g.getFont does not return font set by g.setFont

can anybody explain the following behaviour (entered into the left-hand side of the Web IDE):

>g.setFont12x20();
=Graphics: {
  flip: function () { [native code] },
  drawRoundedRect: function (x1,y1,x2,y2,r) { ... },
  fillRoundedRect: function (x1,y1,x2,y2,r) { ... }
 }
>g.getFont();
="Custom"

I have a similar problem deep inside a program which crashes with

Uncaught Error: Font bitmap must be a String
 at line 1 col 1140
...t!=null){g.setFont(Details.font);}g.setFontAlign(xAlignment,yAli...

In Details.font I've stored a previously configured font, obtained using g.getFont() (which returned Custom, although the font was set using g.setFont12x20() before)

The issue is the 12x20 font is stored inside Espruino as if it was a custom font. When a custom font is loaded, all that's stored in Graphics is the data for the font - so it's pretty much impossible to figure out which function was called to get that data :(

Potentially we could also store the font name in Graphics, but that's not trivial due to restrictions on how many arguments built-in functions can have :(

Well, that's bad but not not tragical.

Are there more fonts like 12x20 that will be reported as Custom?

I just wrote a little "program" to find out which fonts on a Bangle.js 2 will be reported properly and which will not:

print('which fonts will not properly be reported?');
print('');

  let FontList = g.getFonts();
  for (let i = 0, l = FontList.length; i < l; i++) {
    let Font = FontList[i];
    g.setFont(Font);
    if (g.getFont() === Font) {
      print('==  set: "' + Font + '", got "' + Font + '"');
    } else {
      print('<>  set: "' + Font + '", got "' + g.getFont() + '"');
    }
  }

Outcome:

>which fonts will not properly be reported?
>
>==  set: "4x6", got "4x6"
==  set: "6x8", got "6x8"
<>  set: "12x20", got "Custom"
<>  set: "6x15", got "Custom"
==  set: "Vector", got "Vector"
>

Yes, that sounds right - any actual custom fonts added will have the same issue too

Unfortunately no meta data is kept about the custom font (except the fact that it is recognized as a custom font). Therefore, I wrapped in my http://www.espruino.com/ui (doc) / ...UI framework... (forum) the font handling. At the same time I used a palette approach to simplify / application-localize font referencing.

good to know - thank you very much!