493a922208
Use chapter ids instead of numbers, so that we can reorder them, introduce new ones etc. without the numbers becoming out of date.
77 lines
2.8 KiB
XML
77 lines
2.8 KiB
XML
<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> |