transform: Move gsk_transform_dihedral

This is a transform function, so put it in gsktransform.c.

gsk/gpu/gskgpunodeprocessor.c

@@ -1431,22 +1431,6 @@ gsk_gpu_node_processor_add_first_rounded_clip_node (GskGpuNodeProcessor *self,
                                                         gsk_rounded_clip_node_get_child (node));
 }
 
-static GskTransform *
-gsk_transform_dihedral (GskTransform *transform,
-                        GdkDihedral   dihedral)
-{
-  int rotate = dihedral & 3;
-  int flip = dihedral & 4;
-
-  if (flip)
-      transform = gsk_transform_scale (transform, -1.0, 1.0);
-
-  if (rotate)
-      transform = gsk_transform_rotate (transform, rotate * 90.0f);
-
-  return transform;
-}
-
 static void
 gsk_gpu_node_processor_add_transform_node (GskGpuNodeProcessor *self,
                                            GskRenderNode       *node)

gsk/gsktransform.c

@@ -2109,6 +2109,34 @@ gsk_transform_to_dihedral (GskTransform *self,
                                          out_dx, out_dy);
 }
 
+/*< private >
+ * gsk_transform_dihedral:
+ * @next: (nullable) (transfer full): the next transform
+ * @dihedral: dihedral tansform to apply
+ *
+ * Applies a dihedral transform to @next.
+ *
+ * This function consumes @next. Use [method@Gsk.Transform.ref] first
+ * if you want to keep it around.
+ *
+ * Returns: (nullable): The new transform
+ **/
+GskTransform *
+gsk_transform_dihedral (GskTransform *next,
+                        GdkDihedral   dihedral)
+{
+  int rotate = dihedral & 3;
+  int flip = dihedral & 4;
+
+  if (flip)
+    next = gsk_transform_scale (next, -1.0, 1.0);
+
+  if (rotate)
+    next = gsk_transform_rotate (next, rotate * 90.0f);
+
+  return next;
+}
+
 /**
  * gsk_transform_to_translate:
  * @self: a `GskTransform`

gsk/gsktransformprivate.h

@@ -97,6 +97,9 @@ void                    gsk_transform_to_dihedral               (GskTransform
                                                                  float                  *out_dx,
                                                                  float                  *out_dy);
 
+GskTransform *           gsk_transform_dihedral                 (GskTransform *         next,
+                                                                 GdkDihedral            dihedral);
+
 void gsk_matrix_transform_point   (const graphene_matrix_t  *m,
                                    const graphene_point_t   *p,
                                    graphene_point_t         *res);