bool mouseEventsFilter::eventFilter(QObject *obj, QEvent *e) {
    static bool mousePressed = false;
    if(e->type() == QEvent::MouseMove && mousePressed) {
        QMouseEvent *event = static_cast<QMouseEvent*>(e);
        qDebug()<<"moved:"<<event->x();
    } else if(e->type() == QEvent::MouseButtonPress) {
        qDebug()<<"pressed";
        mousePressed = true;
    } else if(e->type() == QEvent::MouseButtonRelease) {
        qDebug()<<"released";
        mousePressed = false;
    }

    return QObject::eventFilter(obj, e);
}

import QtQuick 2.2
import QtQuick.Window 2.1

Window {
    visible: true
    width: 360
    height: 360

    MouseArea {
        anchors.fill: parent
    }

    Text {
        text: qsTr("Hello World")
        anchors.centerIn: parent
    }
}