Initial commit including a linear color smoother

Former-commit-id: ffc00087996324f989e56dc5c95ab734c7c86dfa

libsrc/hyperion/LinearColorSmoothing.cpp

@@ -0,0 +1,91 @@
+// Qt includes
+#include <QDateTime>
+
+#include "LinearColorSmoothing.h"
+
+LinearColorSmoothing::LinearColorSmoothing(LedDevice *ledDevice, double ledUpdateFrequency, double settlingTime) :
+	QObject(),
+	LedDevice(),
+	_ledDevice(ledDevice),
+	_updateInterval(1000.0 / ledUpdateFrequency),
+	_settlingTime(1000 * settlingTime),
+	_timer()
+{
+	_timer.setSingleShot(false);
+	_timer.setInterval(_updateInterval);
+
+	connect(&_timer, SIGNAL(timeout()), this, SLOT(updateLeds()));
+}
+
+LinearColorSmoothing::~LinearColorSmoothing()
+{
+	delete _ledDevice;
+}
+
+int LinearColorSmoothing::write(const std::vector<RgbColor> &ledValues)
+{
+	// received a new target color
+	if (_previousValues.size() == 0)
+	{
+		// not initialized yet
+		_targetTime = QDateTime::currentMSecsSinceEpoch() + _settlingTime;
+		_targetValues = ledValues;
+
+		_previousTime = QDateTime::currentMSecsSinceEpoch();
+		_previousValues = ledValues;
+		_timer.start();
+	}
+	else
+	{
+		_targetTime = QDateTime::currentMSecsSinceEpoch() + _settlingTime;
+		memcpy(_targetValues.data(), ledValues.data(), ledValues.size() * sizeof(RgbColor));
+	}
+
+	return 0;
+}
+
+int LinearColorSmoothing::switchOff()
+{
+	// stop smoothing filter
+	_timer.stop();
+
+	// return to uninitialized state
+	_previousValues.clear();
+	_previousTime = 0;
+	_targetValues.clear();
+	_targetTime = 0;
+
+	// finally switch off all leds
+	return _ledDevice->switchOff();
+}
+
+void LinearColorSmoothing::updateLeds()
+{
+	int64_t now = QDateTime::currentMSecsSinceEpoch();
+	int deltaTime = _targetTime - now;
+
+	if (deltaTime < 0)
+	{
+		memcpy(_previousValues.data(), _targetValues.data(), _targetValues.size() * sizeof(RgbColor));
+		_previousTime = now;
+
+		_ledDevice->write(_previousValues);
+	}
+	else
+	{
+		float k = 1.0f - 1.0f * deltaTime / (_targetTime - _previousTime);
+
+		for (size_t i = 0; i < _previousValues.size(); ++i)
+		{
+			RgbColor & prev = _previousValues[i];
+			RgbColor & target = _targetValues[i];
+
+			prev.red   += k * (target.red   - prev.red);
+			prev.green += k * (target.green - prev.green);
+			prev.blue  += k * (target.blue  - prev.blue);
+		}
+		_previousTime = now;
+
+		_ledDevice->write(_previousValues);
+	}
+}