Thanks for the detailed report Matt; I'll look into it next week.

I seem to have the same issue. I am playing with replacing my own font implementation in pdfjs with opentype.js. Chrome, Firefox (pdf.js) and Mac Preview are displaying the font correctly, however, Adobe Reader messes it up:

Please let me know if I can do anything helping to track down this issue.

@rkusa That's weird -- can you send me the font + code you used to generate this?

I thought I'd add this as well -

Here is my font export code:
https://github.com/mattlag/Glyphr-Studio/blob/master/dev/js/io_otf_export.js

Which relies heavily on the Glyph object:
https://github.com/mattlag/Glyphr-Studio/blob/master/dev/js/obj_glyph.js

I first encountered this, and documented a lot of details in this bug:
glyphr-studio/Glyphr-Studio-1#176

In the process I used TTX to investigate the exported OTF, but couldn't see anything that would cause problems (but, I'm rather novice at the full implications of OTF table values). All the postscript code for the glyphs was exported correctly. @davelab6 did a TTX diff of Merriweather Sans original vs. Merriweather Sans exported through Glyphr Studio:
https://github.com/davelab6/example-bellweather/pull/1/files?diff=split

So, hopefully this helps.

@mattlag thanks so much! I'll investigate and let you know.

I've tracked the bug to the CFF fontMatrix, which defines an affine transform for the glyph outlines. The fontMatrix defaults to [0.001 0 0 0.001 0 0]which works fine with fonts with a UPM of 1000. Other fonts need to set the matrix to a different scale value, e.g. fonts with a UPM of 2048 use 1/2048 = 0.000488281.

OpenType.js didn't set the fontMatrix anywhere, and so all fonts used the default font matrix, which is only suitable for fonts with a UPM of 1000.

I now create a fontMatrix based on the unitsPerEm.

Thanks @mattlag and @davelab6 for helping me find the bug. Especially the TTX export helped in tracking down the bug.

Also, please let me know if anything else is off.

Awesome - thanks! I'll update to 0.4.7 and let you know if anything goes wrong.

@mattlag please use version 0.4.8, which I just pushed (and includes the fix).

Great - will do. Thanks.