WaveformLayer.cpp

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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Sonic Visualiser
    An audio file viewer and annotation editor.
    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2006 Chris Cannam and QMUL.
   
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/

#include "WaveformLayer.h"

#include "base/AudioLevel.h"
#include "view/View.h"
#include "base/Profiler.h"
#include "base/RangeMapper.h"
#include "base/ColourDatabase.h"

#include <QPainter>
#include <QPixmap>
#include <QTextStream>

#include <iostream>
#include <cmath>

//#define DEBUG_WAVEFORM_PAINT 1

using std::cerr;
using std::endl;

WaveformLayer::WaveformLayer() :
    SingleColourLayer(),
    m_model(0),
    m_gain(1.0f),
    m_autoNormalize(false),
    m_showMeans(true),
    m_greyscale(true),
    m_channelMode(SeparateChannels),
    m_channel(-1),
    m_scale(LinearScale),
    m_aggressive(false),
    m_cache(0),
    m_cacheValid(false)
{
    
}

WaveformLayer::~WaveformLayer()
{
    delete m_cache;
}

void
WaveformLayer::setModel(const RangeSummarisableTimeValueModel *model)
{
    bool channelsChanged = false;
    if (m_channel == -1) {
        if (!m_model) {
            if (model) {
                channelsChanged = true;
            }
        } else {
            if (model &&
                m_model->getChannelCount() != model->getChannelCount()) {
                channelsChanged = true;
            }
        }
    }

    m_model = model;
    m_cacheValid = false;
    if (!m_model || !m_model->isOK()) return;

    connectSignals(m_model);

    emit modelReplaced();

    if (channelsChanged) emit layerParametersChanged();
}

Layer::PropertyList
WaveformLayer::getProperties() const
{
    PropertyList list = SingleColourLayer::getProperties();
    list.push_back("Scale");
    list.push_back("Gain");
    list.push_back("Normalize Visible Area");

    if (m_model && m_model->getChannelCount() > 1 && m_channel == -1) {
        list.push_back("Channels");
    }

    return list;
}

QString
WaveformLayer::getPropertyLabel(const PropertyName &name) const
{
    if (name == "Scale") return tr("Scale");
    if (name == "Gain") return tr("Gain");
    if (name == "Normalize Visible Area") return tr("Normalize Visible Area");
    if (name == "Channels") return tr("Channels");
    return SingleColourLayer::getPropertyLabel(name);
}

QString
WaveformLayer::getPropertyIconName(const PropertyName &name) const
{
    if (name == "Normalize Visible Area") return "normalise";
    return "";
}

Layer::PropertyType
WaveformLayer::getPropertyType(const PropertyName &name) const
{
    if (name == "Gain") return RangeProperty;
    if (name == "Normalize Visible Area") return ToggleProperty;
    if (name == "Channels") return ValueProperty;
    if (name == "Scale") return ValueProperty;
    return SingleColourLayer::getPropertyType(name);
}

QString
WaveformLayer::getPropertyGroupName(const PropertyName &name) const
{
    if (name == "Gain" ||
        name == "Normalize Visible Area" ||
        name == "Scale") return tr("Scale");
    return QString();
}

int
WaveformLayer::getPropertyRangeAndValue(const PropertyName &name,
                                        int *min, int *max, int *deflt) const
{
    int val = 0;

    int garbage0, garbage1, garbage2;
    if (!min) min = &garbage0;
    if (!max) max = &garbage1;
    if (!deflt) deflt = &garbage2;

    if (name == "Gain") {

        *min = -50;
        *max = 50;
        *deflt = 0;

        val = lrint(log10(m_gain) * 20.0);
        if (val < *min) val = *min;
        if (val > *max) val = *max;

    } else if (name == "Normalize Visible Area") {

        val = (m_autoNormalize ? 1 : 0);
        *deflt = 0;

    } else if (name == "Channels") {

        *min = 0;
        *max = 2;
        *deflt = 0;
        if (m_channelMode == MixChannels) val = 1;
        else if (m_channelMode == MergeChannels) val = 2;
        else val = 0;

    } else if (name == "Scale") {

        *min = 0;
        *max = 2;
        *deflt = 0;

        val = (int)m_scale;

    } else {
        val = SingleColourLayer::getPropertyRangeAndValue(name, min, max, deflt);
    }

    return val;
}

QString
WaveformLayer::getPropertyValueLabel(const PropertyName &name,
                                    int value) const
{
    if (name == "Scale") {
        switch (value) {
        default:
        case 0: return tr("Linear");
        case 1: return tr("Meter");
        case 2: return tr("dB");
        }
    }
    if (name == "Channels") {
        switch (value) {
        default:
        case 0: return tr("Separate");
        case 1: return tr("Mean");
        case 2: return tr("Butterfly");
        }
    }
    return SingleColourLayer::getPropertyValueLabel(name, value);
}

RangeMapper *
WaveformLayer::getNewPropertyRangeMapper(const PropertyName &name) const
{
    if (name == "Gain") {
        return new LinearRangeMapper(-50, 50, -25, 25, tr("dB"));
    }
    return 0;
}

void
WaveformLayer::setProperty(const PropertyName &name, int value)
{
    if (name == "Gain") {
        setGain(pow(10, float(value)/20.0));
    } else if (name == "Normalize Visible Area") {
        setAutoNormalize(value ? true : false);
    } else if (name == "Channels") {
        if (value == 1) setChannelMode(MixChannels);
        else if (value == 2) setChannelMode(MergeChannels);
        else setChannelMode(SeparateChannels);
    } else if (name == "Scale") {
        switch (value) {
        default:
        case 0: setScale(LinearScale); break;
        case 1: setScale(MeterScale); break;
        case 2: setScale(dBScale); break;
        }
    } else {
        SingleColourLayer::setProperty(name, value);
    }
}

void
WaveformLayer::setGain(float gain)
{
    if (m_gain == gain) return;
    m_gain = gain;
    m_cacheValid = false;
    emit layerParametersChanged();
    emit verticalZoomChanged();
}

void
WaveformLayer::setAutoNormalize(bool autoNormalize)
{
    if (m_autoNormalize == autoNormalize) return;
    m_autoNormalize = autoNormalize;
    m_cacheValid = false;
    emit layerParametersChanged();
}

void
WaveformLayer::setShowMeans(bool showMeans)
{
    if (m_showMeans == showMeans) return;
    m_showMeans = showMeans;
    m_cacheValid = false;
    emit layerParametersChanged();
}

void
WaveformLayer::setUseGreyscale(bool useGreyscale)
{
    if (m_greyscale == useGreyscale) return;
    m_greyscale = useGreyscale;
    m_cacheValid = false;
    emit layerParametersChanged();
}

void
WaveformLayer::setChannelMode(ChannelMode channelMode)
{
    if (m_channelMode == channelMode) return;
    m_channelMode = channelMode;
    m_cacheValid = false;
    emit layerParametersChanged();
}

void
WaveformLayer::setChannel(int channel)
{
//    std::cerr << "WaveformLayer::setChannel(" << channel << ")" << std::endl;

    if (m_channel == channel) return;
    m_channel = channel;
    m_cacheValid = false;
    emit layerParametersChanged();
}

void
WaveformLayer::setScale(Scale scale)
{
    if (m_scale == scale) return;
    m_scale = scale;
    m_cacheValid = false;
    emit layerParametersChanged();
}

void
WaveformLayer::setAggressiveCacheing(bool aggressive)
{
    if (m_aggressive == aggressive) return;
    m_aggressive = aggressive;
    m_cacheValid = false;
    emit layerParametersChanged();
}

int
WaveformLayer::getCompletion(View *) const
{
    int completion = 100;
    if (!m_model || !m_model->isOK()) return completion;
    if (m_model->isReady(&completion)) return 100;
    return completion;
}

bool
WaveformLayer::getValueExtents(float &min, float &max,
                               bool &, QString &unit) const
{
    if (m_scale == LinearScale) {
        min = 0.0;
        max = 1.0;
        unit = "V";
    } else if (m_scale == MeterScale) {
        return false; 
    } else {
        min = AudioLevel::multiplier_to_dB(0.0);
        max = AudioLevel::multiplier_to_dB(1.0);
        unit = "dB";
    }
    return true;
}

int
WaveformLayer::dBscale(float sample, int m) const
{
    if (sample < 0.0) return dBscale(-sample, m);
    float dB = AudioLevel::multiplier_to_dB(sample);
    if (dB < -50.0) return 0;
    if (dB > 0.0) return m;
    return int(((dB + 50.0) * m) / 50.0 + 0.1);
}

size_t
WaveformLayer::getChannelArrangement(size_t &min, size_t &max,
                                     bool &merging, bool &mixing)
    const
{
    if (!m_model || !m_model->isOK()) return 0;

    size_t channels = m_model->getChannelCount();
    if (channels == 0) return 0;

    size_t rawChannels = channels;

    if (m_channel == -1) {
        min = 0;
        if (m_channelMode == MergeChannels ||
            m_channelMode == MixChannels) {
            max = 0;
            channels = 1;
        } else {
            max = channels - 1;
        }
    } else {
        min = m_channel;
        max = m_channel;
        rawChannels = 1;
        channels = 1;
    }

    merging = (m_channelMode == MergeChannels && rawChannels > 1);
    mixing = (m_channelMode == MixChannels && rawChannels > 1);

//    std::cerr << "WaveformLayer::getChannelArrangement: min " << min << ", max " << max << ", merging " << merging << ", channels " << channels << std::endl;

    return channels;
}    

bool
WaveformLayer::isLayerScrollable(const View *) const
{
    return !m_autoNormalize;
}

static float meterdbs[] = { -40, -30, -20, -15, -10,
                            -5, -3, -2, -1, -0.5, 0 };

bool
WaveformLayer::getSourceFramesForX(View *v, int x, size_t modelZoomLevel,
                                   size_t &f0, size_t &f1) const
{
    long viewFrame = v->getFrameForX(x);
    if (viewFrame < 0) {
        f0 = 0;
        f1 = 0;
        return false;
    }

    f0 = viewFrame;
    
    f0 = f0 / modelZoomLevel;
    f0 = f0 * modelZoomLevel;

    viewFrame = v->getFrameForX(x + 1);
    
    f1 = viewFrame;
    f1 = f1 / modelZoomLevel;
    f1 = f1 * modelZoomLevel;
    
    return (f0 < m_model->getEndFrame());
}

float
WaveformLayer::getNormalizeGain(View *v, int channel) const
{
    long startFrame = v->getStartFrame();
    long endFrame = v->getEndFrame();

    // Although a long for purposes of comparison against the view
    // start and end frames, these are known to be non-negative
    long modelStart = long(m_model->getStartFrame());
    long modelEnd = long(m_model->getEndFrame());
    
    size_t rangeStart, rangeEnd;
            
    if (startFrame < modelStart) rangeStart = modelStart;
    else rangeStart = startFrame;

    if (endFrame < 0) rangeEnd = 0;
    else if (endFrame > modelEnd) rangeEnd = modelEnd;
    else rangeEnd = endFrame;

    if (rangeEnd < rangeStart) rangeEnd = rangeStart;

    RangeSummarisableTimeValueModel::Range range =
        m_model->getSummary(channel, rangeStart, rangeEnd - rangeStart);

    size_t minChannel = 0, maxChannel = 0;
    bool mergingChannels = false, mixingChannels = false;

    getChannelArrangement(minChannel, maxChannel,
                          mergingChannels, mixingChannels);

    if (mergingChannels || mixingChannels) {
        RangeSummarisableTimeValueModel::Range otherRange =
            m_model->getSummary(1, rangeStart, rangeEnd - rangeStart);
        range.max = std::max(range.max, otherRange.max);
        range.min = std::min(range.min, otherRange.min);
        range.absmean = std::min(range.absmean, otherRange.absmean);
    }

    return 1.0 / std::max(fabsf(range.max), fabsf(range.min));
}

void
WaveformLayer::paint(View *v, QPainter &viewPainter, QRect rect) const
{
    if (!m_model || !m_model->isOK()) {
        return;
    }
  
    int zoomLevel = v->getZoomLevel();

#ifdef DEBUG_WAVEFORM_PAINT
    Profiler profiler("WaveformLayer::paint", true);
    std::cerr << "WaveformLayer::paint (" << rect.x() << "," << rect.y()
              << ") [" << rect.width() << "x" << rect.height() << "]: zoom " << zoomLevel << ", start " << startFrame << std::endl;
#endif

    size_t channels = 0, minChannel = 0, maxChannel = 0;
    bool mergingChannels = false, mixingChannels = false;

    channels = getChannelArrangement(minChannel, maxChannel,
                                     mergingChannels, mixingChannels);
    if (channels == 0) return;

    int w = v->width();
    int h = v->height();

    bool ready = m_model->isReady();
    QPainter *paint;

    if (m_aggressive) {

#ifdef DEBUG_WAVEFORM_PAINT
        std::cerr << "WaveformLayer::paint: aggressive is true" << std::endl;
#endif

        if (m_cacheValid && (zoomLevel != m_cacheZoomLevel)) {
            m_cacheValid = false;
        }

        if (!m_cache || m_cache->width() != w || m_cache->height() != h) {
#ifdef DEBUG_WAVEFORM_PAINT
            if (m_cache) {
                std::cerr << "WaveformLayer::paint: cache size " << m_cache->width() << "x" << m_cache->height() << " differs from view size " << w << "x" << h << ": regenerating aggressive cache" << std::endl;
            }
#endif
            delete m_cache;
            m_cache = new QPixmap(w, h);
            m_cacheValid = false;
        }

        if (m_cacheValid) {
            viewPainter.drawPixmap(rect, *m_cache, rect);
            return;
        }

        paint = new QPainter(m_cache);

        paint->setPen(Qt::NoPen);
        paint->setBrush(getBackgroundQColor(v));
        paint->drawRect(rect);

        paint->setPen(getForegroundQColor(v));
        paint->setBrush(Qt::NoBrush);

    } else {
        paint = &viewPainter;
    }

    paint->setRenderHint(QPainter::Antialiasing, false);

    int x0 = 0, x1 = w - 1;
    int y0 = 0, y1 = h - 1;

    x0 = rect.left();
    x1 = rect.right();
    y0 = rect.top();
    y1 = rect.bottom();

    if (x0 > 0) --x0;
    if (x1 < v->width()) ++x1;

    // Our zoom level may differ from that at which the underlying
    // model has its blocks.

    // Each pixel within our visible range must always draw from
    // exactly the same set of underlying audio frames, no matter what
    // the range being drawn is.  And that set of underlying frames
    // must remain the same when we scroll one or more pixels left or
    // right.
            
    size_t modelZoomLevel = m_model->getSummaryBlockSize(zoomLevel);

    size_t frame0;
    size_t frame1;
    size_t spare;

    getSourceFramesForX(v, x0, modelZoomLevel, frame0, spare);
    getSourceFramesForX(v, x1, modelZoomLevel, spare, frame1);
    
#ifdef DEBUG_WAVEFORM_PAINT
    std::cerr << "Painting waveform from " << frame0 << " to " << frame1 << " (" << (x1-x0+1) << " pixels at zoom " << zoomLevel << " and model zoom " << modelZoomLevel << ")" <<  std::endl;
#endif

    RangeSummarisableTimeValueModel::RangeBlock *ranges = 
        new RangeSummarisableTimeValueModel::RangeBlock;

    RangeSummarisableTimeValueModel::RangeBlock *otherChannelRanges = 0;
    RangeSummarisableTimeValueModel::Range range;

    QColor baseColour = getBaseQColor();
    std::vector<QColor> greys = getPartialShades(v);
        
    QColor midColour = baseColour;
    if (midColour == Qt::black) {
        midColour = Qt::gray;
    } else if (v->hasLightBackground()) {
        midColour = midColour.light(150);
    } else {
        midColour = midColour.light(50);
    }

    while (m_effectiveGains.size() <= maxChannel) {
        m_effectiveGains.push_back(m_gain);
    }

    for (size_t ch = minChannel; ch <= maxChannel; ++ch) {

        int prevRangeBottom = -1, prevRangeTop = -1;
        QColor prevRangeBottomColour = baseColour, prevRangeTopColour = baseColour;

        m_effectiveGains[ch] = m_gain;

        if (m_autoNormalize) {
            m_effectiveGains[ch] = getNormalizeGain(v, ch);
        }

        float gain = m_effectiveGains[ch];

        int m = (h / channels) / 2;
        int my = m + (((ch - minChannel) * h) / channels);
        
//      std::cerr << "ch = " << ch << ", channels = " << channels << ", m = " << m << ", my = " << my << ", h = " << h << std::endl;

        if (my - m > y1 || my + m < y0) continue;

        if ((m_scale == dBScale || m_scale == MeterScale) &&
            m_channelMode != MergeChannels) {
            m = (h / channels);
            my = m + (((ch - minChannel) * h) / channels);
        }

        paint->setPen(greys[1]);
        paint->drawLine(x0, my, x1, my);

        int n = 10;
        int py = -1;
        
        if (v->hasLightBackground() &&
            v->getViewManager() &&
            v->getViewManager()->shouldShowScaleGuides()) {

            paint->setPen(QColor(240, 240, 240));

            for (int i = 1; i < n; ++i) {
                
                float val = 0.0, nval = 0.0;

                switch (m_scale) {

                case LinearScale:
                    val = (i * gain) / n;
                    if (i > 0) nval = -val;
                    break;

                case MeterScale:
                    val = AudioLevel::dB_to_multiplier(meterdbs[i]) * gain;
                    break;

                case dBScale:
                    val = AudioLevel::dB_to_multiplier(-(10*n) + i * 10) * gain;
                    break;
                }

                if (val < -1.0 || val > 1.0) continue;

                int y = getYForValue(v, val, ch);

                if (py >= 0 && abs(y - py) < 10) continue;
                else py = y;

                int ny = y;
                if (nval != 0.0) {
                    ny = getYForValue(v, nval, ch);
                }

                paint->drawLine(x0, y, x1, y);
                if (ny != y) {
                    paint->drawLine(x0, ny, x1, ny);
                }
            }
        }
  
        m_model->getSummaries(ch, frame0, frame1 - frame0,
                              *ranges, modelZoomLevel);

#ifdef DEBUG_WAVEFORM_PAINT
        std::cerr << ranges->size() << " ranges from " << frame0 << " to " << frame1 << std::endl;
#endif

        if (mergingChannels || mixingChannels) {
            if (m_model->getChannelCount() > 1) {
                if (!otherChannelRanges) {
                    otherChannelRanges =
                        new RangeSummarisableTimeValueModel::RangeBlock;
                }
                m_model->getSummaries
                    (1, frame0, frame1 - frame0, *otherChannelRanges,
                     modelZoomLevel);
            } else {
                if (otherChannelRanges != ranges) delete otherChannelRanges;
                otherChannelRanges = ranges;
            }
        }

        for (int x = x0; x <= x1; ++x) {

            range = RangeSummarisableTimeValueModel::Range();

            size_t f0, f1;
            if (!getSourceFramesForX(v, x, modelZoomLevel, f0, f1)) continue;
            f1 = f1 - 1;

            if (f0 < frame0) {
                std::cerr << "ERROR: WaveformLayer::paint: pixel " << x << " has f0 = " << f0 << " which is less than range frame0 " << frame0 << " for x0 = " << x0 << std::endl;
                continue;
            }

            size_t i0 = (f0 - frame0) / modelZoomLevel;
            size_t i1 = (f1 - frame0) / modelZoomLevel;

#ifdef DEBUG_WAVEFORM_PAINT
            std::cerr << "WaveformLayer::paint: pixel " << x << ": i0 " << i0 << " (f " << f0 << "), i1 " << i1 << " (f " << f1 << ")" << std::endl;
#endif

            if (i1 > i0 + 1) {
                std::cerr << "WaveformLayer::paint: ERROR: i1 " << i1 << " > i0 " << i0 << " plus one (zoom = " << zoomLevel << ", model zoom = " << modelZoomLevel << ")" << std::endl;
            }

            if (ranges && i0 < ranges->size()) {

                range = (*ranges)[i0];

                if (i1 > i0 && i1 < ranges->size()) {
                    range.max = std::max(range.max, (*ranges)[i1].max);
                    range.min = std::min(range.min, (*ranges)[i1].min);
                    range.absmean = (range.absmean + (*ranges)[i1].absmean) / 2;
                }

            } else {
                continue;
            }

            int rangeBottom = 0, rangeTop = 0, meanBottom = 0, meanTop = 0;

            if (mergingChannels) {

                if (otherChannelRanges && i0 < otherChannelRanges->size()) {

                    range.max = fabsf(range.max);
                    range.min = -fabsf((*otherChannelRanges)[i0].max);
                    range.absmean = (range.absmean +
                                     (*otherChannelRanges)[i0].absmean) / 2;

                    if (i1 > i0 && i1 < otherChannelRanges->size()) {
                        // let's not concern ourselves about the mean
                        range.min = std::min
                            (range.min,
                             -fabsf((*otherChannelRanges)[i1].max));
                    }
                }

            } else if (mixingChannels) {

                if (otherChannelRanges && i0 < otherChannelRanges->size()) {

                    range.max = (range.max + (*otherChannelRanges)[i0].max) / 2;
                    range.min = (range.min + (*otherChannelRanges)[i0].min) / 2;
                    range.absmean = (range.absmean + (*otherChannelRanges)[i0].absmean) / 2;
                }
            }

            int greyLevels = 1;
            if (m_greyscale && (m_scale == LinearScale)) greyLevels = 4;

            switch (m_scale) {

            case LinearScale:
                rangeBottom = int( m * greyLevels * range.min * gain);
                rangeTop    = int( m * greyLevels * range.max * gain);
                meanBottom  = int(-m * range.absmean * gain);
                meanTop     = int( m * range.absmean * gain);
                break;

            case dBScale:
                if (!mergingChannels) {
                    int db0 = dBscale(range.min * gain, m);
                    int db1 = dBscale(range.max * gain, m);
                    rangeTop    = std::max(db0, db1);
                    meanTop     = std::min(db0, db1);
                    if (mixingChannels) rangeBottom = meanTop;
                    else rangeBottom = dBscale(range.absmean * gain, m);
                    meanBottom  = rangeBottom;
                } else {
                    rangeBottom = -dBscale(range.min * gain, m * greyLevels);
                    rangeTop    =  dBscale(range.max * gain, m * greyLevels);
                    meanBottom  = -dBscale(range.absmean * gain, m);
                    meanTop     =  dBscale(range.absmean * gain, m);
                }
                break;

            case MeterScale:
                if (!mergingChannels) {
                    int r0 = abs(AudioLevel::multiplier_to_preview(range.min * gain, m));
                    int r1 = abs(AudioLevel::multiplier_to_preview(range.max * gain, m));
                    rangeTop    = std::max(r0, r1);
                    meanTop     = std::min(r0, r1);
                    if (mixingChannels) rangeBottom = meanTop;
                    else rangeBottom = AudioLevel::multiplier_to_preview(range.absmean * gain, m);
                    meanBottom  = rangeBottom;
                } else {
                    rangeBottom = -AudioLevel::multiplier_to_preview(range.min * gain, m * greyLevels);
                    rangeTop    =  AudioLevel::multiplier_to_preview(range.max * gain, m * greyLevels);
                    meanBottom  = -AudioLevel::multiplier_to_preview(range.absmean * gain, m);
                    meanTop     =  AudioLevel::multiplier_to_preview(range.absmean * gain, m);
                }
                break;
            }

            rangeBottom = my * greyLevels - rangeBottom;
            rangeTop    = my * greyLevels - rangeTop;
            meanBottom  = my - meanBottom;
            meanTop     = my - meanTop;

            int topFill = (rangeTop % greyLevels);
            if (topFill > 0) topFill = greyLevels - topFill;

            int bottomFill = (rangeBottom % greyLevels);

            rangeTop = rangeTop / greyLevels;
            rangeBottom = rangeBottom / greyLevels;

            bool clipped = false;

            if (rangeTop < my - m) { rangeTop = my - m; }
            if (rangeTop > my + m) { rangeTop = my + m; }
            if (rangeBottom < my - m) { rangeBottom = my - m; }
            if (rangeBottom > my + m) { rangeBottom = my + m; }

            if (range.max <= -1.0 ||
                range.max >= 1.0) clipped = true;
            
            if (meanBottom > rangeBottom) meanBottom = rangeBottom;
            if (meanTop < rangeTop) meanTop = rangeTop;

            bool drawMean = m_showMeans;
            if (meanTop == rangeTop) {
                if (meanTop < meanBottom) ++meanTop;
                else drawMean = false;
            }
            if (meanBottom == rangeBottom && m_scale == LinearScale) {
                if (meanBottom > meanTop) --meanBottom;
                else drawMean = false;
            }

            if (x != x0 && prevRangeBottom != -1) {
                if (prevRangeBottom > rangeBottom &&
                    prevRangeTop    > rangeBottom) {
//                  paint->setPen(midColour);
                    paint->setPen(baseColour);
                    paint->drawLine(x-1, prevRangeTop, x, rangeBottom);
                    paint->setPen(prevRangeTopColour);
                    paint->drawPoint(x-1, prevRangeTop);
                } else if (prevRangeBottom < rangeTop &&
                           prevRangeTop    < rangeTop) {
//                  paint->setPen(midColour);
                    paint->setPen(baseColour);
                    paint->drawLine(x-1, prevRangeBottom, x, rangeTop);
                    paint->setPen(prevRangeBottomColour);
                    paint->drawPoint(x-1, prevRangeBottom);
                }
            }

            if (ready) {
                if (clipped ) {
                    paint->setPen(Qt::red); 
                } else {
                    paint->setPen(baseColour);
                }
            } else {
                paint->setPen(midColour);
            }

            paint->drawLine(x, rangeBottom, x, rangeTop);

            prevRangeTopColour = baseColour;
            prevRangeBottomColour = baseColour;

            if (m_greyscale && (m_scale == LinearScale) && ready) {
                if (!clipped) {
                    if (rangeTop < rangeBottom) {
                        if (topFill > 0 &&
                            (!drawMean || (rangeTop < meanTop - 1))) {
                            paint->setPen(greys[topFill - 1]);
                            paint->drawPoint(x, rangeTop);
                            prevRangeTopColour = greys[topFill - 1];
                        }
                        if (bottomFill > 0 && 
                            (!drawMean || (rangeBottom > meanBottom + 1))) {
                            paint->setPen(greys[bottomFill - 1]);
                            paint->drawPoint(x, rangeBottom);
                            prevRangeBottomColour = greys[bottomFill - 1];
                        }
                    }
                }
            }
        
            if (drawMean) {
                paint->setPen(midColour);
                paint->drawLine(x, meanBottom, x, meanTop);
            }
        
            prevRangeBottom = rangeBottom;
            prevRangeTop = rangeTop;
        }
    }

    if (m_aggressive) {

        if (ready && rect == v->rect()) {
            m_cacheValid = true;
            m_cacheZoomLevel = zoomLevel;
        }
        paint->end();
        delete paint;
        viewPainter.drawPixmap(rect, *m_cache, rect);
    }

    if (otherChannelRanges != ranges) delete otherChannelRanges;
    delete ranges;
}

QString
WaveformLayer::getFeatureDescription(View *v, QPoint &pos) const
{
    int x = pos.x();

    if (!m_model || !m_model->isOK()) return "";

    int zoomLevel = v->getZoomLevel();

    size_t modelZoomLevel = m_model->getSummaryBlockSize(zoomLevel);

    size_t f0, f1;
    if (!getSourceFramesForX(v, x, modelZoomLevel, f0, f1)) return "";
    
    QString text;

    RealTime rt0 = RealTime::frame2RealTime(f0, m_model->getSampleRate());
    RealTime rt1 = RealTime::frame2RealTime(f1, m_model->getSampleRate());

    if (f1 != f0 + 1 && (rt0.sec != rt1.sec || rt0.msec() != rt1.msec())) {
        text += tr("Time:\t%1 - %2")
            .arg(rt0.toText(true).c_str())
            .arg(rt1.toText(true).c_str());
    } else {
        text += tr("Time:\t%1")
            .arg(rt0.toText(true).c_str());
    }

    size_t channels = 0, minChannel = 0, maxChannel = 0;
    bool mergingChannels = false, mixingChannels = false;

    channels = getChannelArrangement(minChannel, maxChannel,
                                     mergingChannels, mixingChannels);
    if (channels == 0) return "";

    for (size_t ch = minChannel; ch <= maxChannel; ++ch) {

        size_t blockSize = v->getZoomLevel();
        RangeSummarisableTimeValueModel::RangeBlock ranges;
        m_model->getSummaries(ch, f0, f1 - f0, ranges, blockSize);

        if (ranges.empty()) continue;
        
        RangeSummarisableTimeValueModel::Range range = ranges[0];
        
        QString label = tr("Level:");
        if (minChannel != maxChannel) {
            if (ch == 0) label = tr("Left:");
            else if (ch == 1) label = tr("Right:");
            else label = tr("Channel %1").arg(ch + 1);
        }

        bool singleValue = false;
        float min, max;

        if (fabs(range.min) < 0.01) {
            min = range.min;
            max = range.max;
            singleValue = (min == max);
        } else {
            int imin = int(range.min * 1000);
            int imax = int(range.max * 1000);
            singleValue = (imin == imax);
            min = float(imin)/1000;
            max = float(imax)/1000;
        }

        int db = int(AudioLevel::multiplier_to_dB(std::max(fabsf(range.min),
                                                           fabsf(range.max)))
                     * 100);

        if (!singleValue) {
            text += tr("\n%1\t%2 - %3 (%4 dB peak)")
                .arg(label).arg(min).arg(max).arg(float(db)/100);
        } else {
            text += tr("\n%1\t%2 (%3 dB peak)")
                .arg(label).arg(min).arg(float(db)/100);
        }
    }

    return text;
}

int
WaveformLayer::getYForValue(const View *v, float value, size_t channel) const
{
    size_t channels = 0, minChannel = 0, maxChannel = 0;
    bool mergingChannels = false, mixingChannels = false;

    channels = getChannelArrangement(minChannel, maxChannel,
                                     mergingChannels, mixingChannels);

    if (maxChannel < minChannel || channel < minChannel) return 0;

    int h = v->height();
    int m = (h / channels) / 2;
        
    if ((m_scale == dBScale || m_scale == MeterScale) &&
        m_channelMode != MergeChannels) {
        m = (h / channels);
    }

    int my = m + (((channel - minChannel) * h) / channels);

    int vy = 0;

    switch (m_scale) {

    case LinearScale:
        vy = int(m * value);
        break;

    case MeterScale:
        vy = AudioLevel::multiplier_to_preview(value, m);
        break;

    case dBScale:
        vy = dBscale(value, m);
        break;
    }

//    std::cerr << "mergingChannels= " << mergingChannels << ", channel  = " << channel << ", value = " << value << ", vy = " << vy << std::endl;

    return my - vy;
}

float
WaveformLayer::getValueForY(const View *v, int y, size_t &channel) const
{
    size_t channels = 0, minChannel = 0, maxChannel = 0;
    bool mergingChannels = false, mixingChannels = false;

    channels = getChannelArrangement(minChannel, maxChannel,
                                     mergingChannels, mixingChannels);

    if (maxChannel < minChannel) return 0;

    int h = v->height();
    int m = (h / channels) / 2;

    if ((m_scale == dBScale || m_scale == MeterScale) &&
        m_channelMode != MergeChannels) {
        m = (h / channels);
    }
  
    channel = (y * channels) / h + minChannel;

    int my = m + (((channel - minChannel) * h) / channels);

    int vy = my - y;
    float value = 0;
    float thresh = -50.f;

    switch (m_scale) {

    case LinearScale:
        value = float(vy) / m;
        break;

    case MeterScale:
        value = AudioLevel::preview_to_multiplier(vy, m);
        break;

    case dBScale:
        value = (-thresh * float(vy)) / m + thresh;
        value = AudioLevel::dB_to_multiplier(value);
        break;
    }

    return value / m_gain;
}

bool
WaveformLayer::getYScaleValue(const View *v, int y,
                              float &value, QString &unit) const
{
    size_t channel;

    value = getValueForY(v, y, channel);

    if (m_scale == dBScale || m_scale == MeterScale) {

        float thresh = -50.f;
        
        if (value > 0.f) {
            value = 10.f * log10f(value);
            if (value < thresh) value = thresh;
        } else value = thresh;

        unit = "dBV";

    } else {
        unit = "V";
    }

    return true;
}

bool
WaveformLayer::getYScaleDifference(const View *v, int y0, int y1,
                                   float &diff, QString &unit) const
{
    size_t c0, c1;
    float v0 = getValueForY(v, y0, c0);
    float v1 = getValueForY(v, y1, c1);

    if (c0 != c1) {
        // different channels, not comparable
        diff = 0.f;
        unit = "";
        return false;
    }

    if (m_scale == dBScale || m_scale == MeterScale) {

        float thresh = -50.f;

        if (v1 == v0) diff = thresh;
        else {
            if (v1 > v0) diff = v0 / v1;
            else diff = v1 / v0;

            diff = 10.f * log10f(diff);
            if (diff < thresh) diff = thresh;
        }

        unit = "dBV";

    } else {
        diff = fabsf(v1 - v0);
        unit = "V";
    }

    return true;
}

int
WaveformLayer::getVerticalScaleWidth(View *, QPainter &paint) const
{
    if (m_scale == LinearScale) {
        return paint.fontMetrics().width("0.0") + 13;
    } else {
        return std::max(paint.fontMetrics().width(tr("0dB")),
                        paint.fontMetrics().width(tr("-Inf"))) + 13;
    }
}

void
WaveformLayer::paintVerticalScale(View *v, QPainter &paint, QRect rect) const
{
    if (!m_model || !m_model->isOK()) {
        return;
    }

    size_t channels = 0, minChannel = 0, maxChannel = 0;
    bool mergingChannels = false, mixingChannels = false;

    channels = getChannelArrangement(minChannel, maxChannel,
                                     mergingChannels, mixingChannels);
    if (channels == 0) return;

    int h = rect.height(), w = rect.width();
    int textHeight = paint.fontMetrics().height();
    int toff = -textHeight/2 + paint.fontMetrics().ascent() + 1;

    float gain = m_gain;

    for (size_t ch = minChannel; ch <= maxChannel; ++ch) {

        int lastLabelledY = -1;

        if (ch < m_effectiveGains.size()) gain = m_effectiveGains[ch];

        int n = 10;

        for (int i = 0; i <= n; ++i) {

            float val = 0.0, nval = 0.0;
            QString text = "";

            switch (m_scale) {
                
            case LinearScale:
                val = (i * gain) / n;
                text = QString("%1").arg(float(i) / n);
                if (i == 0) text = "0.0";
                else {
                    nval = -val;
                    if (i == n) text = "1.0";
                }
                break;

            case MeterScale:
                val = AudioLevel::dB_to_multiplier(meterdbs[i]) * gain;
                text = QString("%1").arg(meterdbs[i]);
                if (i == n) text = tr("0dB");
                if (i == 0) {
                    text = tr("-Inf");
                    val = 0.0;
                }
                break;

            case dBScale:
                val = AudioLevel::dB_to_multiplier(-(10*n) + i * 10) * gain;
                text = QString("%1").arg(-(10*n) + i * 10);
                if (i == n) text = tr("0dB");
                if (i == 0) {
                    text = tr("-Inf");
                    val = 0.0;
                }
                break;
            }

            if (val < -1.0 || val > 1.0) continue;

            int y = getYForValue(v, val, ch);

            int ny = y;
            if (nval != 0.0) {
                ny = getYForValue(v, nval, ch);
            }

            bool spaceForLabel = (i == 0 ||
                                  abs(y - lastLabelledY) >= textHeight - 1);

            if (spaceForLabel) {

                int tx = 3;
                if (m_scale != LinearScale) {
                    tx = w - 10 - paint.fontMetrics().width(text);
                }
                  
                int ty = y;
                if (ty < paint.fontMetrics().ascent()) {
                    ty = paint.fontMetrics().ascent();
                } else if (ty > h - paint.fontMetrics().descent()) {
                    ty = h - paint.fontMetrics().descent();
                } else {
                    ty += toff;
                }
                paint.drawText(tx, ty, text);

                lastLabelledY = ty - toff;

                if (ny != y) {
                    ty = ny;
                    if (ty < paint.fontMetrics().ascent()) {
                        ty = paint.fontMetrics().ascent();
                    } else if (ty > h - paint.fontMetrics().descent()) {
                        ty = h - paint.fontMetrics().descent();
                    } else {
                        ty += toff;
                    }
                    paint.drawText(tx, ty, text);
                }

                paint.drawLine(w - 7, y, w, y);
                if (ny != y) paint.drawLine(w - 7, ny, w, ny);

            } else {

                paint.drawLine(w - 4, y, w, y);
                if (ny != y) paint.drawLine(w - 4, ny, w, ny);
            }
        }
    }
}

void
WaveformLayer::toXml(QTextStream &stream,
                     QString indent, QString extraAttributes) const
{
    QString s;
    
    QString colourName, colourSpec, darkbg;
    ColourDatabase::getInstance()->getStringValues
        (m_colour, colourName, colourSpec, darkbg);

    s += QString("gain=\"%1\" "
                 "showMeans=\"%2\" "
                 "greyscale=\"%3\" "
                 "channelMode=\"%4\" "
                 "channel=\"%5\" "
                 "scale=\"%6\" "
                 "aggressive=\"%7\" "
                 "autoNormalize=\"%8\"")
        .arg(m_gain)
        .arg(m_showMeans)
        .arg(m_greyscale)
        .arg(m_channelMode)
        .arg(m_channel)
        .arg(m_scale)
        .arg(m_aggressive)
        .arg(m_autoNormalize);

    SingleColourLayer::toXml(stream, indent, extraAttributes + " " + s);
}

void
WaveformLayer::setProperties(const QXmlAttributes &attributes)
{
    bool ok = false;

    SingleColourLayer::setProperties(attributes);

    float gain = attributes.value("gain").toFloat(&ok);
    if (ok) setGain(gain);

    bool showMeans = (attributes.value("showMeans") == "1" ||
                      attributes.value("showMeans") == "true");
    setShowMeans(showMeans);

    bool greyscale = (attributes.value("greyscale") == "1" ||
                      attributes.value("greyscale") == "true");
    setUseGreyscale(greyscale);

    ChannelMode channelMode = (ChannelMode)
        attributes.value("channelMode").toInt(&ok);
    if (ok) setChannelMode(channelMode);

    int channel = attributes.value("channel").toInt(&ok);
    if (ok) setChannel(channel);

    Scale scale = (Scale)
        attributes.value("scale").toInt(&ok);
    if (ok) setScale(scale);

    bool aggressive = (attributes.value("aggressive") == "1" ||
                       attributes.value("aggressive") == "true");
    setUseGreyscale(aggressive);

    bool autoNormalize = (attributes.value("autoNormalize") == "1" ||
                          attributes.value("autoNormalize") == "true");
    setAutoNormalize(autoNormalize);
}

int
WaveformLayer::getVerticalZoomSteps(int &defaultStep) const
{
    defaultStep = 50;
    return 100;
}

int
WaveformLayer::getCurrentVerticalZoomStep() const
{
    int val = lrint(log10(m_gain) * 20.0) + 50;
    if (val < 0) val = 0;
    if (val > 100) val = 100;
    return val;
}

void
WaveformLayer::setVerticalZoomStep(int step)
{
    setGain(pow(10, float(step - 50) / 20.0));
}

---