text: /**********************************************************************
  
    Audacity: A Digital Audio Editor
  
    Compressor.cpp
  
    Dominic Mazzoni
    Martyn Shaw
    Steve Jolly
  
  *******************************************************************//**
  
  \class EffectCompressor
  \brief An Effect derived from EffectTwoPassSimpleMono
  
   - Martyn Shaw made it inherit from EffectTwoPassSimpleMono 10/2005.
   - Steve Jolly made it inherit from EffectSimpleMono.
   - GUI added and implementation improved by Dominic Mazzoni, 5/11/2003.
  
  *//****************************************************************//**
  
  \class CompressorPanel
  \brief Panel used within the EffectCompressor for EffectCompressor.
  
  *//*******************************************************************/
  
  #include "../Audacity.h"
  #include "Compressor.h"
  
  #include <math.h>
  
  #include <wx/brush.h>
  #include <wx/dcclient.h>
  #include <wx/dcmemory.h>
  #include <wx/intl.h>
  
  #include "../AColor.h"
  #include "../Prefs.h"
  #include "../ShuttleGui.h"
  #include "../float_cast.h"
  #include "../widgets/Ruler.h"
  
  #include "../WaveTrack.h"
  #include "../Theme.h"
  #include "../AllThemeResources.h"
  
  enum
  {
     ID_Threshold = 10000,
     ID_NoiseFloor,
     ID_Ratio,
     ID_Attack,
     ID_Decay
  };
  
  // Define keys, defaults, minimums, and maximums for the effect parameters
  //
  //     Name          Type     Key                  Def      Min      Max      Scale
  Param( Threshold,    double,  wxT("Threshold"),     -12.0,   -60.0,   -1.0,    1   );
  Param( NoiseFloor,   double,  wxT("NoiseFloor"),    -40.0,   -80.0,   -20.0,   5   );
  Param( Ratio,        double,  wxT("Ratio"),         2.0,     1.1,     10.0,    10  );
  Param( AttackTime,   double,  wxT("AttackTime"),    0.2,     0.1,     5.0,     100 );
  Param( ReleaseTime,  double,  wxT("ReleaseTime"),   1.0,     1.0,     30.0,    10  );
  Param( Normalize,    bool,    wxT("Normalize"),     true,    false,   true,    1   );
  Param( UsePeak,      bool,    wxT("UsePeak"),       false,   false,   true,    1   );
  
  //----------------------------------------------------------------------------
  // EffectCompressor
  //----------------------------------------------------------------------------
  
  BEGIN_EVENT_TABLE(EffectCompressor, wxEvtHandler)
     EVT_SLIDER(wxID_ANY, EffectCompressor::OnSlider)
  END_EVENT_TABLE()
  
  EffectCompressor::EffectCompressor()
  {
     mThresholdDB = DEF_Threshold;
     mNoiseFloorDB = DEF_NoiseFloor;
     mAttackTime = DEF_AttackTime;          // seconds
     mDecayTime = DEF_ReleaseTime;          // seconds
     mRatio = DEF_Ratio;                    // positive number > 1.0
     mNormalize = DEF_Normalize;
     mUsePeak = DEF_UsePeak;
  
     mThreshold = 0.25;
     mNoiseFloor = 0.01;
     mCompression = 0.5;
     mFollowLen = 0;
  
     SetLinearEffectFlag(false);
  }
  
  EffectCompressor::~EffectCompressor()
  {
  }
  
  // ComponentInterface implementation
  
  ComponentInterfaceSymbol EffectCompressor::GetSymbol()
  {
     return COMPRESSOR_PLUGIN_SYMBOL;
  }
  
  wxString EffectCompressor::GetDescription()
  {
     return _("Compresses the dynamic range of audio");
  }
  
  wxString EffectCompressor::ManualPage()
  {
     return wxT("Compressor");
  }
  
  // EffectDefinitionInterface implementation
  
  EffectType EffectCompressor::GetType()
  {
     return EffectTypeProcess;
  }
  
  // EffectClientInterface implementation
  bool EffectCompressor::DefineParams( ShuttleParams & S ){
     S.SHUTTLE_PARAM( mThresholdDB, Threshold );
     S.SHUTTLE_PARAM( mNoiseFloorDB, NoiseFloor );
     S.SHUTTLE_PARAM( mRatio, Ratio);
     S.SHUTTLE_PARAM( mAttackTime, AttackTime);
     S.SHUTTLE_PARAM( mDecayTime, ReleaseTime);
     S.SHUTTLE_PARAM( mNormalize, Normalize);
     S.SHUTTLE_PARAM( mUsePeak, UsePeak);
     return true;
  }
  
  bool EffectCompressor::GetAutomationParameters(CommandParameters & parms)
  {
     parms.Write(KEY_Threshold, mThresholdDB);
     parms.Write(KEY_NoiseFloor, mNoiseFloorDB);
     parms.Write(KEY_Ratio, mRatio);
     parms.Write(KEY_AttackTime, mAttackTime);
     parms.Write(KEY_ReleaseTime, mDecayTime);
     parms.Write(KEY_Normalize, mNormalize);
     parms.Write(KEY_UsePeak, mUsePeak);
  
     return true;
  }
  
  bool EffectCompressor::SetAutomationParameters(CommandParameters & parms)
  {
     ReadAndVerifyDouble(Threshold);
     ReadAndVerifyDouble(NoiseFloor);
     ReadAndVerifyDouble(Ratio);
     ReadAndVerifyDouble(AttackTime);
     ReadAndVerifyDouble(ReleaseTime);
     ReadAndVerifyBool(Normalize);
     ReadAndVerifyBool(UsePeak);
  
     mThresholdDB = Threshold;
     mNoiseFloorDB = NoiseFloor;
     mRatio = Ratio;
     mAttackTime = AttackTime;
     mDecayTime = ReleaseTime;
     mNormalize = Normalize;
     mUsePeak = UsePeak;
  
     return true;
  }
  
  // Effect Implemenration
  
  bool EffectCompressor::Startup()
  {
     wxString base = wxT("/Effects/Compressor/");
  
     // Migrate settings from 2.1.0 or before
  
     // Already migrated, so bail
     if (gPrefs->Exists(base + wxT("Migrated")))
     {
        return true;
     }
  
     // Load the old "current" settings
     if (gPrefs->Exists(base))
     {
        gPrefs->Read(base + wxT("ThresholdDB"), &mThresholdDB, -12.0f );
        gPrefs->Read(base + wxT("NoiseFloorDB"), &mNoiseFloorDB, -40.0f );
        gPrefs->Read(base + wxT("Ratio"), &mRatio, 2.0f );
        gPrefs->Read(base + wxT("AttackTime"), &mAttackTime, 0.2f );
        gPrefs->Read(base + wxT("DecayTime"), &mDecayTime, 1.0f );
        gPrefs->Read(base + wxT("Normalize"), &mNormalize, true );
        gPrefs->Read(base + wxT("UsePeak"), &mUsePeak, false );
  
        SaveUserPreset(GetCurrentSettingsGroup());
  
        // Do not migrate again
        gPrefs->Write(base + wxT("Migrated"), true);
        gPrefs->Flush();
     }
  
     return true;
  }
  
  void EffectCompressor::PopulateOrExchange(ShuttleGui & S)
  {
     S.SetBorder(5);
  
     S.StartHorizontalLay(wxEXPAND, true);
     {
        S.SetBorder(10);
        mPanel = safenew EffectCompressorPanel(S.GetParent(), wxID_ANY,
                                           mThresholdDB,
                                           mNoiseFloorDB,
                                           mRatio);
        mPanel->SetMinSize(wxSize(400, 200));
        S.Prop(true).AddWindow(mPanel, wxEXPAND | wxALL);
        S.SetBorder(5);
     }
     S.EndHorizontalLay();
  
     S.StartStatic( {} );
     {
        S.StartMultiColumn(3, wxEXPAND);
        {
           S.SetStretchyCol(1);
           mThresholdLabel = S.AddVariableText(_("Threshold:"), true,
                                               wxALIGN_RIGHT | wxALIGN_CENTER_VERTICAL);
           S.SetStyle(wxSL_HORIZONTAL);
           mThresholdSlider = S.Id(ID_Threshold).AddSlider( {},
                                                           DEF_Threshold * SCL_Threshold,
                                                           MAX_Threshold * SCL_Threshold,
                                                           MIN_Threshold * SCL_Threshold);
           mThresholdSlider->SetName(_("Threshold"));
           mThresholdText = S.AddVariableText(wxT("XXX dB"), true,
                                              wxALIGN_LEFT | wxALIGN_CENTER_VERTICAL);
  
           mNoiseFloorLabel = S.AddVariableText(_("Noise Floor:"), true,
                                               wxALIGN_RIGHT | wxALIGN_CENTER_VERTICAL);
           S.SetStyle(wxSL_HORIZONTAL);
           mNoiseFloorSlider = S.Id(ID_NoiseFloor).AddSlider( {},
                                                             DEF_NoiseFloor / SCL_NoiseFloor,
                                                             MAX_NoiseFloor / SCL_NoiseFloor,
                                                             MIN_NoiseFloor / SCL_NoiseFloor);
           mNoiseFloorSlider->SetName(_("Noise Floor"));
           mNoiseFloorText = S.AddVariableText(wxT("XXX dB"), true,
                                              wxALIGN_LEFT | wxALIGN_CENTER_VERTICAL);
  
           mRatioLabel = S.AddVariableText(_("Ratio:"), true,
                                           wxALIGN_RIGHT | wxALIGN_CENTER_VERTICAL);
           S.SetStyle(wxSL_HORIZONTAL);
           mRatioSlider = S.Id(ID_Ratio).AddSlider( {},
                                                   DEF_Ratio * SCL_Ratio,
                                                   MAX_Ratio * SCL_Ratio,
                                                   MIN_Ratio * SCL_Ratio);
           mRatioSlider->SetName(_("Ratio"));
           mRatioSlider->SetPageSize(5);
           mRatioText = S.AddVariableText(wxT("XXXX:1"), true,
                                               wxALIGN_LEFT | wxALIGN_CENTER_VERTICAL);
  
           /* i18n-hint: Particularly in percussion, sounds can be regarded as having
            * an 'attack' phase where the sound builds up and a 'decay' where the
            * sound dies away.  So this means 'onset duration'.  */
           mAttackLabel = S.AddVariableText(_("Attack Time:"), true,
                                           wxALIGN_RIGHT | wxALIGN_CENTER_VERTICAL);
           S.SetStyle(wxSL_HORIZONTAL);
           mAttackSlider = S.Id(ID_Attack).AddSlider( {},
                                                     DEF_AttackTime * SCL_AttackTime,
                                                     MAX_AttackTime * SCL_AttackTime,
                                                     MIN_AttackTime * SCL_AttackTime);
           mAttackSlider->SetName(_("Attack Time"));
           mAttackText = S.AddVariableText(wxT("XXXX secs"), true,
                                           wxALIGN_LEFT | wxALIGN_CENTER_VERTICAL);
  
           mDecayLabel = S.AddVariableText(_("Release Time:"), true,
                                           wxALIGN_RIGHT | wxALIGN_CENTER_VERTICAL);
           S.SetStyle(wxSL_HORIZONTAL);
           mDecaySlider = S.Id(ID_Decay).AddSlider( {},
                                                   DEF_ReleaseTime * SCL_ReleaseTime,
                                                   MAX_ReleaseTime * SCL_ReleaseTime,
                                                   MIN_ReleaseTime * SCL_ReleaseTime);
           mDecaySlider->SetName(_("Release Time"));
           mDecayText = S.AddVariableText(wxT("XXXX secs"), true,
                                          wxALIGN_LEFT | wxALIGN_CENTER_VERTICAL);
        }
        S.EndMultiColumn();
     }
     S.EndStatic();
  
     S.StartHorizontalLay(wxCENTER, false);
     {
        /* i18n-hint: Make-up, i.e. correct for any reduction, rather than fabricate it.*/
        mGainCheckBox = S.AddCheckBox(_("Make-up gain for 0 dB after compressing"),
                                      DEF_Normalize ? wxT("true") : wxT("false"));
        mPeakCheckBox = S.AddCheckBox(_("Compress based on Peaks"),
                                      DEF_UsePeak ? wxT("true") : wxT("false"));
     }
     S.EndHorizontalLay();
  }
  
  bool EffectCompressor::TransferDataToWindow()
  {
     mThresholdSlider->SetValue(lrint(mThresholdDB));
     mNoiseFloorSlider->SetValue(lrint(mNoiseFloorDB / SCL_NoiseFloor));
     mRatioSlider->SetValue(lrint(mRatio * SCL_Ratio));
     mAttackSlider->SetValue(lrint(mAttackTime * SCL_AttackTime));
     mDecaySlider->SetValue(lrint(mDecayTime * SCL_ReleaseTime));
     mGainCheckBox->SetValue(mNormalize);
     mPeakCheckBox->SetValue(mUsePeak);
  
     UpdateUI();
  
     return true;
  }
  
  bool EffectCompressor::TransferDataFromWindow()
  {
     if (!mUIParent->Validate())
     {
        return false;
     }
  
     mThresholdDB = (double) mThresholdSlider->GetValue();
     mNoiseFloorDB = (double) mNoiseFloorSlider->GetValue() * SCL_NoiseFloor;
     mRatio = (double) mRatioSlider->GetValue() / SCL_Ratio;
     mAttackTime = (double) mAttackSlider->GetValue() / 100.0; //SCL_AttackTime;
     mDecayTime = (double) mDecaySlider->GetValue() / SCL_ReleaseTime;
     mNormalize = mGainCheckBox->GetValue();
     mUsePeak = mPeakCheckBox->GetValue();
  
     return true;
  }
  
  // EffectTwoPassSimpleMono implementation
  
  bool EffectCompressor::NewTrackPass1()
  {
     mThreshold = DB_TO_LINEAR(mThresholdDB);
     mNoiseFloor = DB_TO_LINEAR(mNoiseFloorDB);
     mNoiseCounter = 100;
  
     mAttackInverseFactor = exp(log(mThreshold) / (mCurRate * mAttackTime + 0.5));
     mAttackFactor = 1.0 / mAttackInverseFactor;
     mDecayFactor = exp(log(mThreshold) / (mCurRate * mDecayTime + 0.5));
  
     if(mRatio > 1)
        mCompression = 1.0-1.0/mRatio;
     else
        mCompression = 0.0;
  
     mLastLevel = mThreshold;
  
     mCircleSize = 100;
     mCircle.reinit( mCircleSize, true );
     mCirclePos = 0;
     mRMSSum = 0.0;
  
     return true;
  }
  
  bool EffectCompressor::InitPass1()
  {
     mMax=0.0;
     if (!mNormalize)
        DisableSecondPass();
  
     // Find the maximum block length required for any track
     size_t maxlen = inputTracks()->Selected< const WaveTrack >().max(
        &WaveTrack::GetMaxBlockSize
     );
     mFollow1.reset();
     mFollow2.reset();
     // Allocate buffers for the envelope
     if(maxlen > 0) {
        mFollow1.reinit(maxlen);
        mFollow2.reinit(maxlen);
     }
     mFollowLen = maxlen;
  
     return true;
  }
  
  bool EffectCompressor::InitPass2()
  {
     // Actually, this should not even be called, because we call
     // DisableSecondPass() before, if mNormalize is false.
     return mNormalize;
  }
  
  // Process the input with 2 buffers available at a time
  // buffer1 will be written upon return
  // buffer2 will be passed as buffer1 on the next call
  bool EffectCompressor::TwoBufferProcessPass1
     (float *buffer1, size_t len1, float *buffer2, size_t len2)
  {
     // If buffers are bigger than allocated, then abort
     // (this should never happen, but if it does, we don't want to crash)
     if((len1 > mFollowLen) || (len2 > mFollowLen))
        return false;
  
     // This makes sure that the initial value is well-chosen
     // buffer1 == NULL on the first and only the first call
     if (buffer1 == NULL) {
        // Initialize the mLastLevel to the peak level in the first buffer
        // This avoids problems with large spike events near the beginning of the track
        mLastLevel = mThreshold;
        for(size_t i=0; i<len2; i++) {
           if(mLastLevel < fabs(buffer2[i]))
              mLastLevel = fabs(buffer2[i]);
        }
     }
  
     // buffer2 is NULL on the last and only the last call
     if(buffer2 != NULL) {
        Follow(buffer2, mFollow2.get(), len2, mFollow1.get(), len1);
     }
  
     if(buffer1 != NULL) {
        for (size_t i = 0; i < len1; i++) {
           buffer1[i] = DoCompression(buffer1[i], mFollow1[i]);
        }
     }
  
  
  #if 0
     // Copy the envelope over the track data (for debug purposes)
     memcpy(buffer1, mFollow1, len1*sizeof(float));
  #endif
  
     // Rotate the buffer pointers
     mFollow1.swap(mFollow2);
  
     return true;
  }
  
  bool EffectCompressor::ProcessPass2(float *buffer, size_t len)
  {
     if (mMax != 0)
     {
        for (size_t i = 0; i < len; i++)
           buffer[i] /= mMax;
     }
  
     return true;
  }
  
  void EffectCompressor::FreshenCircle()
  {
     // Recompute the RMS sum periodically to prevent accumulation of rounding errors
     // during long waveforms
     mRMSSum = 0;
     for(size_t i=0; i<mCircleSize; i++)
        mRMSSum += mCircle[i];
  }
  
  float EffectCompressor::AvgCircle(float value)
  {
     float level;
  
     // Calculate current level from root-mean-squared of
     // circular buffer ("RMS")
     mRMSSum -= mCircle[mCirclePos];
     mCircle[mCirclePos] = value*value;
     mRMSSum += mCircle[mCirclePos];
     level = sqrt(mRMSSum/mCircleSize);
     mCirclePos = (mCirclePos+1)%mCircleSize;
  
     return level;
  }
  
  void EffectCompressor::Follow(float *buffer, float *env, size_t len, float *previous, size_t previous_len)
  {
     /*
  
     "Follow"ing algorithm by Roger B. Dannenberg, taken from
     Nyquist.  His description follows.  -DMM
  
     Description: this is a sophisticated envelope follower.
      The input is an envelope, e.g. something produced with
      the AVG function. The purpose of this function is to
      generate a smooth envelope that is generally not less
      than the input signal. In other words, we want to "ride"
      the peaks of the signal with a smooth function. The
      algorithm is as follows: keep a current output value
      (called the "value"). The value is allowed to increase
      by at most rise_factor and decrease by at most fall_factor.
      Therefore, the next value should be between
      value * rise_factor and value * fall_factor. If the input
      is in this range, then the next value is simply the input.
      If the input is less than value * fall_factor, then the
      next value is just value * fall_factor, which will be greater
      than the input signal. If the input is greater than value *
      rise_factor, then we compute a rising envelope that meets
      the input value by working bacwards in time, changing the
      previous values to input / rise_factor, input / rise_factor^2,
      input / rise_factor^3, etc. until this NEW envelope intersects
      the previously computed values. There is only a limited buffer
      in which we can work backwards, so if the NEW envelope does not
      intersect the old one, then make yet another pass, this time
      from the oldest buffered value forward, increasing on each
      sample by rise_factor to produce a maximal envelope. This will
      still be less than the input.
  
      The value has a lower limit of floor to make sure value has a
      reasonable positive value from which to begin an attack.
     */
     double level,last;
  
     if(!mUsePeak) {
        // Update RMS sum directly from the circle buffer
        // to avoid accumulation of rounding errors
        FreshenCircle();
     }
     // First apply a peak detect with the requested decay rate
     last = mLastLevel;
     for(size_t i=0; i<len; i++) {
        if(mUsePeak)
           level = fabs(buffer[i]);
        else // use RMS
           level = AvgCircle(buffer[i]);
        // Don't increase gain when signal is continuously below the noise floor
        if(level < mNoiseFloor) {
           mNoiseCounter++;
        } else {
           mNoiseCounter = 0;
        }
        if(mNoiseCounter < 100) {
           last *= mDecayFactor;
           if(last < mThreshold)
              last = mThreshold;
           if(level > last)
              last = level;
        }
        env[i] = last;
     }
     mLastLevel = last;
  
     // Next do the same process in reverse direction to get the requested attack rate
     last = mLastLevel;
     for(size_t i = len; i--;) {
        last *= mAttackInverseFactor;
        if(last < mThreshold)
           last = mThreshold;
        if(env[i] < last)
           env[i] = last;
        else
           last = env[i];
     }
  
     if((previous != NULL) && (previous_len > 0)) {
        // If the previous envelope was passed, propagate the rise back until we intersect
        for(size_t i = previous_len; i--;) {
           last *= mAttackInverseFactor;
           if(last < mThreshold)
              last = mThreshold;
           if(previous[i] < last)
              previous[i] = last;
           else // Intersected the previous envelope buffer, so we are finished
              return;
        }
        // If we can't back up far enough, project the starting level forward
        // until we intersect the desired envelope
        last = previous[0];
        for(size_t i=1; i<previous_len; i++) {
           last *= mAttackFactor;
           if(previous[i] > last)
              previous[i] = last;
           else // Intersected the desired envelope, so we are finished
              return;
        }
        // If we still didn't intersect, then continue ramp up into current buffer
        for(size_t i=0; i<len; i++) {
           last *= mAttackFactor;
           if(buffer[i] > last)
              buffer[i] = last;
           else // Finally got an intersect
              return;
        }
        // If we still didn't intersect, then reset mLastLevel
        mLastLevel = last;
     }
  }
  
  float EffectCompressor::DoCompression(float value, double env)
  {
     float out;
     if(mUsePeak) {
        // Peak values map 1.0 to 1.0 - 'upward' compression
        out = value * pow(1.0/env, mCompression);
     } else {
        // With RMS-based compression don't change values below mThreshold - 'downward' compression
        out = value * pow(mThreshold/env, mCompression);
     }
  
     // Retain the maximum value for use in the normalization pass
     if(mMax < fabs(out))
        mMax = fabs(out);
  
     return out;
  }
  
  void EffectCompressor::OnSlider(wxCommandEvent & WXUNUSED(evt))
  {
     TransferDataFromWindow();
     UpdateUI();
  }
  
  void EffectCompressor::UpdateUI()
  {
     mThresholdLabel->SetName(wxString::Format(_("Threshold %d dB"), (int) mThresholdDB));
     /* i18n-hint: usually leave this as is as dB doesn't get translated*/
     mThresholdText->SetLabel(wxString::Format(_("%3d dB"), (int) mThresholdDB));
     mThresholdText->SetName(mThresholdText->GetLabel()); // fix for bug 577 (NVDA/Narrator screen readers do not read static text in dialogs)
  
     mNoiseFloorLabel->SetName(wxString::Format(_("Noise Floor %d dB"), (int) mNoiseFloorDB));
     mNoiseFloorText->SetLabel(wxString::Format(_("%3d dB"), (int) mNoiseFloorDB));
     mNoiseFloorText->SetName(mNoiseFloorText->GetLabel()); // fix for bug 577 (NVDA/Narrator screen readers do not read static text in dialogs)
  
     if (mRatioSlider->GetValue() % 10 == 0) {
        mRatioLabel->SetName(wxString::Format(_("Ratio %.0f to 1"), mRatio));
        /* i18n-hint: Unless your language has a different convention for ratios,
         * like 8:1, leave as is.*/
        mRatioText->SetLabel(wxString::Format(_("%.0f:1"), mRatio));
     }
     else {
        mRatioLabel->SetName(wxString::Format(_("Ratio %.1f to 1"), mRatio));
        /* i18n-hint: Unless your language has a different convention for ratios,
         * like 8:1, leave as is.*/
        mRatioText->SetLabel(wxString::Format(_("%.1f:1"), mRatio));
     }
     mRatioText->SetName(mRatioText->GetLabel()); // fix for bug 577 (NVDA/Narrator screen readers do not read static text in dialogs)
  
     mAttackLabel->SetName(wxString::Format(_("Attack Time %.2f secs"), mAttackTime));
     mAttackText->SetLabel(wxString::Format(_("%.2f secs"), mAttackTime));
     mAttackText->SetName(mAttackText->GetLabel()); // fix for bug 577 (NVDA/Narrator screen readers do not read static text in dialogs)
  
     mDecayLabel->SetName(wxString::Format(_("Release Time %.1f secs"), mDecayTime));
     mDecayText->SetLabel(wxString::Format(_("%.1f secs"), mDecayTime));
     mDecayText->SetName(mDecayText->GetLabel()); // fix for bug 577 (NVDA/Narrator screen readers do not read static text in dialogs)
  
     mPanel->Refresh(false);
  
     return;
  }
  
  //----------------------------------------------------------------------------
  // EffectCompressorPanel
  //----------------------------------------------------------------------------
  
  BEGIN_EVENT_TABLE(EffectCompressorPanel, wxPanelWrapper)
     EVT_PAINT(EffectCompressorPanel::OnPaint)
     EVT_SIZE(EffectCompressorPanel::OnSize)
  END_EVENT_TABLE()
  
  EffectCompressorPanel::EffectCompressorPanel(wxWindow *parent, wxWindowID winid,
                                               double & threshold,
                                               double & noiseFloor,
                                               double & ratio)
  :  wxPanelWrapper(parent, winid),
     threshold(threshold),
     noiseFloor(noiseFloor),
     ratio(ratio)
  {
  }
  
  void EffectCompressorPanel::OnPaint(wxPaintEvent & WXUNUSED(evt))
  {
     wxPaintDC dc(this);
  
     int width, height;
     GetSize(&width, &height);
  
     double rangeDB = 60;
  
     // Ruler
     int w = 0;
     int h = 0;
  
     Ruler vRuler;
     vRuler.SetBounds(0, 0, width, height);
     vRuler.SetOrientation(wxVERTICAL);
     vRuler.SetRange(0, -rangeDB);
     vRuler.SetFormat(Ruler::LinearDBFormat);
     vRuler.SetUnits(_("dB"));
     vRuler.GetMaxSize(&w, NULL);
  
     Ruler hRuler;
     hRuler.SetBounds(0, 0, width, height);
     hRuler.SetOrientation(wxHORIZONTAL);
     hRuler.SetRange(-rangeDB, 0);
     hRuler.SetFormat(Ruler::LinearDBFormat);
     hRuler.SetUnits(_("dB"));
     hRuler.SetFlip(true);
     hRuler.GetMaxSize(NULL, &h);
  
     vRuler.SetBounds(0, 0, w, height - h);
     hRuler.SetBounds(w, height - h, width, height);
  
     vRuler.SetTickColour( theTheme.Colour( clrGraphLabels ));
     hRuler.SetTickColour( theTheme.Colour( clrGraphLabels ));
  
  #if defined(__WXMSW__)
     dc.Clear();
  #endif
  
     wxRect border;
     border.x = w;
     border.y = 0;
     border.width = width - w;
     border.height = height - h + 1;
  
     dc.SetBrush(*wxWHITE_BRUSH);
     dc.SetPen(*wxBLACK_PEN);
     dc.DrawRectangle(border);
  
     wxRect envRect = border;
     envRect.Deflate( 2, 2 );
  
     int kneeX = lrint((rangeDB+threshold)*envRect.width/rangeDB);
     int kneeY = lrint((rangeDB+threshold/ratio)*envRect.height/rangeDB);
  
     int finalY = envRect.height;
     int startY = lrint((threshold*(1.0/ratio-1.0))*envRect.height/rangeDB);
  
     // Yellow line for threshold
  /*   dc.SetPen(wxPen(wxColour(220, 220, 0), 1, wxSOLID));
     AColor::Line(dc,
                  envRect.x,
                  envRect.y + envRect.height - kneeY,
                  envRect.x + envRect.width - 1,
                  envRect.y + envRect.height - kneeY);*/
  
     // Was: Nice dark red line for the compression diagram
  //   dc.SetPen(wxPen(wxColour(180, 40, 40), 3, wxSOLID));
  
     // Nice blue line for compressor, same color as used in the waveform envelope.
     dc.SetPen( AColor::WideEnvelopePen) ;
  
     AColor::Line(dc,
                  envRect.x,
                  envRect.y + envRect.height - startY,
                  envRect.x + kneeX - 1,
                  envRect.y + envRect.height - kneeY);
  
     AColor::Line(dc,
                  envRect.x + kneeX,
                  envRect.y + envRect.height - kneeY,
                  envRect.x + envRect.width - 1,
                  envRect.y + envRect.height - finalY);
  
     // Paint border again
     dc.SetBrush(*wxTRANSPARENT_BRUSH);
     dc.SetPen(*wxBLACK_PEN);
     dc.DrawRectangle(border);
  
     vRuler.Draw(dc);
     hRuler.Draw(dc);
  }
  
  void EffectCompressorPanel::OnSize(wxSizeEvent & WXUNUSED(evt))
  {
     Refresh(false);
  }
  