QwtScaleEngine::buildInterval() default values

[Uwe]

I have to override QwtLinearScaleEngine::autoScale() method.

Yes, nothing wrong about it.

Uwe

class YourScaleEngine: public QwtLinearScaleEngine
{
   ...
 
    virtual void autoScale( int maxNumSteps,
        double &x1, double &x2, double &stepSize ) const
    {
        if ( x1 == x2 )
        {
            x1 = ...;
            x2 = ...;
            stepSize = ...;
 
            return;
       }
 
       QwtLinearScaleEngine::autoScale( maxNumSteps, x1, x2, stepSize );
    }
};

class YourScaleEngine: public QwtLinearScaleEngine
{
   ...

    virtual void autoScale( int maxNumSteps,
        double &x1, double &x2, double &stepSize ) const
    {
        if ( x1 == x2 )
        {
            x1 = ...;
            x2 = ...;
            stepSize = ...;

            return;
       }

       QwtLinearScaleEngine::autoScale( maxNumSteps, x1, x2, stepSize );
    }
};

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