Improve IME handling

editor.go

@@ -88,8 +88,10 @@ type imeState struct {
 		rng   key.Range
 		caret key.Caret
 	}
-	snippet    key.Snippet
-	start, end int
+	snippet     key.Snippet
+	start, end  int
+	isComposing bool
+	composition key.Range
 }
 
 type EditorEvent interface {
@@ -279,6 +281,7 @@ func (e *Editor) layout(gtx layout.Context) layout.Dimensions {
 		}
 
 		e.paintText(gtx, textColor)
+		e.paintComposition(gtx, textColor)
 	}
 	if gtx.Enabled() {
 		e.paintCaret(gtx, textColor)
@@ -316,6 +319,16 @@ func (e *Editor) paintCaret(gtx layout.Context, material color.Color) {
 	e.text.PaintCaret(gtx, material.Op(gtx.Ops))
 }
 
+func (e *Editor) paintComposition(gtx layout.Context, material color.Color) {
+	e.initBuffer()
+	if !e.ime.isComposing {
+		return
+	}
+
+	e.text.PaintComposition(gtx, e.ime.composition, material.Op(gtx.Ops), "dash")
+
+}
+
 // Len is the length of the editor contents, in runes.
 func (e *Editor) Len() int {
 	e.initBuffer()

event.go

@@ -250,6 +250,40 @@ func (e *Editor) processEditEvents(gtx layout.Context) EditorEvent {
 			e.updateSnippet(gtx, ke.Start, ke.End)
 		case key.EditEvent:
 			e.onTextInput(ke)
+		case key.CompositionEvent:
+			// Since v0.10.1, gio delivers IME composition event. During composition stage,
+			// range marks the current text range of composition. When composition confirmed/canceled,
+			// range becomes (-1, -1).
+			// When there is no IME for text input, no CompositionEvent is delivered.
+			e.ime.composition = key.Range(ke)
+
+			isStart := false
+			isFinish := false
+
+			if ke.Start != -1 && ke.Start != ke.End {
+				if !e.ime.isComposing {
+					isStart = true
+				}
+				e.ime.isComposing = true
+			} else {
+				if e.ime.isComposing {
+					isFinish = true
+				}
+				e.ime.isComposing = false
+			}
+
+			// GroupOp and UnGroupOp must be paired.
+			if isStart {
+				// composition started, ensure the undo transaction has started, and all text of a IME composition
+				// can be undone in a batch.
+				e.buffer.GroupOp()
+			}
+
+			if isFinish {
+				// composition is done, seal the undo transaction.
+				e.buffer.UnGroupOp()
+			}
+
 		case key.SelectionEvent:
 			e.scrollCaret = true
 			e.scroller.Stop()

go.mod

@@ -3,9 +3,9 @@ module github.com/oligo/gvcode
 go 1.25
 
 require (
-	gioui.org v0.9.0
+	gioui.org v0.10.1
 	github.com/andybalholm/stroke v0.0.0-20230904101225-24ef450bc62c
-	github.com/go-text/typesetting v0.3.0
+	github.com/go-text/typesetting v0.3.4
 	github.com/rdleal/intervalst v1.4.1
 	golang.org/x/exp v0.0.0-20250408133849-7e4ce0ab07d0
 	golang.org/x/image v0.26.0
@@ -14,6 +14,7 @@ require (
 require (
 	gioui.org/shader v1.0.8 // indirect
 	golang.org/x/exp/shiny v0.0.0-20250408133849-7e4ce0ab07d0 // indirect
-	golang.org/x/sys v0.33.0 // indirect
-	golang.org/x/text v0.24.0 // indirect
+	golang.org/x/net v0.48.0 // indirect
+	golang.org/x/sys v0.39.0 // indirect
+	golang.org/x/text v0.32.0 // indirect
 )

go.sum

@@ -1,16 +1,16 @@
 eliasnaur.com/font v0.0.0-20230308162249-dd43949cb42d h1:ARo7NCVvN2NdhLlJE9xAbKweuI9L6UgfTbYb0YwPacY=
 eliasnaur.com/font v0.0.0-20230308162249-dd43949cb42d/go.mod h1:OYVuxibdk9OSLX8vAqydtRPP87PyTFcT9uH3MlEGBQA=
-gioui.org v0.9.0 h1:4u7XZwnb5kzQW91Nz/vR0wKD6LdW9CaVF96r3rfy4kc=
-gioui.org v0.9.0/go.mod h1:CjNig0wAhLt9WZxOPAusgFD8x8IRvqt26LdDBa3Jvao=
+gioui.org v0.10.1 h1:Dvp6iDk9RKuZk19jxhOmb4p673CLVvb656LyMxQ+uO0=
+gioui.org v0.10.1/go.mod h1:MZJZsdEPkTBzChdqeE8CiiQhreUQBj43qusDxQNDf7k=
 gioui.org/cpu v0.0.0-20210808092351-bfe733dd3334/go.mod h1:A8M0Cn5o+vY5LTMlnRoK3O5kG+rH0kWfJjeKd9QpBmQ=
 gioui.org/shader v1.0.8 h1:6ks0o/A+b0ne7RzEqRZK5f4Gboz2CfG+mVliciy6+qA=
 gioui.org/shader v1.0.8/go.mod h1:mWdiME581d/kV7/iEhLmUgUK5iZ09XR5XpduXzbePVM=
 github.com/andybalholm/stroke v0.0.0-20230904101225-24ef450bc62c h1:hHefapU8Zg8roqjYi9V8CNFPD0z6tbDDSqNgBgY1O4U=
 github.com/andybalholm/stroke v0.0.0-20230904101225-24ef450bc62c/go.mod h1:ccdDYaY5+gO+cbnQdFxEXqfy0RkoV25H3jLXUDNM3wg=
-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 v0.3.4 h1:YYurUOtEb9kGSOz4uE3k4OpBGsp1dDL8+fjCeaFamAU=
+github.com/go-text/typesetting v0.3.4/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/rdleal/intervalst v1.4.1 h1:8rCuAea0aj3Z6cDSeN3Q3c+LZjmHmrqZhXrJbqfPw0c=
 github.com/rdleal/intervalst v1.4.1/go.mod h1:xO89Z6BC+LQDH+IPQQw/OESt5UADgFD41tYMUINGpxQ=
 golang.org/x/exp v0.0.0-20250408133849-7e4ce0ab07d0 h1:R84qjqJb5nVJMxqWYb3np9L5ZsaDtB+a39EqjV0JSUM=
@@ -19,7 +19,9 @@ golang.org/x/exp/shiny v0.0.0-20250408133849-7e4ce0ab07d0 h1:tMSqXTK+AQdW3LpCbfa
 golang.org/x/exp/shiny v0.0.0-20250408133849-7e4ce0ab07d0/go.mod h1:ygj7T6vSGhhm/9yTpOQQNvuAUFziTH7RUiH74EoE2C8=
 golang.org/x/image v0.26.0 h1:4XjIFEZWQmCZi6Wv8BoxsDhRU3RVnLX04dToTDAEPlY=
 golang.org/x/image v0.26.0/go.mod h1:lcxbMFAovzpnJxzXS3nyL83K27tmqtKzIJpctK8YO5c=
-golang.org/x/sys v0.33.0 h1:q3i8TbbEz+JRD9ywIRlyRAQbM0qF7hu24q3teo2hbuw=
-golang.org/x/sys v0.33.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
-golang.org/x/text v0.24.0 h1:dd5Bzh4yt5KYA8f9CJHCP4FB4D51c2c6JvN37xJJkJ0=
-golang.org/x/text v0.24.0/go.mod h1:L8rBsPeo2pSS+xqN0d5u2ikmjtmoJbDBT1b7nHvFCdU=
+golang.org/x/net v0.48.0 h1:zyQRTTrjc33Lhh0fBgT/H3oZq9WuvRR5gPC70xpDiQU=
+golang.org/x/net v0.48.0/go.mod h1:+ndRgGjkh8FGtu1w1FGbEC31if4VrNVMuKTgcAAnQRY=
+golang.org/x/sys v0.39.0 h1:CvCKL8MeisomCi6qNZ+wbb0DN9E5AATixKsvNtMoMFk=
+golang.org/x/sys v0.39.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/text v0.32.0 h1:ZD01bjUt1FQ9WJ0ClOL5vxgxOI/sVCNgX1YtKwcY0mU=
+golang.org/x/text v0.32.0/go.mod h1:o/rUWzghvpD5TXrTIBuJU77MTaN0ljMWE47kxGJQ7jY=

internal/buffer/piecetable.go

@@ -6,6 +6,7 @@ import (
 	"slices"
 	"strings"
 	"sync"
+	"unicode"
 	"unicode/utf8"
 )
 
@@ -189,12 +190,40 @@ func (pt *PieceTable) insert(runeIndex int, text string) bool {
 }
 
 // Check if this insert action can be optimized by merging the input with previous one.
-// multiple characters input won't be merged.
+// The following rules are applied when deciding merging or not:
+//
+//   - multiple characters input won't be merged.
+//   - unicode space characters are not merged.
+//   - character class transitions: transitions between normal chars and punctuations/symbols.
+//
+// This prevent different chars from being undo as a unit, and similar chars can be combines
+// and undo as a unit.
 func (pt *PieceTable) tryAppendToLastPiece(runeIndex int, text string) bool {
 	if pt.lastAction != actionInsert ||
 		runeIndex != pt.lastActionEndIdx ||
-		pt.lastInsertPiece == nil ||
-		utf8.RuneCountInString(text) > 1 {
+		pt.lastInsertPiece == nil {
+		return false
+	}
+
+	r, size := utf8.DecodeRuneInString(text)
+	if size != len(text) {
+		// Either contains multiple runes or invalid UTF-8
+		return false
+	}
+
+	// Prevent unicode space character from merging.
+	if unicode.IsSpace(r) {
+		return false
+	}
+
+	// get last inserted rune
+	lastRune, _, err := pt.getBuf(pt.lastInsertPiece.source).ReadRuneAt(int64(pt.lastInsertPiece.byteOff + pt.lastInsertPiece.byteLength - 1))
+	if err != nil {
+		// FIXME: return error here?
+		return false
+	}
+	//
+	if isPunctuationOrSymbol(r) != isPunctuationOrSymbol(lastRune) {
 		return false
 	}
 
@@ -213,6 +242,11 @@ func (pt *PieceTable) tryAppendToLastPiece(runeIndex int, text string) bool {
 	return true
 }
 
+// Helper to catch brackets, operators, and punctuation
+func isPunctuationOrSymbol(r rune) bool {
+	return unicode.IsPunct(r) || unicode.IsSymbol(r)
+}
+
 func (pt *PieceTable) insertAtBoundary(runeIndex int, text string, oldPiece *piece) {
 	textRuneOff, textByteOff, textRunes := pt.addToBuffer(modify, []byte(text))
 
@@ -223,7 +257,6 @@ func (pt *PieceTable) insertAtBoundary(runeIndex int, text string, oldPiece *pie
 		byteOff:    textByteOff,
 		byteLength: len(text),
 	}
-	pt.lastInsertPiece = newPiece
 
 	// insertion is at the boundary of 2 pieces.
 	oldPieces := &pieceRange{
@@ -240,6 +273,7 @@ func (pt *PieceTable) insertAtBoundary(runeIndex int, text string, oldPiece *pie
 	pt.seqLength += textRunes
 	pt.seqBytes += len(text)
 	pt.recordAction(actionInsert, runeIndex+textRunes)
+	pt.lastInsertPiece = newPiece
 }
 
 func (pt *PieceTable) insertInMiddle(runeIndex int, text string, oldPiece *piece, inRuneOff int) {
@@ -252,7 +286,6 @@ func (pt *PieceTable) insertInMiddle(runeIndex int, text string, oldPiece *piece
 		byteOff:    textByteOff,
 		byteLength: len(text),
 	}
-	pt.lastInsertPiece = newPiece
 
 	// preserve the old pieces as a pieceRange, and push to the undo stack.
 	oldPieces := &pieceRange{
@@ -294,6 +327,7 @@ func (pt *PieceTable) insertInMiddle(runeIndex int, text string, oldPiece *piece
 	pt.seqLength += textRunes
 	pt.seqBytes += len(text)
 	pt.recordAction(actionInsert, runeIndex+textRunes)
+	pt.lastInsertPiece = newPiece
 }
 
 // undoRedo restores operation saved in src to dest. If there is a valid batchId, the src stack
@@ -547,9 +581,14 @@ func (pt *PieceTable) UnGroupOp() {
 }
 
 func (pt *PieceTable) unGroupOp() {
+	if pt.currentBatch == nil {
+		return
+	}
+
 	*pt.currentBatch--
 	if *pt.currentBatch <= 0 {
 		pt.currentBatch = nil
+
 	}
 }
 

textview/text_paint.go

@@ -5,6 +5,8 @@ import (
 	"image/color"
 	"math"
 
+	"gioui.org/f32"
+	"gioui.org/io/key"
 	"gioui.org/layout"
 	"gioui.org/op"
 	"gioui.org/op/clip"
@@ -13,6 +15,7 @@ import (
 	"gioui.org/unit"
 	lt "github.com/oligo/gvcode/internal/layout"
 	"github.com/oligo/gvcode/internal/painter"
+	"github.com/oligo/gvcode/internal/stroke"
 )
 
 // calculateViewSize determines the size of the current visible content,
@@ -182,6 +185,63 @@ func (e *TextView) HighlightMatchingBrackets(gtx layout.Context, material op.Cal
 	}
 }
 
+func (e *TextView) PaintComposition(gtx layout.Context, rng key.Range, material op.CallOp, pattern string) {
+	if rng == (key.Range{}) || rng.Start < 0 || rng.End < 0 || rng.Start == rng.End {
+		return
+	}
+
+	localViewport := image.Rectangle{Max: e.viewSize}
+	docViewport := image.Rectangle{Max: e.viewSize}.Add(e.scrollOff)
+	defer clip.Rect(localViewport).Push(gtx.Ops).Pop()
+
+	e.regions = e.layouter.Locate(docViewport, rng.Start, rng.End, e.regions)
+	if len(e.regions) == 0 {
+		return
+	}
+
+	thickness := max(gtx.Dp(unit.Dp(1)), 1)
+
+	for _, region := range e.regions {
+		y := region.Bounds.Max.Y - max(region.Baseline*2/3, thickness) // 1/3 below the baseline.
+		underline := image.Rect(region.Bounds.Min.X, y, region.Bounds.Max.X, y+thickness)
+		underline = underline.Intersect(localViewport)
+		if underline.Empty() {
+			continue
+		}
+
+		switch pattern {
+
+		case "dash":
+			path := stroke.Path{}
+			path.Segments = append(path.Segments, stroke.MoveTo(f32.Pt(float32(underline.Min.X), float32(underline.Max.Y))))
+			path.Segments = append(path.Segments, stroke.LineTo(f32.Pt(float32(underline.Max.X), float32(underline.Max.Y))))
+
+			cl := stroke.Stroke{
+				Path:  path,
+				Width: float32(thickness),
+				Cap:   stroke.FlatCap,
+				Join:  stroke.BevelJoin,
+				Dashes: stroke.Dashes{
+					Dashes: []float32{4, 2},
+				},
+			}.Op(gtx.Ops).Push(gtx.Ops)
+
+			material.Add(gtx.Ops)
+			paint.PaintOp{}.Add(gtx.Ops)
+
+			cl.Pop()
+		default:
+			// simple underline
+			stack := clip.Rect(underline).Push(gtx.Ops)
+			material.Add(gtx.Ops)
+			paint.PaintOp{}.Add(gtx.Ops)
+			stack.Pop()
+		}
+
+	}
+
+}
+
 // caretCurrentLine returns the current paragraph that the carent is in.
 // Only the start position is checked.
 func (e *TextView) caretCurrentLine() (start lt.CombinedPos, end lt.CombinedPos, lineIndex int) {