include alpha-delta computation in HSV::delta()

diff --git a/libs/canvas/colors.cc b/libs/canvas/colors.cc
index b053e2d1de20a343d87e5229d2d71a57e026e899..361023d300f50f861635cbe21212da77f5b1be4d 100644 (file)
--- a/libs/canvas/colors.cc
+++ b/libs/canvas/colors.cc
@@ -376,6 +376,7 @@ HSV::delta (const HSV& other) const
                d.s = s - other.s;
                d.v = v - other.v;
        }
+       d.a = a - other.a;
        /* do not clamp - we are returning a delta */
        return d;
 }