text: make Shaper an interface

And rename out the caching implementation to FontRegistry.

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

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