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Refactor sample visualization implementation #7599

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Refactor sample visualization implementation #7599

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16f5394
Rework sample visualization implementation to fix bugs
sakertooth Nov 24, 2024
aff421e
Fix shifting
sakertooth Nov 24, 2024
4ba57bd
Use floor and ceil functions to fix shifting
sakertooth Nov 25, 2024
3e6eb2b
Revert "Fix shifting"
sakertooth Nov 25, 2024
7057882
Improve variable name
sakertooth Nov 25, 2024
aa20241
Draw in reverse when necessary
sakertooth Nov 25, 2024
a146069
Merge remote-tracking branch 'upstream/master' into redo-sample-visua…
sakertooth Nov 26, 2024
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65 changes: 20 additions & 45 deletions src/gui/SampleWaveform.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -28,64 +28,39 @@ namespace lmms::gui {

void SampleWaveform::visualize(Parameters parameters, QPainter& painter, const QRect& rect)
{
const int x = rect.x();
const int height = rect.height();
const int width = rect.width();
const int centerY = rect.center().y();
if (!parameters.buffer || parameters.size == 0) { return; }

const int halfHeight = height / 2;
const auto centerY = rect.center().y();
const auto halfHeight = rect.height() / 2;

const auto color = painter.pen().color();
const auto rmsColor = color.lighter(123);

const float framesPerPixel = std::max(1.0f, static_cast<float>(parameters.size) / width);
const auto samplesPerPixel = std::max(1.0f, static_cast<float>(parameters.size) / rect.width());
const auto numPixelsToDraw = std::min(static_cast<int>(parameters.size), rect.width());

constexpr float maxFramesPerPixel = 512.0f;
const float resolution = std::max(1.0f, framesPerPixel / maxFramesPerPixel);
const float framesPerResolution = framesPerPixel / resolution;
const auto compFn = [](const SampleFrame& a, const SampleFrame& b) { return a.average() < b.average(); };
const auto squaredSumFn = [](const float acc, const SampleFrame& x) { return acc + x.average() * x.average(); };

size_t numPixels = std::min(parameters.size, static_cast<size_t>(width));
auto min = std::vector<float>(numPixels, 1);
auto max = std::vector<float>(numPixels, -1);
auto squared = std::vector<float>(numPixels, 0);

const size_t maxFrames = static_cast<size_t>(numPixels * framesPerPixel);

auto pixelIndex = std::size_t{0};

for (auto i = std::size_t{0}; i < maxFrames; i += static_cast<std::size_t>(resolution))
for (auto i = 0; i < numPixelsToDraw; i++)
{
pixelIndex = i / framesPerPixel;
const auto frameIndex = !parameters.reversed ? i : maxFrames - i;
const auto start = parameters.buffer + static_cast<int>(std::floor(i * samplesPerPixel));
const auto end = parameters.buffer + static_cast<int>(std::ceil((i + 1) * samplesPerPixel));

const auto& frame = parameters.buffer[frameIndex];
const auto value = frame.average();
const auto [min, max] = std::minmax_element(start, end, compFn);
const auto minPeak = min->average();
const auto maxPeak = max->average();

if (value > max[pixelIndex]) { max[pixelIndex] = value; }
if (value < min[pixelIndex]) { min[pixelIndex] = value; }
const auto lineY1 = centerY - maxPeak * halfHeight * parameters.amplification;
const auto lineY2 = centerY - minPeak * halfHeight * parameters.amplification;
const auto lineX = rect.x() + (parameters.reversed ? numPixelsToDraw - i : i);

squared[pixelIndex] += value * value;
}

if (pixelIndex < numPixels)
{
numPixels = pixelIndex;
}
const auto squaredSum = std::accumulate(start, end, 0.0f, squaredSumFn);
const auto rms = std::sqrt(squaredSum / samplesPerPixel);
const auto rmsLineY1 = centerY - rms * halfHeight * parameters.amplification;
const auto rmsLineY2 = centerY + rms * halfHeight * parameters.amplification;

for (auto i = std::size_t{0}; i < numPixels; i++)
{
const int lineY1 = centerY - max[i] * halfHeight * parameters.amplification;
const int lineY2 = centerY - min[i] * halfHeight * parameters.amplification;
const int lineX = static_cast<int>(i) + x;
painter.drawLine(lineX, lineY1, lineX, lineY2);

const float rms = std::sqrt(squared[i] / framesPerResolution);
const float maxRMS = std::clamp(rms, min[i], max[i]);
const float minRMS = std::clamp(-rms, min[i], max[i]);

const int rmsLineY1 = centerY - maxRMS * halfHeight * parameters.amplification;
const int rmsLineY2 = centerY - minRMS * halfHeight * parameters.amplification;

painter.setPen(rmsColor);
painter.drawLine(lineX, rmsLineY1, lineX, rmsLineY2);
painter.setPen(color);
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