Chris@43: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@43: 
Chris@43: /*
Chris@43:     Sonic Visualiser
Chris@43:     An audio file viewer and annotation editor.
Chris@43:     Centre for Digital Music, Queen Mary, University of London.
Chris@43:     This file copyright 2006 QMUL.
Chris@43:     
Chris@43:     This program is free software; you can redistribute it and/or
Chris@43:     modify it under the terms of the GNU General Public License as
Chris@43:     published by the Free Software Foundation; either version 2 of the
Chris@43:     License, or (at your option) any later version.  See the file
Chris@43:     COPYING included with this distribution for more information.
Chris@43: */
Chris@43: 
Chris@43: #include "PlaySpeedRangeMapper.h"
Chris@43: 
Chris@43: #include <iostream>
Chris@43: #include <cmath>
Chris@43: 
Chris@466: // PlaySpeedRangeMapper maps a position in the range [0,120] on to a
Chris@466: // play speed factor on a logarithmic scale in the range 0.125 ->
Chris@466: // 8. This ensures that the desirable speed factors 0.25, 0.5, 1, 2,
Chris@466: // and 4 are all mapped to exact positions (respectively 20, 40, 60,
Chris@466: // 80, 100).
Chris@466: 
Chris@466: // Note that the "factor" referred to below is a play speed factor
Chris@466: // (higher = faster, 1.0 = normal speed), the "value" is a percentage
Chris@466: // (higher = faster, 100 = normal speed), and the "position" is an
Chris@466: // integer step on the dial's scale (0-120, 60 = centre).
Chris@466: 
Chris@466: PlaySpeedRangeMapper::PlaySpeedRangeMapper() :
Chris@466:     m_minpos(0),
Chris@466:     m_maxpos(120)
Chris@43: {
Chris@43: }
Chris@43: 
Chris@43: int
Chris@434: PlaySpeedRangeMapper::getPositionForValue(double value) const
Chris@43: {
Chris@43:     // value is percent
Chris@434:     double factor = getFactorForValue(value);
Chris@43:     int position = getPositionForFactor(factor);
Chris@43:     return position;
Chris@43: }
Chris@43: 
Chris@43: int
Chris@434: PlaySpeedRangeMapper::getPositionForValueUnclamped(double value) const
Chris@330: {
Chris@330:     // We don't really provide this
Chris@330:     return getPositionForValue(value);
Chris@330: }
Chris@330: 
Chris@434: double
Chris@43: PlaySpeedRangeMapper::getValueForPosition(int position) const
Chris@43: {
Chris@434:     double factor = getFactorForPosition(position);
Chris@434:     double pc = getValueForFactor(factor);
Chris@43:     return pc;
Chris@43: }
Chris@43: 
Chris@434: double
Chris@330: PlaySpeedRangeMapper::getValueForPositionUnclamped(int position) const
Chris@330: {
Chris@330:     // We don't really provide this
Chris@330:     return getValueForPosition(position);
Chris@330: }
Chris@330: 
Chris@434: double
Chris@434: PlaySpeedRangeMapper::getValueForFactor(double factor) const
Chris@43: {
Chris@466:     return factor * 100.0;
Chris@43: }
Chris@43: 
Chris@434: double
Chris@434: PlaySpeedRangeMapper::getFactorForValue(double value) const
Chris@43: {
Chris@466:     return value / 100.0;
Chris@466: }
Chris@43: 
Chris@466: int
Chris@466: PlaySpeedRangeMapper::getPositionForFactor(double factor) const
Chris@466: {
Chris@466:     if (factor == 0) return m_minpos;
Chris@466:     int pos = int(lrint((log2(factor) + 3.0) * 20.0));
Chris@466:     if (pos < m_minpos) pos = m_minpos;
Chris@466:     if (pos > m_maxpos) pos = m_maxpos;
Chris@466:     return pos;
Chris@43: }
Chris@43: 
Chris@434: double
Chris@43: PlaySpeedRangeMapper::getFactorForPosition(int position) const
Chris@43: {
Chris@466:     return pow(2.0, double(position) * 0.05 - 3.0);
Chris@43: }
Chris@43: 
Chris@43: QString
Chris@43: PlaySpeedRangeMapper::getUnit() const
Chris@43: {
Chris@43:     return "%";
Chris@43: }