WebCore::GestureSpeedCalc Class Reference

Class for calculating value deltas. More...

#include <GestureSpeedCalc.h>

Public Member Functions
	GestureSpeedCalc ()
void	firstSample (double timestamp, double sample)
	Insert first sample.
void	insertSample (double timestamp, double sample)
	Insert subsequent samples.
double	speed () const
	Query the current speed of data value change.
Private Attributes
double	m_prevTimeStamp
double	m_prevSample
double	m_speed
double	m_prevRawSpeed

Detailed Description

Class for calculating value deltas.

GestureSpeedCalc objects are used by gesture recognizers to determine value deltas, aka. speed values. Values are fed into GestureSpeedCalc as timestamp,value pairs and a simple floating point value for the speed can be queried.

Definition at line 24 of file GestureSpeedCalc.h.

Constructor & Destructor Documentation

WebCore::GestureSpeedCalc::GestureSpeedCalc ( )

Definition at line 26 of file GestureSpeedCalc.cpp.

Member Function Documentation

void WebCore::GestureSpeedCalc::firstSample	(	double	timestamp,
		double	sample
	)

Insert first sample.

Insert the first data sample. Initializes the previous state if any, and sets speed to 0.

Parameters:

	timestamp	Timestamp of data.
	sample	Data value at the given timestamp.

See also:: insertSample; speed

Definition at line 43 of file GestureSpeedCalc.cpp.

References m_prevRawSpeed, m_prevSample, m_prevTimeStamp, and m_speed.

void WebCore::GestureSpeedCalc::insertSample	(	double	timestamp,
		double	sample
	)

Insert subsequent samples.

Insert sample and possibly update speed depending on timestamp difference to previous sample(s).

Parameters:

	timestamp	Timestamp of data.
	sample	Data value at the given timestamp.

See also:: speed

Definition at line 59 of file GestureSpeedCalc.cpp.

References m_prevRawSpeed, m_prevSample, m_prevTimeStamp, m_speed, WebCore::speedAveragingTime, and WebCore::updateSpeedTimeThreshold.

WebCore::GestureSpeedCalc::speed ( ) const [inline]

Query the current speed of data value change.

Queries the current speed at which the data is changing. The speed is determined by the difference between the last two accepted data samples, divided by time difference. Only samples with an undefined time interval between them are considered for speed calculations.