hb-view doesn't auto compute font extents for CBDT color font

[anthrotype]

If I try to render a CBDT/CBLC font (e.g. NotoColorEmoji.ttf) with hb-view, the resulting PNG is always cropped. I need to add very large --margin in order to display something (but then the image is not centered). Manually setting --font-extents doesn't help either, or I can't figure out values that make it look ok.

This is the command I run:

$ hb-view -o /tmp/AD.png -u 1F1E6,1F1E9 Font.ttf

I get this (which is only a small portion of the actual color glyph):

The test font is attached in test-cbdt-font.zip along with a static html file that should display the correct image in Google Chrome - which looks like this:

Am I doing something wrong?

[anthrotype]

forgot to say, I'm running hb-view (compiled from source from latest HEAD) on macOS 12.1

[behdad]

It's a problem hb-ft has with bitmap fonts. It's known issue. I think it works if you pass --font-funcs=ot. Probably duplicate of #489

[anthrotype]

thanks, using --font-funcs=ot works for me!