87 lines
4.3 KiB
HTML
87 lines
4.3 KiB
HTML
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<html>
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<head>
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<title>Buffers, language, script and direction: HarfBuzz Manual</title>
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<div class="chapter">
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<div class="titlepage"><div><div><h2 class="title">
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<a name="buffers-language-script-and-direction"></a>Buffers, language, script and direction</h2></div></div></div>
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<div class="toc"><dl class="toc">
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<dt><span class="section"><a href="buffers-language-script-and-direction.html#creating-and-destroying-buffers">Creating and destroying buffers</a></span></dt>
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<dt><span class="section"><a href="adding-text-to-the-buffer.html">Adding text to the buffer</a></span></dt>
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<dt><span class="section"><a href="setting-buffer-properties.html">Setting buffer properties</a></span></dt>
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<dt><span class="section"><a href="what-about-the-other-scripts.html">What about the other scripts?</a></span></dt>
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<dt><span class="section"><a href="customizing-unicode-functions.html">Customizing Unicode functions</a></span></dt>
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</dl></div>
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<p>
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The input to Harfbuzz is a series of Unicode characters, stored in a
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buffer. In this chapter, we'll look at how to set up a buffer with
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the text that we want and then customize the properties of the
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buffer.
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</p>
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<div class="section">
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
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<a name="creating-and-destroying-buffers"></a>Creating and destroying buffers</h2></div></div></div>
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<p>
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As we saw in our initial example, a buffer is created and
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initialized with <code class="literal">hb_buffer_create()</code>. This
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produces a new, empty buffer object, instantiated with some
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default values and ready to accept your Unicode strings.
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</p>
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<p>
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Harfbuzz manages the memory of objects that it creates (such as
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buffers), so you don't have to. When you have finished working on
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a buffer, you can call <code class="literal">hb_buffer_destroy()</code>:
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</p>
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<pre class="programlisting">
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hb_buffer_t *buffer = hb_buffer_create();
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...
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hb_buffer_destroy(buffer);
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</pre>
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<p>
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This will destroy the object and free its associated memory -
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unless some other part of the program holds a reference to this
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buffer. If you acquire a Harfbuzz buffer from another subsystem
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and want to ensure that it is not garbage collected by someone
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else destroying it, you should increase its reference count:
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</p>
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<pre class="programlisting">
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void somefunc(hb_buffer_t *buffer) {
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buffer = hb_buffer_reference(buffer);
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...
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</pre>
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<p>
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And then decrease it once you're done with it:
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</p>
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<pre class="programlisting">
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hb_buffer_destroy(buffer);
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}
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</pre>
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<p>
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To throw away all the data in your buffer and start from scratch,
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call <code class="literal">hb_buffer_reset(buffer)</code>. If you want to
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throw away the string in the buffer but keep the options, you can
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instead call <code class="literal">hb_buffer_clear_contents(buffer)</code>.
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</p>
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</div>
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