffer</title>
<para>
Now we have a brand new Harfbuzz buffer. Let's start filling it
with text! From Harfbuzz's perspective, a buffer is just a stream
of Unicode codepoints, but your input string is probably in one of
the standard Unicode character encodings (UTF-8, UTF-16, UTF-32)
</para>
</section>
<section id="setting-buffer-properties">
<title>Setting buffer properties</title>
<para>
</para>
</section>
<section id="what-about-the-other-scripts">
<title>What about the other scripts?</title>
<para>
</para>
</section>
<section id="customizing-unicode-functions">
<title>Customizing Unicode functions</title>
<para>
</para>
</section>
</chapter>
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