Please help new to Pebble Smart watch coding try to convert time into number

Question

I just started making pebble watch faces and I want to make a count down timer, that can count how many hours are left in the day and then restarts at 12 am everyday.

the problem is I can not figure out a way to get the math right to display: the current time minus 24 hours and then show it on the watch (including the hours and mins like H:M).

// Time functions
static void update_time() {
  // Get a tm structure
  time_t temp = time(NULL); 
  struct tm *tick_time = localtime(&temp);
double munistime;
  // Create a long-lived buffer
  static char buffer[] = "00:00:00";

  // Write the current hours and minutes into the buffer
  if(clock_is_24h_style() == true) {
    // Use 24 hour format
    strftime(buffer, sizeof("00:00:00"), "%H:%M:%S", tick_time);
    munistime = 24.0 - 19.0;

  } else {
    // Use 12 hour format
    strftime(buffer, sizeof("00:00:00"), "%I:%M:%S", tick_time);
  }

  // Display this time on the TextLayer
  text_layer_set_text(s_time_layer, buffer);
}

static void tick_handler(struct tm *tick_time, TimeUnits units_changed) {
 update_time();
}
// Set the count from the start of the day
Static void update_countdown () {


}

    // Window Functions
    static void main_window_load(Window *window) {
   // Create time TextLayer
  s_time_layer = text_layer_create(GRect(0, 130, 150,50));
  text_layer_set_background_color(s_time_layer, GColorClear);
  text_layer_set_text_color(s_time_layer, GColorBlack);
  text_layer_set_text(s_time_layer, "00:00:00");
  // Improve the layout to be more like a watchface
  text_layer_set_font(s_time_layer, fonts_get_system_font(FONT_KEY_BITHAM_30_BLACK));
  text_layer_set_text_alignment(s_time_layer, GTextAlignmentCenter);


  // Creates A count Timer Layer
  s_countdown_layer = text_layer_create(GRect(0, 40, 150, 50));
  text_layer_set_background_color(s_countdown_layer, GColorBlack);
  text_layer_set_text_color(s_countdown_layer, GColorWhite);
  text_layer_set_text(s_countdown_layer, "00:00:00");
  text_layer_set_text_alignment(s_countdown_layer, GTextAlignmentCenter);
  text_layer_set_font(s_countdown_layer,fonts_get_system_font(FONT_KEY_GOTHIC_28));


  // Add it as a child layer to the Window's root layer
  layer_add_child(window_get_root_layer(window), text_layer_get_layer(s_time_layer));
  layer_add_child(window_get_root_layer(window),text_layer_get_layer(s_countdown_layer));
   update_time();
}

You haven't really asked a question. What, exactly, is the problem? — ChrisGPT was on strike, Dec 28 '14 at 03:10
How to I subtract the current time from 24 and display in the format of %h:%m:%s on the pebble screen? — Josh Martin, Feb 15 '15 at 02:04

score 0 · Answer 1 · answered Jan 13 '15 at 13:53

0

I would get the tick_time in 3 variables - for hours, minutes and seconds. Compute the new values for them and then save them in the buffer for displaying.

answered Jan 13 '15 at 13:53

aniri

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score 0 · Answer 2 · answered Oct 14 '15 at 04:46

It's not bad if you just convert the time to seconds, and subtract from 24 hours:

time_t temp = time(NULL);
struct tm *tick_time = localtime(&temp);
static char buffer[] = "00:00:00";

// 86400 = 24 hours * 60 minutes * 60 seconds
// this gets the total number of seconds remaining before midnight
int secsUntilMidnight = 86400 - (tick_time->tm_hour * 3600 + tick_time->tm_min * 60 + tick_time->tm_sec);

Then, split the values out again:

int hr = secsUntilMidnight / 3600;
int mn = (secsUntilMidnight - (hr*3600)) / 60;
int sc = (secsUntilMidnight - (hr*3600)) - (mn*60);

sprintf (buffer, "%02d:%02d:%02d", hr, mn, sc);

You could make it more efficient by setting secsUntilMidnight once a day and then just subtract 1 second in your tickHandler, and you could make the math of splitting the values out more efficient as well.

Please help new to Pebble Smart watch coding try to convert time into number

2 Answers2