Hi to all,
I wrote a audio wave display widget with a timeline that show the actual position in the audio samples. When playing back the timeline moves on the right.
I would do that when the playline reachs the middle it stops and the widget is scrolled on the left. I have a look at the ensureVisible code but I can no underdstand it very well.
Here the code I wrote:

Qt Code: 
  1. if (newSoundPosition - m_lastDrawnPosition > getWaveWidgetParent()->getWaveGraphModel()->getSamplesPerPixel())
  2.     {
  3.         if (zoomFactor > 1.0)// if zoomIn
  4.         {
  5.             if (widgetPos < center)
  6.             {
  7.                 waveDisplay->updatePlayHead(m_lastDrawnPosition, newSoundPosition);
  8.             }
  9.             else
  10.             {
  11.                 uint fdiff = widgetPos - center;
  12.                 fstart = m_lastFrameStart + fdiff;
  13.                 graphModel->setFrameStart(fstart);
  14.                 m_lastFrameStart = fstart;
  15.             }
  16.         }
  17.         else // when zoom factor = 1.0 always update the 'playline' 
  18.         {
  19.             waveDisplay->updatePlayHead(m_lastDrawnPosition, newSoundPosition);
  20.         }
  21.  
  22.         m_lastDrawnPosition = newSoundPosition;
  23. }
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Basically if the zoom factor ==1 the playline position is always updated as all wave form is displayed. Instead if the zoom factor > 1 is where I would shift the position of the widget keeping the position of the playline in the middle, but the result is not so good.
I can see the playline trembling around a position and I can not achieve what I need.
Any ideas?
Regards