add comments to 'hello there' face

movement/movement_config.h

@@ -20,7 +20,6 @@
 
 const watch_face_t watch_faces[] = {
     simple_clock_face,
-    hello_there_face,
     preferences_face,
     set_time_face,
 };

movement/watch_faces/demos/hello_there_face.c

@@ -4,18 +4,25 @@
 #include "watch.h"
 
 void hello_there_face_setup(movement_settings_t *settings, uint8_t watch_face_index, void ** context_ptr) {
+    // These next two lines just silence the compiler warnings associated with unused parameters.
+    // We have no use for the settings or the watch_face_index, so we make that explicit here.
     (void) settings;
     (void) watch_face_index;
+    // At boot, context_ptr will be NULL indicating that we don't have anyplace to store our context.
     if (*context_ptr == NULL) {
+        // in this case, we allocate an area of memory sufficient to store the stuff we need to track.
         *context_ptr = malloc(sizeof(hello_there_state_t));
-        memset(*context_ptr, 0, sizeof(hello_there_state_t));
     }
 }
 
 void hello_there_face_activate(movement_settings_t *settings, void *context) {
+    // same as above: silence the warning, we don't need to check the settings.
     (void) settings;
+    // we do however need to set some things in our context. Here we cast it to the correct type...
     hello_there_state_t *state = (hello_there_state_t *)context;
+    // ...and set the initial state of our watch face. We start out displaying the word 'Hello',
     state->current_word = 0;
+    // and animate by default.
     state->animating = true;
 }
 
@@ -26,22 +33,45 @@ bool hello_there_face_loop(movement_event_t event, movement_settings_t *settings
     switch (event.event_type) {
         case EVENT_ACTIVATE:
         case EVENT_TICK:
+            // on activate and tick, if we are animating,
             if (state->animating) {
+                // we display the current word,
                 if (state->current_word == 0) watch_display_string("Hello ", 4);
                 else watch_display_string(" there", 4);
+                // and increment it so that it will update on the next tick.
                 state->current_word = (state->current_word + 1) % 2;
             }
             break;
         case EVENT_MODE_BUTTON_UP:
+            // when the user presses 'mode', we tell movement to move to the next watch face.
+            // movement will call our resign function, clear the screen, and transfer control
+            // to the next watch face in the list.
             movement_move_to_next_face();
             break;
         case EVENT_LIGHT_BUTTON_UP:
+            // when the user presses 'light', we illuminate the LED. We could override this if
+            // our UI needed an additional button for input, consuming the light button press
+            // but not illuminating the LED.
             movement_illuminate_led();
             break;
         case EVENT_ALARM_BUTTON_UP:
+            // when the user presses 'alarm', we toggle the state of the animation. If animating,
+            // we stop; if stopped, we resume.
             state->animating = !state->animating;   
             break;
+        case EVENT_LOW_ENERGY_UPDATE:
+            // This low energy mode update occurs once a minute, if the watch face is in the
+            // foreground when Movement enters low energy mode. We have the option of supporting
+            // this mode, but since our watch face animates once a second, the "Hello there" face
+            // isn't very useful in this mode. So we choose not to support it. (continued below)
+            break;
         case EVENT_TIMEOUT:
+            // ... Instead, we respond to the timeout event. This event happens after a configurable
+            // interval on screen (1-30 minutes). The watch will give us this event as a chance to
+            // resign control if we want to, and in this case, we do.
+            // This function will return the watch to the first screen (usually a simple clock),
+            // and it will do it long before the watch enters low energy mode. This ensures we
+            // won't be on screen, and thus opts us out of getting the EVENT_LOW_ENERGY_UPDATE above.
             movement_move_to_face(0);
         default:
             break;
@@ -51,6 +81,8 @@ bool hello_there_face_loop(movement_event_t event, movement_settings_t *settings
 }
 
 void hello_there_face_resign(movement_settings_t *settings, void *context) {
+    // our watch face, like most watch faces, has nothing special to do when resigning.
+    // watch faces that enable a peripheral or interact with a sensor may want to turn it off here.
     (void) settings;
     (void) context;
 }