Fixed a bug where a rearrange was not always done

This happened only when the size of the layout didn't change.

Task-number: QTBUG-31570

Change-Id: Ia090c0062fa8fc3eb6f648592529ee8fcd025593
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>

src/layouts/qquickgridlayoutengine_p.h

@@ -112,8 +112,16 @@ public:
     void setGeometry(const QRectF &rect)
     {
         const QRect r(rect.toRect());
+        const QSize newSize(r.size());
         m_item->setPosition(r.topLeft());
-        m_item->setSize(r.size());
+        QSizeF oldSize(m_item->width(), m_item->height());
+        if (newSize == oldSize) {
+            if (QQuickLayout *lay = qobject_cast<QQuickLayout *>(m_item))
+                if (lay->arrangementIsDirty())
+                    lay->rearrange(newSize);
+        } else {
+            m_item->setSize(newSize);
+        }
     }
 
     QQuickItem *layoutItem() const { return m_item; }

src/layouts/qquicklayout_p.h

@@ -77,9 +77,10 @@ public:
     void componentComplete();
     virtual QSizeF sizeHint(Qt::SizeHint whichSizeHint) const = 0;
     virtual void invalidate(QQuickItem * childItem = 0);
+    virtual void rearrange(const QSizeF &);
+    bool arrangementIsDirty() const { return m_dirty; }
 protected:
     bool event(QEvent *e);
-    virtual void rearrange(const QSizeF &);
 
     enum Orientation {
         Vertical = 0,

tests/auto/controls/data/tst_rowlayout.qml

@@ -658,5 +658,50 @@ Item {
             layout.visible = false
             layout.destroy()    // Do not crash
         }
+
+
+        Component {
+            id: rearrangeNestedLayouts_Component
+            RowLayout {
+                id: layout
+                anchors.fill: parent
+                width: 200
+                height: 20
+                RowLayout {
+                    id: row
+                    spacing: 0
+
+                    Rectangle {
+                        id: fixed
+                        color: 'red'
+                        implicitWidth: 20
+                        implicitHeight: 20
+                    }
+                    Rectangle {
+                        id: filler
+                        color: 'grey'
+                        Layout.fillWidth: true
+                        implicitHeight: 20
+                    }
+                }
+            }
+        }
+
+        function test_rearrangeNestedLayouts()
+        {
+            var layout = rearrangeNestedLayouts_Component.createObject(container)
+            var fixed = layout.children[0].children[0]
+            var filler = layout.children[0].children[1]
+
+            compare(itemRect(fixed),  [0,0,20,20])
+            compare(itemRect(filler), [20,0,180,20])
+
+            fixed.implicitWidth = 100
+            wait(20);    // wait for at least 20 ms (this matches the time between two frame
+                         // repaints for 50hz displays)
+            compare(itemRect(fixed),  [0,0,100,20])
+            compare(itemRect(filler), [100,0,100,20])
+
+        }
     }
 }