Picker fuzzy highlighting is offset when using more than one column

[lazytanuki]

Summary

In pickers that use more than one column (such as the buffer picker, then only one for now I think), the highlight of the fuzzy matching is offset from the second column.

Discovered this issue when working on #2869 .

In helix-term/src/ui/picker.rs:218, I noticed that, in the following code, for each span the grapheme_byte_offset is reset to 0.

let graphemes_with_style: Vec<_> = spans
    .0
    .iter()
    .flat_map(|span| {
        span.content
            .grapheme_indices(true)
            .zip(std::iter::repeat(span.style))
    })
    .map(|((grapheme_byte_offset, grapheme), style)| {
        cell_len += grapheme.len();
        let start = cell_start_byte_offset;

        let grapheme_byte_range =
            grapheme_byte_offset..grapheme_byte_offset + grapheme.len();

        if highlight_byte_ranges.iter().any(|hl_rng| {
            hl_rng.start >= start + grapheme_byte_range.start
                && hl_rng.end <= start + grapheme_byte_range.end
        }) {
            (grapheme, style.patch(highlight_style))
        } else {
            (grapheme, style)
        }
    })
    .collect();

This may be the source of the offset we see.

Reproduction Steps

1. open the buffer picker
2. type in some chars and see the highlighted portion of the line

Helix log

This issue is not visible in the logs.

Platform

Linux

Terminal Emulator

Kitty

Helix Version

master build