title: High performance QImage output to display
body: <p>I'm trying to make video output (sequence of frames) to any qt visible widget. At beginning i thought that QLabel will be enough for this point... but i was wrong. Converting to pixmap is too overloading for processor at large images: 1080p for example.</p>
  
  <p>Any other solution? (not QLabel?)</p>
  
  <p>Example of code for one frame:</p>
  
  <pre><code>QImage m_outputFrameImage(width, height, QImage::Format_RGB888);
  memcpy(m_outputFrameImage.bits(), m_frameRGB-&gt;data[0], height * width * 3);
  QPixmap pixmap = QPixmap::fromImage(m_outputFrameImage); // BAD, slow and high load
  /* Bad too (Same code?)
      QPainter painter;
      painter.begin(&amp;pixmap);
      painter.drawImage(0, 0, m_outputFrameImage);
      painter.end();
  */
  labelVideo-&gt;setPixmap(pixmap);
  </code></pre>