Merge commit 'c1f9978c9d61bcbdb2f280185a3abdea13d7f532' into master-from-4.7

2 files changed, 17 insertions, 14 deletions

diff --git a/src/gui/graphicsview/qgraphicslinearlayout.cpp b/src/gui/graphicsview/qgraphicslinearlayout.cpp
index 1588364..7e8d19f 100644
--- a/src/gui/graphicsview/qgraphicslinearlayout.cpp
+++ b/src/gui/graphicsview/qgraphicslinearlayout.cpp
@@ -275,13 +275,17 @@ void QGraphicsLinearLayout::insertItem(int index, QGraphicsLayoutItem *item)
         qWarning("QGraphicsLinearLayout::insertItem: cannot insert itself");
         return;
     }
+    Q_ASSERT(item);
+
+    //the order of the following instructions is very important because
+    //invalidating the layout before adding the child item will make the layout happen
+    //before we try to paint the item
+    invalidate();
     d->addChildLayoutItem(item);
 
-    Q_ASSERT(item);
     d->fixIndex(&index);
     d->engine.insertRow(index, d->orientation);
     new QGridLayoutItem(&d->engine, item, d->gridRow(index), d->gridColumn(index), 1, 1, 0, index);
-    invalidate();
 }
 
 /*!
diff --git a/src/gui/graphicsview/qgridlayoutengine.cpp b/src/gui/graphicsview/qgridlayoutengine.cpp
index 98e6781..f8cd593 100644
--- a/src/gui/graphicsview/qgridlayoutengine.cpp
+++ b/src/gui/graphicsview/qgridlayoutengine.cpp
@@ -306,20 +306,19 @@ void QGridLayoutRowData::calculateGeometries(int start, int end, qreal targetSiz
                         ultimatePreferredSize = ultimatePreferredSize * 3 / 2;
                         ultimateSumPreferredSizes = ultimateSumPreferredSizes * 3 / 2;
 
-                        qreal ultimateFactor = (stretch * ultimateSumPreferredSizes
-                                                / sumStretches)
-                                               - (box.q_preferredSize);
-                        qreal transitionalFactor = sumCurrentAvailable
-                                                   * (ultimatePreferredSize - box.q_preferredSize)
-                                                   / (ultimateSumPreferredSizes
-                                                      - sumPreferredSizes);
-
-                        qreal alpha = qMin(sumCurrentAvailable,
-                                           ultimateSumPreferredSizes - sumPreferredSizes);
                         qreal beta = ultimateSumPreferredSizes - sumPreferredSizes;
+                        if (!beta) {
+                            factors[i] = 1;
+                        } else {
+                            qreal alpha = qMin(sumCurrentAvailable, beta);
+                            qreal ultimateFactor = (stretch * ultimateSumPreferredSizes / sumStretches)
+                                                   - (box.q_preferredSize);
+                            qreal transitionalFactor = sumCurrentAvailable * (ultimatePreferredSize - box.q_preferredSize) / beta;
+
+                            factors[i] = ((alpha * ultimateFactor)
+                                          + ((beta - alpha) * transitionalFactor)) / beta;
+                        }
 
-                        factors[i] = ((alpha * ultimateFactor)
-                                      + ((beta - alpha) * transitionalFactor)) / beta;
                     }
                     sumFactors += factors[i];
                     if (desired < sumCurrentAvailable)