[gtk/matthiasc/for-master] transform: Improve docs

[Matthias Clasen <matthiasc src gnome org>]

commit bef54a382daf64aff32bd55c5e40b80b39713179
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Sep 17 09:57:07 2021 -0400

    transform: Improve docs
    
    Add an example for reconstructing transforms.

 gsk/gsktransform.c | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/gsk/gsktransform.c b/gsk/gsktransform.c
index b58eb55aad..439d9340fc 100644
--- a/gsk/gsktransform.c
+++ b/gsk/gsktransform.c
@@ -1530,6 +1530,13 @@ gsk_transform_to_2d (GskTransform *self,
  *
  * Converts a `GskTransform` to 2D affine transformation factors.
  *
+ * To recreate an equivalent transform from the factors returned
+ * by this function, use
+ *
+ *     gsk_transform_scale (gsk_transform_translate (NULL,
+ *                                                   &GRAPHENE_POINT_T (dx, dy)),
+ *                          sx, sy)
+ *
  * @self must be a 2D transformation. If you are not
  * sure, use
  *