1767842 - Emoji definition outdated

Status: NEW

(Core :: Layout: Text and Fonts, defect)

Description

[Behdad Esfahbod]

[Context: https://github.com/googlefonts/noto-emoji/issues/391]

Firefox has code to detect emoji sequences that must be rendered in color. The code for that is outdated. My analysis:

Firefox only looks at properties Emoji and Emoji_Presentation, but not Extended_Pictograph:

https://searchfox.org/mozilla-central/source/intl/unicharutil/util/nsUnicodeProperties.h#123-134

For stability reasons the two former properties have not been updated to include more emoji. The definition of the latter though allows for non-stability:

= Yes for pictographic symbols, as well as reserved ranges in blocks largely associated with emoji characters. This enables segmentation rules involving emoji to be specified stably, even in cases where an existing non-emoji pictographic symbol later comes to be treated as an emoji.

So if Firefox wants to be consistent, it should also include Extended_Pictograph as Emoji_Presentation.

The fix for this would be to switch BinaryProperty Emoji from UCHAR_EMOJI to UCHAR_EXTENDED_PICTOGRAPHIC:

https://searchfox.org/mozilla-central/source/intl/components/src/UnicodeProperties.h#144

Comment 1

[Daniel Holbert [:dholbert]]

Seems like S3, though I'll tag jfkthame to confirm / add thoughts on what we should potentially do here.

(I see the github issue had some more discussion after this bug was filed, and jfkthame left some thoughts there.)