harfbuzz/docs/usermanual-buffers-language-script-and-direction.xml

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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 <emphasis>Getting Started</emphasis> 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 (such as buffers) that it
      creates, 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>