> Date: Thu, 10 Apr 2025 19:27:43 -0700 > From: Asmus Freytag via Unicode <[email protected]> > > On 4/10/2025 5:14 PM, Mark E. Shoulson via Unicode wrote: > > does glyph-mirroring make sense for things that don't already have a > mirrored glyph at another > codepoint? > > It does. Contour integral needs to be "mirrored" but the direction of the > arrow (circular) needs to be > preserved. There are no mirrored code points, as the (partially) mirrored > shape *only* exists in RTL display. > > However, math font providers need to know about this and have the correct > glyph available.
That takes us back to the shaping engine and the font part, which I thought someone said was a separate issue? For showing plain text on a text-only terminal, which doesn't know about the underlying font and its rendering, any features that require to interact with the font are a non-starter. By contrast, the simple rules of bidi mirroring stated in UAX#9 work in all cases, including when showing bidi text on dumb text-only terminals. In addition, a related discussion on the HarfBuzz forum (https://github.com/harfbuzz/harfbuzz/discussions/5278) reveals that the relevant OpenType features are probably supported only by a small set of fonts, if at all. So leaving this to fonts and shaping engines will at best solve only a small part of the use cases.
