added timer

mainwindow.h

@@ -4,6 +4,7 @@
 #include <QMainWindow>
 #include <QSettings>
 #include <QStateMachine>
+#include <QTimer>
 
 namespace Ui {
 class MainWindow;
@@ -21,16 +22,22 @@ public:
 
 private slots:
     void on_btn_startstop_clicked();
+    void updateTime();
 
 private:
     Ui::MainWindow *ui;
 
     QSettings* mSettings = nullptr;
-    QStateMachine mState;
+    QStateMachine mStateMachine;
     QByteArray mCss;
+    QTimer mTimer;
+    int mTimeLeft = -1; // in seconds
 
     void initStateMachine();
     void triggerCssUpdate();
+    void keyPressEvent(QKeyEvent *event) override;
+    void timerToggled();
+    void shutdown();
 };
 
 }