Make LenaPi usable on Android devices

- Add app icon
- prevend android device from shutting down cpu while playing music
- fix scaling bug
- fix energy saver for RasPi by reconnecting to music player
- minor refactorings and renaming

LenaPi/EnergySaver.h

@@ -4,27 +4,39 @@
 #include <QObject>
 #include <QTimer>
 
+#ifdef ANDROID
+#include <qandroidjniobject.h>
+#endif
+
 /**
  * @brief Class handling energy saving options.
  *
- * Shut down device if no mouse input is detected and music player
- * has not been active or a certain time interval.
+ * On Android devices, it locks the cpu shutdown while active. On other devices, it
+ * will shut down device on timeout if the options are set accordingly and a shutdown script
+ * is provided.
  *
- * @todo For now this does only work for Lena's RasPi, where the
- * shutdown script is positioned in a ceratin hardcoded path.
- * Enable/disable energy saving option, timeout and path of
- * shutdown script via config
+ * In the context of the LenaPi application, it will prevent cpu shutdown on android devices while playing
+ * music. On other devices, it will shutdown the device if no music has been playing and no mouse input was
+ * detected for a certain time intervall.
  */
 class EnergySaver : public QObject
 {
     Q_OBJECT
 
 protected:
-    explicit EnergySaver(QObject *parent = nullptr) : QObject(parent) {}
+    using QObject::QObject;
 
 public:
+    ~EnergySaver();
+    /**
+     * @brief Create instance if necessary. The instance will have auto shutdown disabeld.
+     *
+     * Used to prevent sleep on android devices.
+     */
+    static void init();
     /**
      * @brief Create instance if necessary, configure it and start timer.
+     * @param enabledAutoShutdown Defines whether device will shutdown on inactivity using shutdownScript
      * @param interval Timer interval in seconds
      * @param shutdownScript Path to shutdown script file
      * @see EnergySaver::instance
@@ -43,7 +55,19 @@ public:
 
 public slots:
     /**
-     * @brief Restart shutdown timer, e.g. because of music player activiti
+     * @brief Deactivate energy saver, e.g., as music is currently playing
+     *
+     * Sets locks on adroid devics and stops shutdown-timer.
+     */
+    void deactivate();
+    /**
+     * @brief Active energy saver
+     *
+     * Releases locks on android devices and restarts shutdown-timer if shutdown option is set.
+     */
+    void activate();
+    /**
+     * @brief Restart shutdown timer, e.g. because of music player activity
      */
     void restartTimer();
 
@@ -54,8 +78,31 @@ private:
      */
     void initTimer(int interval);
     void setShutdownScript(const QString& shutdownScript);
+    /**
+     * @brief Initializes locking or Android devices
+     */
+    void initAdroidLocks();
+    /**
+     * @brief Sets locks on Android devices to prevent sleep.
+     *
+     * Used to prevent cpu sleep as otherwise music will stop.
+     */
+    void setAndroidLock();
+    /**
+     * @brief Releases locks on Android devices to allow the device's cpu to go into sleep mode.
+     */
+    void releaseAndroidLock();
     QTimer mTimer;
     QString mShutdownScript;
+    bool mIsActive{false};
+    bool mIsAutoShutDownEnabled{false};
+
+#ifdef ANDROID
+    /**
+     * @brief Prevent energy saving for Android devices
+     */
+    QAndroidJniObject m_wakeLock;
+#endif
 
 private slots:
     /**
@@ -63,6 +110,7 @@ private slots:
      */
     void onTimeout();
 
+
 };
 
 #endif // ENERGYSAVER_H