Is your feature request related to a problem?
The C layer already measures the display width of a character and of a whole string—it's how text gets laid out—but that isn't surfaced to consumers. There are real use cases for measuring text JS-side (truncating to a column budget, padding or aligning labels) with no way to do it today short of a throwaway render.
Describe the solution you'd like
Expose two pure helpers (exact names TBD), backed by the internal wcwidth table:
charWidth(0x4f60); // 2 (CJK)
stringWidth("你好"); // 4charWidth returns 0/1/2; stringWidth sums codepoints with proper handling for ANSI escape sequences.
Describe alternatives you've considered
Add a JS-side width dependency (duplicates the table we already ship and can drift to a different Unicode version than layout uses), or render into a fit element and read back info.get(id).bounds.width (slow, and gets VS16 emoji clusters wrong).
Additional context
Failing test case on nm/repro/string-width (test · diff). The table is already in C (src/wcwidth.h:8) and exported from the wasm (Makefile:12, --export-all); this is mostly surfacing it from mod.ts.
Is your feature request related to a problem?
The C layer already measures the display width of a character and of a whole string—it's how text gets laid out—but that isn't surfaced to consumers. There are real use cases for measuring text JS-side (truncating to a column budget, padding or aligning labels) with no way to do it today short of a throwaway render.
Describe the solution you'd like
Expose two pure helpers (exact names TBD), backed by the internal
wcwidthtable:charWidthreturns 0/1/2;stringWidthsums codepoints with proper handling for ANSI escape sequences.Describe alternatives you've considered
Add a JS-side width dependency (duplicates the table we already ship and can drift to a different Unicode version than layout uses), or render into a fit element and read back
info.get(id).bounds.width(slow, and gets VS16 emoji clusters wrong).Additional context
Failing test case on
nm/repro/string-width(test · diff). The table is already in C (src/wcwidth.h:8) and exported from the wasm (Makefile:12,--export-all); this is mostly surfacing it frommod.ts.