Add time and frequency pointers

src/mainwindow.cpp

@@ -45,6 +45,8 @@ MainWindow::MainWindow()
     // Connect dock inputs
     connect(dock, &SpectrogramControls::openFile, this, &MainWindow::openFile);
     connect(dock->sampleRate, static_cast<void (QLineEdit::*)(const QString&)>(&QLineEdit::textChanged), this, static_cast<void (MainWindow::*)(QString)>(&MainWindow::setSampleRate));
+    connect(dock->timePointerCheckBox, &QCheckBox::stateChanged, plots, &PlotView::enableTimePointer);
+    connect(dock->frequencyPointerCheckBox, &QCheckBox::stateChanged, plots, &PlotView::enableFrequencyPointer);
     connect(dock, static_cast<void (SpectrogramControls::*)(int, int)>(&SpectrogramControls::fftOrZoomChanged), plots, &PlotView::setFFTAndZoom);
     connect(dock->powerMaxSlider, &QSlider::valueChanged, plots, &PlotView::setPowerMax);
     connect(dock->powerMinSlider, &QSlider::valueChanged, plots, &PlotView::setPowerMin);

src/plotview.cpp

@@ -50,6 +50,8 @@ PlotView::PlotView(InputSource *input) : cursors(this), viewRange({0, 0})
     auto tunerOutput = std::dynamic_pointer_cast<SampleSource<std::complex<float>>>(spectrogramPlot->output());
 
     enableScales(true);
+    timePointerEnabled = false;
+    frequencyPointerEnabled = false;
 
     enableAnnotations(true);
     enableAnnotationCommentsTooltips(true);
@@ -223,6 +225,21 @@ void PlotView::enableCursors(bool enabled)
     viewport()->update();
 }
 
+void PlotView::enableTimePointer(bool enabled)
+{
+    timePointerEnabled = enabled;
+    spectrogramPlot->enableTimeFrequencyPointers(timePointerEnabled, frequencyPointerEnabled);
+
+    viewport()->update();
+}
+
+void PlotView::enableFrequencyPointer(bool enabled)
+{
+    frequencyPointerEnabled = enabled;
+    spectrogramPlot->enableTimeFrequencyPointers(timePointerEnabled, frequencyPointerEnabled);
+
+    viewport()->update();
+}
 bool PlotView::viewportEvent(QEvent *event) {
     // Handle wheel events for zooming (before the parent's handler to stop normal scrolling)
     if (event->type() == QEvent::Wheel) {
@@ -286,6 +303,9 @@ bool PlotView::viewportEvent(QEvent *event) {
         if (cursorsEnabled)
             if (cursors.mouseEvent(event->type(), mouseEvent))
                 return true;
+
+        if (timePointerEnabled || frequencyPointerEnabled)
+            updateView();
     }
 
     if (event->type() == QEvent::Leave) {

src/plotview.h

@@ -44,6 +44,8 @@ class PlotView : public QGraphicsView, Subscriber
 
 public slots:
     void cursorsMoved();
+    void enableTimePointer(bool enabled);
+    void enableFrequencyPointer(bool enabled);
     void enableCursors(bool enabled);
     void enableScales(bool enabled);
     void enableAnnotations(bool enabled);
@@ -79,6 +81,8 @@ public slots:
     int zoomLevel = 1;
     int powerMin;
     int powerMax;
+    bool timePointerEnabled;
+    bool frequencyPointerEnabled;
     bool cursorsEnabled;
     double sampleRate = 0.0;
     bool timeScaleEnabled;

src/spectrogramcontrols.cpp

@@ -41,6 +41,12 @@ SpectrogramControls::SpectrogramControls(const QString & title, QWidget * parent
     sampleRate->setValidator(double_validator);
     layout->addRow(new QLabel(tr("Sample rate:")), sampleRate);
 
+    // Frequency and time pointer settings
+    frequencyPointerCheckBox = new QCheckBox(widget);
+    layout->addRow(new QLabel(tr("Enable frequency pointer:")), frequencyPointerCheckBox);
+    timePointerCheckBox = new QCheckBox(widget);
+    layout->addRow(new QLabel(tr("Enable time pointer:")), timePointerCheckBox);
+
     // Spectrogram settings
     layout->addRow(new QLabel()); // TODO: find a better way to add an empty row?
     layout->addRow(new QLabel(tr("<b>Spectrogram</b>")));

src/spectrogramcontrols.h

@@ -63,6 +63,8 @@ private slots:
 public:
     QPushButton *fileOpenButton;
     QLineEdit *sampleRate;
+    QCheckBox *timePointerCheckBox;
+    QCheckBox *frequencyPointerCheckBox;
     QSlider *fftSizeSlider;
     QSlider *zoomLevelSlider;
     QSlider *powerMaxSlider;

src/spectrogramplot.cpp

@@ -42,6 +42,8 @@ SpectrogramPlot::SpectrogramPlot(std::shared_ptr<SampleSource<std::complex<float
     sampleRate = 0;
     frequencyScaleEnabled = false;
     sigmfAnnotationsEnabled = true;
+    timePointerEnabled = false;
+    frequencyPointerEnabled = false;
 
     for (int i = 0; i < 256; i++) {
         float p = (float)i / 256;
@@ -72,6 +74,54 @@ void SpectrogramPlot::paintFront(QPainter &painter, QRect &rect, range_t<size_t>
 
     if (sigmfAnnotationsEnabled)
         paintAnnotations(painter, rect, sampleRange);
+
+    if (timePointerEnabled || frequencyPointerEnabled)
+        paintTimeFrequencyPointers(painter, rect, sampleRange);
+}
+
+void SpectrogramPlot::paintTimeFrequencyPointers(QPainter &painter, QRect &rect, range_t<size_t> sampleRange)
+{
+    if (sampleRate == 0) {
+        return;
+    }
+
+    if (sampleRate / 2 > UINT64_MAX) {
+        return;
+    }
+
+    int plotHeight = rect.height();
+    if (inputSource->realSignal())
+        plotHeight *= 2;
+
+    double bwPerPixel = (double)sampleRate / plotHeight;
+
+    painter.save();
+
+    QPen pen(Qt::white, 1, Qt::SolidLine);
+    painter.setPen(pen);
+    QFontMetrics fm(painter.font());
+
+
+    char buf[128];
+    if (frequencyPointerEnabled) {
+        int freqHz = ((plotHeight / 2) - mouseY) * bwPerPixel;
+        snprintf(buf, sizeof(buf), "Frequency: %d Hz", freqHz);
+
+        painter.drawLine(0, mouseY, mouseX, mouseY);
+        painter.drawText(mouseX + 15, mouseY, buf);
+    }
+    if (timePointerEnabled) {
+        float timeStart = sampleRange.minimum / sampleRate;
+        float timeEnd = sampleRange.maximum / sampleRate;
+        float secondsPerPixel = (timeEnd - timeStart) / rect.width();
+        float timeAtPointer = timeStart + mouseX * secondsPerPixel;
+        snprintf(buf, sizeof(buf), "Time: %.6f s", timeAtPointer);
+
+        painter.drawText(mouseX + 15, mouseY + fm.height(), buf);
+        painter.drawLine(mouseX, 0, mouseX, mouseY);
+    }
+
+    painter.restore();
 }
 
 void SpectrogramPlot::paintFrequencyScale(QPainter &painter, QRect &rect)
@@ -356,6 +406,11 @@ bool SpectrogramPlot::mouseEvent(QEvent::Type type, QMouseEvent *event)
     if (tunerEnabled())
         return tuner.mouseEvent(type, event);
 
+    if (timePointerEnabled || frequencyPointerEnabled) {
+        mouseX = event->x();
+        mouseY = event->y();
+    }
+
     return false;
 }
 
@@ -448,6 +503,11 @@ void SpectrogramPlot::tunerMoved()
     emit repaint();
 }
 
+void SpectrogramPlot::enableTimeFrequencyPointers(bool timePointer, bool frequencyPointer) {
+    timePointerEnabled = timePointer;
+    frequencyPointerEnabled = frequencyPointer;
+}
+
 uint qHash(const TileCacheKey &key, uint seed)
 {
     return key.fftSize ^ key.zoomLevel ^ key.sample ^ seed;

src/spectrogramplot.h

@@ -74,6 +74,7 @@ class SpectrogramPlot : public Plot
     bool tunerEnabled();
     void enableScales(bool enabled);
     void enableAnnotations(bool enabled);
+    void enableTimeFrequencyPointers(bool timePointer, bool frequencyPointer);
     bool isAnnotationsEnabled();
     QString *mouseAnnotationComment(const QMouseEvent *event);
 
@@ -103,6 +104,11 @@ public slots:
     double sampleRate;
     bool frequencyScaleEnabled;
     bool sigmfAnnotationsEnabled;
+    bool timePointerEnabled;
+    bool frequencyPointerEnabled;
+
+    int mouseX;
+    int mouseY;
 
     Tuner tuner;
     std::shared_ptr<TunerTransform> tunerTransform;
@@ -116,6 +122,7 @@ public slots:
     int linesPerTile();
     void paintFrequencyScale(QPainter &painter, QRect &rect);
     void paintAnnotations(QPainter &painter, QRect &rect, range_t<size_t> sampleRange);
+    void paintTimeFrequencyPointers(QPainter &painter, QRect &rect, range_t<size_t> sampleRange);
 };
 
 class AnnotationLocation