Find if QDial was rotated clockwise or counter clockwise

Question

Is there any way by which I can detect if QDial (with wrapped property set to true) was rotated clockwise or anticlockwise?

Answer 1

Let 0 the minimum and 100 the maximum of your wrapped QDial. If the difference between two consecutive value changes is positive then you have an anti-clockwise rotation, if not you have a clockwise rotation (you have to adjust it to your actual values)

You should subclass QDial and use the sliderMoved signal :

This signal is emitted when sliderDown is true and the slider moves. This usually happens when the user is dragging the slider. The value is the new slider position.

This signal is emitted even when tracking is turned off.

Connect this signal to a slot that calculates if the rotation was clockwise or anti-clockwise

connect(this, SIGNAL(sliderMoved(int)), this, SLOT(calculateRotationDirection(int)));

void calculateRotationDirection(int v)
{
   int difference = previousValue - v;

   // make sure we have not reached the start...
   if (v == 0)
   {
       if (previousValue == 100)
          direction = DIRECTION_CLOCKWISE;
       else
          direction = DIRECTION_ANTICLOCKWISE;
   }
   else if (v == 100)
   {
       if (previousValue == 0)
          direction = DIRECTION_ANTICLOCKWISE;
       else
          direction = DIRECTION_CLOCKWISE;
   } 
   else
   {   
      if (difference > 0)
         direction = DIRECTION_ANTICLOCKWISE; // a simple enum
      else if (difference  < 0)
         direction = DIRECTION_CLOCKWISE;  
   }
   previousValue = v; // store the previous value
}

Now you can add a function that returns the direction property of your subclass.