feat: use two-column diagonal diff hatching (DISCARDED)

2026-10-14 00:01:10 +02:00
parent a8428f9dde
commit 628f397040
4 changed files with 34 additions and 14 deletions
@@ -40,7 +40,7 @@ U+1FBD0/U+1FBD1 are **light box-drawing strokes**. The chart separately labels U

 - Unicode 16.0 repertoire support is a prerequisite; the existence of these characters does not establish coverage in the selected terminal/font. Missing glyphs or fallback glyphs remain possible, and fallback geometry must be checked in the intended renderer. Unicode explicitly says its chart glyph shapes are **not prescriptive** and actual fonts may vary ([chart, page 1](https://www.unicode.org/Public/17.0.0/charts/PDF/U1FB00.pdf)). Pixel-perfect joins or 45° rendering cannot be promised.
 - The pair has East Asian Width **Neutral (`N`)**, from `1FB94..1FBEF` in [EastAsianWidth.txt](https://www.unicode.org/Public/17.0.0/ucd/EastAsianWidth.txt). This is not a terminal-width guarantee: [UAX #11, §2 and §4](https://www.unicode.org/reports/tr11/) explicitly requires terminal-specific tailoring and distinguishes font/layout width from the property. Both the application and terminal must agree on one column per glyph.
- Current rendering writes one `╱` per column with `DarkGray` foreground and reset background in [src/tui.rs:3308–3316](../src/tui.rs#L3308-L3316); the documented behavior is [docs/editing.md:426](editing.md#L426). This note proposes no implementation change. Any later cutover would need a defined pair phase and odd-width clipping behavior, plus terminal/font evidence.
+- Rendering now alternates `🯐` and `🯑`, starting at each pane's left content edge, with `DarkGray` foreground and reset background in [src/tui.rs:3308–3316](../src/tui.rs#L3308-L3316). The phase stays fixed during scrolling; odd widths clip the final pair. Actual empty source lines remain unhatched. See [docs/editing.md:426](editing.md#L426).

 ## Terminal support

@@ -54,4 +54,4 @@ U+1FBD0/U+1FBD1 are **light box-drawing strokes**. The chart separately labels U

 An executed disposable `rustc` smoke program used the repository's actual compiled `ratatui` and `unicode-width` dependencies, a fixed viewport, `Terminal<CrosstermBackend<Vec<u8>>>`, and the same per-cell `set_symbol`/style logic as the current renderer. Both U+1FBD0 and U+1FBD1 returned width `Some(1)`. At three rows high, widths 1, 2, 3, and 12 emitted exactly 3, 6, 9, and 36 glyphs respectively: no dropped or double-width cells. This establishes application-side width/emission behavior, **not** actual terminal glyph coverage, pixel joins, or the visible angle; those were not visually verified. The disposable program and binary were removed.

-Investigation only: no production code changed and no TODO marked complete.
+Implemented with no new dependency or graphics protocol. Verification: `cargo test diff_` (94 passing checks), `cargo build`, and `cargo fmt --package vamp --check`. A live PTY session opened `:diff` against a disposable jj baseline with two removed rows and emitted paired hatching at 100, 101, and 77 terminal columns; no U+2571 was emitted, the editor exited cleanly, and fixture content stayed unchanged. The fixture was removed. Terminal pixel joins remain visually unverified. The TODO item is complete.