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Logscale: Fix negative ranges

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This fixes errors that happen on models that have both logarithmic scale and a range that goes to the negative.
This commit is contained in:
Vesa
2014-06-21 10:56:28 +03:00
parent 8da423412c
commit f7042977a9
2 changed files with 18 additions and 4 deletions
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16
include/lmms_math.h
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@@ -128,13 +128,24 @@ static inline double sinc( double _x )
}
//! @brief Exponential function that deals with negative bases
static inline float signedPowf( float v, float e )
{
return v < 0
? powf( -v, e ) * -1.0f
: powf( v, e );
}
//! @brief Scales @value from linear to logarithmic.
//! Value should be within [0,1]
static inline float logToLinearScale( float min, float max, float value )
{
if( min < 0 )
{
return powf( value * ( 1.0f - min / max ) + min / max, F_E ) * ( max - min ) + min;
const float mmax = qMax( qAbs( min ), qAbs( max ) );
const float val = value * ( max - min ) + min;
return signedPowf( val / mmax, F_E ) * mmax;
}
return powf( value, F_E ) * ( max - min ) + min;
}
@@ -147,7 +158,8 @@ static inline float linearToLogScale( float min, float max, float value )
const float val = ( value - min ) / ( max - min );
if( min < 0 )
{
return powf( val * ( 1.0f - min / max ) + min / max, EXP ) * ( max - min ) + min;
const float mmax = qMax( qAbs( min ), qAbs( max ) );
return signedPowf( value / mmax, EXP ) * mmax;
}
return powf( val, EXP ) * ( max - min ) + min;
}

6
src/gui/widgets/knob.cpp
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@@ -674,8 +674,10 @@ void knob::setPosition( const QPoint & _p )
if( model()->isScaleLogarithmic() ) // logarithmic code
{
const float pos = ( oldValue - model()->minValue() ) / model()->range();
const float ratio = 0.1f + pos * 15.f;
const float pos = model()->minValue() < 0
? oldValue / qMax( qAbs( model()->maxValue() ), qAbs( model()->minValue() ) )
: ( oldValue - model()->minValue() ) / model()->range();
const float ratio = 0.1f + qAbs( pos ) * 15.f;
float newValue = value * ratio;
if( qAbs( newValue ) >= step )
{