Solving issue 2341: "Pipette and flat curves - no line colors"

rtgui/curvelistener.h

@@ -23,14 +23,43 @@ class CurveEditor;
 
 class CurveListener {
 
-	private:
-		bool multi;
+    private:
+        bool multi;
     public:
+        CurveListener() : multi(false) {}
+        virtual ~CurveListener() {}
         virtual void curveChanged () {}
         virtual void curveChanged (CurveEditor* ce) {}
         void setMulti(bool value) { multi = value; }
         bool isMulti() { return multi; }
-        CurveListener() : multi(false) {}
+
+        /** @brief Blend pipette values from its different channels into a single value
+        If the buffer has more than one channel and one channel, this method will blend them together.
+        @param chan1 first channel's value
+        @param chan2 second channel's value
+        @param chan3 third channel's value
+        @return the blended value */
+        virtual float blendPipetteValues(float chan1, float chan2, float chan3) {
+            float retVal = 0.f;
+            int n = 0;
+            if (chan1 != -1.f) {
+                retVal += chan1;
+                ++n;
+            }
+            if (chan2 != -1.f) {
+                retVal += chan2;
+                ++n;
+            }
+            if (chan3 != -1.f) {
+                retVal += chan3;
+                ++n;
+            }
+            if (n>1)
+                retVal /= n;
+            else if (!n)
+                retVal = -1.f;
+            return retVal;
+        }
 };
 
 #endif