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| author | Nicolas Pitre <npitre@baylibre.com> | 2025-04-17 21:45:05 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-04-26 12:22:03 +0300 |
| commit | 95b05de0a56699392e67590d000df76fedec609a (patch) | |
| tree | 1cccefd12bfe1a0caddf00c8a20edc5b93e261d0 /include | |
| parent | 07bc3f442f47b4d158468c2e0146475bdf009091 (diff) | |
| download | linux-95b05de0a56699392e67590d000df76fedec609a.tar.xz | |
vt: properly support zero-width Unicode code points
Zero-width Unicode code points are causing misalignment in vertically
aligned content, disrupting the visual layout. Let's handle zero-width
code points more intelligently.
Double-width code points are stored in the screen grid followed by a white
space code point to create the expected screen layout. When a double-width
code point is followed by a zero-width code point in the console incoming
bytestream (e.g., an emoji with a presentation selector) then we may
replace the white space padding by that zero-width code point instead of
dropping it. This maximize screen content information while preserving
proper layout.
If a zero-width code point is preceded by a single-width code point then
the above trick is not possible and such zero-width code point must
be dropped.
VS16 (Variation Selector 16, U+FE0F) is special as it typically doubles
the width of the preceding single-width code point. We handle that case
by giving VS16 a width of 1 instead of 0 when that happens.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250417184849.475581-4-nico@fluxnic.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/consolemap.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/consolemap.h b/include/linux/consolemap.h index caf079bcb8c9..7d778752dcef 100644 --- a/include/linux/consolemap.h +++ b/include/linux/consolemap.h @@ -29,6 +29,11 @@ u32 conv_8bit_to_uni(unsigned char c); int conv_uni_to_8bit(u32 uni); void console_map_init(void); bool ucs_is_double_width(uint32_t cp); +static inline bool ucs_is_zero_width(uint32_t cp) +{ + /* coming soon */ + return false; +} #else static inline u16 inverse_translate(const struct vc_data *conp, u16 glyph, bool use_unicode) @@ -63,6 +68,11 @@ static inline bool ucs_is_double_width(uint32_t cp) { return false; } + +static inline bool ucs_is_zero_width(uint32_t cp) +{ + return false; +} #endif /* CONFIG_CONSOLE_TRANSLATIONS */ #endif /* __LINUX_CONSOLEMAP_H__ */ |