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  24 <a name="object-model-blobs"></a>Blobs</h2></div></div></div>
  25 <p>
  26       While most of HarfBuzz's object types are specific to the
  27       shaping process, <span class="emphasis"><em>blobs</em></span> are somewhat
  28       different.
  29     </p>
  30 <p>
  31       Blobs are an abstraction designed to negotiate lifecycle and
  32       permissions for raw pieces of data.  For example, when you load
  33       the raw font data into memory and want to pass it to HarfBuzz,
  34       you do so in a <code class="literal">hb_blob_t</code> wrapper.
  35     </p>
  36 <p>
  37       This allows you to take advantage of HarfBuzz's
  38       reference-counting and <code class="function">destroy</code>
  39       callbacks. If you allocated the memory for the data using
  40       <code class="function">malloc()</code>, you would create the blob using
  41     </p>
  42 <pre class="programlisting">
  43       hb_blob_create (data, length, HB_MEMORY_MODE_WRITABLE, data, free)
  44     </pre>
  45 <p>
  46       That way, HarfBuzz will call <code class="function">free()</code> on the
  47       allocated memory whenever the blob drops its last reference and
  48       is deconstructed.  Consequently, the user code can stop worrying
  49       about freeing memory and let the reference-counting machinery
  50       take care of that.
  51     </p>
  52 <p>
  53       Most of the time, blobs are read-only, facilitating their use in
  54       immutable objects.
  55     </p>
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