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   5 <title>Buffers, language, script and direction: HarfBuzz Manual</title>
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  22 <div class="chapter">
  23 <div class="titlepage"><div><div><h2 class="title">
  24 <a name="buffers-language-script-and-direction"></a>Buffers, language, script and direction</h2></div></div></div>
  25 <div class="toc"><dl class="toc">
  26 <dt><span class="section"><a href="buffers-language-script-and-direction.html#creating-and-destroying-buffers">Creating and destroying buffers</a></span></dt>
  27 <dt><span class="section"><a href="adding-text-to-the-buffer.html">Adding text to the buffer</a></span></dt>
  28 <dt><span class="section"><a href="setting-buffer-properties.html">Setting buffer properties</a></span></dt>
  29 <dt><span class="section"><a href="what-about-the-other-scripts.html">What about the other scripts?</a></span></dt>
  30 <dt><span class="section"><a href="customizing-unicode-functions.html">Customizing Unicode functions</a></span></dt>
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  32 <p>
  33     The input to HarfBuzz is a series of Unicode characters, stored in a
  34     buffer. In this chapter, we'll look at how to set up a buffer with
  35     the text that we want and then customize the properties of the
  36     buffer.
  37   </p>
  38 <div class="section">
  39 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
  40 <a name="creating-and-destroying-buffers"></a>Creating and destroying buffers</h2></div></div></div>
  41 <p>
  42       As we saw in our <span class="emphasis"><em>Getting Started</em></span> example, a
  43       buffer is created and
  44       initialized with <code class="literal">hb_buffer_create()</code>. This
  45       produces a new, empty buffer object, instantiated with some
  46       default values and ready to accept your Unicode strings.
  47     </p>
  48 <p>
  49       HarfBuzz manages the memory of objects (such as buffers) that it
  50       creates, so you don't have to. When you have finished working on
  51       a buffer, you can call <code class="literal">hb_buffer_destroy()</code>:
  52     </p>
  53 <pre class="programlisting">
  54   hb_buffer_t *buffer = hb_buffer_create();
  55   ...
  56   hb_buffer_destroy(buffer);
  57 </pre>
  58 <p>
  59       This will destroy the object and free its associated memory -
  60       unless some other part of the program holds a reference to this
  61       buffer. If you acquire a HarfBuzz buffer from another subsystem
  62       and want to ensure that it is not garbage collected by someone
  63       else destroying it, you should increase its reference count:
  64     </p>
  65 <pre class="programlisting">
  66 void somefunc(hb_buffer_t *buffer) {
  67   buffer = hb_buffer_reference(buffer);
  68   ...
  69 </pre>
  70 <p>
  71       And then decrease it once you're done with it:
  72     </p>
  73 <pre class="programlisting">
  74   hb_buffer_destroy(buffer);
  75 }
  76 </pre>
  77 <p>
  78       To throw away all the data in your buffer and start from scratch,
  79       call <code class="literal">hb_buffer_reset(buffer)</code>. If you want to
  80       throw away the string in the buffer but keep the options, you can
  81       instead call <code class="literal">hb_buffer_clear_contents(buffer)</code>.
  82     </p>
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