77 lines
2.8 KiB
XML
77 lines
2.8 KiB
XML
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<chapter id="buffers-language-script-and-direction">
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<title>Buffers, language, script and direction</title>
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<para>
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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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</para>
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<section id="creating-and-destroying-buffers">
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<title>Creating and destroying buffers</title>
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<para>
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As we saw in our initial example, a buffer is created and
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initialized with <literal>hb_buffer_create()</literal>. 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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</para>
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<para>
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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 <literal>hb_buffer_destroy()</literal>:
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</para>
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<programlisting language="C">
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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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</programlisting>
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<para>
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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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</para>
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<programlisting language="C">
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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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</programlisting>
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<para>
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And then decrease it once you're done with it:
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</para>
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<programlisting language="C">
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hb_buffer_destroy(buffer);
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}
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</programlisting>
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<para>
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To throw away all the data in your buffer and start from scratch,
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call <literal>hb_buffer_reset(buffer)</literal>. 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 <literal>hb_buffer_clear_contents(buffer)</literal>.
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</para>
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</section>
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<section id="adding-text-to-the-buffer">
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<title>Adding text to the buffer</title>
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<para>
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Now we have a brand new HarfBuzz buffer. Let's start filling it
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with text! From HarfBuzz's perspective, a buffer is just a stream
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of Unicode codepoints, but your input string is probably in one of
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the standard Unicode character encodings (UTF-8, UTF-16, UTF-32)
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</para>
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</section>
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<section id="setting-buffer-properties">
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<title>Setting buffer properties</title>
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<para>
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</para>
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</section>
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<section id="what-about-the-other-scripts">
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<title>What about the other scripts?</title>
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<para>
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</para>
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</section>
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<section id="customizing-unicode-functions">
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<title>Customizing Unicode functions</title>
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<para>
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</para>
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</section>
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</chapter>
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