 {
     /* Init Mono OLED 128x64 for Arduboy. 6 - RESET, 12 - CS, 4 - D/C */
     ssd1306_128x64_spi_init(6, 12, 4);
-
+    /* initialize engine */
     engine.begin();
-    engine.setFrameRate(45);
+    engine.setFrameRate(45);          // Set frame rate
     engine.drawCallback( drawAll );  // Set callback to draw content
     engine.connectArduboyKeys();     // Connect Arduboy keypad
     engine.refresh();                // Makes engine to refresh whole display content at start-up


void loop()
{
    if (!engine.nextFrame()) return;
    NanoPoint point = {0,0};
    if (engine.pressed( BUTTON_RIGHT )) point.x = +1;
    if (engine.pressed( BUTTON_LEFT ))  point.x = -1;
    if (engine.pressed( BUTTON_UP ))    point.y = -1;


NanoEngine1 engine;

/* Define rect to move on the display */
NanoRect rect = { {15,12}, {60,35} }; 

/*
 * This function is called every time engine needs to refresh display content.
 * Just draw here all you need as usual.
 * If the function returns false, then block, pointed by engine.canvas.offset will
 * not be refreshed
 */
bool drawAll()
{
    engine.canvas.clear();
