Merge pull request #875 from diizy/logs

Logscale models: fix all issues and finalize the implementation

include/AutomatableModel.h

@@ -162,7 +162,11 @@ public:
 	{
 		return castValue<T>( m_step );
 	}
-
+	
+	//! @brief Returns value scaled with the scale type and min/max values of this model
+	float scaledValue( float value ) const;
+	//! @brief Returns value applied with the inverse of this model's scale type
+	float inverseScaledValue( float value ) const;
 
 	void setInitValue( const float value );
 
@@ -187,6 +191,10 @@ public:
 	{
 		setScaleType( setToTrue ? Logarithmic : Linear );
 	}
+	bool isScaleLogarithmic() const
+	{
+		return m_scaleType == Logarithmic;
+	}
 
 	void setStep( const float step );
 
@@ -224,16 +232,7 @@ public:
 		return "automatablemodel";
 	}
 
-	QString displayValue( const float val ) const
-	{
-		switch( m_dataType )
-		{
-			case Float: return QString::number( castValue<float>( val ) );
-			case Integer: return QString::number( castValue<int>( val ) );
-			case Bool: return QString::number( castValue<bool>( val ) );
-		}
-		return "0";
-	}
+	QString displayValue( const float val ) const;
 
 	bool hasLinkedModels() const
 	{

include/lmms_constants.h

@@ -22,10 +22,11 @@
  *
  */
 
-#ifndef _LMMS_CONSTANTS_H
-#define _LMMS_CONSTANTS_H
+#ifndef LMMS_CONSTANTS_H
+#define LMMS_CONSTANTS_H
 
 const float F_PI = 3.1415926535f;
+const float F_E =  2.718281828459045f;
 const float F_2PI = 2*F_PI;
 const float F_PI_2 = F_PI*0.5;
 

include/lmms_math.h

@@ -128,5 +128,40 @@ 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 )
+	{
+		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;
+}
+
+
+//! @brief Scales value from logarithmic to linear. Value should be in min-max range.
+static inline float linearToLogScale( float min, float max, float value )
+{
+	static const float EXP = 1.0f / F_E;
+	const float val = ( value - min ) / ( max - min );
+	if( min < 0 )
+	{
+		const float mmax = qMax( qAbs( min ), qAbs( max ) );
+		return signedPowf( value / mmax, EXP ) * mmax;
+	}
+	return powf( val, EXP ) * ( max - min ) + min;
+}
 
 #endif