[gtk/wip/otte/for-master: 1/3] transform: Add optimization for common case

[Benjamin Otte <otte src gnome org>]

commit 41ef6e9fa5c22d3a889f82f5fe96f633cdd6959d
Author: Benjamin Otte <otte redhat com>
Date:   Thu Feb 20 00:02:19 2020 +0100

    transform: Add optimization for common case
    
    Transforming identity by an other transform does not mean we need to
    painstakingly apply the individual steps of other to construct a new
    transform, it means we can just return other.
    
    Or in math terms:
      I * B = B
    so just return B.

 gsk/gsktransform.c | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/gsk/gsktransform.c b/gsk/gsktransform.c
index c8e0d321b7..df6cb63bdd 100644
--- a/gsk/gsktransform.c
+++ b/gsk/gsktransform.c
@@ -1622,6 +1622,12 @@ gsk_transform_transform (GskTransform *next,
   if (other == NULL)
     return next;
 
+  if (gsk_transform_is_identity (next))
+    {
+      gsk_transform_unref (next);
+      return gsk_transform_ref (other);
+    }
+
   next = gsk_transform_transform (next, other->next);
   return other->transform_class->apply (other, next);
 }