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Scalable LFO graph (#7203)
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## Scalable LFO graph
Make the rendering of the LFO graph scalable. Change the fixed size to a minimum size. Adjust the rendering code such that it uses the width and height of the widget instead of the background pixmap.

Only draw only poly line once instead of many line segments. Collect the points in the for-loop to be able to do so. This makes the code a bit more understandable because we now compute exacly one point per iteration in the for-loop.

Use the same interpolation for the line color like in the envelope graph.

Rename some variables to make them consistent with the other code.

Remove the member `m_params` which is not used anyway. This also allows for the removal of the overridden `modelChanged` method.

## Use "Hz" instead of "ms/LFO"
Use the more common unit "Hz" to display the frequency of the LFO instead of "ms/LFO". The frequency is always displayed with three digits after the decimal separator to prevent "jumps".

## Take "Freq * 100" into account
This commit fixes a bug where the "Freq * 100" option was not taken into account when computing and displaying the frequency of the LFO.

## Keep info text legible
Draw a slightly transparent black rectangle underneath the text to keep it legible, e.g. for high frequencies with an LFO amount of 1 which results in a very bright and dense graph.

## Extract drawing of info text into method
Extract the drawing of the info text into its own private method `drawInfoText`.
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@michaelgregorius
michaelgregorius committed Apr 14, 2024
1 parent 8e40038 commit 815f88d
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Showing 2 changed files with 72 additions and 46 deletions.
5 changes: 1 addition & 4 deletions include/LfoGraph.h
View file
Expand Up @@ -45,19 +45,16 @@ class LfoGraph : public QWidget, public ModelView
LfoGraph(QWidget* parent);

protected:
void modelChanged() override;

void mousePressEvent(QMouseEvent* me) override;
void paintEvent(QPaintEvent* pe) override;

private:
void drawInfoText(const EnvelopeAndLfoParameters&);
void toggleAmountModel();

private:
QPixmap m_lfoGraph = embed::getIconPixmap("lfo_graph");

EnvelopeAndLfoParameters* m_params = nullptr;

float m_randomGraph {0.};
};

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113 changes: 71 additions & 42 deletions src/gui/instrument/LfoGraph.cpp
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Expand Up @@ -30,6 +30,7 @@

#include "EnvelopeAndLfoParameters.h"
#include "Oscillator.h"
#include "ColorHelper.h"

#include "gui_templates.h"

Expand All @@ -45,12 +46,7 @@ LfoGraph::LfoGraph(QWidget* parent) :
QWidget(parent),
ModelView(nullptr, this)
{
setFixedSize(m_lfoGraph.size());
}

void LfoGraph::modelChanged()
{
m_params = castModel<EnvelopeAndLfoParameters>();
setMinimumSize(m_lfoGraph.size());
}

void LfoGraph::mousePressEvent(QMouseEvent* me)
Expand Down Expand Up @@ -78,81 +74,114 @@ void LfoGraph::paintEvent(QPaintEvent*)
const f_cnt_t attackFrames = params->getLfoAttackFrames();
const f_cnt_t oscillationFrames = params->getLfoOscillationFrames();
const bool x100 = params->getX100Model().value();
const int waveModel = params->getLfoWaveModel().value();
const int lfoWaveModel = params->getLfoWaveModel().value();
const auto * userWave = params->getLfoUserWave().get();

int LFO_GRAPH_W = m_lfoGraph.width() - 3; // subtract border
int LFO_GRAPH_H = m_lfoGraph.height() - 6; // subtract border
int graph_x_base = 2;
int graph_y_base = 3 + LFO_GRAPH_H / 2;
const int margin = 3;
const int lfoGraphWidth = width() - margin; // subtract margin
const int lfoGraphHeight = height() - 2 * margin; // subtract margin
int graphBaseX = 2;
int graphBaseY = margin + lfoGraphHeight / 2;

const float frames_for_graph =
const float framesForGraph =
SECS_PER_LFO_OSCILLATION * Engine::audioEngine()->baseSampleRate() / 10;

const float gray = 1.0 - fabsf(amount);
const auto red = static_cast<int>(96 * gray);
const auto green = static_cast<int>(255 - 159 * gray);
const auto blue = static_cast<int>(128 - 32 * gray);
const QColor penColor(red, green, blue);
p.setPen(QPen(penColor, 1.5));
float oscFrames = oscillationFrames * (x100 ? 100. : 1.);

float osc_frames = oscillationFrames;
QPolygonF polyLine;
polyLine << QPointF(graphBaseX - 1, graphBaseY);

if (x100) { osc_frames *= 100.0f; }

float old_y = 0;
for (int x = 0; x <= LFO_GRAPH_W; ++x)
// Collect the points for the poly line by sampling the LFO according to its shape
for (int x = 0; x <= lfoGraphWidth; ++x)
{
float val = 0.0;
float cur_sample = x * frames_for_graph / LFO_GRAPH_W;
if (static_cast<f_cnt_t>(cur_sample) > predelayFrames)
float value = 0.0;
float currentSample = x * framesForGraph / lfoGraphWidth;
const auto sampleAsFrameCount = static_cast<f_cnt_t>(currentSample);
if (sampleAsFrameCount > predelayFrames)
{
float phase = (cur_sample -= predelayFrames) / osc_frames;
switch (static_cast<EnvelopeAndLfoParameters::LfoShape>(waveModel))
currentSample -= predelayFrames;
const float phase = currentSample / oscFrames;

const auto lfoShape = static_cast<EnvelopeAndLfoParameters::LfoShape>(lfoWaveModel);
switch (lfoShape)
{
case EnvelopeAndLfoParameters::LfoShape::SineWave:
default:
val = Oscillator::sinSample(phase);
value = Oscillator::sinSample(phase);
break;
case EnvelopeAndLfoParameters::LfoShape::TriangleWave:
val = Oscillator::triangleSample(phase);
value = Oscillator::triangleSample(phase);
break;
case EnvelopeAndLfoParameters::LfoShape::SawWave:
val = Oscillator::sawSample(phase);
value = Oscillator::sawSample(phase);
break;
case EnvelopeAndLfoParameters::LfoShape::SquareWave:
val = Oscillator::squareSample(phase);
value = Oscillator::squareSample(phase);
break;
case EnvelopeAndLfoParameters::LfoShape::RandomWave:
if (x % (int)(900 * lfoSpeed + 1) == 0)
{
m_randomGraph = Oscillator::noiseSample(0.0);
}
val = m_randomGraph;
value = m_randomGraph;
break;
case EnvelopeAndLfoParameters::LfoShape::UserDefinedWave:
val = Oscillator::userWaveSample(m_params->getLfoUserWave().get(), phase);
value = Oscillator::userWaveSample(userWave, phase);
break;
}

if (static_cast<f_cnt_t>(cur_sample) <= attackFrames)
if (sampleAsFrameCount <= attackFrames)
{
val *= cur_sample / attackFrames;
value *= currentSample / attackFrames;
}
}

float cur_y = -LFO_GRAPH_H / 2.0f * val;
p.drawLine(QLineF(graph_x_base + x - 1, graph_y_base + old_y, graph_x_base + x, graph_y_base + cur_y));
old_y = cur_y;
const float currentY = -lfoGraphHeight / 2.0f * value;

polyLine << QPointF(graphBaseX + x, graphBaseY + currentY);
}

// Draw the info text
int ms_per_osc = static_cast<int>(SECS_PER_LFO_OSCILLATION * lfoSpeed * 1000.0);
// Compute the color of the lines based on the amount of the LFO
const float absAmount = std::abs(amount);
const QColor noAmountColor{96, 91, 96};
const QColor fullAmountColor{0, 255, 128};
const QColor lineColor{ColorHelper::interpolateInRgb(noAmountColor, fullAmountColor, absAmount)};

p.setPen(QPen(lineColor, 1.5));

p.drawPolyline(polyLine);

drawInfoText(*params);
}

void LfoGraph::drawInfoText(const EnvelopeAndLfoParameters& params)
{
QPainter p(this);

const float lfoSpeed = params.getLfoSpeedModel().value();
const bool x100 = params.getX100Model().value();

const float hertz = 1. / (SECS_PER_LFO_OSCILLATION * lfoSpeed) * (x100 ? 100. : 1.);
const auto infoText = tr("%1 Hz").arg(hertz, 0, 'f', 3);

// First configure the font so that we get correct results for the font metrics used below
QFont f = p.font();
f.setPixelSize(height() * 0.2);
p.setFont(f);

// This is the position where the text and its rectangle will be rendered
const QPoint textPosition(4, height() - 6);

// Draw a slightly transparent black rectangle underneath the text to keep it legible
const QFontMetrics fontMetrics(f);
// This gives the bounding rectangle if the text was rendered at the origin ...
const auto boundingRect = fontMetrics.boundingRect(infoText);
// ... so we translate it to the actual position where the text will be rendered.
p.fillRect(boundingRect.translated(textPosition), QColor{0, 0, 0, 192});

// Now draw the actual info text
p.setPen(QColor(201, 201, 225));
p.drawText(4, m_lfoGraph.height() - 6, tr("%1 ms/LFO").arg(ms_per_osc));
p.drawText(textPosition, infoText);
}

void LfoGraph::toggleAmountModel()
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