harfbuzz/docs/usermanual-hello-harfbuzz.xml

<chapter id="hello-harfbuzz">
  <title>Hello, HarfBuzz</title>
  <para>
    Here's the simplest HarfBuzz that can possibly work. We will improve
    it later.
  </para>
  <orderedlist numeration="arabic">
    <listitem>
      <para>
        Create a buffer and put your text in it.
      </para>
    </listitem>
  </orderedlist>
  <programlisting language="C">
  #include &lt;hb.h&gt;
  hb_buffer_t *buf;
  buf = hb_buffer_create();
  hb_buffer_add_utf8(buf, text, strlen(text), 0, strlen(text));
</programlisting>
  <orderedlist numeration="arabic">
    <listitem override="2">
      <para>
        Guess the script, language and direction of the buffer.
      </para>
    </listitem>
  </orderedlist>
  <programlisting language="C">
  hb_buffer_guess_segment_properties(buf);
</programlisting>
  <orderedlist numeration="arabic">
    <listitem override="3">
      <para>
        Create a face and a font, using FreeType for now.
      </para>
    </listitem>
  </orderedlist>
  <programlisting language="C">
  #include &lt;hb-ft.h&gt;
  FT_New_Face(ft_library, font_path, index, &amp;face)
  hb_font_t *font = hb_ft_font_create(face);
</programlisting>
  <orderedlist numeration="arabic">
    <listitem override="4">
      <para>
        Shape!
      </para>
    </listitem>
  </orderedlist>
  <programlisting>
  hb_shape(font, buf, NULL, 0);
</programlisting>
  <orderedlist numeration="arabic">
    <listitem override="5">
      <para>
        Get the glyph and position information.
      </para>
    </listitem>
  </orderedlist>
  <programlisting language="C">
  hb_glyph_info_t *glyph_info    = hb_buffer_get_glyph_infos(buf, &amp;glyph_count);
  hb_glyph_position_t *glyph_pos = hb_buffer_get_glyph_positions(buf, &amp;glyph_count);
</programlisting>
  <orderedlist numeration="arabic">
    <listitem override="6">
      <para>
        Iterate over each glyph.
      </para>
    </listitem>
  </orderedlist>
  <programlisting language="C">
  for (i = 0; i &lt; glyph_count; ++i) {
    glyphid = glyph_info[i].codepoint;
    x_offset = glyph_pos[i].x_offset / 64.0;
    y_offset = glyph_pos[i].y_offset / 64.0;
    x_advance = glyph_pos[i].x_advance / 64.0;
    y_advance = glyph_pos[i].y_advance / 64.0;
    draw_glyph(glyphid, cursor_x + x_offset, cursor_y + y_offset);
    cursor_x += x_advance;
    cursor_y += y_advance;
  }
</programlisting>
  <orderedlist numeration="arabic">
    <listitem override="7">
      <para>
        Tidy up.
      </para>
    </listitem>
  </orderedlist>
  <programlisting language="C">
  hb_buffer_destroy(buf);
  hb_font_destroy(hb_ft_font);
</programlisting>

<para>
  This example shows enough to get us started using HarfBuzz. Now we
  are going to use the remainder of HarfBuzz's API to refine that
  example and improve our text shaping capabilities.
</para>
</chapter>