Use NMEA speed data if available

Now using median speed filtering

src/gpx.cpp

@@ -3,9 +3,12 @@
 #include "ll.h"
 #include "gpx.h"
 
+#include <QDebug>
+
+
+#define ALPHA  0.5
+#define WINDOW 5
 
-#define ALPHA_E 0.5
-#define ALPHA_S 0.1
 
 bool GPX::loadFile(const QString &fileName)
 {
@@ -38,14 +41,25 @@ void GPX::elevationGraph(QVector<QPointF> &graph) const
 	for (int i = 1; i < _data.size(); i++) {
 		dist += llDistance(_data.at(i).coordinates, _data.at(i-1).coordinates);
 		dh = _data.at(i).elevation;
-		acc = (i == 1) ? dh : (ALPHA_E * dh) + (1.0 - ALPHA_E) * acc;
+		acc = (i == 1) ? dh : (ALPHA * dh) + (1.0 - ALPHA) * acc;
 		graph.append(QPointF(dist, acc));
 	}
 }
 
+static bool lt(const QPointF &p1, const QPointF &p2)
+{
+	return p1.y() < p2.y();
+}
+
+static qreal median(QVector<QPointF> v)
+{
+	qSort(v.begin(), v.end(), lt);
+	return v.at(v.size() / 2).y();
+}
+
 void GPX::speedGraph(QVector<QPointF> &graph) const
 {
-	qreal dist = 0, v, ds, dt, acc;
+	qreal dist = 0, v, ds, dt;
 
 	if (!_data.size())
 		return;
@@ -54,13 +68,21 @@ void GPX::speedGraph(QVector<QPointF> &graph) const
 	for (int i = 1; i < _data.size(); i++) {
 		ds = llDistance(_data.at(i).coordinates, _data.at(i-1).coordinates);
 		dt = _data.at(i-1).timestamp.msecsTo(_data.at(i).timestamp) / 1000.0;
+		dist += ds;
+
+		if (_data.at(i).speed < 0) {
 			if (dt == 0)
 				continue;
-		dist += ds;
 			v = ds / dt;
-		acc = (i == 1) ? v : (ALPHA_S * v) + (1.0 - ALPHA_S) * acc;
-		graph.append(QPointF(dist, acc));
+		} else
+			v = _data.at(i).speed;
+
+		graph.append(QPointF(dist, v));
 	}
+
+	if (graph.size() > WINDOW)
+		for (int i = WINDOW/2; i < graph.size() - WINDOW/2; i++)
+			graph[i].setY(median(graph.mid(i - WINDOW/2, WINDOW)));
 }
 
 void GPX::track(QVector<QPointF> &track) const

src/parser.cpp

@@ -1,5 +1,14 @@
 #include "parser.h"
 
+#include <QDebug>
+
+
+void Parser::handleExtensionData(QVector<TrackPoint> &data,
+  QStringRef element, const QString &value)
+{
+	if (element == "speed")
+		data.last().speed = value.toDouble();
+}
 
 void Parser::handleTrekPointData(QVector<TrackPoint> &data,
   QStringRef element, const QString &value)
@@ -19,11 +28,23 @@ void Parser::handleTrekPointAttributes(QVector<TrackPoint> &data,
 }
 
 
+void Parser::extensions(QVector<TrackPoint> &data)
+{
+	while (_reader.readNextStartElement()) {
+		if (_reader.name() == "speed")
+			handleExtensionData(data, _reader.name(), _reader.readElementText());
+		else
+			_reader.skipCurrentElement();
+	}
+}
+
 void Parser::trekPointData(QVector<TrackPoint> &data)
 {
 	while (_reader.readNextStartElement()) {
 		if (_reader.name() == "ele" || _reader.name() == "time")
 			handleTrekPointData(data, _reader.name(), _reader.readElementText());
+		else if (_reader.name() == "extensions")
+			extensions(data);
 		else
 			_reader.skipCurrentElement();
 	}

src/parser.h

@@ -10,6 +10,9 @@ struct TrackPoint
 	QPointF coordinates;
 	QDateTime timestamp;
 	qreal elevation;
+	qreal speed;
+
+	TrackPoint() {speed = -1;}
 };
 
 class Parser
@@ -23,12 +26,15 @@ private:
 	void gpx(QVector<TrackPoint> &data);
 	void trek(QVector<TrackPoint> &data);
 	void trekPoints(QVector<TrackPoint> &data);
+	void extensions(QVector<TrackPoint> &data);
 	void trekPointData(QVector<TrackPoint> &data);
 
 	void handleTrekPointAttributes(QVector<TrackPoint> &data,
 	  const QXmlStreamAttributes &attr);
 	void handleTrekPointData(QVector<TrackPoint> &data, QStringRef element,
 	  const QString &value);
+	void handleExtensionData(QVector<TrackPoint> &data, QStringRef element,
+	  const QString &value);
 
 	QXmlStreamReader _reader;
 };

src/speedgraph.cpp

@@ -1,5 +1,7 @@
 #include "speedgraph.h"
 
+#include <QDebug>
+
 SpeedGraph::SpeedGraph()
 {
 	_max = 0;
@@ -14,26 +16,35 @@ SpeedGraph::SpeedGraph()
 
 void SpeedGraph::loadData(const QVector<QPointF> &data)
 {
-	qreal max = 0, sum = 0, avg, distance, w;
+	qreal max = 0, sum = 0, w = 0, avg;
+	qreal dist;
+
+	if (data.size() < 2)
+		return;
+
+	dist = data.at(data.size() - 1).x() - data.at(0).x();
 
-	distance = (data.at(data.size() - 1).x() - data.at(0).x());
 
 	for (int i = 1; i < data.size(); i++) {
-		qreal val = data.at(i).y();
+		QPointF cur = data.at(i);
+		QPointF prev = data.at(i-1);
+		qreal ds = cur.x() - prev.x();
 
-		sum += val;
+		if (cur.y() == 0)
+			continue;
+		sum += ds;
+		w += ds / cur.y();
 
-		if (val > max)
-			max = val;
+		max = qMax(max, cur.y());
 	}
-	avg = sum / data.size();
+	avg = sum / w;
 
-	_avg.append(QPointF(avg, distance));
+	_avg.append(QPointF(dist, avg));
 
 	sum = 0; w = 0;
 	for (QList<QPointF>::iterator it = _avg.begin(); it != _avg.end(); it++) {
-		sum += it->x() * it->y();
-		w += it->y();
+		sum += it->y() * it->x();
+		w += it->x();
 	}
 	avg = sum / w;