Detecting Swipe gesture in Qt

In continuation of my previous post of long press gesture in Qt, I created another simple gesture class to detect swipe gesture.

In my implementation, I am storing initial coordinate on mouse press event and comparing initial coordinate with coordinate on mouse release event.In this code I have not considered speed of swipe but we can easily measure speed of swipe by measuring time difference between two event.

myswipegesture.h file

#ifndef MYSWIPEGESTURE_H
#define MYSWIPEGESTURE_H

#include <QObject>
#include <QPoint>

class MySwipeGesture : public QObject
{
    Q_OBJECT
public:
    explicit MySwipeGesture(QObject *parent = 0);
    void handleEvent( QEvent *event);
public:
    enum SwipeDirection {
        Left = 0,
        Right,
        Up,
        Down
    };
signals:
    void handleSwipe( MySwipeGesture::SwipeDirection direction );
private:
    QPoint _startPoint;
    QPoint _endPoint;
};
#endif // MYSWIPEGESTURE_H

myswipegesture.cpp file

#include "myswipegesture.h"
#include <QEvent>
#include <QMouseEvent>

MySwipeGesture::MySwipeGesture(QObject *parent)
    :QObject(parent),_startPoint(0,0),_endPoint(0,0)
{}

void MySwipeGesture::handleEvent( QEvent *event)
{
    if( event->type() == QEvent::MouseButtonPress ) {
    QMouseEvent* mouseEvent = static_cast<QMouseEvent*> (event);
        _startPoint = mouseEvent->pos();
    } else if( event->type() == QEvent::MouseButtonRelease ) {
    QMouseEvent* mouseEvent = static_cast<QMouseEvent*> (event);
        _endPoint = mouseEvent->pos();

        //process distance and direction
        int xDiff = _startPoint.x() - _endPoint.x();
        int yDiff = _startPoint.y() - _endPoint.y();
        if( qAbs(xDiff) > qAbs(yDiff) ) {
            // horizontal swipe detected, now find direction
            if( _startPoint.x() > _endPoint.x() ) {
                emit handleSwipe( Left);
            } else {
                emit handleSwipe( Right);
            }
        } else {
            // vertical swipe detected, now find direction
            if( _startPoint.y() > _endPoint.y() ) {
                emit handleSwipe( Up);
            } else {
                emit handleSwipe( Down);
            }
        }
    } else if( event->type() == QEvent::MouseMove ) {
        //ignore event
    }
}

Some test code.

#include "myswipegesture.h"

TestWidget::TestWidget(QWidget *parent) : QWidget(parent)
{
    _swipeGesture = new MySwipeGesture(this);
    connect(_swipeGesture,SIGNAL(handleSwipe(MySwipeGesture::SwipeDirection)),this,SLOT(swipe(MySwipeGesture::SwipeDirection)));
}

bool TestWidget::event(QEvent *event)
{
    _swipeGesture->handleEvent(event);
    return QWidget::event(event);
}

void TestWidget::swipe(MySwipeGesture::SwipeDirection direction)
{
    qDebug() << "swipe" << direction;
}

Hope this helps.