Moon phase widget slow?

I'm using the northern hemisphere moon phase widget (in the SE UK in case that makes a difference!) It seems a bit 'slow' to me - i.e. I'm looking out the window right now at what looks like a full moon, the phase on my Bangle JS2 widget looks like it's at least 1 phase behind. Has anyone else noticed this? Is it to do with how often it updates?

Full moon is tomorrow night.

i noticed that offset too, i guess the threshold between two phase should be enhanced a litlle bit

Thanks @myownself - good to know!
@nicoboss feels like it could 'tip' a bit earlier - I wonder if I notice this more when it's waxing as it is now than when it's waning.

It's 7.30am in London, the moon phase widget is showing a full moon and yet the moon I can see out of my window right now looks like it's ever so slightly slightly waning, it looks a bit less full than it did when I posted this thread. I guess it's a moot (moon?!) point when you change from one discrete phase image to another, but it certainly looks like it needs shifting forwards a bit.

Good morning!

I just compared the moon phase calculation of the moon phase widget with that of my moon phase complication for analog clocks using the following code:

  function compareMoonphasesAt (today) {
  /**** Code from Moonphase Widget ****/
  
    const MC = 29.5305882, NM = 694039.09;
    var r = 11, mx = this.x + 12; my = this.y + 12;
  
    function moonPhase(d) {
      var tmp, month = d.getMonth(), year = d.getFullYear(), day = d.getDate();
      if (month < 3) {year--; month += 12;}
      tmp = ((365.25 * year + 30.6 * ++month + day - NM) / MC);
      return Math.round(((tmp - (tmp | 0)) * 7)+1);
    }
  
  /**** Code from Moonphase Complication ****/
  
    const MillisPerDay   = 86400000;
    const synodicalMonth = 29.530588;
  
    let Phase = (
      (today/MillisPerDay - new Date(2009,11,31, 20,12,36)/MillisPerDay) % synodicalMonth
    ) / synodicalMonth;
  
    if (Phase < 0) { Phase += 1; } // just in case that date is completely wrong
  
  /**** make the latter comparable to the former ****/
  
    Phase -= 0.5; if (Phase < 0) { Phase += 1; }
    Phase = Math.round(Phase * 7)+1;
  
  /**** print comparison ****/
  
    let day = today.getDate();
    print(
      '2022-01-' + (day < 10 ? '0' : '') + day + ': ' + 
      moonPhase(today) + ' vs. ' + Phase
    );
  }

  for (let Day = 17-14; Day < 17+14; Day++) {
    compareMoonphasesAt(new Date(2022,0,Day));
  }

The output of that little script is:

2022-01-03: 8 vs. 8
2022-01-04: 1 vs. 1
2022-01-05: 1 vs. 1
2022-01-06: 2 vs. 2
2022-01-07: 2 vs. 2
2022-01-08: 2 vs. 2
2022-01-09: 2 vs. 2
2022-01-10: 3 vs. 3
2022-01-11: 3 vs. 3
2022-01-12: 3 vs. 3
2022-01-13: 3 vs. 3
2022-01-14: 4 vs. 4
2022-01-15: 4 vs. 4
2022-01-16: 4 vs. 4
2022-01-17: 4 vs. 4
2022-01-18: 5 vs. 5
2022-01-19: 5 vs. 5
2022-01-20: 5 vs. 5
2022-01-21: 5 vs. 5
2022-01-22: 5 vs. 5
2022-01-23: 6 vs. 6
2022-01-24: 6 vs. 6
2022-01-25: 6 vs. 6
2022-01-26: 6 vs. 6
2022-01-27: 7 vs. 7
2022-01-28: 7 vs. 7
2022-01-29: 7 vs. 7
2022-01-30: 7 vs. 7

This looks as if the calculation itself is correct.

What might lead to less optimal graphics is the low number of different indices - compared to user requirements (e.g., according to the numbers, "full moon" is shown from Jan 14 to Jan 17 incl. - this collides with "it's ever so slightly slightly waning")

Thus, what may (might?) finish this discussion could be a more detailed drawing of the current moon phase in the widget?

Thus, what may (might?) finish this discussion could be a more detailed drawing of the current moon phase in the widget?

It's on my to-do list, you've already done some great work in http://forum.espruino.com/comments/16328­587/

Well, since our formulae seem to be comparable, you may just copy all the code from my moon phase complication and adapt it for your radius and color settings - that's it. Everything else would require more work.

@blogmywiki: I can confirm the difference of the rendered phases with the visual moon.

Nevertheless I can confirm the the calculation itself seems correct as also @Andreas_Rozek tested.

From my point of view:

1. It's hard to render a -always correct- circle view projection within 23 px
   
2. Typically a moon projection shows als the full circle; but see 1. with a doted 1px line ... I don't expect to be more precise for our eyes
   
3. I guess using the same code (moonphase calculation) in more than one app/widget or the cool overlays that @Andreas_Rozek provides (e.g. a module) would be very helpfull
   

The moon widget has no internal update, it depends on widgets draw to be updated 😉.

I've replaced the 8 phases with the drawing function from @Andreas_Rozek, see https://github.com/espruino/BangleApps/p­ull/1430

Maybe you find some time and go for a setting option, because there are two hemispheres and because of this there are two widgets - that would be great.

1 Attachment

oops - I guess, it would also be a good idea to add such an option to my moon phase "complication"...

I'm planning to use mylocation.json for this.

so I'll wait for you to solve that problem and see if I can copy your solution

I'm now using the data from the "My Location" app in https://github.com/espruino/BangleApps/p­­ull/1430

You can try out the new widget on https://hilmarst.github.io/BangleApps/#m­oon