debugui: replace uniseg with go-text/typesetting segmenter for line breaking

Closes #49

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: hajimehoshi

context.go

@@ -9,6 +9,7 @@ import (
 	"maps"
 	"slices"
 
+	"github.com/go-text/typesetting/segmenter"
 	"github.com/hajimehoshi/ebiten/v2"
 )
 
@@ -54,9 +55,25 @@ type Context struct {
 	screenWidth  int
 	screenHeight int
 
+	segStack    []segmenter.Segmenter
+	segStackIdx int
+
 	err error
 }
 
+func (c *Context) pushSegmenter() *segmenter.Segmenter {
+	if c.segStackIdx >= len(c.segStack) {
+		c.segStack = append(c.segStack, segmenter.Segmenter{})
+	}
+	seg := &c.segStack[c.segStackIdx]
+	c.segStackIdx++
+	return seg
+}
+
+func (c *Context) popSegmenter() {
+	c.segStackIdx--
+}
+
 func (c *Context) wrapEventHandlerAndError(f func() (EventHandler, error)) EventHandler {
 	if c.err != nil {
 		return &nullEventHandler{}

go.mod

@@ -3,20 +3,20 @@ module github.com/ebitengine/debugui
 go 1.24.0
 
 require (
+	github.com/go-text/typesetting v0.3.5-0.20260309142344-94fe510e6837
 	github.com/hajimehoshi/bitmapfont/v4 v4.1.0
 	github.com/hajimehoshi/ebiten/v2 v2.9.8
 	github.com/kisielk/errcheck v1.10.0
-	github.com/rivo/uniseg v0.4.7
 	golang.org/x/tools v0.42.0
 )
 
 require (
 	github.com/ebitengine/gomobile v0.0.0-20250923094054-ea854a63cce1 // indirect
 	github.com/ebitengine/hideconsole v1.0.0 // indirect
 	github.com/ebitengine/purego v0.9.0 // indirect
-	github.com/go-text/typesetting v0.3.0 // indirect
 	github.com/jezek/xgb v1.1.1 // indirect
 	github.com/pierrec/lz4/v4 v4.1.22 // indirect
+	github.com/rivo/uniseg v0.4.7 // indirect
 	golang.org/x/image v0.31.0 // indirect
 	golang.org/x/mod v0.33.0 // indirect
 	golang.org/x/sync v0.19.0 // indirect

go.sum

@@ -4,10 +4,10 @@ github.com/ebitengine/hideconsole v1.0.0 h1:5J4U0kXF+pv/DhiXt5/lTz0eO5ogJ1iXb8Yj
 github.com/ebitengine/hideconsole v1.0.0/go.mod h1:hTTBTvVYWKBuxPr7peweneWdkUwEuHuB3C1R/ielR1A=
 github.com/ebitengine/purego v0.9.0 h1:mh0zpKBIXDceC63hpvPuGLiJ8ZAa3DfrFTudmfi8A4k=
 github.com/ebitengine/purego v0.9.0/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=
-github.com/go-text/typesetting v0.3.0 h1:OWCgYpp8njoxSRpwrdd1bQOxdjOXDj9Rqart9ML4iF4=
-github.com/go-text/typesetting v0.3.0/go.mod h1:qjZLkhRgOEYMhU9eHBr3AR4sfnGJvOXNLt8yRAySFuY=
-github.com/go-text/typesetting-utils v0.0.0-20241103174707-87a29e9e6066 h1:qCuYC+94v2xrb1PoS4NIDe7DGYtLnU2wWiQe9a1B1c0=
-github.com/go-text/typesetting-utils v0.0.0-20241103174707-87a29e9e6066/go.mod h1:DDxDdQEnB70R8owOx3LVpEFvpMK9eeH1o2r0yZhFI9o=
+github.com/go-text/typesetting v0.3.5-0.20260309142344-94fe510e6837 h1:UDgW/cvxs0VfC5ATr1PCk+09SpdNzcpdq/BL6pcBCII=
+github.com/go-text/typesetting v0.3.5-0.20260309142344-94fe510e6837/go.mod h1:4qZCQphq4KSgGTAeI0uMEkVbROgfah8BuyF5LRYr7XY=
+github.com/go-text/typesetting-utils v0.0.0-20260223113751-2d88ac90dae3 h1:drBZzMgdYPbmyXqOto4YhhJGrFIQCX94FpR4MzTCsos=
+github.com/go-text/typesetting-utils v0.0.0-20260223113751-2d88ac90dae3/go.mod h1:3/62I4La/HBRX9TcTpBj4eipLiwzf+vhI+7whTc9V7o=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/hajimehoshi/bitmapfont/v4 v4.1.0 h1:eE3qa5Do4qhowZVIHjsrX5pYyyPN6sAFWMsO7QREm3U=

text.go

@@ -8,50 +8,59 @@ import (
 	"iter"
 	"strings"
 	"unicode"
-
-	"github.com/rivo/uniseg"
 )
 
 func removeSpaceAtLineTail(str string) string {
 	return strings.TrimRightFunc(str, unicode.IsSpace)
 }
 
-func lines(text string, width int) iter.Seq[string] {
+func sanitizeUTF8(s string) string {
+	var b strings.Builder
+	for _, r := range s {
+		b.WriteRune(r)
+	}
+	return b.String()
+}
+
+func (c *Context) lines(text string, width int) iter.Seq[string] {
 	return func(yield func(string) bool) {
+		seg := c.pushSegmenter()
+		defer c.popSegmenter()
+
+		if err := seg.InitWithString(text); err != nil {
+			text = sanitizeUTF8(text)
+			if err := seg.InitWithString(text); err != nil {
+				panic("debugui: segmenter.InitWithString failed even after sanitizing: " + err.Error())
+			}
+		}
+
 		var line string
-		var word string
-		state := -1
-		for len(text) > 0 {
-			cluster, nextText, boundaries, nextState := uniseg.StepString(text, state)
-			switch m := boundaries & uniseg.MaskLine; m {
-			default:
-				word += cluster
-			case uniseg.LineCanBreak, uniseg.LineMustBreak:
-				if line == "" {
-					line += word + cluster
-				} else {
-					if l := removeSpaceAtLineTail(line + word + cluster); textWidth(l) > width {
-						if !yield(removeSpaceAtLineTail(line)) {
-							return
-						}
-						line = word + cluster
-					} else {
-						line += word + cluster
-					}
-				}
-				word = ""
-				if m == uniseg.LineMustBreak {
+		it := seg.LineIterator()
+		for it.Next() {
+			l := it.Line()
+			segment := text[l.OffsetInBytes : l.OffsetInBytes+l.LengthInBytes]
+
+			if line == "" {
+				line = segment
+			} else {
+				if trimmed := removeSpaceAtLineTail(line + segment); textWidth(trimmed) > width {
 					if !yield(removeSpaceAtLineTail(line)) {
 						return
 					}
-					line = ""
+					line = segment
+				} else {
+					line += segment
+				}
+			}
+
+			if l.IsMandatoryBreak {
+				if !yield(removeSpaceAtLineTail(line)) {
+					return
 				}
+				line = ""
 			}
-			state = nextState
-			text = nextText
 		}
 
-		line += word
 		if len(line) > 0 {
 			if !yield(removeSpaceAtLineTail(line)) {
 				return
@@ -63,7 +72,7 @@ func lines(text string, width int) iter.Seq[string] {
 // Text creates a text label.
 func (c *Context) Text(text string) {
 	c.GridCell(func(bounds image.Rectangle) {
-		for line := range lines(text, bounds.Dx()-c.style().padding) {
+		for line := range c.lines(text, bounds.Dx()-c.style().padding) {
 			_, _ = c.widget(widgetID{}, 0, nil, nil, func(bounds image.Rectangle) {
 				c.drawWidgetText(line, bounds, colorText, 0)
 			})