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Feature Request: Add support for Symbols for Legacy Computing (U+1FB00…U+1FBFF) #597

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PhMajerus opened this issue Nov 6, 2021 · 2 comments

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@PhMajerus
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PhMajerus commented Nov 6, 2021

Unicode 14 added most glyphs that were used for text-based drawing on 8-bit computers as a new Symbols for Legacy Computing block (U+1FB00…U+1FBFF, see https://en.wikipedia.org/wiki/Symbols_for_Legacy_Computing).

Symbols_for_Legacy_Computing_Unicode_block

These were originally part of character sets of 8-bit computers (Atari, C=64, TRS-80, ...) to be able to do some drawing on text-mode displays, either for simplicity, or because the computer did not offer any graphics mode at all.
Consoles and Terminals are the evolution of those text modes, block elements and box drawing characters inherited from the IBM PC Extended ASCII are simply IBM's version of such glyphs.

It would be nice for Cascadia Mono to include these symbols, making it possible to render contents from legacy text modes as well. Some terminals already render these correctly, such as gnome-terminal on Ubuntu.

The Symbols for Legacy Computing block is an extension of the existing block elements and box drawing characters, and should be consistent with some existing symbols.
For example, the TRS-80 squots (2x3 matrix block elements, see https://en.wikipedia.org/wiki/TRS-80_character_set) have been included in the new range, but relie on existing █, ▐, and ▌ to complete the set.
If mixed from different fonts through font fallback, they can have problems fitting together, so including them in a single font would be better.

Related issue in Windows Terminal : microsoft/terminal#11694

@PhMajerus
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Slowly getting there…
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@SHJordan
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SHJordan commented Mar 8, 2024

I hope this goes through! Great work btw!

DHowett pushed a commit that referenced this issue Apr 23, 2024
…extants, segmented digits, and large type pieces (#723)

## New diagonals, octants, sedecimants & eights, separated quadrants &
sextants, segmented digits, and large type pieces (Symbols for Legacy
Computing)

- Added diagonals `U+1FB3C` - `U+1FB67`
- Added octants (2×4 mosaics) `U+1CD00` - `U+1CDE5`
- Added sedecimants (4×4 mosaics) `U+1CE90` - `U+1CEAF`
- Added eights (8×8 patterns) `U+1FB70` - `U+1FB80`, `U+1FB82` -
`U+1FB8B`
- Added misc. blocks `U+1FB97`, `U+1FBCE`, `U+1FBCF`
- Added separated quadrants (2×2) `U+1CC21` - `U+1CC2F`
- Added separated sextants (2×3) `U+1CE51` - `U+1CE8F`
- Added segmented digits (LED/LCD display style) `U+1CCF0` - `U+1CCF9`
- Added large type pieces (see #709) `U+1CE1A` - `U+1CE50`

This update does not modify any existing character, it is only adding
new characters from the Symbols for Legacy Computing blocks (original
and supplement).  These characters use the same unified coordinates as
my previous #708 submission. It continues the sextants with diagonal
fills that meet the sextants corners, adds octants, most of the 8×8
pixels-based lines and fills (sedecimants & eights), as well as the
separated mosaics, segmented digits, and large type pieces.  Some
existing mosaic characters are not perfectly aligned on the same grid,
and it would be best to adjust them to fit the unified grid as well, but
that is not part of this PR, and I guess we won't have the time to do
that for the next release.

Note it does not complete the original Symbols for Legacy Computing
block yet, as it does not include the extra lines/box-drawing
characters, shaded mosaics, MouseText, and some other specific symbols.
The focus has been on completing the mosaics part, including the ones
coming in Unicode 16.0, and the Large Type Pieces.

This one is quite big, containing almost all the glyphs I've been
working on at once. This is to meet the short deadline for the next
release of Cascadia Code, as discussed with @aaronbell. It contains 948
glyphs for 479 characters.

Many of the glyphs are pure geometric shapes with no artistic liberty at
all, they simply follow the unified grid and handle both GDI and DWrite
("stypo") variants.

All the glyphs have been added to the `features.fea::@NotSpace` list of
non-italic fonts, except for the segmented digits, which have been added
to `@Digit` instead of `@NotSpace`.

The segmented digits `U+1CCF0` - `U+1CCF9` are based on their original
Atari ST design and Unicode reference design, with the bounding box and
segments widths adjusted to fit the `H` character, and spaces between
the segments large enough to be visible even at 12pt on 100% DPI.

The Large Type Pieces are based on their original HP 2640 Series
terminals design and Unicode reference design, but I took liberties to
reinterpret the pieces to make them more rounded and, I believe, more in
line with the Cascadia Code design.  Note the Unicode reference design
is somewhat wrong as their diagonals do not join perfectly, while my
version takes great care to support all the combinations alignments with
straight diagonal lines.  The only piece where more artistic liberty is
available is the `Q` stem `U+1CE45`, where I tried to make it more
reminiscent of Cascadia's `Q` design.

More details and screenshots of the large type pieces are available in
issue #709.

Finally, `U+1FB97` is the same pattern as `U+1CDB7`, they have different
origins, but I'm not sure why Unicode repeated it for octants instead of
reusing the existing one as they did for some other existing pattern. I
included them as separate glyphs as well.

* Continues #708 
* Improves #715 (does not close it, but greatly improves coverage)
* Improves #597 (does not close it, but greatly improves coverage)
* Closes #711
* Closes #709

Co-authored-by: Philippe Majerus <phm@live.com>
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