text: make Shaper an interface

And rename out the caching implementation to FontRegistry.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

font/font.go

@@ -12,12 +12,12 @@ import (
 var (
 	mu          sync.Mutex
 	initialized bool
-	shaper      = new(text.Shaper)
+	shaper      = new(text.FontRegistry)
 )
 
 // Default returns a singleton *text.Shaper that contains
 // the registered fonts.
-func Default() *text.Shaper {
+func Default() *text.FontRegistry {
 	mu.Lock()
 	defer mu.Unlock()
 	initialized = true

text/shaper.go

@@ -12,12 +12,19 @@ import (
 	"golang.org/x/image/math/fixed"
 )
 
-// Shaper implements layout and shaping of text and a cache of
+// Shaper implements layout and shaping of text.
+type Shaper interface {
+	Layout(c unit.Converter, font Font, str string, opts LayoutOptions) *Layout
+	Shape(c unit.Converter, font Font, str String) op.CallOp
+	Metrics(c unit.Converter, font Font) font.Metrics
+}
+
+// FontRegistry implements layout and shaping of text and a cache of
 // computed results.
 //
-// If a font matches no registered shape, Shaper falls back to the
+// If a font matches no registered shape, FontRegistry falls back to the
 // first registered face.
-type Shaper struct {
+type FontRegistry struct {
 	def   Typeface
 	faces map[Font]*face
 }
@@ -28,7 +35,7 @@ type face struct {
 	pathCache   pathCache
 }
 
-func (s *Shaper) Register(font Font, tf Face) {
+func (s *FontRegistry) Register(font Font, tf Face) {
 	if s.faces == nil {
 		s.def = font.Typeface
 		s.faces = make(map[Font]*face)
@@ -43,22 +50,22 @@ func (s *Shaper) Register(font Font, tf Face) {
 	}
 }
 
-func (s *Shaper) Layout(c unit.Converter, font Font, str string, opts LayoutOptions) *Layout {
+func (s *FontRegistry) Layout(c unit.Converter, font Font, str string, opts LayoutOptions) *Layout {
 	tf := s.faceForFont(font)
 	return tf.layout(fixed.I(c.Px(font.Size)), str, opts)
 }
 
-func (s *Shaper) Shape(c unit.Converter, font Font, str String) op.CallOp {
+func (s *FontRegistry) Shape(c unit.Converter, font Font, str String) op.CallOp {
 	tf := s.faceForFont(font)
 	return tf.shape(fixed.I(c.Px(font.Size)), str)
 }
 
-func (s *Shaper) Metrics(c unit.Converter, font Font) font.Metrics {
+func (s *FontRegistry) Metrics(c unit.Converter, font Font) font.Metrics {
 	tf := s.faceForFont(font)
 	return tf.metrics(fixed.I(c.Px(font.Size)))
 }
 
-func (s *Shaper) faceForStyle(font Font) *face {
+func (s *FontRegistry) faceForStyle(font Font) *face {
 	tf := s.faces[font]
 	if tf == nil {
 		font := font
@@ -79,7 +86,7 @@ func (s *Shaper) faceForStyle(font Font) *face {
 	return tf
 }
 
-func (s *Shaper) faceForFont(font Font) *face {
+func (s *FontRegistry) faceForFont(font Font) *face {
 	font.Size = unit.Value{}
 	tf := s.faceForStyle(font)
 	if tf == nil {

widget/editor.go

@@ -213,7 +213,7 @@ func (e *Editor) Focus() {
 }
 
 // Layout lays out the editor.
-func (e *Editor) Layout(gtx *layout.Context, sh *text.Shaper, font text.Font) {
+func (e *Editor) Layout(gtx *layout.Context, sh text.Shaper, font text.Font) {
 	// Flush events from before the previous frame.
 	copy(e.events, e.events[e.prevEvents:])
 	e.events = e.events[:len(e.events)-e.prevEvents]
@@ -226,7 +226,7 @@ func (e *Editor) Layout(gtx *layout.Context, sh *text.Shaper, font text.Font) {
 	e.layout(gtx, sh)
 }
 
-func (e *Editor) layout(gtx *layout.Context, sh *text.Shaper) {
+func (e *Editor) layout(gtx *layout.Context, sh text.Shaper) {
 	// Crude configuration change detection.
 	if scale := gtx.Px(unit.Sp(100)); scale != e.scale {
 		e.invalidate()
@@ -430,7 +430,7 @@ func (e *Editor) moveCoord(c unit.Converter, pos image.Point) {
 	e.moveToLine(x, carLine)
 }
 
-func (e *Editor) layoutText(c unit.Converter, s *text.Shaper, font text.Font) ([]text.Line, layout.Dimensions) {
+func (e *Editor) layoutText(c unit.Converter, s text.Shaper, font text.Font) ([]text.Line, layout.Dimensions) {
 	txt := e.rr.String()
 	opts := text.LayoutOptions{MaxWidth: e.maxWidth}
 	textLayout := s.Layout(c, font, txt, opts)

widget/label.go

@@ -82,7 +82,7 @@ func (l *lineIterator) Next() (text.String, f32.Point, bool) {
 	return text.String{}, f32.Point{}, false
 }
 
-func (l Label) Layout(gtx *layout.Context, s *text.Shaper, font text.Font, txt string) {
+func (l Label) Layout(gtx *layout.Context, s text.Shaper, font text.Font, txt string) {
 	cs := gtx.Constraints
 	textLayout := s.Layout(gtx, font, txt, text.LayoutOptions{MaxWidth: cs.Width.Max})
 	lines := textLayout.Lines

widget/material/button.go

@@ -24,7 +24,7 @@ type Button struct {
 	Font         text.Font
 	Background   color.RGBA
 	CornerRadius unit.Value
-	shaper       *text.Shaper
+	shaper       text.Shaper
 }
 
 type IconButton struct {

widget/material/checkable.go

@@ -20,7 +20,7 @@ type checkable struct {
 	Font               text.Font
 	IconColor          color.RGBA
 	Size               unit.Value
-	shaper             *text.Shaper
+	shaper             text.Shaper
 	checkedStateIcon   *Icon
 	uncheckedStateIcon *Icon
 }

widget/material/editor.go

@@ -21,7 +21,7 @@ type Editor struct {
 	// HintColor is the color of hint text.
 	HintColor color.RGBA
 
-	shaper *text.Shaper
+	shaper text.Shaper
 }
 
 func (t *Theme) Editor(hint string) Editor {

widget/material/label.go

@@ -23,7 +23,7 @@ type Label struct {
 	MaxLines int
 	Text     string
 
-	shaper *text.Shaper
+	shaper text.Shaper
 }
 
 func (t *Theme) H1(txt string) Label {

widget/material/theme.go

@@ -16,7 +16,7 @@ import (
 )
 
 type Theme struct {
-	Shaper *text.Shaper
+	Shaper text.Shaper
 	Color  struct {
 		Primary color.RGBA
 		Text    color.RGBA