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<h1>luaharfbuzz</h1>




<h2>Examples</h2>
<ul class="nowrap">
  <li><a href="../examples/core_types.lua.html">core_types.lua</a></li>
  <li><a href="../examples/custom_callbacks.lua.html">custom_callbacks.lua</a></li>
  <li><a href="../examples/harfbuzz_setup.lua.html">harfbuzz_setup.lua</a></li>
  <li><strong>ot_font_loader.lua</strong></li>
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    <h2>ot_font_loader.lua</h2>
<pre>
<span class="keyword">local</span> harfbuzz = <span class="global">require</span>(<span class="string">'harfbuzz'</span>)

<span class="comment">-- Load OpenType font.
</span><span class="comment">-- https://tug.org/TUGboat/tb33-1/tb103isambert.pdf
</span><span class="keyword">local</span> <span class="keyword">function</span> read_font (name, size, fontid)
  <span class="keyword">if</span> size &lt; <span class="number">0</span> <span class="keyword">then</span>
    size = size * tex.sp(<span class="string">"10pt"</span>) / -<span class="number">1000</span>
  <span class="keyword">end</span>

  <span class="comment">-- Load file using fontloader.open
</span>  <span class="keyword">local</span> f = fontloader.open (name)
  <span class="keyword">local</span> fonttable = fontloader.to_table(f)
  fontloader.close(f)

  <span class="keyword">local</span> metrics = {
    name = fonttable.fontname,
    fullname = fonttable.fontname..fontid,
    psname = fonttable.fontname,
    <span class="global">type</span> = <span class="string">"real"</span>,
    filename = name,
    format = <span class="global">string</span>.match(<span class="global">string</span>.lower(name), <span class="string">"otf$"</span>) <span class="keyword">and</span> <span class="string">"opentype"</span> <span class="keyword">or</span> <span class="global">string</span>.match(<span class="global">string</span>.lower(name), <span class="string">"ttf$"</span>) <span class="keyword">and</span> <span class="string">"truetype"</span>,
    embedding = <span class="string">'subset'</span>,
    size = size,
    designsize = fonttable.design_size*<span class="number">6553.6</span>,
    cidinfo = fonttable.cidinfo,
    units_per_em = fonttable.units_per_em
  }

  <span class="comment">-- Scaling for font metrics
</span>  <span class="keyword">local</span> mag = size / fonttable.units_per_em

  <span class="comment">-- Find glyph for 0x20, and get width for spacing glue.
</span>  <span class="keyword">local</span> space_glyph = fonttable.map.map[<span class="number">0x20</span>]
  <span class="keyword">local</span> space_glyph_table = fonttable.glyphs[space_glyph]
  <span class="keyword">local</span> space_glyph_width = space_glyph_table.width * mag

  metrics.parameters = {
    slant = <span class="number">0</span>,
    space = space_glyph_width,
    space_stretch = <span class="number">1.5</span> * space_glyph_width,
    space_shrink = <span class="number">0.5</span> * space_glyph_width,
    x_height = fonttable.pfminfo.os2_xheight * mag,
    quad = <span class="number">1.0</span> * size,
    extra_space = <span class="number">0</span>
  }

  <span class="comment">-- Save backmap in TeX font, so we can get char code from glyph index
</span>  <span class="comment">-- obtainded from Harfbuzz
</span>  metrics.backmap = fonttable.map.backmap

  metrics.characters = { }
  <span class="keyword">for</span> char, glyph <span class="keyword">in</span> <span class="global">pairs</span>(fonttable.map.map) <span class="keyword">do</span>
    <span class="keyword">local</span> glyph_table = fonttable.glyphs[glyph]
    metrics.characters[char] = {
      index = glyph,
      width = glyph_table.width * mag,
      name = glyph_table.name,
    }
    <span class="keyword">if</span> glyph_table.boundingbox[<span class="number">4</span>] <span class="keyword">then</span>
      metrics.characters[char].height = glyph_table.boundingbox[<span class="number">4</span>] * mag
    <span class="keyword">end</span>
    <span class="keyword">if</span> glyph_table.boundingbox[<span class="number">2</span>] <span class="keyword">then</span>
      metrics.characters[char].depth = -glyph_table.boundingbox[<span class="number">2</span>] * mag
    <span class="keyword">end</span>
  <span class="keyword">end</span>

  <span class="comment">-- Store Harfbuzz data in the font to retrieve it in the shaping routine.
</span>  <span class="keyword">local</span> face = harfbuzz.Face.new(name)
  metrics.harfbuzz = {
    face = face,
    font = harfbuzz.Font.new(face)
  }

  <span class="keyword">return</span> metrics
<span class="keyword">end</span>

<span class="comment">-- Register OpenType font loader in define_font callback.
</span>callback.register(<span class="string">'define_font'</span>, read_font, <span class="string">"font loader"</span>)</pre>


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