3 files changed, 64 insertions, 12 deletions

diff --git a/src/gui/graphicsview/qgraphicsanchorlayout.cpp b/src/gui/graphicsview/qgraphicsanchorlayout.cpp
index 6718a28..f504c54 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout.cpp
+++ b/src/gui/graphicsview/qgraphicsanchorlayout.cpp
@@ -321,14 +321,14 @@ void QGraphicsAnchorLayout::addCornerAnchors(QGraphicsLayoutItem *firstItem,
     // Horizontal anchor
     Qt::AnchorPoint firstEdge = (firstCorner & 1 ? Qt::AnchorRight: Qt::AnchorLeft);
     Qt::AnchorPoint secondEdge = (secondCorner & 1 ? Qt::AnchorRight: Qt::AnchorLeft);
-    d->addAnchor(firstItem, firstEdge, secondItem, secondEdge);
+    if (d->addAnchor(firstItem, firstEdge, secondItem, secondEdge)) {
+        // Vertical anchor
+        firstEdge = (firstCorner & 2 ? Qt::AnchorBottom: Qt::AnchorTop);
+        secondEdge = (secondCorner & 2 ? Qt::AnchorBottom: Qt::AnchorTop);
+        d->addAnchor(firstItem, firstEdge, secondItem, secondEdge);
 
-    // Vertical anchor
-    firstEdge = (firstCorner & 2 ? Qt::AnchorBottom: Qt::AnchorTop);
-    secondEdge = (secondCorner & 2 ? Qt::AnchorBottom: Qt::AnchorTop);
-    d->addAnchor(firstItem, firstEdge, secondItem, secondEdge);
-
-    invalidate();
+        invalidate();
+    }
 }
 
 /*!
@@ -351,11 +351,14 @@ void QGraphicsAnchorLayout::addAnchors(QGraphicsLayoutItem *firstItem,
                                        QGraphicsLayoutItem *secondItem,
                                        Qt::Orientations orientations)
 {
+    bool ok = true;
     if (orientations & Qt::Horizontal) {
-        addAnchor(secondItem, Qt::AnchorLeft, firstItem, Qt::AnchorLeft);
-        addAnchor(firstItem, Qt::AnchorRight, secondItem, Qt::AnchorRight);
+        // Currently, if the first is ok, then the rest of the calls should be ok
+        ok = addAnchor(secondItem, Qt::AnchorLeft, firstItem, Qt::AnchorLeft) != 0;
+        if (ok)
+            addAnchor(firstItem, Qt::AnchorRight, secondItem, Qt::AnchorRight);
     }
-    if (orientations & Qt::Vertical) {
+    if (orientations & Qt::Vertical && ok) {
         addAnchor(secondItem, Qt::AnchorTop, firstItem, Qt::AnchorTop);
         addAnchor(firstItem, Qt::AnchorBottom, secondItem, Qt::AnchorBottom);
     }
diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
index 03ed63d..1dc6873 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
@@ -1666,6 +1666,13 @@ QGraphicsAnchor *QGraphicsAnchorLayoutPrivate::addAnchor(QGraphicsLayoutItem *fi
         return 0;
     }
 
+    const QGraphicsLayoutItem *parentWidget = q->parentLayoutItem();
+    if (firstItem == parentWidget || secondItem == parentWidget) {
+        qWarning("QGraphicsAnchorLayout::addAnchor(): "
+                 "You cannot add the parent of the layout to the layout.");
+        return 0;
+    }
+
     // In QGraphicsAnchorLayout, items are represented in its internal
     // graph as four anchors that connect:
     //  - Left -> HCenter
diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index c879c5c..d955f16 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -10537,6 +10537,20 @@ void QGraphicsItemGroup::addToGroup(QGraphicsItem *item)
     if (!item->pos().isNull())
         newItemTransform *= QTransform::fromTranslate(-item->x(), -item->y());
 
+    // removing additional transformations properties applied with itemTransform()
+    QPointF origin = item->transformOriginPoint();
+    QMatrix4x4 m;
+    QList<QGraphicsTransform*> transformList = item->transformations();
+    for (int i = 0; i < transformList.size(); ++i)
+        transformList.at(i)->applyTo(&m);
+    newItemTransform *= m.toTransform().inverted();
+    newItemTransform.translate(origin.x(), origin.y());
+    newItemTransform.rotate(-item->rotation());
+    newItemTransform.scale(1/item->scale(), 1/item->scale());
+    newItemTransform.translate(-origin.x(), -origin.y());
+
+    // ### Expensive, we could maybe use dirtySceneTransform bit for optimization
+
     item->setTransform(newItemTransform);
     item->d_func()->setIsMemberOfGroup(true);
     prepareGeometryChange();
@@ -10561,11 +10575,39 @@ void QGraphicsItemGroup::removeFromGroup(QGraphicsItem *item)
     }
 
     QGraphicsItem *newParent = d_ptr->parent;
+
+    // COMBINE
+    bool ok;
+    QTransform itemTransform;
+    if (newParent)
+        itemTransform = item->itemTransform(newParent, &ok);
+    else
+        itemTransform = item->sceneTransform();
+
     QPointF oldPos = item->mapToItem(newParent, 0, 0);
     item->setParentItem(newParent);
-    // ### This function should remap the item's matrix to keep the item's
-    // transformation unchanged relative to the scene.
     item->setPos(oldPos);
+
+    // removing position from translation component of the new transform
+    if (!item->pos().isNull())
+        itemTransform *= QTransform::fromTranslate(-item->x(), -item->y());
+
+    // removing additional transformations properties applied
+    // with itemTransform() or sceneTransform()
+    QPointF origin = item->transformOriginPoint();
+    QMatrix4x4 m;
+    QList<QGraphicsTransform*> transformList = item->transformations();
+    for (int i = 0; i < transformList.size(); ++i)
+        transformList.at(i)->applyTo(&m);
+    itemTransform *= m.toTransform().inverted();
+    itemTransform.translate(origin.x(), origin.y());
+    itemTransform.rotate(-item->rotation());
+    itemTransform.scale(1 / item->scale(), 1 / item->scale());
+    itemTransform.translate(-origin.x(), -origin.y());
+
+    // ### Expensive, we could maybe use dirtySceneTransform bit for optimization
+
+    item->setTransform(itemTransform);
     item->d_func()->setIsMemberOfGroup(item->group() != 0);
 
     // ### Quite expensive. But removeFromGroup() isn't called very often.