[PATCH 13/15] Added channel flags test for KoCompositeOpCopyChannel class and changed Color Dodge and Burn.

[Silvio Heinrich]

The dodge and burn algorithms where changed to fit the definition
in ISO 32000 part 2.
---
 .../compositeops/KoCompositeOpCopyChannel.h        |    9 +++++--
 libs/pigment/compositeops/KoCompositeOpFunctions.h |   24 +++++++++++++++-----
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/libs/pigment/compositeops/KoCompositeOpCopyChannel.h b/libs/pigment/compositeops/KoCompositeOpCopyChannel.h
index 7bb6b40..1747334 100644
--- a/libs/pigment/compositeops/KoCompositeOpCopyChannel.h
+++ b/libs/pigment/compositeops/KoCompositeOpCopyChannel.h
@@ -48,10 +48,13 @@ public:
     inline static channels_type composeColorChannels(const channels_type* src, channels_type srcAlpha,
                                                      channels_type*       dst, channels_type dstAlpha,
                                                      channels_type opacity, const QBitArray& channelFlags) {
-        if(channel_pos == alpha_pos)
-            return lerp(dstAlpha, srcAlpha, opacity);
+        if(allChannelFlags || channelFlags.testBit(channel_pos)) {
+            if(channel_pos == alpha_pos)
+                return lerp(dstAlpha, srcAlpha, opacity);
+            
+            dst[channel_pos] = lerp(dst[channel_pos], src[channel_pos], opacity);
+        }
         
-        dst[channel_pos] = lerp(dst[channel_pos], src[channel_pos], opacity);
         return dstAlpha;
     }
 };
diff --git a/libs/pigment/compositeops/KoCompositeOpFunctions.h b/libs/pigment/compositeops/KoCompositeOpFunctions.h
index a6ec380..9b75faf 100644
--- a/libs/pigment/compositeops/KoCompositeOpFunctions.h
+++ b/libs/pigment/compositeops/KoCompositeOpFunctions.h
@@ -214,9 +214,15 @@ inline void cfHue(TReal sr, TReal sg, TReal sb, TReal& dr, TReal& dg, TReal& db)
 
 template<class T>
 inline T cfColorBurn(T src, T dst) {
-    if(src != KoColorSpaceMathsTraits<T>::zeroValue)
-        return inv(clamp<T>(div(inv(dst), src)));
-    return KoColorSpaceMathsTraits<T>::zeroValue;
+    if(dst == KoColorSpaceMathsTraits<T>::unitValue)
+        return KoColorSpaceMathsTraits<T>::unitValue;
+    
+    T invDst = inv(dst);
+    
+    if(src < invDst)
+        return KoColorSpaceMathsTraits<T>::zeroValue;
+    
+    return inv(clamp<T>(div(invDst, src)));
 }
 
 template<class T>
@@ -227,9 +233,15 @@ inline T cfLinearBurn(T src, T dst) {
 
 template<class T>
 inline T cfColorDodge(T src, T dst) {
-    if(src != KoColorSpaceMathsTraits<T>::unitValue)
-        return clamp<T>(div(dst, inv(src)));
-    return KoColorSpaceMathsTraits<T>::unitValue;
+    if(dst == KoColorSpaceMathsTraits<T>::zeroValue)
+        return KoColorSpaceMathsTraits<T>::zeroValue;
+    
+    T invSrc = inv(src);
+    
+    if(invSrc < dst)
+        return KoColorSpaceMathsTraits<T>::unitValue;
+    
+    return clamp<T>(div(dst, invSrc));
 }
 
 template<class T>
-- 
1.7.1