Fix a bug that got revealed by 604c51f1fc5c79b7fad12cda911b06b9e6e5005f

The bug has been around for a while, but change 604c51f1fc5c7 made it
emerge.
The problem was that stretches were combined by always *maxing* them.
The values of 'stretch' can be interpreted as this:

-1: (the default) it means that the items should be stretched with
    the stretch factor dervived from the size hints. (In practice this
    means that they are distributed fairly).
 0: Means that the item should not be stretched
>0: Means that the item should be stretch with that number as a factor.

This meant that combining one item with a fixed size(0) and another
item with a default stretch (-1) the combined row stretch would end
up being fixed.

This also fixes how stretches are combined for spanning items too.

Task-number: QTBUG-13551
Reviewed-by: John Tapsell
(cherry picked from commit 7fbf1829e11504eca6a55f1e5dbddf2f658b5302)

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp b/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
index a024f65..62ba1b4 100644
--- a/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
+++ b/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
@@ -106,6 +106,7 @@ private slots:
     void testAlignmentInLargerLayout();
     void testOffByOneInLargerLayout();
     void testDefaultAlignment();
+    void combineSizePolicies();
 
     // Task specific tests
     void task218400_insertStretchCrash();
@@ -1583,6 +1584,31 @@ void tst_QGraphicsLinearLayout::testDefaultAlignment()
     QCOMPARE(w2->geometry(), QRectF(0,50,100,100));
 }
 
+void tst_QGraphicsLinearLayout::combineSizePolicies()
+{
+    QGraphicsWidget *widget = new QGraphicsWidget;
+    QGraphicsLinearLayout *layout = new QGraphicsLinearLayout(Qt::Horizontal, widget);
+    layout->setContentsMargins(0, 0, 0, 0);
+    layout->setSpacing(0);
+
+    QGraphicsWidget *w1 = new QGraphicsWidget;
+    w1->setMaximumSize(200,200);
+    w1->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);
+    layout->addItem(w1);
+
+    QGraphicsWidget *w2 = new QGraphicsWidget;
+    w2->setPreferredSize(50,50);
+    w2->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
+    layout->addItem(w2);
+    QCOMPARE(layout->maximumHeight(), qreal(200));
+
+    // now remove the fixed vertical size policy, and set instead the maximum height to 50
+    // this should in effect give the same maximumHeight
+    w2->setMaximumHeight(50);
+    w2->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Preferred);
+    QCOMPARE(layout->maximumHeight(), qreal(200));
+}
+
 QTEST_MAIN(tst_QGraphicsLinearLayout)
 #include "tst_qgraphicslinearlayout.moc"