Extend colorspace testing and fix bug it uncovered

When changing transferfunction the look-up-tables needs to be
regenerated.

Change-Id: I83ca5fe570f85d478a374f52c0a82db84e70c3b8
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
(cherry picked from commit b2631c72c0628e68c0fae7567fd12e6646455efc)
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

2 files changed, 2 insertions, 1 deletions

diff --git a/src/gui/painting/qcolorspace.cpp b/src/gui/painting/qcolorspace.cpp
index ed25ead262..c9c32c6bb7 100644
--- a/src/gui/painting/qcolorspace.cpp
+++ b/src/gui/painting/qcolorspace.cpp
@@ -331,6 +331,7 @@ void QColorSpacePrivate::setTransferFunction()
     }
     trc[1] = trc[0];
     trc[2] = trc[0];
+    lut.generated.storeRelease(0);
 }
 
 QColorTransform QColorSpacePrivate::transformationToColorSpace(const QColorSpacePrivate *out) const
diff --git a/src/gui/painting/qcolortrc_p.h b/src/gui/painting/qcolortrc_p.h
index 3ef9d442fc..058be3c7ce 100644
--- a/src/gui/painting/qcolortrc_p.h
+++ b/src/gui/painting/qcolortrc_p.h
@@ -114,7 +114,7 @@ public:
         if (x >= 0.0f && x <= 1.0f)
             return applyInverse(x);
         if (m_type == Type::Function)
-            return std::copysign(applyInverse(x), x);
+            return std::copysign(applyInverse(std::abs(x)), x);
         if (m_type == Type::Table)
             return x < 0.0f ? 0.0f : 1.0f;
         return x;