From a5c0e784b54d4c433209a99789950d6e156548aa Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Sun, 29 Jun 2014 17:50:33 -0400
Subject: Add color-scale procedure.

* sly/color.scm (color-scale): New procedure.
---
 sly/color.scm | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sly/color.scm b/sly/color.scm
index c8ba248..3384510 100644
--- a/sly/color.scm
+++ b/sly/color.scm
@@ -36,6 +36,7 @@
             rgba
             rgb
             color*
+            color-scale
             color+
             color-
             color-inverse
@@ -128,6 +129,13 @@ For example: #xffffff will return a color with RGBA values 1, 1, 1,
               (* (color-a a)
                  (color-a b))))
 
+(define (color-scale c k)
+  "Multiple the RGBA channels of the color C by the scalar K."
+  (make-color (* (color-r c) k)
+              (* (color-g c) k)
+              (* (color-b c) k)
+              (* (color-a c) k)))
+
 (define (color+ a b)
   "Add the RGBA channels of colors A and B."
   (make-color (+ (color-r a)
-- 
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