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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="integration-uniscribe"></a>Uniscribe integration</h2></div></div></div>
<p>
      If your client program is running on Windows, HarfBuzz offers
      an additional API that can help integrate with Microsoft's
      Uniscribe engine and the Windows GDI.
    </p>
<p>
      Overall, the Uniscribe API covers a broader set of typographic
      layout functions than HarfBuzz implements, but HarfBuzz's
      shaping API can serve as a drop-in replacement for Uniscribe's shaping
      functionality. In fact, one of HarfBuzz's design goals is to
      accurately reproduce the same output for shaping a given text
      segment that Uniscribe produces — even to the point of
      duplicating known shaping bugs or deviations from the
      specification — so you can be confident that your users'
      documents with their existing fonts will not be affected adversely by
      switching to HarfBuzz.
    </p>
<p>
      At a basic level, HarfBuzz's <code class="function">hb_shape()</code>
      function replaces both the <a class="ulink" href="" target="_top"><code class="function">ScriptShape()</code></a>
      and <a class="ulink" href="https://docs.microsoft.com/en-us/windows/desktop/api/Usp10/nf-usp10-scriptplace" target="_top"><code class="function">ScriptPlace()</code></a>
      functions from Uniscribe. 
    </p>
<p>
      However, whereas <code class="function">ScriptShape()</code> returns the
      glyphs and clusters for a shaped sequence and
      <code class="function">ScriptPlace()</code> returns the advances and
      offsets for those glyphs, <code class="function">hb_shape()</code>
      handles both. After <code class="function">hb_shape()</code> shapes a
      buffer, the output glyph IDs and cluster IDs are returned as
      an array of <span class="structname">hb_glyph_info_t</span> structures, and the
      glyph advances and offsets are returned as an array of
      <span class="structname">hb_glyph_position_t</span> structures. 
    </p>
<p>
      Your client program only needs to ensure that it coverts
      correctly between HarfBuzz's low-level data types (such as
      <span class="type">hb_position_t</span>) and Windows's corresponding types
      (such as <span class="type">GOFFSET</span> and <span class="type">ABC</span>). Be sure you
      read the <a class="xref" href="buffers-language-script-and-direction.html" title="Buffers, language, script and direction"><i>Buffers, language, script and direction</i></a> 
      chapter for a full explanation of how HarfBuzz input buffers are
      used, and see <a class="xref" href="shaping-and-shape-plans.html#shaping-buffer-output" title="Shaping and buffer output">the section called “Shaping and buffer output”</a> for the
      details of what <code class="function">hb_shape()</code> returns in the
      output buffer when shaping is complete. 
    </p>
<p>
      Although <code class="function">hb_shape()</code> itself is functionally
      equivalent to Uniscribe's shaping routines, there are two
      additional HarfBuzz functions you may want to use to integrate
      the libraries in your code. Both are used to link HarfBuzz font
      objects to the equivalent Windows structures.
    </p>
<p>
      The <code class="function">hb_uniscribe_font_get_logfontw()</code>
      function takes a <span class="type">hb_font_t</span> font object and returns
      a pointer to the <a class="ulink" href="https://docs.microsoft.com/en-us/windows/desktop/api/wingdi/ns-wingdi-logfontw" target="_top"><span class="type">LOGFONTW</span></a>
      "logical font" that corresponds to it. A <span class="type">LOGFONTW</span>
      structure holds font-wide attributes, including metrics, size,
      and style information.
    </p>
<p>
      The <code class="function">hb_uniscribe_font_get_hfont()</code> function
      also takes a <span class="type">hb_font_t</span> font object, but it returns
      an <span class="type">HFONT</span> — a handle to the underlying logical
      font — instead.
    </p>
<p>
      <span class="type">LOGFONTW</span>s and <span class="type">HFONT</span>s are both needed
      by other Uniscribe functions.
    </p>
<p>
      As a final note, you may notice a reference to an optional
      <code class="literal">uniscribe</code> shaper back-end in the <a class="xref" href="building.html#configuration" title="Configuration options">the section called “Configuration options”</a> section of the HarfBuzz manual. This
      option is not a Uniscribe-integration facility.
    </p>
<p>
      Instead, it is a internal code path used in the
      <span class="command"><strong>hb-shape</strong></span> command-line utility, which hands
      shaping functionality over to Uniscribe entirely, when run on a
      Windows system. That allows testing HarfBuzz's native output
      against the Uniscribe engine, for tracking compatibility and
      debugging.
    </p>
<p>
      Because this back-end is only used when testing HarfBuzz
      functionality, it is disabled by default when building the
      HarfBuzz binaries.
    </p>
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