/**********************************************************************

Audacity: A Digital Audio Editor

WaveformView.cpp

Paul Licameli split from WaveChannelView.cpp

**********************************************************************/


#include "WaveformView.h"

#include "WaveformAppearance.h"
#include "ClipParameters.h"
#include "WaveChannelView.h"
#include "WaveChannelViewConstants.h"
#include "WaveformVRulerControls.h"

#include "SampleHandle.h"
#include "../../../ui/EnvelopeHandle.h"
#include "../../../ui/TimeShiftHandle.h"
#include "AColor.h"
#include "Envelope.h"
#include "../../../../EnvelopeEditor.h"
#include "PendingTracks.h"
#include "../../../../ProjectSettings.h"
#include "SelectedRegion.h"
#include "SyncLock.h"
#include "../../../../TrackArt.h"
#include "../../../../TrackArtist.h"
#include "../../../../TrackPanelDrawingContext.h"
#include "../../../../TrackPanelMouseEvent.h"
#include "ViewInfo.h"
#include "WaveChannelUtilities.h"
#include "WaveClip.h"
#include "WaveTrack.h"
#include "WaveTrackUtilities.h"
#include "../../../../WaveTrackLocation.h"
#include "prefs/WaveformScale.h"
#include "WaveformSettings.h"

#include "FrameStatistics.h"

#include <wx/graphics.h>
#include <wx/dc.h>
#include <wx/gdicmn.h>

#include <wx/dcmemory.h>
#include "waveform/WaveBitmapCache.h"
#include "waveform/WaveDataCache.h"
#include "waveform/WavePaintParameters.h"

#include <atomic>

#include "prefs/GUIPrefs.h"


static WaveChannelSubView::Type sType{
   WaveChannelViewConstants::Waveform,
   { wxT("Waveform"), XXO("Wa&veform") }
};

static WaveChannelSubViewType::RegisteredType reg{ sType };

WaveformView::~WaveformView() = default;

std::vector<UIHandlePtr> WaveformView::DetailedHitTest(
   const TrackPanelMouseState &st,
   const AudacityProject *pProject, int currentTool, bool bMultiTool )
{
   auto &view = *this;
   const auto pChannel = view.FindChannel<WaveChannel>();

   auto pair = WaveChannelSubView::DoDetailedHitTest(
      st, pProject, currentTool, bMultiTool, pChannel);
   auto &results = pair.second;

   if (!pair.first) {
      UIHandlePtr result;

      if (bMultiTool) {
         // Conditional hit tests
         // If Tools toolbar were eliminated, we would keep these
         // The priority of these, in case more than one might apply at one
         // point, seems arbitrary
         if (nullptr != (result = EnvelopeHandle::WaveChannelHitTest(
            view.mEnvelopeHandle, st.state, st.rect,
            pProject, pChannel)))
            results.push_back(result);
         if (nullptr != (result = TimeShiftHandle::HitTest(
            view.mTimeShiftHandle, st.state, st.rect,
               pChannel->GetTrack().SharedPointer())))
            // This is the hit test on the "grips" drawn left and
            // right in Multi only
            results.push_back(result);
         if (nullptr != (result = SampleHandle::HitTest(
            view.mSampleHandle, st.state, st.rect,
            pProject, pChannel)))
            results.push_back(result);
      }
      else {
         switch ( currentTool ) {
               // Unconditional hits appropriate to the tool
               // If tools toolbar were eliminated, we would eliminate these
            case ToolCodes::envelopeTool: {
               auto &viewInfo = ViewInfo::Get(*pProject);
               auto time =
                  viewInfo.PositionToTime(st.state.m_x, st.rect.GetX());
               const auto envelope =
                  WaveChannelUtilities::GetEnvelopeAtTime(*pChannel, time);
               result = EnvelopeHandle::HitAnywhere(
                  view.mEnvelopeHandle, envelope,
                  std::dynamic_pointer_cast<const Channel>(pChannel),
                  false);
               break;
            }
            case ToolCodes::drawTool:
               result = SampleHandle::HitAnywhere(
                  view.mSampleHandle, st.state, pChannel);
               break;
            default:
               result = {};
               break;
         }
         if (result)
            results.push_back(result);
      }
   }

   return std::move( results );
}

void WaveformView::DoSetMinimized( bool minimized )
{
   auto wt = FindWaveChannel();

   bool bHalfWave;
   gPrefs->Read(wxT("/GUI/CollapseToHalfWave"), &bHalfWave, false);
   if (wt &&  bHalfWave) {
      auto &cache = WaveformScale::Get(*wt);
      if (minimized)
         // Zoom to show fractionally more than the top half of the wave.
         cache.SetDisplayBounds( -0.01f, 1.0f );
      else
         // Zoom out full
         cache.SetDisplayBounds( -1.0f, 1.0f );
   }

   ChannelView::DoSetMinimized(minimized);
}

auto WaveformView::SubViewType() const -> const Type &
{
   return sType;
}

std::shared_ptr<ChannelVRulerControls> WaveformView::DoGetVRulerControls()
{
   return std::make_shared<WaveformVRulerControls>(shared_from_this());
}

namespace
{


graphics::Color ColorFromWXPen(const wxPen& pen)
{
   const auto c = pen.GetColour();
   return graphics::Color(c.Red(), c.Green(), c.Blue());
}

graphics::Color ColorFromWXBrush(const wxBrush& brush)
{
   const auto c = brush.GetColour();
   return graphics::Color(c.Red(), c.Green(), c.Blue());
}


struct WaveBitmapCacheElementWX final : public WaveBitmapCacheElement
{
   uint8_t* Allocate(size_t width, size_t height) override
   {
      mImage = wxImage(width, height, false);
      mBitmap = wxBitmap();
      return mImage.GetData();
   }

   wxBitmap& GetBitmap()
   {
      if(!mBitmap.IsOk() && mImage.IsOk())
         mBitmap = wxBitmap(mImage);
      return mBitmap;
   }

   size_t Width() const override
   {
      return mImage.GetWidth();
   }

   size_t Height() const override
   {
      return mImage.GetHeight();
   }

private:
   wxBitmap mBitmap;
   wxImage  mImage;
};


class WaveformPainter final
   : public WaveClipListener
{
public:

   static WaveformPainter& Get(const WaveClip& clip);

   WaveformPainter()
   {
   }

   WaveformPainter& EnsureClip (const WaveClip& clip)
   {
      const auto changed = mChanged.exchange(false);
      if (&clip != mWaveClip || changed)
         mChannelCaches.clear();

      const auto nChannels = clip.NChannels();

      if (mChannelCaches.size() == nChannels)
         return *this;

      mWaveClip = &clip;

      mChannelCaches.reserve(nChannels);

      for (auto channelIndex = 0; channelIndex < nChannels; ++channelIndex)
      {
         auto dataCache = std::make_shared<WaveDataCache>(clip, channelIndex);

         auto bitmapCache = std::make_unique<WaveBitmapCache>(
            clip, dataCache,
            [] { return std::make_unique<WaveBitmapCacheElementWX>(); });

         mChannelCaches.push_back(
            { std::move(dataCache), std::move(bitmapCache) });
      }

      return *this;
   }

   void SetSelection(const ZoomInfo& zoomInfo, float t0, float t1, bool selected)
   {
      for (auto& channelCache : mChannelCaches)
         channelCache.BitmapCache->SetSelection(zoomInfo, t0, t1, selected);
   }

   void Draw(
      int channelIndex, wxDC& dc, const WavePaintParameters& params,
      const ZoomInfo& zoomInfo, const wxRect& targetRect, int leftOffset,
      double from, double to)
   {
      auto& channelCache = mChannelCaches[channelIndex];

      channelCache.BitmapCache->SetPaintParameters(params);

      auto range = channelCache.BitmapCache->PerformLookup(zoomInfo, from, to);

      auto left   = targetRect.x + leftOffset;
      auto height = targetRect.height;

      const auto top = targetRect.y;

      wxMemoryDC memdc;
      for (auto it = range.begin(); it != range.end(); ++it)
      {
         const auto elementLeftOffset  = it.GetLeftOffset();
         const auto elementRightOffset = it.GetRightOffset();

         const auto width = WaveBitmapCache::CacheElementWidth -
                            elementLeftOffset - elementRightOffset;

         auto& bitmap = static_cast<WaveBitmapCacheElementWX&>(*it).GetBitmap();
         memdc.SelectObject(bitmap);
         dc.Blit(
            wxPoint(left, targetRect.y), wxSize(width, it->Height()), &memdc,
            wxPoint(elementLeftOffset, 0));

         left += width;
      }
   }

   void SwapChannels() override
   {
      //Wave data cache captures channel index which becomes
      //part of it's state, request cache rebuild...
      mChanged.store(true);
   }

   void MarkChanged() noexcept override
   {
      //Triggered when any part of the waveform has changed
      //TODO: invalidate parts of the cache that intersect changes
      mChanged.store(true);
   }

   void Invalidate() override
   {
      for (auto& channelCache : mChannelCaches)
      {
         channelCache.DataCache->Invalidate();
         channelCache.BitmapCache->Invalidate();
      }
   }

   std::unique_ptr<WaveClipListener> Clone() const override
   {
      return std::make_unique<WaveformPainter>();
   }

private:
   const WaveClip* mWaveClip {};

   struct ChannelCaches final
   {
      std::shared_ptr<WaveDataCache> DataCache;
      std::unique_ptr<WaveBitmapCache> BitmapCache;
   };

   std::vector<ChannelCaches> mChannelCaches;
   std::atomic<bool> mChanged = false;
};

void DrawWaveform(
   TrackPanelDrawingContext& context, const WaveTrack& track, const WaveChannelInterval& channelInterval,
   int leftOffset, double t0, double t1,
   const wxRect & rect, float zoomMin, float zoomMax, bool dB, float dBRange,
   bool muted)
{
   auto& clip = channelInterval.GetClip();
   const auto channelIndex = channelInterval.GetChannelIndex();

   const auto artist = TrackArtist::Get(context);
   const ZoomInfo zoomInfo(0.0, artist->pZoomInfo->GetZoom());

   auto& clipPainter = WaveformPainter::Get(clip);

   const auto trimLeft = clip.GetTrimLeft();
   const auto sequenceStartTime = clip.GetSequenceStartTime();

   WavePaintParameters paintParameters;

   paintParameters
      .SetDisplayParameters(
         rect.GetHeight(), zoomMin, zoomMax, ShowClippingPref().Read())
      .SetDBParameters(dBRange, dB)
      .SetBlankColor(ColorFromWXBrush(artist->blankBrush))
      .SetZeroLineColor(graphics::Colors::Black)
      .SetShowRMS(ShowRMSPref().Read())
      .SetSampleColors(
         ColorFromWXPen(muted ? artist->muteSamplePen : artist->samplePen),
         ColorFromWXPen(muted ? artist->muteSamplePen : artist->samplePen))
      .SetRMSColors(
         ColorFromWXPen(muted ? artist->muteRmsPen : artist->rmsPen),
         ColorFromWXPen(muted ? artist->muteRmsPen : artist->rmsPen))
      .SetBackgroundColors(
         ColorFromWXBrush(artist->unselectedBrush),
         ColorFromWXBrush(artist->selectedBrush))
      .SetClippingColors(
         ColorFromWXPen(muted ? artist->muteClippedPen : artist->clippedPen),
         ColorFromWXPen(muted ? artist->muteClippedPen : artist->clippedPen))
      .SetEnvelope(clip.GetEnvelope());

   clipPainter.SetSelection(
      zoomInfo, artist->pSelectedRegion->t0() - sequenceStartTime,
      artist->pSelectedRegion->t1() - sequenceStartTime,
      SyncLock::IsSelectedOrSyncLockSelected(track));

   clipPainter.Draw(
      channelIndex, context.dc, paintParameters, zoomInfo, rect, leftOffset,
      t0 + trimLeft, t1 + trimLeft);
}



void DrawWaveformBackground(TrackPanelDrawingContext &context,
                                         int leftOffset, const wxRect &rect,
                                         const double env[],
                                         float zoomMin, float zoomMax,
                                         int zeroLevelYCoordinate,
                                         bool dB, float dBRange,
                                         double t0, double t1,
                                         bool bIsSyncLockSelected,
                                         bool highlightEnvelope)
{
   auto &dc = context.dc;
   const auto artist = TrackArtist::Get( context );
   const auto &zoomInfo = *artist->pZoomInfo;

   // Visually (one vertical slice of the waveform background, on its side;
   // the "*" is the actual waveform background we're drawing
   //
   //1.0                              0.0                             -1.0
   // |--------------------------------|--------------------------------|
   //      ***************                           ***************
   //      |             |                           |             |
   //    maxtop        maxbot                      mintop        minbot

   int h = rect.height;
   int halfHeight = wxMax(h / 2, 1);
   int maxtop, lmaxtop = 0;
   int mintop, lmintop = 0;
   int maxbot, lmaxbot = 0;
   int minbot, lminbot = 0;
   bool sel, lsel = false;
   int xx, lx = 0;
   int l, w;

   const auto &blankBrush = artist->blankBrush;
   const auto &selectedBrush = artist->selectedBrush;
   const auto &unselectedBrush = artist->unselectedBrush;
   const auto &envelopeBackgroundBrush = artist->envelopeBackgroundBrush;

   dc.SetPen(*wxTRANSPARENT_PEN);
   dc.SetBrush(envelopeBackgroundBrush);
   dc.DrawRectangle(rect);

   // Bug 2389 - always draw at least one pixel of selection.
   int selectedX = zoomInfo.TimeToPosition(t0, -leftOffset);

   double time = zoomInfo.PositionToTime(0, -leftOffset), nextTime;
   for (xx = 0; xx < rect.width; ++xx, time = nextTime) {
      nextTime = zoomInfo.PositionToTime(xx + 1, -leftOffset);
      // First we compute the truncated shape of the waveform background.
      // If drawEnvelope is true, then we compute the lower border of the
      // envelope.

      maxtop = GetWaveYPos(env[xx], zoomMin, zoomMax,
                               h, dB, true, dBRange, true);
      maxbot = GetWaveYPos(env[xx], zoomMin, zoomMax,
                               h, dB, false, dBRange, true);

      mintop = GetWaveYPos(-env[xx], zoomMin, zoomMax,
                               h, dB, false, dBRange, true);
      minbot = GetWaveYPos(-env[xx], zoomMin, zoomMax,
                               h, dB, true, dBRange, true);

      // Make sure it's odd so that a that max and min mirror each other
      mintop +=1;
      minbot +=1;

      const auto drawEnvelope = artist->drawEnvelope;
      if (!drawEnvelope || maxbot > mintop) {
         maxbot = halfHeight;
         mintop = halfHeight;
      }

      sel = (t0 <= time && nextTime < t1);
      sel = sel || (xx == selectedX);
      // We don't draw selection color for sync-lock selected tracks.
      sel = sel && !bIsSyncLockSelected;

      if (lmaxtop == maxtop &&
          lmintop == mintop &&
          lmaxbot == maxbot &&
          lminbot == minbot &&
          lsel == sel) {
         continue;
      }

      dc.SetBrush(lsel ? selectedBrush : unselectedBrush);

      l = rect.x + lx;
      w = xx - lx;
      if (lmaxbot < lmintop - 1) {
         dc.DrawRectangle(l, rect.y + lmaxtop, w, lmaxbot - lmaxtop);
         dc.DrawRectangle(l, rect.y + lmintop, w, lminbot - lmintop);
      }
      else {
         dc.DrawRectangle(l, rect.y + lmaxtop, w, lminbot - lmaxtop);
      }

      if (highlightEnvelope && lmaxbot < lmintop - 1) {
         dc.SetBrush( AColor::uglyBrush );
         dc.DrawRectangle(l, rect.y + lmaxbot, w, lmintop - lmaxbot);
      }

      lmaxtop = maxtop;
      lmintop = mintop;
      lmaxbot = maxbot;
      lminbot = minbot;
      lsel = sel;
      lx = xx;
   }

   dc.SetBrush(lsel ? selectedBrush : unselectedBrush);
   l = rect.x + lx;
   w = xx - lx;
   if (lmaxbot < lmintop - 1) {
      dc.DrawRectangle(l, rect.y + lmaxtop, w, lmaxbot - lmaxtop);
      dc.DrawRectangle(l, rect.y + lmintop, w, lminbot - lmintop);
   }
   else {
      dc.DrawRectangle(l, rect.y + lmaxtop, w, lminbot - lmaxtop);
   }
   if (highlightEnvelope && lmaxbot < lmintop - 1) {
      dc.SetBrush( AColor::uglyBrush );
      dc.DrawRectangle(l, rect.y + lmaxbot, w, lmintop - lmaxbot);
   }

   // If sync-lock selected, draw in linked graphics.
   if (bIsSyncLockSelected && t0 < t1) {
      const int begin = std::max(0, std::min(rect.width, (int)(zoomInfo.TimeToPosition(t0, -leftOffset))));
      const int end = std::max(0, std::min(rect.width, (int)(zoomInfo.TimeToPosition(t1, -leftOffset))));
      TrackArt::DrawSyncLockTiles( context,
         { rect.x + begin, rect.y, end - 1 - begin, rect.height } );
   }

   //OK, the display bounds are between min and max, which
   //is spread across rect.height.  Draw the line at the proper place.
   if (zeroLevelYCoordinate >= rect.GetTop() &&
       zeroLevelYCoordinate <= rect.GetBottom()) {
      dc.SetPen(*wxBLACK_PEN);
      AColor::Line(dc, rect.x, zeroLevelYCoordinate,
                   rect.x + rect.width - 1, zeroLevelYCoordinate);
   }
}

struct WavePortion {
   wxRect rect;
   double averageZoom;
   bool inFisheye;
   WavePortion(int x, int y, int w, int h, double zoom, bool i)
      : rect(x, y, w, h), averageZoom(zoom), inFisheye(i)
   {}
};

void FindWavePortions
   (std::vector<WavePortion> &portions, const wxRect &rect, const ZoomInfo &zoomInfo,
    const ClipParameters &params)
{
   // If there is no fisheye, then only one rectangle has nonzero width.
   // If there is a fisheye, make rectangles for before and after
   // (except when they are squeezed to zero width), and at least one for inside
   // the fisheye.

   const auto intervals = zoomInfo.FindIntervals(rect.width, rect.x);
   ZoomInfo::Intervals::const_iterator it = intervals.begin(), end = intervals.end(), prev;
   wxASSERT(it != end && it->position == rect.x);
   const int rightmost = rect.x + rect.width;
   for (int left = rect.x; left < rightmost;) {
      while (it != end && it->position <= left)
         prev = it++;
      if (it == end)
         break;
      const int right = std::max(left, (int)(it->position));
      const int width = right - left;
      if (width > 0)
         portions.push_back(
            WavePortion(left, rect.y, width, rect.height,
                        prev->averageZoom, prev->inFisheye)
         );
      left = right;
   }
}

void DrawIndividualSamples(TrackPanelDrawingContext &context,
   int leftOffset, const wxRect &rect,
   float zoomMin, float zoomMax,
   bool dB, float dBRange,
   const WaveChannelInterval &clip,
   bool showPoints, bool muted,
   bool highlight)
{
   const Envelope &envelope = clip.GetEnvelope();
   auto &dc = context.dc;
   const auto artist = TrackArtist::Get(context);
   const auto &zoomInfo = *artist->pZoomInfo;

   const double toffset = clip.GetPlayStartTime();
   const double rate = clip.GetRate() / clip.GetStretchRatio();
   const double t0 = std::max(0.0, zoomInfo.PositionToTime(0, -leftOffset) - toffset);
   const auto s0 = sampleCount(floor(t0 * rate));
   const auto snSamples = clip.GetVisibleSampleCount();
   if (s0 > snSamples)
      return;

   const double t1 = zoomInfo.PositionToTime(rect.width - 1, -leftOffset) - toffset;
   const auto s1 = sampleCount(ceil(t1 * rate));

   // Assume size_t will not overflow, else we wouldn't be here drawing the
   // few individual samples
   auto slen = std::min(snSamples - s0, s1 - s0 + 1).as_size_t();

   if (slen <= 0)
      return;

   Floats buffer{ size_t(slen) };
   clip.GetSamples((samplePtr)buffer.get(), floatSample, s0, slen,
                    // Suppress exceptions in this drawing operation:
                    false);

   ArrayOf<int> xpos{ size_t(slen) };
   ArrayOf<int> ypos{ size_t(slen) };
   ArrayOf<int> clipped;
   int clipcnt = 0;

   const auto bShowClipping = ShowClippingPref().Read();
   if (bShowClipping)
      clipped.reinit( size_t(slen) );

   const auto &muteSamplePen = artist->muteSamplePen;
   const auto &samplePen = artist->samplePen;
   auto &pen = highlight ? AColor::uglyPen : muted ? muteSamplePen : samplePen;
   dc.SetPen( pen );

   for (decltype(slen) s = 0; s < slen; s++) {
      const double time = toffset + (s + s0).as_double() / rate;
      const int xx = // An offset into the rectangle rect
         std::max(-10000, std::min(10000,
            (int)(zoomInfo.TimeToPosition(time, -leftOffset))));
      xpos[s] = xx;

      // Calculate sample as it would be rendered, so quantize time
      double value = envelope.GetValue(time, 1.0 / clip.GetRate());
      const double tt = buffer[s] * value;

      if (clipped && bShowClipping && ((tt <= -MAX_AUDIO) || (tt >= MAX_AUDIO)))
         clipped[clipcnt++] = xx;
      ypos[s] =
         std::max(-1,
            std::min(rect.height,
               GetWaveYPos(tt, zoomMin, zoomMax,
                                  rect.height, dB, true, dBRange, false)));
   }


   if (showPoints) {
      // Draw points where spacing is enough
      const auto bigPoints = artist->bigPoints;
      const int tickSize = bigPoints ? 4 : 3;// Bigger ellipses when draggable.
      wxRect pr;
      pr.width = tickSize;
      pr.height = tickSize;
      //different colour when draggable.
      const auto &dragsampleBrush = artist->dragsampleBrush;
      const auto &sampleBrush = artist->sampleBrush;
      auto &brush = highlight
         ? AColor::uglyBrush
         : bigPoints ? dragsampleBrush : sampleBrush;
      dc.SetBrush( brush );
      for (decltype(slen) s = 0; s < slen; s++) {
         if (ypos[s] >= 0 && ypos[s] < rect.height) {
            pr.x = rect.x + xpos[s] - tickSize/2;
            pr.y = rect.y + ypos[s] - tickSize/2;
            dc.DrawEllipse(pr);
         }
      }
   }

   const auto sampleDisplay = artist->mSampleDisplay;
   if (showPoints &&
       (sampleDisplay == (int) WaveChannelViewConstants::StemPlot)
   ){
      // Draw vertical lines
      int yZero = GetWaveYPos(0.0, zoomMin, zoomMax, rect.height, dB, true, dBRange, false);
      yZero = rect.y + std::max(-1, std::min(rect.height, yZero));
      for (decltype(slen) s = 0; s < slen; s++) {
         AColor::Line(dc,
                     rect.x + xpos[s], rect.y + ypos[s],
                     rect.x + xpos[s], yZero);
      }
   }
   else {
      // Connect samples with straight lines
      for (decltype(slen) s = 0; s < slen - 1; s++) {
         AColor::Line(dc,
                     rect.x + xpos[s], rect.y + ypos[s],
                     rect.x + xpos[s + 1], rect.y + ypos[s + 1]);
      }
   }

   // Draw clipping
   if (clipcnt) {
      const auto &muteClippedPen = artist->muteClippedPen;
      const auto &clippedPen = artist->clippedPen;
      dc.SetPen(muted ? muteClippedPen : clippedPen);
      while (--clipcnt >= 0) {
         auto s = clipped[clipcnt];
         AColor::Line(dc, rect.x + s, rect.y, rect.x + s, rect.y + rect.height);
      }
   }
}

void DrawEnvLine(
   TrackPanelDrawingContext &context,
   const wxRect &rect, int x0, int y0, int cy, bool top )
{
   auto &dc = context.dc;

   int xx = rect.x + x0;
   int yy = rect.y + cy;

   if (y0 < 0) {
      if (x0 % 4 != 3) {
         AColor::Line(dc, xx, yy, xx, yy + 3);
      }
   }
   else if (y0 > rect.height) {
      if (x0 % 4 != 3) {
         AColor::Line(dc, xx, yy - 3, xx, yy);
      }
   }
   else {
      if (top) {
         AColor::Line(dc, xx, yy, xx, yy + 3);
      }
      else {
         AColor::Line(dc, xx, yy - 3, xx, yy);
      }
   }
}

void DrawEnvelope(TrackPanelDrawingContext &context,
                               const wxRect &rect, const double env[],
                               float zoomMin, float zoomMax,
                               bool dB, float dBRange, bool highlight)
{
   auto &dc = context.dc;

   int h = rect.height;

   auto &pen = highlight ? AColor::uglyPen : AColor::envelopePen;
   dc.SetPen( pen );

   for (int x0 = 0; x0 < rect.width; ++x0) {
      int cenvTop = GetWaveYPos(env[x0], zoomMin, zoomMax,
                                h, dB, true, dBRange, true);

      int cenvBot = GetWaveYPos(-env[x0], zoomMin, zoomMax,
                                h, dB, true, dBRange, true);

      int envTop = GetWaveYPos(env[x0], zoomMin, zoomMax,
                               h, dB, true, dBRange, false);

      int envBot = GetWaveYPos(-env[x0], zoomMin, zoomMax,
                               h, dB, true, dBRange, false);

      // Make the collision at zero actually look solid
      if (cenvBot - cenvTop < 9) {
         int value = (int)((zoomMax / (zoomMax - zoomMin)) * h);
         cenvTop = value - 4;
         cenvBot = value + 4;
      }

      DrawEnvLine( context, rect, x0, envTop, cenvTop, true );
      DrawEnvLine( context, rect, x0, envBot, cenvBot, false );
   }
}

// Headers needed only for experimental drawing below
//#include "tracks/playabletrack/wavetrack/ui/SampleHandle.h"
//#include "tracks/ui/EnvelopeHandle.h"
void DrawClipWaveform(TrackPanelDrawingContext &context,
   const WaveChannel &channel, const WaveChannelInterval &clip,
   const wxRect &rect, bool dB, bool muted, bool selected)
{
   const Envelope &envelope = clip.GetEnvelope();
   auto &dc = context.dc;
   const auto artist = TrackArtist::Get(context);
   const auto &selectedRegion = *artist->pSelectedRegion;
   const auto &zoomInfo = *artist->pZoomInfo;

   auto sw = FrameStatistics::CreateStopwatch(FrameStatistics::SectionID::WaveformView);

   bool highlightEnvelope = false;
#ifdef EXPERIMENTAL_TRACK_PANEL_HIGHLIGHTING
   auto target = dynamic_cast<EnvelopeHandle*>(context.target.get());
   highlightEnvelope = target && target->GetEnvelope() == &envelope;
#endif

   //If clip is "too small" draw a placeholder instead of
   //attempting to fit the contents into a few pixels
   if (!WaveChannelView::ClipDetailsVisible(clip, zoomInfo, rect))
   {
      auto clipRect = ClipParameters::GetClipRect(clip, zoomInfo, rect);
      TrackArt::DrawClipFolded(dc, clipRect);
      return;
   }

   const ClipParameters params { clip, rect, zoomInfo };
   const wxRect &hiddenMid = params.hiddenMid;
   // The "hiddenMid" rect contains the part of the display actually
   // containing the waveform, as it appears without the fisheye.  If it's empty, we're done.
   if (hiddenMid.width <= 0) {
      return;
   }

   const double &t0 = params.t0;
   const double &t1 = params.t1;
   const double playStartTime = clip.GetPlayStartTime();
   const double &trackRectT0 = params.trackRectT0;
   const double &averagePixelsPerSecond = params.averagePixelsPerSecond;
   const double sampleRate = clip.GetRate();
   const double stretchRatio = clip.GetStretchRatio();
   double leftOffset = params.leftOffset;
   const wxRect &mid = params.mid;

   auto &settings = WaveformSettings::Get(channel);
   const float dBRange = settings.dBRange;

   dc.SetPen(*wxTRANSPARENT_PEN);
   int iColorIndex = WaveColorAttachment::Get(clip).GetColorIndex();
   artist->SetColours( iColorIndex );

   // The bounds (controlled by vertical zooming; -1.0...1.0
   // by default)
   float zoomMin, zoomMax;
   auto &cache = WaveformScale::Get(channel);
   cache.GetDisplayBounds(zoomMin, zoomMax);

   std::vector<double> vEnv(mid.width);
   double *const env = &vEnv[0];
   CommonChannelView::GetEnvelopeValues(envelope, playStartTime,

      // PRL: change back to make envelope evaluate only at sample times
      // and then interpolate the display
      0, // 1.0 / sampleRate,

      env, mid.width, leftOffset, zoomInfo);

   // Draw the background of the track, outlining the shape of
   // the envelope and using a colored pen for the selected
   // part of the waveform
   {
      double tt0, tt1;
      const auto &track = channel.GetTrack();
      if (SyncLock::IsSelectedOrSyncLockSelected(track)) {
         tt0 = track.SnapToSample(selectedRegion.t0());
         tt1 = track.SnapToSample(selectedRegion.t1());
      }
      else
         tt0 = tt1 = 0.0;
      DrawWaveformBackground(context, leftOffset, mid,
         env,
         zoomMin, zoomMax,
         cache.ZeroLevelYCoordinate(mid),
         dB, dBRange,
         tt0, tt1,
         !track.GetSelected(), highlightEnvelope);
   }

   // Require at least 1/2 pixel per sample for drawing individual samples.
   const double threshold1 = 0.5 * sampleRate / stretchRatio;
   // Require at least 3 pixels per sample for drawing the draggable points.
   const double threshold2 = 3 * sampleRate / stretchRatio;

   bool highlight = false;
#ifdef EXPERIMENTAL_TRACK_PANEL_HIGHLIGHTING
      auto target = dynamic_cast<SampleHandle*>(context.target.get());
      highlight = target && target->FindChannel().get() == &track;
#endif

   const bool showIndividualSamples = zoomInfo.GetZoom() > threshold1;
   const bool showPoints = zoomInfo.GetZoom() > threshold2;

   if(!showIndividualSamples)
   {
      DrawWaveform(
         context, channel.GetTrack(), clip, leftOffset, t0, t1,
         rect, zoomMin, zoomMax, dB, dBRange, muted);
   }
   else
   {
      std::vector<WavePortion> portions;
      FindWavePortions(portions, rect, zoomInfo, params);
      auto offset = leftOffset;
      for(const auto& portion : portions)
      {
         assert(!portion.inFisheye && portion.averageZoom > threshold1);
         if(portion.inFisheye || portion.averageZoom <= threshold1)
            continue;

         wxRect rectPortion = portion.rect;
         rectPortion.Intersect(mid);
         DrawIndividualSamples(
            context, offset, rectPortion, zoomMin, zoomMax, dB, dBRange, clip,
            showPoints, muted, highlight);
         offset += rectPortion.width;
      }

   }

   const auto drawEnvelope = artist->drawEnvelope;
   if (drawEnvelope) {
      DrawEnvelope(
         context, mid, env, zoomMin, zoomMax, dB, dBRange, highlightEnvelope);
      EnvelopeEditor::DrawPoints(envelope,
          context, mid, dB, dBRange, zoomMin, zoomMax, true, rect.x - mid.x);
   }

   // Draw arrows on the left side if the track extends to the left of the
   // beginning of time.  :)
   if (trackRectT0 == 0.0 && playStartTime < 0.0)
   {
      TrackArt::DrawNegativeOffsetTrackArrows( context, rect );
   }
   {
      auto clipRect = ClipParameters::GetClipRect(clip, zoomInfo, rect);
      TrackArt::DrawClipEdges(dc, clipRect, selected);
   }
}

void DrawTimeSlider( TrackPanelDrawingContext &context,
                                  const wxRect & rect,
                                  bool rightwards, bool highlight )
{
   auto &dc = context.dc;

   const int border = 3; // 3 pixels all round.
   const int width = 6; // width of the drag box.
   const int taper = 6; // how much the box tapers by.
   const int barSpacing = 4; // how far apart the bars are.
   const int barWidth = 3;
   const int xFlat = 3;

   //Enough space to draw in?
   if (rect.height <= ((taper+border + barSpacing) * 2)) {
      return;
   }
   if (rect.width <= (width * 2 + border * 3)) {
      return;
   }

   // The draggable box is tapered towards the direction you drag it.
   int leftTaper  = rightwards ? 0 : 6;
   int rightTaper = rightwards ? 6 : 0;

   int xLeft = rightwards ? (rect.x + border - 2)
                          : (rect.x + rect.width + 1 - (border + width));
   int yTop  = rect.y + border;
   int yBot  = rect.y + rect.height - border - 1;

   AColor::Light(&dc, false, highlight);
   AColor::Line(dc, xLeft,         yBot - leftTaper, xLeft,         yTop + leftTaper);
   AColor::Line(dc, xLeft,         yTop + leftTaper, xLeft + xFlat, yTop);
   AColor::Line(dc, xLeft + xFlat, yTop,             xLeft + width, yTop + rightTaper);

   AColor::Dark(&dc, false, highlight);
   AColor::Line(dc, xLeft + width,         yTop + rightTaper, xLeft + width,       yBot - rightTaper);
   AColor::Line(dc, xLeft + width,         yBot - rightTaper, xLeft + width-xFlat, yBot);
   AColor::Line(dc, xLeft + width - xFlat, yBot,              xLeft,               yBot - leftTaper);

   int firstBar = yTop + taper + taper / 2;
   int nBars    = (yBot - yTop - taper * 3) / barSpacing + 1;
   xLeft += (width - barWidth + 1) / 2;
   int yy;
   int i;

   AColor::Light(&dc, false, highlight);
   for (i = 0;i < nBars; i++) {
      yy = firstBar + barSpacing * i;
      AColor::Line(dc, xLeft, yy, xLeft + barWidth, yy);
   }
   AColor::Dark(&dc, false, highlight);
   for(i = 0;i < nBars; i++){
      yy = firstBar + barSpacing * i + 1;
      AColor::Line(dc, xLeft, yy, xLeft + barWidth, yy);
   }
}

}

// Header needed only for experimental drawing below
//#include "tracks/ui/TimeShiftHandle.h"
void WaveformView::DoDraw(TrackPanelDrawingContext &context,
   const WaveChannel &channel,
   const WaveTrack::Interval* selectedClip,
   const wxRect& rect,
   bool muted)
{
   auto &dc = context.dc;
   const auto artist = TrackArtist::Get( context );

   bool highlight = false;
   bool gripHit = false;
#ifdef EXPERIMENTAL_TRACK_PANEL_HIGHLIGHTING
   auto target = dynamic_cast<TimeShiftHandle*>(context.target.get());
   gripHit = target && target->IsGripHit();
   highlight = target && target->FindTrack().get() ==
      &static_cast<const Track &>(channel.GetChannelGroup());
#endif

   const bool dB = !WaveformSettings::Get(channel).isLinear();

   const auto &blankSelectedBrush = artist->blankSelectedBrush;
   const auto &blankBrush = artist->blankBrush;
   TrackArt::DrawBackgroundWithSelection(
      context, rect, channel, blankSelectedBrush, blankBrush );

   for (const auto &pInterval : channel.Intervals()) {
      bool selected = selectedClip &&
         selectedClip == &pInterval->GetClip();
      DrawClipWaveform(context, channel, *pInterval, rect, dB, muted, selected);
   }
   DrawBoldBoundaries(context, channel, rect);

   const auto drawSliders = artist->drawSliders;
   if (drawSliders) {
      DrawTimeSlider( context, rect, true, highlight && gripHit );  // directed right
      DrawTimeSlider( context, rect, false, highlight && gripHit ); // directed left
   }
}

void WaveformView::Draw(
   TrackPanelDrawingContext &context, const wxRect &rect, unsigned iPass )
{
   if ( iPass == TrackArtist::PassTracks ) {
      const auto artist = TrackArtist::Get(context);
      const auto &pendingTracks = *artist->pPendingTracks;
      auto &dc = context.dc;

      const auto pChannel = FindChannel();
      if (!pChannel)
         return;
      const auto &wc = static_cast<const WaveChannel&>(
         pendingTracks.SubstitutePendingChangedChannel(*pChannel));

      const auto hasSolo = artist->hasSolo;
      bool muted = (hasSolo || wc.GetTrack().GetMute()) &&
         !wc.GetTrack().GetSolo();

#if defined(__WXMAC__)
      wxAntialiasMode aamode = dc.GetGraphicsContext()->GetAntialiasMode();
      dc.GetGraphicsContext()->SetAntialiasMode(wxANTIALIAS_NONE);
#endif

      auto waveChannelView = GetWaveChannelView().lock();
      wxASSERT(waveChannelView.use_count());

      auto selectedClip = waveChannelView->GetSelectedClip();
      DoDraw(context, wc, selectedClip.get(), rect, muted);

#if defined(__WXMAC__)
      dc.GetGraphicsContext()->SetAntialiasMode(aamode);
#endif
   }
   WaveChannelSubView::Draw(context, rect, iPass);
}

static const WaveChannelSubViews::RegisteredFactory key{
   [](WaveChannelView &view) {
      return std::make_shared<WaveformView>( view );
   }
};

// The following attaches the wave color sub-menu to the wave track popup
// menu.  It is appropriate only to waveform view and so is kept in this
// source file with the rest of the waveform view implementation.

#include <mutex> // for std::call_once
#include "WaveTrackControls.h"
#include "../../../../widgets/PopupMenuTable.h"
#include "ProjectAudioIO.h"
#include "ProjectHistory.h"
#include "../../../../RefreshCode.h"

//=============================================================================
// Table class for a sub-menu
struct WaveColorMenuTable : PopupMenuTable
{
   WaveColorMenuTable() : PopupMenuTable{ "WaveColor", XO("&Wave Color") } {}
   DECLARE_POPUP_MENU(WaveColorMenuTable);

   static WaveColorMenuTable &Instance();

   void InitUserData(void *pUserData) override;

   PlayableTrackControls::InitMenuData *mpData{};

   int IdOfWaveColor(int WaveColor);
   void OnWaveColorChange(wxCommandEvent & event);

   int OnInstrument1ID, OnInstrument2ID, OnInstrument3ID, OnInstrument4ID;
};

WaveColorMenuTable &WaveColorMenuTable::Instance()
{
   static WaveColorMenuTable instance;
   return instance;
}

void WaveColorMenuTable::InitUserData(void *pUserData)
{
   mpData = static_cast<PlayableTrackControls::InitMenuData*>(pUserData);
}

namespace {
using ValueFinder = std::function< int( WaveTrack& ) >;

const TranslatableString GetWaveColorStr(int colorIndex)
{
   return XXO("Instrument %i").Format( colorIndex+1 );
}
}

BEGIN_POPUP_MENU(WaveColorMenuTable)
   static const auto fn = []( PopupMenuHandler &handler, wxMenu &menu, int id ){
      auto &me = static_cast<WaveColorMenuTable&>( handler );
      auto pData = me.mpData;
      const auto &track = static_cast<WaveTrack&>(pData->track);
      auto &project = pData->project;
      bool unsafe = ProjectAudioIO::Get( project ).IsAudioActive();

      menu.Check(id, id == me.IdOfWaveColor(
         WaveformAppearance::Get(track).GetColorIndex()));
      menu.Enable( id, !unsafe );
   };

   static std::once_flag flag;
   std::call_once( flag, [this]{
      auto &hostTable = GetWaveTrackMenuTable();
      OnInstrument1ID = hostTable.ReserveId();
      OnInstrument2ID = hostTable.ReserveId();
      OnInstrument3ID = hostTable.ReserveId();
      OnInstrument4ID = hostTable.ReserveId();
   } );

   AppendRadioItem( "Instrument1", OnInstrument1ID,
      GetWaveColorStr(0), POPUP_MENU_FN( OnWaveColorChange ), fn );
   AppendRadioItem( "Instrument2", OnInstrument2ID,
      GetWaveColorStr(1), POPUP_MENU_FN( OnWaveColorChange ), fn );
   AppendRadioItem( "Instrument3", OnInstrument3ID,
      GetWaveColorStr(2), POPUP_MENU_FN( OnWaveColorChange ), fn );
   AppendRadioItem( "Instrument4", OnInstrument4ID,
      GetWaveColorStr(3), POPUP_MENU_FN( OnWaveColorChange ), fn );

END_POPUP_MENU()

/// Converts a WaveColor enumeration to a wxWidgets menu item Id.
int WaveColorMenuTable::IdOfWaveColor(int WaveColor)
{  return OnInstrument1ID + WaveColor;}

/// Handles the selection from the WaveColor submenu of the
/// track menu.
void WaveColorMenuTable::OnWaveColorChange(wxCommandEvent & event)
{
   int id = event.GetId();
   wxASSERT(id >= OnInstrument1ID && id <= OnInstrument4ID);
   auto &track = static_cast<WaveTrack&>(mpData->track);

   int newWaveColor = id - OnInstrument1ID;

   AudacityProject *const project = &mpData->project;

   WaveformAppearance::Get(track).SetColorIndex(newWaveColor);

   ProjectHistory::Get( *project )
      .PushState(XO("Changed '%s' to %s")
         .Format(track.GetName(), GetWaveColorStr(newWaveColor)),
      XO("WaveColor Change"));

   using namespace RefreshCode;
   mpData->result = RefreshAll | FixScrollbars;
}

namespace {
PopupMenuTable::AttachedItem sAttachment{
   GetWaveTrackMenuTable(),
   { "SubViews/Extra" },
   std::make_unique<PopupMenuSection>( "WaveColor",
      // Conditionally add sub-menu for wave color, if showing waveform
      PopupMenuTable::Adapt<WaveTrackPopupMenuTable>(
         [](WaveTrackPopupMenuTable &table) {
            const auto pTrack = &table.FindWaveTrack();
            const auto &view = WaveChannelView::GetFirst(*pTrack);
            const auto displays = view.GetDisplays();
            bool hasWaveform = (displays.end() != std::find(
               displays.begin(), displays.end(),
               WaveChannelSubView::Type{
                  WaveChannelViewConstants::Waveform, {} }
            ) );
            return hasWaveform
               ? Registry::Indirect(WaveColorMenuTable::Instance()
                  .Get(table.mpData))
               : nullptr;
         } ) )
};

}

static WaveClip::Attachments::RegisteredFactory sKeyW{ [](WaveClip&) {
   return std::make_unique<WaveformPainter>();
} };

WaveformPainter &WaveformPainter::Get( const WaveClip &clip )
{
   return const_cast< WaveClip& >( clip ) // Consider it mutable data
      .Attachments::Get<WaveformPainter>(sKeyW).EnsureClip(clip);
}
