tui: strip syntax highlight backgrounds

commit: b5ab07f9a0fbce8f29fc936b7e98332d229e1d9d
author: patriceckhart · 5mo ago · 2026-05-04 13:54 UTC
parent: 17dec30
signature: unsigned

1 file · +61 -1

M internal/tui/highlight.go +61 -1


@@ -48,7 +48,7 @@ func HighlightCode(src, lang string) []string {
48	48		highlightCache.store(lang, src, out)
49	49		return out
50	50		}
51		-	out := strings.Split(strings.TrimRight(buf.String(), "\n"), "\n")
	51	+	out := strings.Split(strings.TrimRight(stripANSIBackgrounds(buf.String()), "\n"), "\n")
52	52		highlightCache.store(lang, src, out)
53	53		return out
54	54		}

@@ -110,6 +110,66 @@ func LanguageFromPath(p string) string {
110	110
111	111		// chooseLexer picks the best lexer for a language hint; falls back to
112	112		// nil (no highlighting) if the hint is empty or unknown.
	113	+	// stripANSIBackgrounds removes SGR background-color attributes emitted by
	114	+	// terminal syntax formatters while preserving foreground colors and styles.
	115	+	// Chroma's inherited styles can assign black backgrounds to a few tokens
	116	+	// (notably punctuation/error-ish spans), which looks like random black blocks
	117	+	// inside zot's dark-gray tool boxes. Foreground color is enough for code.
	118	+	func stripANSIBackgrounds(s string) string {
	119	+	var out strings.Builder
	120	+	out.Grow(len(s))
	121	+	for i := 0; i < len(s); {
	122	+	if s[i] != 0x1b \|\| i+1 >= len(s) \|\| s[i+1] != '[' {
	123	+	out.WriteByte(s[i])
	124	+	i++
	125	+	continue
	126	+	}
	127	+	j := i + 2
	128	+	for j < len(s) && s[j] != 'm' {
	129	+	j++
	130	+	}
	131	+	if j >= len(s) {
	132	+	out.WriteString(s[i:])
	133	+	break
	134	+	}
	135	+	params := strings.Split(s[i+2:j], ";")
	136	+	kept := make([]string, 0, len(params))
	137	+	for p := 0; p < len(params); p++ {
	138	+	param := params[p]
	139	+	switch param {
	140	+	case "48":
	141	+	// 48;5;N or 48;2;R;G;B background color.
	142	+	if p+1 < len(params) && params[p+1] == "5" {
	143	+	p += 2
	144	+	continue
	145	+	}
	146	+	if p+1 < len(params) && params[p+1] == "2" {
	147	+	p += 4
	148	+	continue
	149	+	}
	150	+	continue
	151	+	case "49":
	152	+	continue
	153	+	}
	154	+	// 40-47 and 100-107 are ANSI background colors.
	155	+	if len(param) == 2 && param[0] == '4' && param[1] >= '0' && param[1] <= '7' {
	156	+	continue
	157	+	}
	158	+	if len(param) == 3 && param[0] == '1' && param[1] == '0' && param[2] >= '0' && param[2] <= '7' {
	159	+	continue
	160	+	}
	161	+	kept = append(kept, param)
	162	+	}
	163	+	if len(kept) > 0 {
	164	+	out.WriteString("\x1b[")
	165	+	out.WriteString(strings.Join(kept, ";"))
	166	+	out.WriteByte('m')
	167	+	}
	168	+	i = j + 1
	169	+	}
	170	+	return out.String()
	171	+	}
	172	+
113	173		func chooseLexer(lang string) chroma.Lexer {
114	174		if lang == "" {
115	175		return nil


@@ -48,7 +48,7 @@ func HighlightCode(src, lang string) []string {
48		highlightCache.store(lang, src, out)	48		highlightCache.store(lang, src, out)
49		return out	49		return out
50		}	50		}
51	-	out := strings.Split(strings.TrimRight(buf.String(), "\n"), "\n")	51	+	out := strings.Split(strings.TrimRight(stripANSIBackgrounds(buf.String()), "\n"), "\n")
52		highlightCache.store(lang, src, out)	52		highlightCache.store(lang, src, out)
53		return out	53		return out
54		}	54		}

@@ -110,6 +110,66 @@ func LanguageFromPath(p string) string {
110			110
111		// chooseLexer picks the best lexer for a language hint; falls back to	111		// chooseLexer picks the best lexer for a language hint; falls back to
112		// nil (no highlighting) if the hint is empty or unknown.	112		// nil (no highlighting) if the hint is empty or unknown.
			113	+	// stripANSIBackgrounds removes SGR background-color attributes emitted by
			114	+	// terminal syntax formatters while preserving foreground colors and styles.
			115	+	// Chroma's inherited styles can assign black backgrounds to a few tokens
			116	+	// (notably punctuation/error-ish spans), which looks like random black blocks
			117	+	// inside zot's dark-gray tool boxes. Foreground color is enough for code.
			118	+	func stripANSIBackgrounds(s string) string {
			119	+	var out strings.Builder
			120	+	out.Grow(len(s))
			121	+	for i := 0; i < len(s); {
			122	+	if s[i] != 0x1b \|\| i+1 >= len(s) \|\| s[i+1] != '[' {
			123	+	out.WriteByte(s[i])
			124	+	i++
			125	+	continue
			126	+	}
			127	+	j := i + 2
			128	+	for j < len(s) && s[j] != 'm' {
			129	+	j++
			130	+	}
			131	+	if j >= len(s) {
			132	+	out.WriteString(s[i:])
			133	+	break
			134	+	}
			135	+	params := strings.Split(s[i+2:j], ";")
			136	+	kept := make([]string, 0, len(params))
			137	+	for p := 0; p < len(params); p++ {
			138	+	param := params[p]
			139	+	switch param {
			140	+	case "48":
			141	+	// 48;5;N or 48;2;R;G;B background color.
			142	+	if p+1 < len(params) && params[p+1] == "5" {
			143	+	p += 2
			144	+	continue
			145	+	}
			146	+	if p+1 < len(params) && params[p+1] == "2" {
			147	+	p += 4
			148	+	continue
			149	+	}
			150	+	continue
			151	+	case "49":
			152	+	continue
			153	+	}
			154	+	// 40-47 and 100-107 are ANSI background colors.
			155	+	if len(param) == 2 && param[0] == '4' && param[1] >= '0' && param[1] <= '7' {
			156	+	continue
			157	+	}
			158	+	if len(param) == 3 && param[0] == '1' && param[1] == '0' && param[2] >= '0' && param[2] <= '7' {
			159	+	continue
			160	+	}
			161	+	kept = append(kept, param)
			162	+	}
			163	+	if len(kept) > 0 {
			164	+	out.WriteString("\x1b[")
			165	+	out.WriteString(strings.Join(kept, ";"))
			166	+	out.WriteByte('m')
			167	+	}
			168	+	i = j + 1
			169	+	}
			170	+	return out.String()
			171	+	}
			172	+
113		func chooseLexer(lang string) chroma.Lexer {	173		func chooseLexer(lang string) chroma.Lexer {
114		if lang == "" {	174		if lang == "" {
115		return nil	175		return nil