Implement word wrapping in the preview window

Example:
  fzf --preview 'bat --style=plain --color=always {}' \
      --preview-window wrap-word \
      --bind space:toggle-preview-wrap-word

Close https://github.com/junegunn/fzf/discussions/3383

src/tui/tcell.go

@@ -5,6 +5,7 @@ package tui
 import (
 	"os"
 	"regexp"
+	"strings"
 	"time"
 
 	"github.com/gdamore/tcell/v2"
@@ -53,6 +54,7 @@ type TcellWindow struct {
 	showCursor    bool
 	wrapSign      string
 	wrapSignWidth int
+	tabstop       int
 }
 
 func (w *TcellWindow) Top() int {
@@ -757,7 +759,8 @@ func (r *FullscreenRenderer) NewWindow(top int, left int, width int, height int,
 		height:      height,
 		normal:      normal,
 		borderStyle: borderStyle,
-		showCursor:  r.showCursor}
+		showCursor:  r.showCursor,
+		tabstop:     r.tabstop}
 	w.Erase()
 	return w
 }
@@ -894,10 +897,8 @@ func (w *TcellWindow) CPrint(pair ColorPair, text string) {
 	w.printString(text, pair)
 }
 
-func (w *TcellWindow) fillString(text string, pair ColorPair) FillReturn {
-	lx := 0
+func (w *TcellWindow) pairStyle(pair ColorPair) tcell.Style {
 	a := pair.Attr()
-
 	var style tcell.Style
 	if w.color {
 		style = pair.style()
@@ -919,61 +920,61 @@ func (w *TcellWindow) fillString(text string, pair ColorPair) FillReturn {
 	} else {
 		style = style.Underline(false)
 	}
-	style = w.withUrl(style)
+	return w.withUrl(style)
+}
 
+func (w *TcellWindow) renderGraphemes(text string, style tcell.Style) {
 	gr := uniseg.NewGraphemes(text)
-Loop:
 	for gr.Next() {
 		st := style
 		rs := gr.Runes()
-		if len(rs) == 1 {
-			r := rs[0]
-			switch r {
-			case '\r':
-				st = style.Dim(true)
-				rs[0] = '␍'
-			case '\n':
-				w.lastY++
-				w.lastX = 0
-				lx = 0
-				continue Loop
-			}
-		}
-
-		// word wrap:
-		xPos := w.left + w.lastX + lx
-		if xPos >= w.left+w.width {
-			w.lastY++
-			if w.lastY >= w.height {
-				return FillSuspend
-			}
-			w.lastX = 0
-			lx = 0
-			xPos = w.left
-			sign := w.wrapSign
-			if w.wrapSignWidth > w.width {
-				runes, _ := util.Truncate(sign, w.width)
-				sign = string(runes)
-			}
-			wgr := uniseg.NewGraphemes(sign)
-			for wgr.Next() {
-				rs := wgr.Runes()
-				_screen.SetContent(w.left+lx, w.top+w.lastY, rs[0], rs[1:], style.Dim(true))
-				lx += uniseg.StringWidth(string(rs))
-			}
-			xPos = w.left + lx
+		if len(rs) == 1 && rs[0] == '\r' {
+			st = style.Dim(true)
+			rs[0] = '␍'
 		}
 
+		xPos := w.left + w.lastX
 		yPos := w.top + w.lastY
-		if yPos >= (w.top + w.height) {
-			return FillSuspend
+		if xPos < (w.left+w.width) && yPos < (w.top+w.height) {
+			_screen.SetContent(xPos, yPos, rs[0], rs[1:], st)
 		}
-
-		_screen.SetContent(xPos, yPos, rs[0], rs[1:], st)
-		lx += util.StringWidth(string(rs))
+		w.lastX += util.StringWidth(string(rs))
 	}
-	w.lastX += lx
-	if w.lastX == w.width {
+}
+
+func (w *TcellWindow) renderWrapSign(style tcell.Style) {
+	sign := w.wrapSign
+	if w.wrapSignWidth > w.width {
+		runes, _ := util.Truncate(sign, w.width)
+		sign = string(runes)
+	}
+	gr := uniseg.NewGraphemes(sign)
+	for gr.Next() {
+		rs := gr.Runes()
+		_screen.SetContent(w.left+w.lastX, w.top+w.lastY, rs[0], rs[1:], style.Dim(true))
+		w.lastX += uniseg.StringWidth(string(rs))
+	}
+}
+
+func (w *TcellWindow) fillString(text string, pair ColorPair) FillReturn {
+	style := w.pairStyle(pair)
+
+	for i, segment := range strings.Split(text, "\n") {
+		for j, wl := range WrapLine(segment, w.lastX, w.width, w.tabstop, w.wrapSignWidth) {
+			if i > 0 || j > 0 {
+				w.lastY++
+				if w.lastY >= w.height {
+					return FillSuspend
+				}
+				w.lastX = 0
+				if j > 0 {
+					w.renderWrapSign(style)
+				}
+			}
+			w.renderGraphemes(wl.Text, style)
+		}
+	}
+	if w.lastX >= w.width {
 		w.lastY++
 		w.lastX = 0
 		return FillNextLine