Added MouseEventSpy as base for an auto shutdown

LenaPi/MouseEventSpy.cpp

@@ -0,0 +1,45 @@
+#include "MouseEventSpy.h"
+
+#include <QEvent>
+#include <QGuiApplication>
+#include <QDebug>
+
+MouseEventSpy::MouseEventSpy(QObject *parent) : QObject(parent)
+{
+    qDebug() << "created Instance";
+}
+
+/**
+ * Implements the SINGLETON PATTERN
+ */
+MouseEventSpy* MouseEventSpy::instance()
+{
+    static MouseEventSpy* inst;
+    if (inst == nullptr)
+    {
+        // If no instance has been created yet, create a new and install it as event filter.
+        // Uppon first use of the instance, it will automatically
+        // install itself in the QGuiApplication
+        inst = new MouseEventSpy();
+        QGuiApplication* app = qGuiApp;
+        app->installEventFilter(inst);
+    }
+    return inst;
+}
+
+/**
+ * This is the method is necessary for 'installEventFilter'
+ */
+bool MouseEventSpy::eventFilter(QObject* watched, QEvent* event)
+{
+    QEvent::Type t = event->type();
+    if ((t == QEvent::MouseButtonDblClick
+         || t == QEvent::MouseButtonPress
+         || t == QEvent::MouseButtonRelease
+         || t == QEvent::MouseMove)
+            && event->spontaneous() // Take only mouse events from outside of Qt
+            )
+        emit mouseEventDetected();
+        qDebug("MouseEvent detected.");
+    return QObject::eventFilter(watched, event);
+}