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Allow visualizing both stereo channels of sample clips #8497

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db34fa9
feat (samples): generate thumbnails of stereo channels
Itreza2 Aug 4, 2026
a39f02e
feat (samples): draw stereo channels thumbnails
Itreza2 Aug 4, 2026
6dfeb46
feat (setup dialog): add a combo box that set the policy for display of
Itreza2 Aug 4, 2026
e7db72f
fix (setup dialog): update config manager on change
Itreza2 Aug 4, 2026
8292f6d
feat (samples): update sample clip view painting method
Itreza2 Aug 4, 2026
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20 changes: 13 additions & 7 deletions include/SampleThumbnail.h
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Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,8 @@ namespace lmms::gui {
class LMMS_EXPORT SampleThumbnail
{
public:
enum Type { MONO, LEFT, RIGHT };

struct VisualizeParameters
{
QRect sampleRect; //!< A rectangle that covers the entire range of samples.
Expand All @@ -70,6 +72,8 @@ class LMMS_EXPORT SampleThumbnail
float sampleEnd = 1.0f; //!< Where the sample ends for drawing.

bool reversed = false; //!< Determines if the waveform is drawn in reverse or not.

Type waveType = Type::MONO; //!< Determines which stereo channel is drawn
};

SampleThumbnail() = default;
Expand Down Expand Up @@ -104,20 +108,22 @@ class LMMS_EXPORT SampleThumbnail
};

Thumbnail() = default;
Thumbnail(std::vector<Peak> peaks, double samplesPerPeak);
Thumbnail(const float* buffer, size_t size, size_t width);
Thumbnail(std::vector<Peak> right_peaks, std::vector<Peak> left_peaks, double samplesPerPeak);
Thumbnail(const SampleBuffer* buffer, size_t width);

Thumbnail zoomOut(float factor) const;

Peak* data() { return m_peaks.data(); }
Peak& operator[](size_t index) { return m_peaks[index]; }

@Itreza2 Itreza2 Aug 4, 2026

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These operators no longer makes a lot of sense since the class is now holding 3 different arrays. Because they were unused anyway I've chosen to remove them.

const Peak& operator[](size_t index) const { return m_peaks[index]; }
Peak* mono() { return m_mono_peaks.data(); }
Peak* right() { return m_right_peaks.data(); }
Peak* left() { return m_left_peaks.data(); }

int width() const { return m_peaks.size(); }
int width() const { return m_mono_peaks.size(); }
double samplesPerPeak() const { return m_samplesPerPeak; }

private:
std::vector<Peak> m_peaks;
std::vector<Peak> m_mono_peaks;
std::vector<Peak> m_right_peaks;
std::vector<Peak> m_left_peaks;
double m_samplesPerPeak = 0.0;
};

Expand Down
3 changes: 3 additions & 0 deletions include/SetupDialog.h
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Original file line number Diff line number Diff line change
Expand Up @@ -87,6 +87,7 @@ private slots:
void toggleOpenLastProject(bool enabled);
void detachBehaviorChanged();
void loopMarkerModeChanged();
void stereoChannelsPolicyChanged();
void setLanguage(int lang);

// Performance settings widget.
Expand Down Expand Up @@ -153,6 +154,8 @@ private slots:
QComboBox* m_detachBehaviorComboBox;
QString m_loopMarkerMode;
QComboBox* m_loopMarkerComboBox;
QString m_stereoChannelsPolicy;
QComboBox* m_stereoChannelsComboBox;
QString m_autoScroll;
QComboBox* m_autoScrollComboBox;
QString m_lang;
Expand Down
106 changes: 79 additions & 27 deletions src/gui/SampleThumbnail.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -25,10 +25,14 @@

#include "SampleThumbnail.h"

#include <algorithm>
#include <cassert>
#include <QFileInfo>
#include <QPainter>

#include "Sample.h"
#include "SampleBuffer.h"
#include "SampleFrame.h"

namespace {
constexpr auto MaxSampleThumbnailCacheSize = 32;
Expand All @@ -37,38 +41,60 @@ namespace {

namespace lmms::gui {

SampleThumbnail::Thumbnail::Thumbnail(std::vector<Peak> peaks, double samplesPerPeak)
: m_peaks(std::move(peaks))
SampleThumbnail::Thumbnail::Thumbnail(std::vector<Peak> right_peaks, std::vector<Peak> left_peaks, double samplesPerPeak)
: m_mono_peaks(right_peaks.size())
, m_right_peaks(std::move(right_peaks))
, m_left_peaks(std::move(left_peaks))
, m_samplesPerPeak(samplesPerPeak)
{
assert(m_right_peaks.size() == m_left_peaks.size() && "Stereo peaks arrays lengths don't match");

@Itreza2 Itreza2 Aug 4, 2026

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This kind of precondition is bad, but Thumbnail is private in SampleThumbnail so it is unlikely this would cause any issue in the future.


for (size_t i = 0; i < m_right_peaks.size(); i++)
{
m_mono_peaks[i] = m_right_peaks[i] + m_left_peaks[i];
}
}

SampleThumbnail::Thumbnail::Thumbnail(const float* buffer, size_t size, size_t width)
: m_peaks(width)
, m_samplesPerPeak(std::max(static_cast<double>(size) / width, 1.0))
SampleThumbnail::Thumbnail::Thumbnail(const SampleBuffer* buffer, size_t width)
: m_mono_peaks(width)
, m_right_peaks(width)
, m_left_peaks(width)
, m_samplesPerPeak(std::max(static_cast<double>(buffer->size()) / width, 1.0))
{
for (auto peakIndex = std::size_t{0}; peakIndex < width; ++peakIndex)
{
const auto beginSample = buffer + static_cast<size_t>(std::floor(peakIndex * m_samplesPerPeak));
const auto endSample = buffer + static_cast<size_t>(std::ceil((peakIndex + 1) * m_samplesPerPeak));
const auto [min, max] = std::minmax_element(beginSample, endSample);
m_peaks[peakIndex] = Peak{*min, *max};
const auto beginSample = buffer->data() + static_cast<size_t>(std::floor(peakIndex * m_samplesPerPeak));
const auto endSample = buffer->data() + static_cast<size_t>(std::ceil((peakIndex + 1) * m_samplesPerPeak));
const auto [right_min, right_max] = std::minmax_element(beginSample, endSample,
[](const SampleFrame& a, const SampleFrame& b){ return a.right() < b.right();}
);
const auto [left_min, left_max] = std::minmax_element(beginSample, endSample,
[](const SampleFrame& a, const SampleFrame& b){ return a.left() < b.left();}
);
m_right_peaks[peakIndex] = Peak{right_min->right(), right_max->right()};
m_left_peaks[peakIndex] = Peak{left_min->left(), left_max->left()};
m_mono_peaks[peakIndex] = m_right_peaks[peakIndex] + m_left_peaks[peakIndex];
}
}

SampleThumbnail::Thumbnail SampleThumbnail::Thumbnail::zoomOut(float factor) const
{
assert(factor >= 1 && "Invalid zoom out factor");

auto peaks = std::vector<Peak>(m_peaks.size() / factor);
for (auto peakIndex = std::size_t{0}; peakIndex < peaks.size(); ++peakIndex)
auto right_peaks = std::vector<Peak>(m_right_peaks.size() / factor);
auto left_peaks = std::vector<Peak>(m_left_peaks.size() / factor);

for (auto peakIndex = std::size_t{0}; peakIndex < right_peaks.size(); ++peakIndex)
{
const auto beginAggregationAt = m_peaks.begin() + static_cast<size_t>(std::floor(peakIndex * factor));
const auto endAggregationAt = m_peaks.begin() + static_cast<size_t>(std::ceil((peakIndex + 1) * factor));
peaks[peakIndex] = std::accumulate(beginAggregationAt, endAggregationAt, Peak{});
}
const auto beginRightAggregationAt = m_right_peaks.begin() + static_cast<size_t>(std::floor(peakIndex * factor));
const auto endRightAggregationAt = m_right_peaks.begin() + static_cast<size_t>(std::ceil((peakIndex + 1) * factor));
right_peaks[peakIndex] = std::accumulate(beginRightAggregationAt, endRightAggregationAt, Peak{});

return Thumbnail{std::move(peaks), m_samplesPerPeak * factor};
const auto beginLeftAggregationAt = m_left_peaks.begin() + static_cast<size_t>(std::floor(peakIndex * factor));
const auto endLeftAggregationAt = m_left_peaks.begin() + static_cast<size_t>(std::ceil((peakIndex + 1) * factor));
left_peaks[peakIndex] = std::accumulate(beginLeftAggregationAt, endLeftAggregationAt, Peak{});
}
return Thumbnail{std::move(right_peaks), std::move(left_peaks), m_samplesPerPeak * factor};
}

SampleThumbnail::SampleThumbnail(const Sample& sample)
Expand All @@ -94,9 +120,7 @@ SampleThumbnail::SampleThumbnail(const Sample& sample)
s_sampleThumbnailCacheMap[std::move(entry)] = m_thumbnailCache;
}

const auto flatBuffer = m_buffer->data()->data();
const auto flatBufferSize = m_buffer->size() * DEFAULT_CHANNELS;
m_thumbnailCache->emplace_back(flatBuffer, flatBufferSize, flatBufferSize / AggregationPerZoomStep);
m_thumbnailCache->emplace_back(m_buffer.get(), m_buffer->size() / AggregationPerZoomStep);

while (m_thumbnailCache->back().width() >= AggregationPerZoomStep)
{
Expand Down Expand Up @@ -141,7 +165,11 @@ void SampleThumbnail::visualize(VisualizeParameters parameters, QPainter& painte
{
if (useOriginalBuffer && drawOriginalBuffer)
{
const auto value = m_buffer->data()->data()[i];
const auto value = (

@Itreza2 Itreza2 Aug 4, 2026

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I'm unsure about this block and what its previous version was aiming for.
The conditions for it to be executed are very uncommon tho.

parameters.waveType == Type::RIGHT ? m_buffer->data()[i][0] :
parameters.waveType == Type::LEFT ? m_buffer->data()[i][1] :
(m_buffer->data()[i][0] + m_buffer->data()[i][1]) / 2
);
painter.drawPoint(x, renderRect.center().y() - value * yScale);
continue;
}
Expand All @@ -155,16 +183,40 @@ void SampleThumbnail::visualize(VisualizeParameters parameters, QPainter& painte

if (useOriginalBuffer)
{
const auto flatBuffer = m_buffer->data()->data();
const auto [min, max] = std::minmax_element(flatBuffer + beginIndex, flatBuffer + endIndex);
minPeak = *min;
maxPeak = *max;
const auto frameBuffer = m_buffer->data();

if (parameters.waveType == RIGHT)
{
const auto [min, max] = std::minmax_element(frameBuffer + beginIndex, frameBuffer + endIndex,
[](const SampleFrame& a, const SampleFrame& b){ return a.right() < b.right(); }
);
minPeak = min->right();
maxPeak = max->right();
}
else if (parameters.waveType == LEFT)
{
const auto [min, max] = std::minmax_element(frameBuffer + beginIndex, frameBuffer + endIndex,
[](const SampleFrame& a, const SampleFrame& b){ return a.left() < b.left(); }
);
minPeak = min->left();
maxPeak = max->left();
}
else
{
const auto flatBuffer = frameBuffer->data();
const auto [min, max] = std::minmax_element(flatBuffer + (2 * beginIndex), flatBuffer + (2 * endIndex));
minPeak = *min;
maxPeak = *max;
}
}
else
{
const auto beginAggregationAt = finerThumbnail->data() + beginIndex;
const auto endAggregationAt = finerThumbnail->data() + endIndex;
const auto peak = std::accumulate(beginAggregationAt, endAggregationAt, Thumbnail::Peak{});
const Thumbnail::Peak* peaks = (
parameters.waveType == Type::RIGHT ? finerThumbnail->right() :
parameters.waveType == Type::LEFT ? finerThumbnail->left() :
finerThumbnail->mono()
);
const auto peak = std::accumulate(peaks + beginIndex, peaks + endIndex, Thumbnail::Peak{});
minPeak = peak.min;
maxPeak = peak.max;
}
Expand Down
31 changes: 25 additions & 6 deletions src/gui/clips/SampleClipView.cpp
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Expand Up @@ -26,17 +26,20 @@

#include <QApplication>
#include <QMenu>
#include <QObject>
#include <QPainter>

#include "FileDialog.h"
#include "GuiApplication.h"
#include "AutomationEditor.h"
#include "ConfigManager.h"
#include "embed.h"
#include "FileDialog.h"
#include "GuiApplication.h"
#include "PathUtil.h"
#include "SampleClip.h"
#include "SampleThumbnail.h"
#include "Song.h"
#include "StringPairDrag.h"
#include "Track.h"
#include "TrackContainerView.h"
#include "TrackView.h"

Expand Down Expand Up @@ -206,153 +209,169 @@



void SampleClipView::paintEvent( QPaintEvent * pe )
{
QPainter painter( this );

if( !needsUpdate() )
{
painter.drawPixmap(m_paintPixmapXPosition, 0, m_paintPixmap);
return;
}

setNeedsUpdate( false );

const auto trackViewWidth = getTrackView()->rect().width();

// Use the clip's height to avoid artifacts when rendering while something else is overlaying the clip.
const auto viewPortRect = QRect(0, 0, trackViewWidth * 2, rect().height());

m_paintPixmapXPosition = std::max(0, pe->rect().x() - trackViewWidth);

if (m_paintPixmap.isNull() || m_paintPixmap.size() != viewPortRect.size())
{
m_paintPixmap = QPixmap(viewPortRect.size());
}

QPainter p( &m_paintPixmap );

bool muted = m_clip->getTrack()->isMuted() || m_clip->isMuted();
bool selected = isSelected();

QLinearGradient lingrad(0, 0, 0, height());
QColor c = painter.background().color();
if (muted) { c = c.darker(150); }
if (selected) { c = c.darker(150); }

lingrad.setColorAt( 1, c.darker( 300 ) );
lingrad.setColorAt( 0, c );

// paint a black rectangle under the clip to prevent glitches with transparent backgrounds
p.fillRect( rect(), QColor( 0, 0, 0 ) );

if( gradient() )
{
p.fillRect( rect(), lingrad );
}
else
{
p.fillRect( rect(), c );
}

auto clipColor = m_clip->color().value_or(m_clip->getTrack()->color().value_or(painter.pen().brush().color()));

p.setPen(clipColor);

if (muted)
{
QColor penColor = p.pen().brush().color();
penColor.setHsv(penColor.hsvHue(), penColor.hsvSaturation() / 4, penColor.value());
p.setPen(penColor.darker(250));
}
if (selected)
{
p.setPen(p.pen().brush().color().darker(150));
}

const int spacing = BORDER_WIDTH + 1;
const float ppb = fixedClips() ?
( parentWidget()->width() - 2 * BORDER_WIDTH )
/ (float) m_clip->length().getBar() :
pixelsPerBar();

float nom = Engine::getSong()->getTimeSigModel().getNumerator();
float den = Engine::getSong()->getTimeSigModel().getDenominator();
float ticksPerBar = DefaultTicksPerBar * nom / den;
float offsetStart = m_clip->startTimeOffset() / ticksPerBar * pixelsPerBar();
float sampleLength = m_clip->sampleLength() * ppb / ticksPerBar;

const auto& sample = m_clip->m_sample;

const auto sampleRextX = static_cast<int>(offsetStart) - m_paintPixmapXPosition;
const auto sampleRectX = static_cast<int>(offsetStart) - m_paintPixmapXPosition;

if (sample.sampleSize() > 0)
{
const auto param = SampleThumbnail::VisualizeParameters{
.sampleRect = QRect(sampleRextX, spacing, sampleLength, height() - spacing),
auto param = SampleThumbnail::VisualizeParameters{
.viewportRect = viewPortRect,
.amplification = sample.amplification(),
.reversed = sample.reversed()
};
const QString policy = ConfigManager::inst()->value("app", "stereochannelspolicy", "height");
if (policy == "never" || (policy == "height" && height() < DEFAULT_TRACK_HEIGHT * 2))
{
param.sampleRect = QRect(sampleRectX, spacing, sampleLength, height() - spacing);
param.waveType = SampleThumbnail::Type::MONO;
m_sampleThumbnail.visualize(param, p);
}
else
{
const int halfHeight = height() / 2;

m_sampleThumbnail.visualize(param, p);
param.sampleRect = QRect(sampleRectX, spacing, sampleLength, halfHeight - spacing);
param.waveType = SampleThumbnail::Type::LEFT;
m_sampleThumbnail.visualize(param, p);

param.sampleRect = QRect(sampleRectX, halfHeight + spacing, sampleLength, height() - spacing);
param.waveType = SampleThumbnail::Type::RIGHT;
m_sampleThumbnail.visualize(param, p);
}
}

QString name = PathUtil::cleanName(m_clip->m_sample.sampleFile());
paintTextLabel(name, p);

// disable antialiasing for borders, since its not needed
p.setRenderHint( QPainter::Antialiasing, false );

// inner border
p.setPen( c.lighter( 135 ) );
p.drawRect(
-m_paintPixmapXPosition + 1,
1,
rect().right() - BORDER_WIDTH,
rect().bottom() - BORDER_WIDTH );

// outer border
p.setPen( c.darker( 200 ) );
p.drawRect(-m_paintPixmapXPosition, 0, rect().right(), rect().bottom());

// draw the 'muted' pixmap only if the clip was manually muted
if( m_clip->isMuted() )
{
const int spacing = BORDER_WIDTH;
const int size = 14;
p.drawPixmap( spacing, height() - ( size + spacing ),
embed::getIconPixmap( "muted", size, size ) );
}

if ( m_marker )
{
p.setPen(markerColor());
p.drawLine(m_markerPos, rect().bottom(), m_markerPos, rect().top());
}
// recording sample tracks is not possible at the moment

/* if( m_clip->isRecord() )
{
p.setFont( pointSize<7>( p.font() ) );

p.setPen( textShadowColor() );
p.drawText( 10, p.fontMetrics().height()+1, "Rec" );
p.setPen( textColor() );
p.drawText( 9, p.fontMetrics().height(), "Rec" );

p.setBrush( QBrush( textColor() ) );
p.drawEllipse( 4, 5, 4, 4 );
}*/

p.end();

painter.drawPixmap(m_paintPixmapXPosition, 0, m_paintPixmap);
}




Check notice on line 374 in src/gui/clips/SampleClipView.cpp

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codefactor.io / CodeFactor

src/gui/clips/SampleClipView.cpp#L212-L374 

Complex Method
void SampleClipView::reverseSample()
{
m_clip->m_sample.setReversed(!m_clip->m_sample.reversed());
Expand Down
21 changes: 21 additions & 0 deletions src/gui/modals/SetupDialog.cpp
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Expand Up @@ -121,6 +121,7 @@ SetupDialog::SetupDialog(ConfigTab tab_to_open) :
"app", "openlastproject").toInt()),
m_detachBehavior{ConfigManager::inst()->value("ui", "detachbehavior", "show")},
m_loopMarkerMode{ConfigManager::inst()->value("app", "loopmarkermode", "dual")},
m_stereoChannelsPolicy{ConfigManager::inst()->value("app", "stereochannelspolicy", "height")},
m_autoScroll(ConfigManager::inst()->value("ui", "autoscroll", "stepped")),
m_lang(ConfigManager::inst()->value(
"app", "language")),
Expand Down Expand Up @@ -284,6 +285,19 @@ SetupDialog::SetupDialog(ConfigTab tab_to_open) :
guiGroupLayout->addWidget(new QLabel{tr("Loop edit mode"), guiGroupBox});
guiGroupLayout->addWidget(m_loopMarkerComboBox);

m_stereoChannelsComboBox = new QComboBox{guiGroupBox};

m_stereoChannelsComboBox->addItem(tr("Depending on track height"), "height");
m_stereoChannelsComboBox->addItem(tr("Always"), "always");
m_stereoChannelsComboBox->addItem(tr("Never"), "never");

m_stereoChannelsComboBox->setCurrentIndex(m_stereoChannelsComboBox->findData(m_stereoChannelsPolicy));
connect(m_stereoChannelsComboBox, qOverload<int>(&QComboBox::currentIndexChanged),
this, &SetupDialog::stereoChannelsPolicyChanged);

guiGroupLayout->addWidget(new QLabel{tr("Show samples stereo channels"), guiGroupBox});
guiGroupLayout->addWidget(m_stereoChannelsComboBox);

m_autoScrollComboBox = new QComboBox{guiGroupBox};
m_autoScrollComboBox->addItem(tr("Disabled"), TimeLineWidget::AutoScrollDisabledString);
m_autoScrollComboBox->addItem(tr("Stepped (Scroll once the playhead goes out of view)"), TimeLineWidget::AutoScrollSteppedString);
Expand Down Expand Up @@ -1009,6 +1023,7 @@ void SetupDialog::accept()
QString::number(m_openLastProject));
ConfigManager::inst()->setValue("ui", "detachbehavior", m_detachBehavior);
ConfigManager::inst()->setValue("app", "loopmarkermode", m_loopMarkerMode);
ConfigManager::inst()->setValue("app", "stereochannelspolicy", m_stereoChannelsPolicy);
ConfigManager::inst()->setValue("app", "language", m_lang);
ConfigManager::inst()->setValue("ui", "autoscroll", m_autoScroll);
ConfigManager::inst()->setValue("ui", "saveinterval",
Expand Down Expand Up @@ -1160,6 +1175,12 @@ void SetupDialog::loopMarkerModeChanged()
}


void SetupDialog::stereoChannelsPolicyChanged()
{
m_stereoChannelsPolicy = m_stereoChannelsComboBox->currentData().toString();
}


void SetupDialog::setLanguage(int lang)
{
m_lang = m_languages[lang];
Expand Down
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