text/v2: remove the common UnsafeInternal and add ones to GoTextFaceSource and StdFace

Updates #2454

text/v2/gotext.go

@@ -202,11 +202,6 @@ func (g *GoTextFace) Metrics() Metrics {
 	return m
 }
 
-// UnsafeInternal implements Face.
-func (g *GoTextFace) UnsafeInternal() any {
-	return g.Source.f
-}
-
 func (g *GoTextFace) ensureVariationsString() string {
 	if g.variationsString != "" {
 		return g.variationsString

text/v2/gotextfacesource.go

@@ -157,6 +157,13 @@ func (g *GoTextFaceSource) Metadata() Metadata {
 	return g.metadata
 }
 
+// UnsafeInternal returns its font.Face.
+//
+// This is unsafe since this might make internal cache states out of sync.
+func (g *GoTextFaceSource) UnsafeInternal() font.Face {
+	return g.f
+}
+
 func (g *GoTextFaceSource) shape(text string, face *GoTextFace) (shaping.Output, []glyph) {
 	g.copyCheck()
 

text/v2/std.go

@@ -74,8 +74,10 @@ func (s *StdFace) Metrics() Metrics {
 	}
 }
 
-// UnsafeInternal implements Face.
-func (s *StdFace) UnsafeInternal() any {
+// UnsafeInternal returns its internal font.Face.
+//
+// This is unsafe since this might make internal cache states out of sync.
+func (s *StdFace) UnsafeInternal() font.Face {
 	s.copyCheck()
 	return s.f.f
 }

text/v2/text.go

@@ -32,11 +32,6 @@ type Face interface {
 	// Metrics returns the metrics for this Face.
 	Metrics() Metrics
 
-	// UnsafeInternal returns the internal object for this face.
-	// The returned value is either a semi-standard font.Face or go-text's font.Face.
-	// This is unsafe since this might make internal cache states out of sync.
-	UnsafeInternal() any
-
 	advance(text string) float64
 
 	appendGlyphsForLine(glyphs []Glyph, line string, indexOffset int, originX, originY float64) []Glyph