made caching not happen sooner than needed when switching faces

movement.c

@@ -59,6 +59,7 @@ void * watch_face_contexts[MOVEMENT_NUM_FACES];
 watch_date_time_t scheduled_tasks[MOVEMENT_NUM_FACES];
 const int32_t movement_le_inactivity_deadlines[8] = {INT_MAX, 600, 3600, 7200, 21600, 43200, 86400, 604800};
 const int16_t movement_timeout_inactivity_deadlines[4] = {60, 120, 300, 1800};
+static watch_date_time_t _dst_last_cache;
 movement_event_t event;
 
 int8_t _movement_dst_offset_cache[NUM_ZONE_NAMES] = {0};
@@ -115,11 +116,10 @@ static watch_date_time_t _movement_convert_udate_to_date_time(udatetime_t date_t
     };
 }
 
-static bool _movement_update_dst_offset_cache(void) {
+static bool _movement_update_dst_offset_cache(watch_date_time_t system_date_time) {
     uzone_t local_zone;
     udatetime_t udate_time;
     bool dst_changed = false;
-    watch_date_time_t system_date_time = watch_rtc_get_date_time();
 
     for (uint8_t i = 0; i < NUM_ZONE_NAMES; i++) {
         unpack_zone(&zone_defns[i], "", &local_zone);
@@ -140,7 +140,7 @@ static bool _movement_update_dst_offset_cache(void) {
             _movement_dst_offset_cache[i] = TIMEZONE_DOES_NOT_OBSERVE;
         }
     }
-
+    _dst_last_cache.reg = system_date_time.reg;
     return dst_changed;
 }
 
@@ -206,7 +206,8 @@ static inline void _movement_disable_fast_tick_if_possible(void) {
 }
 
 static void _movement_handle_top_of_minute(void) {
-    watch_date_time_t date_time = watch_rtc_get_date_time();
+    watch_date_time_t utc_now = movement_get_utc_date_time();
+    watch_date_time_t date_time = watch_utility_date_time_convert_zone(utc_now, 0, movement_get_current_timezone_offset());
 
 #ifdef HAS_ACCELEROMETER
     // every minute, we want to log whether the accelerometer is asleep or awake.
@@ -215,7 +216,7 @@ static void _movement_handle_top_of_minute(void) {
 
     // update the DST offset cache if the current time matches the DST minute, hour, and month
     if (_movement_check_dst_changeover_occurring_now(date_time)) {
-        _movement_update_dst_offset_cache();
+        _movement_update_dst_offset_cache(utc_now);
     }
 
     for(uint8_t i = 0; i < MOVEMENT_NUM_FACES; i++) {
@@ -466,12 +467,26 @@ watch_date_time_t movement_get_utc_date_time(void) {
 }
 
 bool movement_update_dst_offset_cache(void) {
-    return _movement_update_dst_offset_cache();
+    return _movement_update_dst_offset_cache(movement_get_utc_date_time());
+}
+
+bool movement_update_dst_offset_cache_if_needed(watch_date_time_t utc_now) {
+    const uint8_t min_to_trigger = 30;  // We want to check every half-hour, but no need to cache more than once in a hour-hour.
+    // Checks if the last 20 bits don't match (hours, days, months, years)
+    uint32_t ydmh_compare = (utc_now.reg ^ _dst_last_cache.reg) & 0xFFFFF;
+    if(ydmh_compare != 0) return _movement_update_dst_offset_cache(utc_now);
+    int8_t delta_actual = utc_now.unit.minute - _dst_last_cache.unit.minute;
+    if (delta_actual == 0) return false;
+    int8_t delta_min = min_to_trigger - (_dst_last_cache.unit.minute % min_to_trigger);
+    if (delta_actual >= delta_min || delta_actual < 0) return _movement_update_dst_offset_cache(utc_now);
+    return false;  
 }
 
 watch_date_time_t movement_get_date_time_in_zone(uint8_t zone_index) {
+    watch_date_time_t date_time = movement_get_utc_date_time();
     int32_t offset = movement_get_current_timezone_offset_for_zone(zone_index);
-    return watch_utility_date_time_convert_zone(watch_rtc_get_date_time(), 0, offset);
+    movement_update_dst_offset_cache_if_needed(date_time);
+    return watch_utility_date_time_convert_zone(date_time, 0, offset);
 }
 
 watch_date_time_t movement_get_local_date_time(void) {
@@ -644,7 +659,7 @@ void app_setup(void) {
         }
 
         // populate the DST offset cache
-        _movement_update_dst_offset_cache();
+        _movement_update_dst_offset_cache(movement_get_utc_date_time());
 
 #if __EMSCRIPTEN__
         int32_t time_zone_offset = EM_ASM_INT({

movement.h

@@ -348,6 +348,7 @@ watch_date_time_t movement_get_utc_date_time(void);
 watch_date_time_t movement_get_local_date_time(void);
 watch_date_time_t movement_get_date_time_in_zone(uint8_t zone_index);
 bool movement_update_dst_offset_cache(void);
+bool movement_update_dst_offset_cache_if_needed(watch_date_time_t utc_now);
 
 void movement_set_local_date_time(watch_date_time_t date_time);
 

movement/watch_faces/clock/world_clock2_face.c

@@ -152,7 +152,7 @@ void world_clock2_face_activate(void *context)
             movement_request_tick_frequency(4);
             break;
     }
-    movement_update_dst_offset_cache();
+    movement_update_dst_offset_cache_if_needed(movement_get_utc_date_time());
     refresh_face = true;
 }
 

movement/watch_faces/settings/finetune_face.c

@@ -239,5 +239,4 @@ void finetune_face_resign(void *context) {
     if (total_adjustment != 0) {
         finetune_update_correction_time();
     }
-    movement_update_dst_offset_cache();
 }

movement/watch_faces/settings/set_time_hackwatch_face.c

@@ -262,8 +262,8 @@ bool set_time_hackwatch_face_loop(movement_event_t event, void *context) {
 }
 
 void set_time_hackwatch_face_resign(void *context) {
-    (void) context;
+    uint8_t current_page = *((uint8_t *)context);
     watch_set_led_off();
     movement_store_settings();
-    movement_update_dst_offset_cache();
+    if (current_page == 6) movement_update_dst_offset_cache();
 }

watch-faces/clock/world_clock_face.c

@@ -49,7 +49,7 @@ void world_clock_face_activate(void *context) {
     world_clock_state_t *state = (world_clock_state_t *)context;
 
     state->current_screen = 0;
-    movement_update_dst_offset_cache();
+    movement_update_dst_offset_cache_if_needed(movement_get_utc_date_time());
     _update_timezone_offset(state);
 
     if (watch_sleep_animation_is_running()) watch_stop_sleep_animation();

watch-faces/complication/sunrise_sunset_face.c

@@ -323,7 +323,7 @@ void sunrise_sunset_face_activate(void *context) {
     movement_location_t movement_location = (movement_location_t) watch_get_backup_data(1);
     state->working_latitude = _sunrise_sunset_face_struct_from_latlon(movement_location.bit.latitude);
     state->working_longitude = _sunrise_sunset_face_struct_from_latlon(movement_location.bit.longitude);
-    movement_update_dst_offset_cache();
+    movement_update_dst_offset_cache_if_needed(movement_get_utc_date_time());
 }
 
 bool sunrise_sunset_face_loop(movement_event_t event, void *context) {

watch-faces/settings/set_time_face.c

@@ -198,8 +198,8 @@ bool set_time_face_loop(movement_event_t event, void *context) {
 }
 
 void set_time_face_resign(void *context) {
-    (void) context;
+    uint8_t current_page = *((uint8_t *)context);
     watch_set_led_off();
     movement_store_settings();
-    movement_update_dst_offset_cache();
+    if (current_page == SET_TIME_TZ) movement_update_dst_offset_cache();
 }