From 03eb1cd97019422318396446929dc0de178ec4ae Mon Sep 17 00:00:00 2001
From: Hannes Matuschek <hmatuschek@gmail.com>
Date: Wed, 23 Jul 2014 18:36:40 +0200
Subject: [PATCH] Implemented waterfall spectrogram.

---
 src/gui/gui.hh           |  1 +
 src/gui/waterfallview.cc | 83 ++++++++++++++++++++++++++++++++++++++--
 src/gui/waterfallview.hh | 58 +++++++++++++++++++++++++++-
 3 files changed, 137 insertions(+), 5 deletions(-)

diff --git a/src/gui/gui.hh b/src/gui/gui.hh
index ea7d540..63036f9 100644
--- a/src/gui/gui.hh
+++ b/src/gui/gui.hh
@@ -2,5 +2,6 @@
 #define __SDR_GUI_GUI_HH__
 
 #include "spectrumview.hh"
+#include "waterfallview.hh"
 
 #endif
diff --git a/src/gui/waterfallview.cc b/src/gui/waterfallview.cc
index f647364..00fdbd2 100644
--- a/src/gui/waterfallview.cc
+++ b/src/gui/waterfallview.cc
@@ -1,11 +1,88 @@
 #include "waterfallview.hh"
+#include <QPainter>
+#include <QPaintEvent>
 
 using namespace sdr;
 using namespace sdr::gui;
 
 
-WaterFallView::WaterFallView(Spectrum *spectrum, QWidget *parent)
-  : QWidget(parent), _spectrum(spectrum)
-{
 
+/* ****************************************************************************************** *
+ *  Implementation of ColorMap
+ * ****************************************************************************************** */
+ColorMap::ColorMap() {
+  // pass...
 }
+
+ColorMap::~ColorMap() {
+  // pass...
+}
+
+/* ****************************************************************************************** *
+ *  Implementation of GrayScaleColorMap
+ * ****************************************************************************************** */
+GrayScaleColorMap::GrayScaleColorMap(double mindB)
+  : ColorMap(), _mindB(mindB)
+{
+  // pass...
+}
+
+GrayScaleColorMap::~GrayScaleColorMap() {
+  // pass...
+}
+
+QColor
+GrayScaleColorMap::operator ()(const double &value) {
+  if (value > 0) { return Qt::white; }
+  if (value < _mindB) { return Qt::black; }
+  int h = (255*(value-_mindB))/std::abs(_mindB);
+  return QColor(h,h,h);
+}
+
+
+/* ****************************************************************************************** *
+ *  Implementation of GrayScaleColorMap
+ * ****************************************************************************************** */
+WaterFallView::WaterFallView(Spectrum *spectrum, size_t height, QWidget *parent)
+  : QWidget(parent), _spectrum(spectrum), _N(_spectrum->fftSize()), _M(height), _waterfall(_N,_M)
+{
+  // Fill waterfall pixmap
+  _waterfall.fill(Qt::black);
+  // Create color map
+  _colorMap = new GrayScaleColorMap();
+
+  // Get notified once a new spectrum is available:
+  QObject::connect(_spectrum, SIGNAL(spectrumUpdated()), this, SLOT(_onSpectrumUpdated()));
+}
+
+void
+WaterFallView::_onSpectrumUpdated() {
+  if (_waterfall.isNull() || (_M==0) || (_N==0)) { return; }
+  QPainter painter(&_waterfall);
+  // scroll pixmap one pixel up
+  QRect target(0,0, _N, _M-1), source(0,1,_N,_M-1);
+  painter.drawPixmap(target, _waterfall, source);
+
+  // Draw new spectrum
+  for (size_t i=0; i<_N; i++) {
+    double value = 10*log10(_spectrum->spectrum()[i])-10*log10(_N);
+    painter.setPen((*_colorMap)(value));
+    painter.drawPoint(i, _M-1);
+  }
+
+  // Trigger update
+  this->update();
+}
+
+void
+WaterFallView::paintEvent(QPaintEvent *evt) {
+  QPainter painter(this);
+  painter.save();
+  // Draw scaled pixmap
+  painter.drawPixmap(evt->rect(), _waterfall.scaled(this->width(), this->height()), evt->rect());
+  painter.restore();
+}
+
+
+
+
diff --git a/src/gui/waterfallview.hh b/src/gui/waterfallview.hh
index 2b54b9f..40bbcc9 100644
--- a/src/gui/waterfallview.hh
+++ b/src/gui/waterfallview.hh
@@ -9,16 +9,70 @@
 namespace sdr {
 namespace gui {
 
+/** Interface for all color maps. */
+class ColorMap
+{
+protected:
+  /** Hidden constructor. */
+  ColorMap();
+
+public:
+  /** Destructor. */
+  virtual ~ColorMap();
+  /** Needs to be implemented by all sub-classes. Maps the value (dB) to a color value. */
+  virtual QColor operator()(const double &value) = 0;
+};
+
+/** A simple gray-scale color map. */
+class GrayScaleColorMap: public ColorMap
+{
+public:
+  /** Constructor.
+   * @param mindB Specifices the minimum value in dB of the color-scale. Mapping values [0, mindB]
+   * to a gray-scale. */
+  GrayScaleColorMap(double mindB=-120);
+  /** Destructor. */
+  virtual ~GrayScaleColorMap();
+  /** Implements the color mapping. */
+  virtual QColor operator()(const double &value);
+
+protected:
+  /** The minimum value. */
+  double _mindB;
+};
+
+
+/** A simple waterfall display of the spectrogram. */
 class WaterFallView : public QWidget
 {
   Q_OBJECT
 
 public:
-  explicit WaterFallView(Spectrum *spectrum, QWidget *parent = 0);
+  /** Constructor.
+   * @param spectrum Specifies the spectrum sink.
+   * @param height Specifies the number of PSDs to display.
+   * @param parent The parent widget. */
+  explicit WaterFallView(Spectrum *spectrum, size_t height=100, QWidget *parent = 0);
 
 protected:
+  /** Draws the scaled waterfall spectrogram. */
+  virtual void paintEvent(QPaintEvent *evt);
+
+protected slots:
+  /** Gets called once a new PSD is available. */
+  void _onSpectrumUpdated();
+
+protected:
+  /** The spectrum sink. */
   Spectrum *_spectrum;
-  QImage *_waterfall;
+  /** The size of the spectrum. */
+  size_t _N;
+  /** "Height of the spectrum. */
+  size_t _M;
+  /** The waterfall spectrogram. */
+  QPixmap _waterfall;
+  /** The color map to be used. */
+  ColorMap *_colorMap;
 };
 
 }