title: Add custom fonts in C++ and call them by their family name in QML
body: <p>In my <code>qrc</code> file, I have the following fonts:</p>
  
  <p><a href="https://i.stack.imgur.com/hbCDh.png" rel="nofollow"><img src="https://i.stack.imgur.com/hbCDh.png" alt="enter image description here"></a></p>
  
  <p>If I install them on the OS (Windows here), I will be able to call them in <code>QML</code> with the following name:</p>
  
  <pre><code>import QtQuick.Controls 2.0
  
  Label {
      id: label
      font.family: "Universalis ADF Std"
  }
  </code></pre>
  
  <p>But if they're not installed, I'd still like to make them available to my <code>QML</code> files.</p>
  
  <p>Of course, adding the fonts one by one with <code>QFontDatabase</code> works:</p>
  
  <pre><code>QDir    dir{"path/to/fonts"};
  for (auto file : dir.entryList(QDir::Files))
  {
      if (QFontDatabase::addApplicationFont("path/to/fonts/" + file))
          std::cerr &lt;&lt; "Fail to add font " &lt;&lt; file &lt;&lt; std::endl;
  }
  </code></pre>
  
  <p>But I won't be able to call the whole group with "Universalis ADF Std". Note that the <code>C++</code> part happens before loading the <code>QML</code> files. How could I do that?</p>