Add a function to protect textures

texture.go

@@ -12,3 +12,18 @@ type Texture interface {
 	// the original texture as well.
 	Clip (image.Rectangle) Texture
 }
+
+type protectedTexture struct {
+	Texture
+}
+
+func (protectedTexture) Close () error {
+	return nil
+}
+
+// Protect makes the Close() method of a texture do nothing. This is useful if
+// several of the same texture are given out to different objects, but only one
+// has the responsibility of closing it.
+func Protect (texture Texture) Texture {
+	return protectedTexture { Texture: texture }
+}