add image-from-codec to c api

include/c/sk_image.h

Index: include/c/sk_image.h
diff --git a/include/c/sk_image.h b/include/c/sk_image.h
index 244956399c868e6b84f7267cc374cafdd7acb472..34682c72d3dba04895e2c59c6f0e8438b0f37611 100644
--- a/include/c/sk_image.h
+++ b/include/c/sk_image.h
@@ -20,6 +20,18 @@ SK_C_PLUS_PLUS_BEGIN_GUARD
  *  Balance with a call to sk_image_unref().
  */
 sk_image_t* sk_image_new_raster_copy(const sk_imageinfo_t*, const void* pixels, size_t rowBytes);
+
+/**
+ *  If the specified data can be interpreted as a compressed image (e.g. PNG or JPEG) then this
+ *  returns an image. If the encoded data is not supported, returns NULL.
+ *
+ *  On success, the encoded data may be processed immediately, or it may be ref()'d for later
+ *  use.
+ */
+sk_image_t* sk_image_new_from_data(const sk_data_t* encoded);
+
+sk_data_t* sk_image_encode(const sk_image_t*);
+
 void sk_image_ref(const sk_image_t*);
 void sk_image_unref(const sk_image_t*);
 int sk_image_get_width(const sk_image_t*);