diff --git a/font/opentype/opentype.go b/font/opentype/opentype.go
index 04ca2f45..3e89cefc 100644
--- a/font/opentype/opentype.go
+++ b/font/opentype/opentype.go
@@ -5,6 +5,7 @@
 package opentype
 
 import (
+	"bytes"
 	"io"
 	"unicode"
 	"unicode/utf8"
@@ -36,6 +37,13 @@ type opentype struct {
 	Hinting font.Hinting
 }
 
+// a glyph represents a rune and its advance according to a Font.
+// TODO: remove this type and work on io.Readers directly.
+type glyph struct {
+	Rune    rune
+	Advance fixed.Int26_6
+}
+
 // NewFont parses an SFNT font, such as TTF or OTF data, from a []byte
 // data source.
 func Parse(src []byte) (*Font, error) {
@@ -110,7 +118,7 @@ func (f *Font) Layout(ppem fixed.Int26_6, maxWidth int, txt io.Reader) ([]text.L
 	return layoutText(&buf, ppem, maxWidth, fonts, glyphs)
 }
 
-func (f *Font) Shape(ppem fixed.Int26_6, str []text.Glyph) op.CallOp {
+func (f *Font) Shape(ppem fixed.Int26_6, str text.Layout) op.CallOp {
 	var buf sfnt.Buffer
 	return textPath(&buf, ppem, []*opentype{{Font: f.font, Hinting: font.HintingFull}}, str)
 }
@@ -130,7 +138,7 @@ func (c *Collection) Layout(ppem fixed.Int26_6, maxWidth int, txt io.Reader) ([]
 	return layoutText(&buf, ppem, maxWidth, c.fonts, glyphs)
 }
 
-func (c *Collection) Shape(ppem fixed.Int26_6, str []text.Glyph) op.CallOp {
+func (c *Collection) Shape(ppem fixed.Int26_6, str text.Layout) op.CallOp {
 	var buf sfnt.Buffer
 	return textPath(&buf, ppem, c.fonts, str)
 }
@@ -147,7 +155,7 @@ func fontForGlyph(buf *sfnt.Buffer, fonts []*opentype, r rune) *opentype {
 	return fonts[0] // Use replacement character from the first font if necessary
 }
 
-func layoutText(sbuf *sfnt.Buffer, ppem fixed.Int26_6, maxWidth int, fonts []*opentype, glyphs []text.Glyph) ([]text.Line, error) {
+func layoutText(sbuf *sfnt.Buffer, ppem fixed.Int26_6, maxWidth int, fonts []*opentype, glyphs []glyph) ([]text.Line, error) {
 	var lines []text.Line
 	var nextLine text.Line
 	updateBounds := func(f *opentype) {
@@ -180,8 +188,7 @@ func layoutText(sbuf *sfnt.Buffer, ppem fixed.Int26_6, maxWidth int, fonts []*op
 			prev.f = fonts[0]
 		}
 		updateBounds(prev.f)
-		nextLine.Layout = glyphs[:prev.idx:prev.idx]
-		nextLine.Len = prev.len
+		nextLine.Layout = toLayout(glyphs[:prev.idx:prev.idx])
 		nextLine.Width = prev.x + prev.adv
 		nextLine.Bounds.Max.X += prev.x
 		lines = append(lines, nextLine)
@@ -242,20 +249,32 @@ func layoutText(sbuf *sfnt.Buffer, ppem fixed.Int26_6, maxWidth int, fonts []*op
 	return lines, nil
 }
 
-func textPath(buf *sfnt.Buffer, ppem fixed.Int26_6, fonts []*opentype, str []text.Glyph) op.CallOp {
+// toLayout converts a slice of glyphs to a text.Layout.
+func toLayout(glyphs []glyph) text.Layout {
+	var buf bytes.Buffer
+	advs := make([]fixed.Int26_6, len(glyphs))
+	for i, g := range glyphs {
+		buf.WriteRune(g.Rune)
+		advs[i] = glyphs[i].Advance
+	}
+	return text.Layout{Text: buf.String(), Advances: advs}
+}
+
+func textPath(buf *sfnt.Buffer, ppem fixed.Int26_6, fonts []*opentype, str text.Layout) op.CallOp {
 	var lastPos f32.Point
 	var builder clip.Path
 	ops := new(op.Ops)
 	m := op.Record(ops)
 	var x fixed.Int26_6
 	builder.Begin(ops)
-	for _, g := range str {
-		if !unicode.IsSpace(g.Rune) {
-			f := fontForGlyph(buf, fonts, g.Rune)
+	rune := 0
+	for _, r := range str.Text {
+		if !unicode.IsSpace(r) {
+			f := fontForGlyph(buf, fonts, r)
 			if f == nil {
 				continue
 			}
-			segs, ok := f.LoadGlyph(buf, ppem, g.Rune)
+			segs, ok := f.LoadGlyph(buf, ppem, r)
 			if !ok {
 				continue
 			}
@@ -301,14 +320,15 @@ func textPath(buf *sfnt.Buffer, ppem fixed.Int26_6, fonts []*opentype, str []tex
 			}
 			lastPos = lastPos.Add(lastArg)
 		}
-		x += g.Advance
+		x += str.Advances[rune]
+		rune++
 	}
 	builder.Outline().Add(ops)
 	return m.Stop()
 }
 
-func readGlyphs(r io.Reader) ([]text.Glyph, error) {
-	var glyphs []text.Glyph
+func readGlyphs(r io.Reader) ([]glyph, error) {
+	var glyphs []glyph
 	buf := make([]byte, 0, 1024)
 	for {
 		n, err := r.Read(buf[len(buf):cap(buf)])
@@ -322,7 +342,7 @@ func readGlyphs(r io.Reader) ([]text.Glyph, error) {
 		for i < lim {
 			c, s := utf8.DecodeRune(buf[i:])
 			i += s
-			glyphs = append(glyphs, text.Glyph{Rune: c})
+			glyphs = append(glyphs, glyph{Rune: c})
 		}
 		n = copy(buf, buf[i:])
 		buf = buf[:n]
diff --git a/text/shaper.go b/text/shaper.go
index 8e95befa..71d7301d 100644
--- a/text/shaper.go
+++ b/text/shaper.go
@@ -14,13 +14,10 @@ import (
 type Shaper interface {
 	// Layout a text according to a set of options.
 	Layout(font Font, size fixed.Int26_6, maxWidth int, txt io.Reader) ([]Line, error)
-	// Shape a line of text and return a clipping operation for its outline.
-	Shape(font Font, size fixed.Int26_6, layout []Glyph) op.CallOp
-
-	// LayoutString is like Layout, but for strings.
+	// LayoutString is Layout for strings.
 	LayoutString(font Font, size fixed.Int26_6, maxWidth int, str string) []Line
-	// ShapeString is like Shape for lines previously laid out by LayoutString.
-	ShapeString(font Font, size fixed.Int26_6, str string, layout []Glyph) op.CallOp
+	// Shape a line of text and return a clipping operation for its outline.
+	Shape(font Font, size fixed.Int26_6, layout Layout) op.CallOp
 }
 
 // A FontFace is a Font and a matching Face.
@@ -91,24 +88,23 @@ func NewCache(collection []FontFace) *Cache {
 	return c
 }
 
+// Layout implements the Shaper interface.
 func (s *Cache) Layout(font Font, size fixed.Int26_6, maxWidth int, txt io.Reader) ([]Line, error) {
 	cache := s.lookup(font)
 	return cache.face.Layout(size, maxWidth, txt)
 }
 
-func (s *Cache) Shape(font Font, size fixed.Int26_6, layout []Glyph) op.CallOp {
-	cache := s.lookup(font)
-	return cache.face.Shape(size, layout)
-}
-
+// LayoutString is a caching implementation of the Shaper interface.
 func (s *Cache) LayoutString(font Font, size fixed.Int26_6, maxWidth int, str string) []Line {
 	cache := s.lookup(font)
 	return cache.layout(size, maxWidth, str)
 }
 
-func (s *Cache) ShapeString(font Font, size fixed.Int26_6, str string, layout []Glyph) op.CallOp {
+// Shape is a caching implementation of the Shaper interface. Shape assumes that the layout
+// argument is unchanged from a call to Layout or LayoutString.
+func (s *Cache) Shape(font Font, size fixed.Int26_6, layout Layout) op.CallOp {
 	cache := s.lookup(font)
-	return cache.shape(size, str, layout)
+	return cache.shape(size, layout)
 }
 
 func (f *faceCache) layout(ppem fixed.Int26_6, maxWidth int, str string) []Line {
@@ -128,13 +124,13 @@ func (f *faceCache) layout(ppem fixed.Int26_6, maxWidth int, str string) []Line
 	return l
 }
 
-func (f *faceCache) shape(ppem fixed.Int26_6, str string, layout []Glyph) op.CallOp {
+func (f *faceCache) shape(ppem fixed.Int26_6, layout Layout) op.CallOp {
 	if f == nil {
 		return op.CallOp{}
 	}
 	pk := pathKey{
 		ppem: ppem,
-		str:  str,
+		str:  layout.Text,
 	}
 	if clip, ok := f.pathCache.Get(pk); ok {
 		return clip
diff --git a/text/text.go b/text/text.go
index 927ab118..ed8695fc 100644
--- a/text/text.go
+++ b/text/text.go
@@ -11,9 +11,7 @@ import (
 
 // A Line contains the measurements of a line of text.
 type Line struct {
-	Layout []Glyph
-	// Len is the length in UTF8 bytes of the line.
-	Len int
+	Layout Layout
 	// Width is the width of the line.
 	Width fixed.Int26_6
 	// Ascent is the height above the baseline.
@@ -25,9 +23,9 @@ type Line struct {
 	Bounds fixed.Rectangle26_6
 }
 
-type Glyph struct {
-	Rune    rune
-	Advance fixed.Int26_6
+type Layout struct {
+	Text     string
+	Advances []fixed.Int26_6
 }
 
 // Style is the font style.
@@ -50,7 +48,7 @@ type Font struct {
 // methods must be safe for concurrent use.
 type Face interface {
 	Layout(ppem fixed.Int26_6, maxWidth int, txt io.Reader) ([]Line, error)
-	Shape(ppem fixed.Int26_6, str []Glyph) op.CallOp
+	Shape(ppem fixed.Int26_6, str Layout) op.CallOp
 }
 
 // Typeface identifies a particular typeface design. The empty
diff --git a/widget/editor.go b/widget/editor.go
index 608e9b66..7d925b99 100644
--- a/widget/editor.go
+++ b/widget/editor.go
@@ -4,6 +4,7 @@ package widget
 
 import (
 	"bufio"
+	"bytes"
 	"image"
 	"io"
 	"math"
@@ -390,7 +391,7 @@ func (e *Editor) layout(gtx layout.Context) layout.Dimensions {
 	}
 	e.shapes = e.shapes[:0]
 	for {
-		_, _, layout, off, ok := it.Next()
+		layout, off, ok := it.Next()
 		if !ok {
 			break
 		}
@@ -568,8 +569,8 @@ func (e *Editor) layoutText(s text.Shaper) ([]text.Line, layout.Dimensions) {
 	for i := 0; i < len(lines)-1; i++ {
 		// To avoid layout flickering while editing, assume a soft newline takes
 		// up all available space.
-		if layout := lines[i].Layout; len(layout) > 0 {
-			r := layout[len(layout)-1].Rune
+		if layout := lines[i].Layout; len(layout.Text) > 0 {
+			r := layout.Text[len(layout.Text)-1]
 			if r != '\n' {
 				dims.Size.X = e.maxWidth
 				break
@@ -602,11 +603,11 @@ loop:
 		l := e.lines[line]
 		y += (prevDesc + l.Ascent).Ceil()
 		prevDesc = l.Descent
-		for _, g := range l.Layout {
+		for _, adv := range l.Layout.Advances {
 			if idx == e.rr.caret {
 				break loop
 			}
-			x += g.Advance
+			x += adv
 			_, s := e.rr.runeAt(idx)
 			idx += s
 			col++
@@ -706,7 +707,7 @@ func (e *Editor) moveToLine(x fixed.Int26_6, line int) {
 		prevDesc = l.Descent
 		e.caret.line--
 		l = e.lines[e.caret.line]
-		e.caret.col = len(l.Layout) - 1
+		e.caret.col = len(l.Layout.Advances) - 1
 	}
 
 	e.moveStart()
@@ -718,15 +719,15 @@ func (e *Editor) moveToLine(x fixed.Int26_6, line int) {
 		end = 1
 	}
 	// Move to rune closest to x.
-	for i := 0; i < len(l.Layout)-end; i++ {
-		g := l.Layout[i]
+	for i := 0; i < len(l.Layout.Advances)-end; i++ {
+		adv := l.Layout.Advances[i]
 		if e.caret.x >= x {
 			break
 		}
-		if e.caret.x+g.Advance-x >= x-e.caret.x {
+		if e.caret.x+adv-x >= x-e.caret.x {
 			break
 		}
-		e.caret.x += g.Advance
+		e.caret.x += adv
 		_, s := e.rr.runeAt(e.rr.caret)
 		e.rr.caret += s
 		e.caret.col++
@@ -748,7 +749,7 @@ func (e *Editor) Move(distance int) {
 		_, s := e.rr.runeBefore(e.rr.caret)
 		e.rr.caret -= s
 		e.caret.col--
-		e.caret.x -= l[e.caret.col].Advance
+		e.caret.x -= l.Advances[e.caret.col]
 	}
 	for ; distance > 0 && e.rr.caret < e.rr.len(); distance-- {
 		l := e.lines[e.caret.line].Layout
@@ -757,12 +758,12 @@ func (e *Editor) Move(distance int) {
 		if e.caret.line < len(e.lines)-1 {
 			end = 1
 		}
-		if e.caret.col >= len(l)-end {
+		if e.caret.col >= len(l.Advances)-end {
 			// Move to start of next line.
 			e.moveToLine(0, e.caret.line+1)
 			continue
 		}
-		e.caret.x += l[e.caret.col].Advance
+		e.caret.x += l.Advances[e.caret.col]
 		_, s := e.rr.runeAt(e.rr.caret)
 		e.rr.caret += s
 		e.caret.col++
@@ -776,7 +777,7 @@ func (e *Editor) moveStart() {
 	for i := e.caret.col - 1; i >= 0; i-- {
 		_, s := e.rr.runeBefore(e.rr.caret)
 		e.rr.caret -= s
-		e.caret.x -= layout[i].Advance
+		e.caret.x -= layout.Advances[i]
 	}
 	e.caret.col = 0
 	e.caret.xoff = -e.caret.x
@@ -791,8 +792,8 @@ func (e *Editor) moveEnd() {
 		end = 1
 	}
 	layout := l.Layout
-	for i := e.caret.col; i < len(layout)-end; i++ {
-		adv := layout[i].Advance
+	for i := e.caret.col; i < len(layout.Advances)-end; i++ {
+		adv := layout.Advances[i]
 		_, s := e.rr.runeAt(e.rr.caret)
 		e.rr.caret += s
 		e.caret.x += adv
@@ -915,14 +916,14 @@ func (e *Editor) NumLines() int {
 }
 
 func nullLayout(r io.Reader) ([]text.Line, error) {
-	var layout []text.Glyph
 	rr := bufio.NewReader(r)
 	var rerr error
 	var n int
+	var buf bytes.Buffer
 	for {
 		r, s, err := rr.ReadRune()
 		n += s
-		layout = append(layout, text.Glyph{Rune: r})
+		buf.WriteRune(r)
 		if err != nil {
 			rerr = err
 			break
@@ -930,8 +931,10 @@ func nullLayout(r io.Reader) ([]text.Line, error) {
 	}
 	return []text.Line{
 		{
-			Layout: layout,
-			Len:    n,
+			Layout: text.Layout{
+				Text:     buf.String(),
+				Advances: make([]fixed.Int26_6, n),
+			},
 		},
 	}, rerr
 }
diff --git a/widget/editor_test.go b/widget/editor_test.go
index 3b003ad7..bc9c2921 100644
--- a/widget/editor_test.go
+++ b/widget/editor_test.go
@@ -62,9 +62,9 @@ func TestEditor(t *testing.T) {
 
 	// When a password mask is applied, it should replace all visible glyphs
 	for i, line := range e.lines {
-		for j, glyph := range line.Layout {
-			if glyph.Rune != e.Mask && !unicode.IsSpace(glyph.Rune) {
-				t.Errorf("glyph at (%d, %d) is unmasked rune %d", i, j, glyph.Rune)
+		for j, r := range line.Layout.Text {
+			if r != e.Mask && !unicode.IsSpace(r) {
+				t.Errorf("glyph at (%d, %d) is unmasked rune %d", i, j, r)
 			}
 		}
 	}
diff --git a/widget/label.go b/widget/label.go
index e59c7886..2cf4890d 100644
--- a/widget/label.go
+++ b/widget/label.go
@@ -38,7 +38,7 @@ type lineIterator struct {
 
 const inf = 1e6
 
-func (l *lineIterator) Next() (int, int, []text.Glyph, f32.Point, bool) {
+func (l *lineIterator) Next() (text.Layout, f32.Point, bool) {
 	for len(l.Lines) > 0 {
 		line := l.Lines[0]
 		l.Lines = l.Lines[1:]
@@ -54,34 +54,38 @@ func (l *lineIterator) Next() (int, int, []text.Glyph, f32.Point, bool) {
 		}
 		layout := line.Layout
 		start := l.txtOff
-		l.txtOff += line.Len
+		l.txtOff += len(line.Layout.Text)
 		if (off.Y + line.Bounds.Max.Y).Ceil() < l.Clip.Min.Y {
 			continue
 		}
-		for len(layout) > 0 {
-			g := layout[0]
-			adv := g.Advance
+		for len(layout.Advances) > 0 {
+			_, n := utf8.DecodeRuneInString(layout.Text)
+			adv := layout.Advances[0]
 			if (off.X + adv + line.Bounds.Max.X - line.Width).Ceil() >= l.Clip.Min.X {
 				break
 			}
 			off.X += adv
-			layout = layout[1:]
-			start += utf8.RuneLen(g.Rune)
+			layout.Text = layout.Text[n:]
+			layout.Advances = layout.Advances[1:]
+			start += n
 		}
 		end := start
 		endx := off.X
-		for i, g := range layout {
+		rune := 0
+		for n, r := range layout.Text {
 			if (endx + line.Bounds.Min.X).Floor() > l.Clip.Max.X {
-				layout = layout[:i]
+				layout.Advances = layout.Advances[:rune]
+				layout.Text = layout.Text[:n]
 				break
 			}
-			end += utf8.RuneLen(g.Rune)
-			endx += g.Advance
+			end += utf8.RuneLen(r)
+			endx += layout.Advances[rune]
+			rune++
 		}
 		offf := f32.Point{X: float32(off.X) / 64, Y: float32(off.Y) / 64}
-		return start, end, layout, offf, true
+		return layout, offf, true
 	}
-	return 0, 0, nil, f32.Point{}, false
+	return text.Layout{}, f32.Point{}, false
 }
 
 func (l Label) Layout(gtx layout.Context, s text.Shaper, font text.Font, size unit.Value, txt string) layout.Dimensions {
@@ -102,14 +106,13 @@ func (l Label) Layout(gtx layout.Context, s text.Shaper, font text.Font, size un
 		Width:     dims.Size.X,
 	}
 	for {
-		start, end, l, off, ok := it.Next()
+		l, off, ok := it.Next()
 		if !ok {
 			break
 		}
 		stack := op.Push(gtx.Ops)
 		op.Offset(off).Add(gtx.Ops)
-		str := txt[start:end]
-		s.ShapeString(font, textSize, str, l).Add(gtx.Ops)
+		s.Shape(font, textSize, l).Add(gtx.Ops)
 		paint.PaintOp{}.Add(gtx.Ops)
 		stack.Pop()
 	}