Correct Flipable back item based on parent, not scene transform

Flipable transformation consists of two parts:
    1.  Detecting that the back face is visible
    2.  Transforming the back item as though "it were on the front"
These are two steps.  The first should be done in scene coordinates, and
the second relative to the Flipable parent.

QTBUG-10532

1 files changed, 9 insertions, 6 deletions

diff --git a/src/declarative/graphicsitems/qdeclarativeflipable.cpp b/src/declarative/graphicsitems/qdeclarativeflipable.cpp
index e2fc809..d926119 100644
--- a/src/declarative/graphicsitems/qdeclarativeflipable.cpp
+++ b/src/declarative/graphicsitems/qdeclarativeflipable.cpp
@@ -190,12 +190,15 @@ void QDeclarativeFlipablePrivate::updateSceneTransformFromParent()
     QPointF p2(1, 0);
     QPointF p3(1, 1);
 
-    p1 = sceneTransform.map(p1);
-    p2 = sceneTransform.map(p2);
-    p3 = sceneTransform.map(p3);
-
-    qreal cross = (p1.x() - p2.x()) * (p3.y() - p2.y()) -
-                  (p1.y() - p2.y()) * (p3.x() - p2.x());
+    QPointF scenep1 = sceneTransform.map(p1);
+    QPointF scenep2 = sceneTransform.map(p2);
+    QPointF scenep3 = sceneTransform.map(p3);
+    p1 = q->mapToParent(p1);
+    p2 = q->mapToParent(p2);
+    p3 = q->mapToParent(p3);
+
+    qreal cross = (scenep1.x() - scenep2.x()) * (scenep3.y() - scenep2.y()) -
+                  (scenep1.y() - scenep2.y()) * (scenep3.x() - scenep2.x());
 
     wantBackYFlipped = p1.x() >= p2.x();
     wantBackXFlipped = p2.y() >= p3.y();