colors.gray: adding rgba>gray.

diff --git a/basis/colors/gray/gray.factor b/basis/colors/gray/gray.factor
index 5d628dc409b58b0f69ef76d2d4e7752cf229e53c..680d08713061147c8ae7e14364228fe0094e79aa 100644 (file)
--- a/basis/colors/gray/gray.factor
+++ b/basis/colors/gray/gray.factor
@@ -14,4 +14,9 @@ M: gray red>> gray>> ;
 
 M: gray green>> gray>> ;
 
-M: gray blue>> gray>> ;
\ No newline at end of file
+M: gray blue>> gray>> ;
+
+: rgba>gray ( rgba -- gray )
+    >rgba-components [
+        [ 0.3 * ] [ 0.59 * ] [ 0.11 * ] tri* + +
+    ] dip <gray> ;