Add underline style variants and underline color support

Support double, curly, dotted, and dashed underline styles via --color
(e.g. underline-curly) and ANSI passthrough (SGR 4:N, 58, 59) with --ansi.

Close #4633
Close #4678

Thanks to @shtse8 for the test cases.

CHANGELOG.md

@@ -1,6 +1,39 @@
 CHANGELOG
 =========
 
+0.68.0
+------
+- Added support for underline style variants in `--color`:
+  `underline-double`, `underline-curly`, `underline-dotted`, `underline-dashed`
+  ```sh
+  fzf --color 'fg:underline-curly,current-fg:underline-dashed'
+  ```
+- Added support for underline styles (`4:N`) and underline colors (SGR 58/59)
+  ```sh
+  # In the list section
+  printf '\e[4:3;58;2;255;0;0mRed curly underline\e[0m\n' | fzf --ansi
+
+  # In the preview window
+  fzf --preview "printf '\e[4:3;58;2;255;0;0mRed curly underline\e[0m\n'"
+  ```
+- Added `alt-gutter` color option (#4602) (@hedgieinsocks)
+- Added fish completion support (#4605) (@lalvarezt)
+- zsh: Handle multi-line history selection (#4595) (@LangLangBart)
+- Bug fixes
+    - Fixed symlinks to directories being returned as files (#4676) (@skk64)
+    - Fixed SIGHUP signal handling (#4668) (@LangLangBart)
+    - Fixed preview process not killed on exit
+    - Fixed coloring of items with zero-width characters
+    - Fixed `track-current` unset after a combined movement action
+    - Fixed `--accept-nth` being ignored in filter mode (#4636) (@charemma)
+    - Fixed display width calculation with `maxWidth` (#4596) (@LangLangBart)
+    - Fixed clearing of the rest of the current line on start
+    - Fixed `x-api-key` header not required for GET requests
+    - Fixed key reading not cancelled when `execute` triggered via a server request (#4653)
+    - Fixed rebind of readline command `redraw-current-line` (#4635) (@jameslazo)
+    - Fixed `fzf-tmux` `TERM` quoting and added `mktemp` usage (#4664) (@Goofygiraffe06)
+    - Do not allow very long queries in `FuzzyMatchV2`
+
 0.67.0
 ------
 - Added `--freeze-left=N` option to keep the leftmost N columns always visible.

man/man1/fzf.1

@@ -326,10 +326,14 @@ color mappings. Each entry is separated by a comma and/or whitespaces.
     \fB#rrggbb    \fR24-bit colors
 
 .B ANSI ATTRIBUTES: (Only applies to foreground colors)
-    \fBregular        \fRClear previously set attributes; should precede the other ones
+    \fBregular           \fRClear previously set attributes; should precede the other ones
-    \fBstrip          \fRRemove colors
+    \fBstrip             \fRRemove colors
     \fBbold\fR
     \fBunderline\fR
+    \fBunderline-double\fR
+    \fBunderline-curly\fR
+    \fBunderline-dotted\fR
+    \fBunderline-dashed\fR
     \fBreverse\fR
     \fBdim\fR
     \fBitalic\fR

src/ansi.go

@@ -22,20 +22,21 @@ type url struct {
 type ansiState struct {
 	fg   tui.Color
 	bg   tui.Color
+	ul   tui.Color
 	attr tui.Attr
 	lbg  tui.Color
 	url  *url
 }
 
 func (s *ansiState) colored() bool {
-	return s.fg != -1 || s.bg != -1 || s.attr > 0 || s.lbg >= 0 || s.url != nil
+	return s.fg != -1 || s.bg != -1 || s.ul != -1 || s.attr > 0 || s.lbg >= 0 || s.url != nil
 }
 
 func (s *ansiState) equals(t *ansiState) bool {
 	if t == nil {
 		return !s.colored()
 	}
-	return s.fg == t.fg && s.bg == t.bg && s.attr == t.attr && s.lbg == t.lbg && s.url == t.url
+	return s.fg == t.fg && s.bg == t.bg && s.ul == t.ul && s.attr == t.attr && s.lbg == t.lbg && s.url == t.url
 }
 
 func (s *ansiState) ToString() string {
@@ -54,7 +55,18 @@ func (s *ansiState) ToString() string {
 		ret += "3;"
 	}
 	if s.attr&tui.Underline > 0 {
-		ret += "4;"
+		switch s.attr.UnderlineStyle() {
+		case tui.UlStyleDouble:
+			ret += "4:2;"
+		case tui.UlStyleCurly:
+			ret += "4:3;"
+		case tui.UlStyleDotted:
+			ret += "4:4;"
+		case tui.UlStyleDashed:
+			ret += "4:5;"
+		default:
+			ret += "4;"
+		}
 	}
 	if s.attr&tui.Blink > 0 {
 		ret += "5;"
@@ -66,6 +78,9 @@ func (s *ansiState) ToString() string {
 		ret += "9;"
 	}
 	ret += toAnsiString(s.fg, 30) + toAnsiString(s.bg, 40)
+	if s.ul != -1 {
+		ret += toAnsiStringUl(s.ul)
+	}
 
 	ret = "\x1b[" + strings.TrimSuffix(ret, ";") + "m"
 	if s.url != nil {
@@ -74,6 +89,20 @@ func (s *ansiState) ToString() string {
 	return ret
 }
 
+func toAnsiStringUl(color tui.Color) string {
+	col := int(color)
+	if col < 0 {
+		return ""
+	}
+	if col >= (1 << 24) {
+		r := strconv.Itoa((col >> 16) & 0xff)
+		g := strconv.Itoa((col >> 8) & 0xff)
+		b := strconv.Itoa(col & 0xff)
+		return "58;2;" + r + ";" + g + ";" + b + ";"
+	}
+	return "58;5;" + strconv.Itoa(col) + ";"
+}
+
 func toAnsiString(color tui.Color, offset int) string {
 	col := int(color)
 	ret := ""
@@ -338,15 +367,19 @@ func extractColor(str string, state *ansiState, proc func(string, *ansiState) bo
 	return trimmed, nil, state
 }
 
-func parseAnsiCode(s string) (int, string) {
+func parseAnsiCode(s string) (int, byte, string) {
 	var remaining string
-	var i int
+	var sep byte
-	// Faster than strings.IndexAny(";:")
+	// Find the first separator (either ; or :)
-	i = strings.IndexByte(s, ';')
+	i := -1
-	if i < 0 {
+	for j := 0; j < len(s); j++ {
-		i = strings.IndexByte(s, ':')
+		if s[j] == ';' || s[j] == ':' {
+			i = j
+			break
+		}
 	}
 	if i >= 0 {
+		sep = s[i]
 		remaining = s[i+1:]
 		s = s[:i]
 	}
@@ -358,14 +391,14 @@ func parseAnsiCode(s string) (int, string) {
 		for _, ch := range stringBytes(s) {
 			ch -= '0'
 			if ch > 9 {
-				return -1, remaining
+				return -1, sep, remaining
 			}
 			code = code*10 + int(ch)
 		}
-		return code, remaining
+		return code, sep, remaining
 	}
 
-	return -1, remaining
+	return -1, sep, remaining
 }
 
 func interpretCode(ansiCode string, prevState *ansiState) ansiState {
@@ -373,14 +406,14 @@ func interpretCode(ansiCode string, prevState *ansiState) ansiState {
 		if prevState != nil {
 			return *prevState
 		}
-		return ansiState{-1, -1, 0, -1, nil}
+		return ansiState{-1, -1, -1, 0, -1, nil}
 	}
 
 	var state ansiState
 	if prevState == nil {
-		state = ansiState{-1, -1, 0, -1, nil}
+		state = ansiState{-1, -1, -1, 0, -1, nil}
 	} else {
-		state = ansiState{prevState.fg, prevState.bg, prevState.attr, prevState.lbg, prevState.url}
+		state = ansiState{prevState.fg, prevState.bg, prevState.ul, prevState.attr, prevState.lbg, prevState.url}
 	}
 	if ansiCode[0] != '\x1b' || ansiCode[1] != '[' || ansiCode[len(ansiCode)-1] != 'm' {
 		if prevState != nil && (strings.HasSuffix(ansiCode, "0K") || strings.HasSuffix(ansiCode, "[K")) {
@@ -405,6 +438,7 @@ func interpretCode(ansiCode string, prevState *ansiState) ansiState {
 	reset := func() {
 		state.fg = -1
 		state.bg = -1
+		state.ul = -1
 		state.attr = 0
 	}
 
@@ -420,7 +454,8 @@ func interpretCode(ansiCode string, prevState *ansiState) ansiState {
 	count := 0
 	for len(ansiCode) != 0 {
 		var num int
-		if num, ansiCode = parseAnsiCode(ansiCode); num != -1 {
+		var sep byte
+		if num, sep, ansiCode = parseAnsiCode(ansiCode); num != -1 {
 			count++
 			switch state256 {
 			case 0:
@@ -431,10 +466,15 @@ func interpretCode(ansiCode string, prevState *ansiState) ansiState {
 				case 48:
 					ptr = &state.bg
 					state256++
+				case 58:
+					ptr = &state.ul
+					state256++
 				case 39:
 					state.fg = -1
 				case 49:
 					state.bg = -1
+				case 59:
+					state.ul = -1
 				case 1:
 					state.attr = state.attr | tui.Bold
 				case 2:
@@ -442,7 +482,30 @@ func interpretCode(ansiCode string, prevState *ansiState) ansiState {
 				case 3:
 					state.attr = state.attr | tui.Italic
 				case 4:
-					state.attr = state.attr | tui.Underline
+					if sep == ':' {
+						// SGR 4:N — underline style sub-parameter
+						var subNum int
+						subNum, _, ansiCode = parseAnsiCode(ansiCode)
+						state.attr = state.attr &^ tui.UnderlineStyleMask
+						switch subNum {
+						case 0:
+							state.attr = state.attr &^ tui.Underline
+						case 1:
+							state.attr = state.attr | tui.Underline
+						case 2:
+							state.attr = state.attr | tui.Underline | tui.UlStyleDouble
+						case 3:
+							state.attr = state.attr | tui.Underline | tui.UlStyleCurly
+						case 4:
+							state.attr = state.attr | tui.Underline | tui.UlStyleDotted
+						case 5:
+							state.attr = state.attr | tui.Underline | tui.UlStyleDashed
+						default:
+							state.attr = state.attr | tui.Underline
+						}
+					} else {
+						state.attr = state.attr | tui.Underline
+					}
 				case 5:
 					state.attr = state.attr | tui.Blink
 				case 7:
@@ -456,6 +519,7 @@ func interpretCode(ansiCode string, prevState *ansiState) ansiState {
 					state.attr = state.attr &^ tui.Italic
 				case 24: // tput rmul
 					state.attr = state.attr &^ tui.Underline
+					state.attr = state.attr &^ tui.UnderlineStyleMask
 				case 25:
 					state.attr = state.attr &^ tui.Blink
 				case 27:

src/ansi_test.go

@@ -369,10 +369,10 @@ func TestAnsiCodeStringConversion(t *testing.T) {
 		}
 	}
 	assert("\x1b[m", nil, "")
-	assert("\x1b[m", &ansiState{attr: tui.Blink, lbg: -1}, "")
+	assert("\x1b[m", &ansiState{attr: tui.Blink, ul: -1, lbg: -1}, "")
-	assert("\x1b[0m", &ansiState{fg: 4, bg: 4, lbg: -1}, "")
+	assert("\x1b[0m", &ansiState{fg: 4, bg: 4, ul: -1, lbg: -1}, "")
-	assert("\x1b[;m", &ansiState{fg: 4, bg: 4, lbg: -1}, "")
+	assert("\x1b[;m", &ansiState{fg: 4, bg: 4, ul: -1, lbg: -1}, "")
-	assert("\x1b[;;m", &ansiState{fg: 4, bg: 4, lbg: -1}, "")
+	assert("\x1b[;;m", &ansiState{fg: 4, bg: 4, ul: -1, lbg: -1}, "")
 
 	assert("\x1b[31m", nil, "\x1b[31;49m")
 	assert("\x1b[41m", nil, "\x1b[39;41m")
@@ -380,36 +380,142 @@ func TestAnsiCodeStringConversion(t *testing.T) {
 	assert("\x1b[92m", nil, "\x1b[92;49m")
 	assert("\x1b[102m", nil, "\x1b[39;102m")
 
-	assert("\x1b[31m", &ansiState{fg: 4, bg: 4, lbg: -1}, "\x1b[31;44m")
+	assert("\x1b[31m", &ansiState{fg: 4, bg: 4, ul: -1, lbg: -1}, "\x1b[31;44m")
-	assert("\x1b[1;2;31m", &ansiState{fg: 2, bg: -1, attr: tui.Reverse, lbg: -1}, "\x1b[1;2;7;31;49m")
+	assert("\x1b[1;2;31m", &ansiState{fg: 2, bg: -1, ul: -1, attr: tui.Reverse, lbg: -1}, "\x1b[1;2;7;31;49m")
 	assert("\x1b[38;5;100;48;5;200m", nil, "\x1b[38;5;100;48;5;200m")
 	assert("\x1b[38:5:100:48:5:200m", nil, "\x1b[38;5;100;48;5;200m")
 	assert("\x1b[48;5;100;38;5;200m", nil, "\x1b[38;5;200;48;5;100m")
 	assert("\x1b[48;5;100;38;2;10;20;30;1m", nil, "\x1b[1;38;2;10;20;30;48;5;100m")
 	assert("\x1b[48;5;100;38;2;10;20;30;7m",
-		&ansiState{attr: tui.Dim | tui.Italic, fg: 1, bg: 1},
+		&ansiState{attr: tui.Dim | tui.Italic, fg: 1, bg: 1, ul: -1},
 		"\x1b[2;3;7;38;2;10;20;30;48;5;100m")
+
+	// Underline styles
+	assert("\x1b[4:3m", nil, "\x1b[4:3;39;49m")
+	assert("\x1b[4:2m", nil, "\x1b[4:2;39;49m")
+	assert("\x1b[4:4m", nil, "\x1b[4:4;39;49m")
+	assert("\x1b[4:5m", nil, "\x1b[4:5;39;49m")
+	assert("\x1b[4:1m", nil, "\x1b[4;39;49m")
+
+	// Underline color (256-color)
+	assert("\x1b[4;58;5;100m", nil, "\x1b[4;39;49;58;5;100m")
+	// Underline color (24-bit)
+	assert("\x1b[4;58;2;255;0;128m", nil, "\x1b[4;39;49;58;2;255;0;128m")
+	// Curly underline + underline color
+	assert("\x1b[4:3;58;2;255;0;0m", nil, "\x1b[4:3;39;49;58;2;255;0;0m")
+	// SGR 59 resets underline color
+	assert("\x1b[59m", &ansiState{fg: 1, bg: -1, ul: 100, lbg: -1}, "\x1b[31;49m")
 }
 
 func TestParseAnsiCode(t *testing.T) {
 	tests := []struct {
-		In, Exp string
+		In  string
-		N       int
+		Exp string
+		N   int
+		Sep byte
 	}{
-		{"123", "", 123},
+		{"123", "", 123, 0},
-		{"1a", "", -1},
+		{"1a", "", -1, 0},
-		{"1a;12", "12", -1},
+		{"1a;12", "12", -1, ';'},
-		{"12;a", "a", 12},
+		{"12;a", "a", 12, ';'},
-		{"-2", "", -1},
+		{"-2", "", -1, 0},
+		// Colon sub-parameters: earliest separator wins (@shtse8)
+		{"4:3", "3", 4, ':'},
+		{"4:3;31", "3;31", 4, ':'},
+		{"38:2:255:0:0", "2:255:0:0", 38, ':'},
+		{"58:5:200", "5:200", 58, ':'},
+		// Semicolon before colon
+		{"4;38:2:0:0:0", "38:2:0:0:0", 4, ';'},
 	}
 	for _, x := range tests {
-		n, s := parseAnsiCode(x.In)
+		n, sep, s := parseAnsiCode(x.In)
-		if n != x.N || s != x.Exp {
+		if n != x.N || s != x.Exp || sep != x.Sep {
-			t.Fatalf("%q: got: (%d %q) want: (%d %q)", x.In, n, s, x.N, x.Exp)
+			t.Fatalf("%q: got: (%d %q %q) want: (%d %q %q)", x.In, n, s, string(sep), x.N, x.Exp, string(x.Sep))
 		}
 	}
 }
 
+// Test cases adapted from @shtse8 (PR #4678)
+func TestInterpretCodeUnderlineStyles(t *testing.T) {
+	// 4:0 = no underline
+	state := interpretCode("\x1b[4:0m", nil)
+	if state.attr&tui.Underline != 0 {
+		t.Error("4:0 should not set underline")
+	}
+
+	// 4:1 = single underline
+	state = interpretCode("\x1b[4:1m", nil)
+	if state.attr&tui.Underline == 0 {
+		t.Error("4:1 should set underline")
+	}
+
+	// 4:3 = curly underline
+	state = interpretCode("\x1b[4:3m", nil)
+	if state.attr&tui.Underline == 0 {
+		t.Error("4:3 should set underline")
+	}
+	if state.attr.UnderlineStyle() != tui.UlStyleCurly {
+		t.Error("4:3 should set curly underline style")
+	}
+
+	// 4:3 should NOT set italic (3 is a sub-param, not SGR 3)
+	if state.attr&tui.Italic != 0 {
+		t.Error("4:3 should not set italic")
+	}
+
+	// 4:2;31 = double underline + red fg
+	state = interpretCode("\x1b[4:2;31m", nil)
+	if state.attr&tui.Underline == 0 {
+		t.Error("4:2;31 should set underline")
+	}
+	if state.fg != 1 {
+		t.Errorf("4:2;31 should set fg to red (1), got %d", state.fg)
+	}
+	if state.attr&tui.Dim != 0 {
+		t.Error("4:2;31 should not set dim")
+	}
+
+	// Plain 4 still works
+	state = interpretCode("\x1b[4m", nil)
+	if state.attr&tui.Underline == 0 {
+		t.Error("4 should set underline")
+	}
+
+	// 4;2 (semicolon) = underline + dim
+	state = interpretCode("\x1b[4;2m", nil)
+	if state.attr&tui.Underline == 0 {
+		t.Error("4;2 should set underline")
+	}
+	if state.attr&tui.Dim == 0 {
+		t.Error("4;2 should set dim")
+	}
+}
+
+// Test cases adapted from @shtse8 (PR #4678)
+func TestInterpretCodeUnderlineColor(t *testing.T) {
+	// 58:2:R:G:B should not affect fg or bg
+	state := interpretCode("\x1b[58:2:255:0:0m", nil)
+	if state.fg != -1 || state.bg != -1 {
+		t.Errorf("58:2:R:G:B should not affect fg/bg, got fg=%d bg=%d", state.fg, state.bg)
+	}
+
+	// 58:5:200 should not affect fg or bg
+	state = interpretCode("\x1b[58:5:200m", nil)
+	if state.fg != -1 || state.bg != -1 {
+		t.Errorf("58:5:N should not affect fg/bg, got fg=%d bg=%d", state.fg, state.bg)
+	}
+
+	// 58:2:R:G:B combined with 38:2:R:G:B should only set fg
+	state = interpretCode("\x1b[58:2:255:0:0;38:2:0:255:0m", nil)
+	expectedFg := tui.Color(1<<24 | 0<<16 | 255<<8 | 0)
+	if state.fg != expectedFg {
+		t.Errorf("expected fg=%d, got %d", expectedFg, state.fg)
+	}
+	if state.bg != -1 {
+		t.Errorf("bg should be -1, got %d", state.bg)
+	}
+}
+
 // kernel/bpf/preload/iterators/README
 const ansiBenchmarkString = "\x1b[38;5;81m\x1b[01;31m\x1b[Kkernel/\x1b[0m\x1b[38:5:81mbpf/" +
 	"\x1b[0m\x1b[38:5:81mpreload/\x1b[0m\x1b[38;5;81miterators/" +

src/options.go

@@ -1407,6 +1407,14 @@ func parseTheme(defaultTheme *tui.ColorTheme, str string) (*tui.ColorTheme, *tui
 						cattr.Attr |= tui.Italic
 					case "underline":
 						cattr.Attr |= tui.Underline
+					case "underline-double":
+						cattr.Attr |= tui.Underline | tui.UlStyleDouble
+					case "underline-curly":
+						cattr.Attr |= tui.Underline | tui.UlStyleCurly
+					case "underline-dotted":
+						cattr.Attr |= tui.Underline | tui.UlStyleDotted
+					case "underline-dashed":
+						cattr.Attr |= tui.Underline | tui.UlStyleDashed
 					case "blink":
 						cattr.Attr |= tui.Blink
 					case "reverse":

src/result.go

@@ -206,7 +206,7 @@ func (result *Result) colorOffsets(matchOffsets []Offset, nthOffsets []Offset, t
 		if bg == -1 {
 			bg = colBase.Bg()
 		}
-		return tui.NewColorPair(fg, bg, ansi.color.attr).MergeAttr(base)
+		return tui.NewColorPair(fg, bg, ansi.color.attr).WithUl(ansi.color.ul).MergeAttr(base)
 	}
 	var colors []colorOffset
 	add := func(idx int) {

src/result_test.go

@@ -124,10 +124,10 @@ func TestColorOffset(t *testing.T) {
 	item := Result{
 		item: &Item{
 			colors: &[]ansiOffset{
-				{[2]int32{0, 20}, ansiState{1, 5, 0, -1, nil}},
+				{[2]int32{0, 20}, ansiState{1, 5, -1, 0, -1, nil}},
-				{[2]int32{22, 27}, ansiState{2, 6, tui.Bold, -1, nil}},
+				{[2]int32{22, 27}, ansiState{2, 6, -1, tui.Bold, -1, nil}},
-				{[2]int32{30, 32}, ansiState{3, 7, 0, -1, nil}},
+				{[2]int32{30, 32}, ansiState{3, 7, -1, 0, -1, nil}},
-				{[2]int32{33, 40}, ansiState{4, 8, tui.Bold, -1, nil}}}}}
+				{[2]int32{33, 40}, ansiState{4, 8, -1, tui.Bold, -1, nil}}}}}
 
 	colBase := tui.NewColorPair(89, 189, tui.AttrUndefined)
 	colMatch := tui.NewColorPair(99, 199, tui.AttrUndefined)

src/terminal.go

@@ -1549,7 +1549,7 @@ func (t *Terminal) parsePrompt(prompt string) (func(), int) {
 	//             // unless the part has a non-default ANSI state
 	loc := whiteSuffix.FindStringIndex(trimmed)
 	if loc != nil {
-		blankState := ansiOffset{[2]int32{int32(loc[0]), int32(loc[1])}, ansiState{tui.ColPrompt.Fg(), tui.ColPrompt.Bg(), tui.AttrClear, -1, nil}}
+		blankState := ansiOffset{[2]int32{int32(loc[0]), int32(loc[1])}, ansiState{tui.ColPrompt.Fg(), tui.ColPrompt.Bg(), -1, tui.AttrClear, -1, nil}}
 		if item.colors != nil {
 			lastColor := (*item.colors)[len(*item.colors)-1]
 			if lastColor.offset[1] < int32(loc[1]) {
@@ -4144,7 +4144,7 @@ Loop:
 					top := true
 					for ; y < height; y++ {
 						t.pwindow.MoveAndClear(y, 0)
-						t.pwindow.CFill(tui.ColPreview.Fg(), tui.ColPreview.Bg(), tui.AttrRegular, t.makeImageBorder(maxWidth, top))
+						t.pwindow.CFill(tui.ColPreview.Fg(), tui.ColPreview.Bg(), -1, tui.AttrRegular, t.makeImageBorder(maxWidth, top))
 						top = false
 					}
 					wireframe = true
@@ -4209,13 +4209,13 @@ Loop:
 					prefixWidth = width
 					colored := ansi != nil && ansi.colored()
 					if t.theme.Colored && colored {
-						fillRet = t.pwindow.CFill(ansi.fg, ansi.bg, ansi.attr, str)
+						fillRet = t.pwindow.CFill(ansi.fg, ansi.bg, ansi.ul, ansi.attr, str)
 					} else {
 						attr := tui.AttrRegular
 						if colored {
 							attr = ansi.attr
 						}
-						fillRet = t.pwindow.CFill(tui.ColPreview.Fg(), tui.ColPreview.Bg(), attr, str)
+						fillRet = t.pwindow.CFill(tui.ColPreview.Fg(), tui.ColPreview.Bg(), -1, attr, str)
 					}
 				}
 				return !isTrimmed &&
@@ -4235,7 +4235,7 @@ Loop:
 				break
 			}
 			if t.theme.Colored && lbg >= 0 {
-				fillRet = t.pwindow.CFill(-1, lbg, tui.AttrRegular,
+				fillRet = t.pwindow.CFill(-1, lbg, -1, tui.AttrRegular,
 					strings.Repeat(" ", t.pwindow.Width()-t.pwindow.X())+"\n")
 			} else {
 				fillRet = t.pwindow.Fill("\n")

src/tui/light.go

@@ -1323,7 +1323,18 @@ func attrCodes(attr Attr) []string {
 		codes = append(codes, "3")
 	}
 	if (attr & Underline) > 0 {
-		codes = append(codes, "4")
+		switch attr.UnderlineStyle() {
+		case UlStyleDouble:
+			codes = append(codes, "4:2")
+		case UlStyleCurly:
+			codes = append(codes, "4:3")
+		case UlStyleDotted:
+			codes = append(codes, "4:4")
+		case UlStyleDashed:
+			codes = append(codes, "4:5")
+		default:
+			codes = append(codes, "4")
+		}
 	}
 	if (attr & Blink) > 0 {
 		codes = append(codes, "5")
@@ -1361,8 +1372,27 @@ func colorCodes(fg Color, bg Color) []string {
 	return codes
 }
 
-func (w *LightWindow) csiColor(fg Color, bg Color, attr Attr) (bool, string) {
+func ulColorCode(c Color) string {
+	if c == colDefault {
+		return ""
+	}
+	if c.is24() {
+		r := (c >> 16) & 0xff
+		g := (c >> 8) & 0xff
+		b := (c) & 0xff
+		return fmt.Sprintf("58;2;%d;%d;%d", r, g, b)
+	}
+	if c >= 0 && c < 256 {
+		return fmt.Sprintf("58;5;%d", c)
+	}
+	return ""
+}
+
+func (w *LightWindow) csiColor(fg Color, bg Color, ul Color, attr Attr) (bool, string) {
 	codes := append(attrCodes(attr), colorCodes(fg, bg)...)
+	if ulCode := ulColorCode(ul); ulCode != "" {
+		codes = append(codes, ulCode)
+	}
 	code := w.csi(";" + strings.Join(codes, ";") + "m")
 	return len(codes) > 0, code
 }
@@ -1376,13 +1406,13 @@ func cleanse(str string) string {
 }
 
 func (w *LightWindow) CPrint(pair ColorPair, text string) {
-	_, code := w.csiColor(pair.Fg(), pair.Bg(), pair.Attr())
+	_, code := w.csiColor(pair.Fg(), pair.Bg(), pair.Ul(), pair.Attr())
 	w.stderrInternal(cleanse(text), false, code)
 	w.csi("0m")
 }
 
 func (w *LightWindow) cprint2(fg Color, bg Color, attr Attr, text string) {
-	hasColors, code := w.csiColor(fg, bg, attr)
+	hasColors, code := w.csiColor(fg, bg, colDefault, attr)
 	if hasColors {
 		defer w.csi("0m")
 	}
@@ -1472,7 +1502,7 @@ func (w *LightWindow) fill(str string, resetCode string) FillReturn {
 
 func (w *LightWindow) setBg() string {
 	if w.bg != colDefault {
-		_, code := w.csiColor(colDefault, w.bg, AttrRegular)
+		_, code := w.csiColor(colDefault, w.bg, colDefault, AttrRegular)
 		return code
 	}
 	// Should clear dim attribute after ␍ in the preview window
@@ -1494,7 +1524,7 @@ func (w *LightWindow) Fill(text string) FillReturn {
 	return w.fill(text, code)
 }
 
-func (w *LightWindow) CFill(fg Color, bg Color, attr Attr, text string) FillReturn {
+func (w *LightWindow) CFill(fg Color, bg Color, ul Color, attr Attr, text string) FillReturn {
 	w.Move(w.posy, w.posx)
 	if fg == colDefault {
 		fg = w.fg
@@ -1502,7 +1532,7 @@ func (w *LightWindow) CFill(fg Color, bg Color, attr Attr, text string) FillRetu
 	if bg == colDefault {
 		bg = w.bg
 	}
-	if hasColors, resetCode := w.csiColor(fg, bg, attr); hasColors {
+	if hasColors, resetCode := w.csiColor(fg, bg, ul, attr); hasColors {
 		defer w.csi("0m")
 		return w.fill(text, resetCode)
 	}

src/tui/tcell.go

@@ -825,6 +825,21 @@ func (w *TcellWindow) withUrl(style tcell.Style) tcell.Style {
 	return style
 }
 
+func underlineStyleFromAttr(a Attr) tcell.UnderlineStyle {
+	switch a.UnderlineStyle() {
+	case UlStyleDouble:
+		return tcell.UnderlineStyleDouble
+	case UlStyleCurly:
+		return tcell.UnderlineStyleCurly
+	case UlStyleDotted:
+		return tcell.UnderlineStyleDotted
+	case UlStyleDashed:
+		return tcell.UnderlineStyleDashed
+	default:
+		return tcell.UnderlineStyleSolid
+	}
+}
+
 func (w *TcellWindow) printString(text string, pair ColorPair) {
 	lx := 0
 	a := pair.Attr()
@@ -833,11 +848,18 @@ func (w *TcellWindow) printString(text string, pair ColorPair) {
 	if a&AttrClear == 0 {
 		style = style.
 			Reverse(a&Attr(tcell.AttrReverse) != 0).
-			Underline(a&Attr(tcell.AttrUnderline) != 0).
 			StrikeThrough(a&Attr(tcell.AttrStrikeThrough) != 0).
 			Italic(a&Attr(tcell.AttrItalic) != 0).
 			Blink(a&Attr(tcell.AttrBlink) != 0).
 			Dim(a&Attr(tcell.AttrDim) != 0)
+		if a&Attr(tcell.AttrUnderline) != 0 {
+			style = style.Underline(underlineStyleFromAttr(a))
+			if pair.Ul() != colDefault {
+				style = style.Underline(asTcellColor(pair.Ul()))
+			}
+		} else {
+			style = style.Underline(false)
+		}
 	}
 	style = w.withUrl(style)
 
@@ -887,9 +909,16 @@ func (w *TcellWindow) fillString(text string, pair ColorPair) FillReturn {
 		Bold(a&Attr(tcell.AttrBold) != 0 || a&BoldForce != 0).
 		Dim(a&Attr(tcell.AttrDim) != 0).
 		Reverse(a&Attr(tcell.AttrReverse) != 0).
-		Underline(a&Attr(tcell.AttrUnderline) != 0).
 		StrikeThrough(a&Attr(tcell.AttrStrikeThrough) != 0).
 		Italic(a&Attr(tcell.AttrItalic) != 0)
+	if a&Attr(tcell.AttrUnderline) != 0 {
+		style = style.Underline(underlineStyleFromAttr(a))
+		if pair.Ul() != colDefault {
+			style = style.Underline(asTcellColor(pair.Ul()))
+		}
+	} else {
+		style = style.Underline(false)
+	}
 	style = w.withUrl(style)
 
 	gr := uniseg.NewGraphemes(text)
@@ -967,14 +996,14 @@ func (w *TcellWindow) LinkEnd() {
 	w.params = nil
 }
 
-func (w *TcellWindow) CFill(fg Color, bg Color, a Attr, str string) FillReturn {
+func (w *TcellWindow) CFill(fg Color, bg Color, ul Color, a Attr, str string) FillReturn {
 	if fg == colDefault {
 		fg = w.normal.Fg()
 	}
 	if bg == colDefault {
 		bg = w.normal.Bg()
 	}
-	return w.fillString(str, NewColorPair(fg, bg, a))
+	return w.fillString(str, NewColorPair(fg, bg, a).WithUl(ul))
 }
 
 func (w *TcellWindow) DrawBorder() {

src/tui/tui.go

@@ -17,15 +17,34 @@ const (
 	BoldForce     = Attr(1 << 10)
 	FullBg        = Attr(1 << 11)
 	Strip         = Attr(1 << 12)
+
+	// Underline style stored in bits 13-15 (3 bits, values 0-4)
+	// Only meaningful when the Underline attribute bit is also set.
+	// 0 = solid (default)
+	UnderlineStyleShift = 13
+	UnderlineStyleMask  = Attr(0b111 << UnderlineStyleShift)
+	UlStyleDouble       = Attr(0b001 << UnderlineStyleShift)
+	UlStyleCurly        = Attr(0b010 << UnderlineStyleShift)
+	UlStyleDotted       = Attr(0b011 << UnderlineStyleShift)
+	UlStyleDashed       = Attr(0b100 << UnderlineStyleShift)
 )
 
+func (a Attr) UnderlineStyle() Attr {
+	return a & UnderlineStyleMask
+}
+
 func (a Attr) Merge(b Attr) Attr {
 	if b&AttrRegular > 0 {
 		// Only keep bold attribute set by the system
 		return (b &^ AttrRegular) | (a & BoldForce)
 	}
 
-	return (a &^ AttrRegular) | b
+	merged := (a &^ AttrRegular) | b
+	// When b sets Underline, use b's underline style instead of OR'ing
+	if b&Underline > 0 {
+		merged = (merged &^ UnderlineStyleMask) | (b & UnderlineStyleMask)
+	}
+	return merged
 }
 
 // Types of user action
@@ -352,6 +371,7 @@ const (
 type ColorPair struct {
 	fg   Color
 	bg   Color
+	ul   Color
 	attr Attr
 }
 
@@ -363,11 +383,11 @@ func HexToColor(rrggbb string) Color {
 }
 
 func NewColorPair(fg Color, bg Color, attr Attr) ColorPair {
-	return ColorPair{fg, bg, attr}
+	return ColorPair{fg, bg, colDefault, attr}
 }
 
 func NoColorPair() ColorPair {
-	return ColorPair{-1, -1, 0}
+	return ColorPair{-1, -1, -1, 0}
 }
 
 func (p ColorPair) Fg() Color {
@@ -378,6 +398,16 @@ func (p ColorPair) Bg() Color {
 	return p.bg
 }
 
+func (p ColorPair) Ul() Color {
+	return p.ul
+}
+
+func (p ColorPair) WithUl(ul Color) ColorPair {
+	dup := p
+	dup.ul = ul
+	return dup
+}
+
 func (p ColorPair) Attr() Attr {
 	return p.attr
 }
@@ -404,6 +434,9 @@ func (p ColorPair) merge(other ColorPair, except Color) ColorPair {
 	if other.bg != except {
 		dup.bg = other.bg
 	}
+	if other.ul != except {
+		dup.ul = other.ul
+	}
 	return dup
 }
 
@@ -415,13 +448,13 @@ func (p ColorPair) WithAttr(attr Attr) ColorPair {
 
 func (p ColorPair) WithFg(fg ColorAttr) ColorPair {
 	dup := p
-	fgPair := ColorPair{fg.Color, colUndefined, fg.Attr}
+	fgPair := ColorPair{fg.Color, colUndefined, colUndefined, fg.Attr}
 	return dup.Merge(fgPair)
 }
 
 func (p ColorPair) WithBg(bg ColorAttr) ColorPair {
 	dup := p
-	bgPair := ColorPair{colUndefined, bg.Color, bg.Attr}
+	bgPair := ColorPair{colUndefined, bg.Color, colUndefined, bg.Attr}
 	return dup.Merge(bgPair)
 }
 
@@ -783,7 +816,7 @@ type Window interface {
 	Print(text string)
 	CPrint(color ColorPair, text string)
 	Fill(text string) FillReturn
-	CFill(fg Color, bg Color, attr Attr, text string) FillReturn
+	CFill(fg Color, bg Color, ul Color, attr Attr, text string) FillReturn
 	LinkBegin(uri string, params string)
 	LinkEnd()
 	Erase()
@@ -1271,7 +1304,7 @@ func initPalette(theme *ColorTheme) {
 		if fg.Color == colDefault && (fg.Attr&Reverse) > 0 {
 			bg.Color = colDefault
 		}
-		return ColorPair{fg.Color, bg.Color, fg.Attr}
+		return ColorPair{fg.Color, bg.Color, colDefault, fg.Attr}
 	}
 	blank := theme.ListFg
 	blank.Attr = AttrRegular