Problem upgrading to 2.x version in CJK fonts

[HarelM]

Hi,

We have upgraded tiny-sdf from version 1.x to 2.x.
As part of the upgrade we understood we need to use the return value of the draw method to get the actual values, which was a breaking change from version 1.x
We did the required changes but now we see that there's an issue with the top offset returned from tiny-sdf as can be seen in the following issue:
maplibre/maplibre-gl-js#1002
Can you please elaborate what should be the right way to use this library to get a correct value for the offset top for CJK fonts?

Thanks again for all the hard work invested in this library!

[mourner]

The related change was introduced in v1.2.4, it was just not marked as breaking because it used an optional metrics pathway (which became the default later, in v2). See #30. The adjustment GL JS uses is basically top = glyphTop - 27, but it's because of the way fonts are generated server-side, not any flaws in TinySDF logic. Quoting @ChrisLoer:

TinySDF's "top" is the distance from the alphabetic baseline to the top of the glyph. Server-generated fonts specify "top" relative to an origin above the em box (the origin comes from FreeType, but I'm unclear on exactly how it's derived)
ref: https://github.com/mapbox/sdf-glyph-foundry

Server fonts don't yet include baseline information, so we can't line up exactly with them (and they don't line up with each other)
ref: mapbox/node-fontnik#160

To approximately align TinySDF glyphs with server-provided glyphs, we use this baseline adjustment factor calibrated to be in between DIN Pro and Arial Unicode (but closer to Arial Unicode)

[HarelM]

Thanks for the info and the super fast response!