device.cpp

@@ -12,6 +12,8 @@ Device::Device(QObject *parent) :
 
 qint64 Device::readData(char *data, qint64 maxlen)
 {
+    Q_UNUSED(data)
+    Q_UNUSED(maxlen)
     qFatal("oida");
 }
 
@@ -24,7 +26,7 @@ qint64 Device::writeData(const char *data, qint64 len)
 }
 
 FakeDevice::FakeDevice(QObject *parent) :
-    QObject(parent), m_timerId(startTimer(1000/60))
+    QObject(parent), m_timerId(startTimer(1000/60)), m_dingsDesHaltHochZaehlt(0)
 {
 }
 

device.h

@@ -5,10 +5,12 @@
 
 #define qvoid void
 
-struct SamplePair {
+template<typename T> struct SamplePairT {
-    qint16 x, y;
+    T x, y;
 };
 
+typedef SamplePairT<qint16> SamplePair;
+
 class Device : public QIODevice
 {
     Q_OBJECT

mainwindow.cpp

@@ -5,9 +5,10 @@
 #include <QAudioDeviceInfo>
 #include <QButtonGroup>
 
-MainWindow::MainWindow(QWidget *parent) :
+MainWindow::MainWindow(QWidget *parent)
-    QMainWindow(parent),
+    : QMainWindow(parent)
-    m_audioDevices(QAudioDeviceInfo::availableDevices(QAudio::AudioInput))
+    , m_audioDevices(QAudioDeviceInfo::availableDevices(QAudio::AudioInput))
+    , m_ui()
 {
     m_ui.setupUi(this);
 
@@ -16,7 +17,15 @@ MainWindow::MainWindow(QWidget *parent) :
     //connect(&m_fakeDevice, &FakeDevice::samplesReceived, m_ui.widget, &OsciWidget::samplesReceived);
 
     for (const auto &device : m_audioDevices)
-        m_ui.comboBoxDevices->addItem(device.deviceName());
+    {
+        auto name = device.deviceName();
+        m_ui.comboBoxDevices->addItem(name);
+        // Select last element containing monitor if available
+        if(name.contains("monitor"))
+        {
+            m_ui.comboBoxDevices->setCurrentIndex(m_ui.comboBoxDevices->count()-1);
+        }
+    }
 
     for (const auto samplerate : { 44100, 48000, 96000, 192000 })
         m_ui.comboBoxSamplerate->addItem(tr("%0").arg(samplerate), samplerate);
@@ -88,6 +97,9 @@ void MainWindow::toggle()
         format.setCodec("audio/pcm");
         format.setByteOrder(QAudioFormat::LittleEndian);
 
+        if(m_audioDevices.empty()){
+            qFatal("No audio devices found");
+        }
         m_input = std::make_unique<QAudioInput>(m_audioDevices.at(m_ui.comboBoxDevices->currentIndex()), format);
         m_input->start(&m_device);
         m_input->setBufferSize(format.sampleRate()/60*sizeof(qint16)*2);

osciwidget.cpp

@@ -4,25 +4,11 @@
 
 #include <QLine>
 
-namespace {
-template<typename T>
-auto pythagoras(const T &dx, const T &dy)
-{
-    return std::sqrt(dx * dx + dy * dy);
-}
-
-auto pythagoras(const QLine &line)
-{
-    return pythagoras(line.dx(), line.dy());
-}
-}
-
 OsciWidget::OsciWidget(QWidget *parent) :
-    QWidget(parent)
+    QOpenGLWidget(parent)
 {
     restartTimer();
     resizePixmap();
-    createBlendPixmap();
 }
 
 int OsciWidget::framerate() const
@@ -60,7 +46,6 @@ void OsciWidget::setBlend(int blend)
     qDebug() << "change blend to" << blend;
 
     m_blend = blend;
-    createBlendPixmap();
 }
 
 void OsciWidget::setFactor(float factor)
@@ -76,22 +61,26 @@ void OsciWidget::renderSamples(const SamplePair *begin, const SamplePair *end)
 
     QPen pen;
     pen.setWidth(2);
+    pen.setColor(QColor(0, 255, 0));
+    painter.setPen(pen);
+
+    // Paint from center
+    painter.translate(width()/2, height()/2);
 
     for (auto i = begin; i < end; i++)
     {
-        const qint32 x = (float(i->x) / std::numeric_limits<qint16>::max() / 2 * width() / 2 * m_factor) + (width() / 2);
+        const qreal x = (qreal(i->x) / std::numeric_limits<qint16>::max() / 2 * width() / 2 * m_factor);
-        const qint32 y = (float(-i->y) / std::numeric_limits<qint16>::max() / 2 * height() / 2 * m_factor) + (height() / 2);
+        const qreal y = (qreal(i->y) / std::numeric_limits<qint16>::max() / 2 * height() / 2 * m_factor);
-        const QPoint p{x,y};
+        const QPointF p{x, y};
 
         if (Q_LIKELY(m_lastPoint.has_value()))
         {
-            auto dist = pythagoras(QLine(*m_lastPoint, p));
+            auto speed = QLineF(*m_lastPoint, p).length();
-            if (dist < 1)
+            if (speed < 1)
-                dist = 1;
+                speed = 1;
-
+            auto brightness = 1./speed;
-            pen.setColor(QColor(0, 1./dist*255, 0));
-            painter.setPen(pen);
 
+            painter.setOpacity(brightness);
             painter.drawLine(*m_lastPoint, p);
         }
 
@@ -109,10 +98,11 @@ void OsciWidget::paintEvent(QPaintEvent *event)
     painter.begin(this);
     painter.drawPixmap(0, 0, m_pixmap);
     painter.end();
+    // Fade pixmap by multiplying all pixels by m_blend
 
     painter.begin(&m_pixmap);
     painter.setCompositionMode(QPainter::CompositionMode_Multiply);
-    painter.drawPixmap(0, 0, m_fadeoutPixmap);
+    painter.fillRect(m_pixmap.rect(), QColor(m_blend,m_blend,m_blend));
     painter.end();
 }
 
@@ -131,15 +121,23 @@ void OsciWidget::resizeEvent(QResizeEvent *event)
     Q_UNUSED(event)
 
     resizePixmap();
-    createBlendPixmap();
+}
+
+void OsciWidget::stop()
+{
+    if (m_timerId != -1)
+        killTimer(m_timerId);
+}
+
+void OsciWidget::start()
+{
+    m_timerId = startTimer(1000/m_framerate);
 }
 
 void OsciWidget::restartTimer()
 {
-    if (m_timerId != -1)
+    stop();
-        killTimer(m_timerId);
+    start();
-
-    m_timerId = startTimer(1000/m_framerate);
 }
 
 void OsciWidget::resizePixmap()
@@ -147,9 +145,3 @@ void OsciWidget::resizePixmap()
     m_pixmap = QPixmap(size());
     m_pixmap.fill(QColor());
 }
-
-void OsciWidget::createBlendPixmap()
-{
-    m_fadeoutPixmap = QPixmap(size());
-    m_fadeoutPixmap.fill(QColor(m_blend, m_blend, m_blend));
-}

osciwidget.h

@@ -1,6 +1,8 @@
 #pragma once
 
 #include <QWidget>
+
+#include <QOpenGLWidget>
 #include <QDebug>
 #include <QPainter>
 #include <QPixmap>
@@ -12,7 +14,7 @@
 
 #include "device.h"
 
-class OsciWidget : public QWidget
+class OsciWidget : public QOpenGLWidget
 {
     Q_OBJECT
 
@@ -22,6 +24,8 @@ public:
     int framerate() const;
     int blend() const;
     float factor() const;
+    void start();
+    void stop();
 
 public slots:
     void setFramerate(int framerate);
@@ -46,7 +50,6 @@ private:
     float m_factor{4.f};
 
     QPixmap m_pixmap;
-    QPixmap m_fadeoutPixmap;
 
-    std::optional<QPoint> m_lastPoint;
+    std::optional<QPointF> m_lastPoint;
 };