Make sure itemAt() reflects the visual order.

This means it should respect the order that was defined with
insertItem() and addItem().
Note that this is not strictly necessary (as now explicitly written in
the docs for QGraphicsLayout::itemAt()), but commit
2ec56d158dc140f68efb45e2e0613f0e4026ddf6 broke the order and for people
that relied on this that commit caused a regression.

In addition, after commit 2ec56d158dc140f68efb45e2e0613f0e4026ddf6 it
was not longer possible to query the "item at visual index". Thus,
instead of adding another function (like QGGL::itemAt(int,int)) we make
sure that itemAt() also returns the "item at visual index".

5 files changed, 50 insertions, 8 deletions

diff --git a/src/gui/graphicsview/qgraphicslayout.cpp b/src/gui/graphicsview/qgraphicslayout.cpp
index 58c174c..df6be90 100644
--- a/src/gui/graphicsview/qgraphicslayout.cpp
+++ b/src/gui/graphicsview/qgraphicslayout.cpp
@@ -390,8 +390,10 @@ void QGraphicsLayout::widgetEvent(QEvent *e)
     QGraphicsLayout to return a pointer to the item at index \a i. The
     reimplementation can assume that \a i is valid (i.e., it respects the
     value of count()).
+    Together with count(), it is provided as a means of iterating over all items in a layout.
 
-    The subclass is free to decide how to store the items.
+    The subclass is free to decide how to store the items, and the visual arrangement
+    does not have to be reflected through this function.
 
     \sa count(), removeAt()
 */
diff --git a/src/gui/graphicsview/qgraphicslinearlayout.cpp b/src/gui/graphicsview/qgraphicslinearlayout.cpp
index 185780a..1b271e5 100644
--- a/src/gui/graphicsview/qgraphicslinearlayout.cpp
+++ b/src/gui/graphicsview/qgraphicslinearlayout.cpp
@@ -277,7 +277,7 @@ void QGraphicsLinearLayout::insertItem(int index, QGraphicsLayoutItem *item)
     Q_ASSERT(item);
     d->fixIndex(&index);
     d->engine.insertRow(index, d->orientation);
-    new QGridLayoutItem(&d->engine, item, d->gridRow(index), d->gridColumn(index));
+    new QGridLayoutItem(&d->engine, item, d->gridRow(index), d->gridColumn(index), 1, 1, 0, index);
     invalidate();
 }
 
@@ -471,6 +471,7 @@ int QGraphicsLinearLayout::count() const
 
 /*!
     \reimp
+    When iterating from 0 and up, it will return the items in the visual arranged order.
 */
 QGraphicsLayoutItem *QGraphicsLinearLayout::itemAt(int index) const
 {
diff --git a/src/gui/graphicsview/qgridlayoutengine.cpp b/src/gui/graphicsview/qgridlayoutengine.cpp
index 5ad6ac9..beb9cb0 100644
--- a/src/gui/graphicsview/qgridlayoutengine.cpp
+++ b/src/gui/graphicsview/qgridlayoutengine.cpp
@@ -461,7 +461,7 @@ void QGridLayoutRowData::dump(int indent) const
 
 QGridLayoutItem::QGridLayoutItem(QGridLayoutEngine *engine, QGraphicsLayoutItem *layoutItem,
                                  int row, int column, int rowSpan, int columnSpan,
-                                 Qt::Alignment alignment)
+                                 Qt::Alignment alignment, int itemAtIndex)
     : q_engine(engine), q_layoutItem(layoutItem), q_alignment(alignment)
 {
     q_firstRows[Hor] = column;
@@ -471,7 +471,7 @@ QGridLayoutItem::QGridLayoutItem(QGridLayoutEngine *engine, QGraphicsLayoutItem
     q_stretches[Hor] = -1;
     q_stretches[Ver] = -1;
 
-    q_engine->addItem(this);
+    q_engine->insertItem(this, itemAtIndex);
 }
 
 int QGridLayoutItem::firstRow(Qt::Orientation orientation) const
@@ -937,11 +937,20 @@ Qt::Alignment QGridLayoutEngine::effectiveAlignment(const QGridLayoutItem *layou
     return align;
 }
 
-void QGridLayoutEngine::addItem(QGridLayoutItem *item)
+/*!
+    \internal
+    The \a index is only used by QGraphicsLinearLayout to ensure that itemAt() reflects the order
+    of visual arrangement. Strictly speaking it does not have to, but most people expect it to.
+    (And if it didn't we would have to add itemArrangedAt(int index) or something..)
+ */
+void QGridLayoutEngine::insertItem(QGridLayoutItem *item, int index)
 {
     maybeExpandGrid(item->lastRow(), item->lastColumn());
 
-    q_items.append(item);
+    if (index == -1)
+        q_items.append(item);
+    else
+        q_items.insert(index, item);
 
     for (int i = item->firstRow(); i <= item->lastRow(); ++i) {
         for (int j = item->firstColumn(); j <= item->lastColumn(); ++j) {
@@ -952,6 +961,11 @@ void QGridLayoutEngine::addItem(QGridLayoutItem *item)
     }
 }
 
+void QGridLayoutEngine::addItem(QGridLayoutItem *item)
+{
+    insertItem(item, -1);
+}
+
 void QGridLayoutEngine::removeItem(QGridLayoutItem *item)
 {
     Q_ASSERT(q_items.contains(item));
diff --git a/src/gui/graphicsview/qgridlayoutengine_p.h b/src/gui/graphicsview/qgridlayoutengine_p.h
index 8f3eb13..aab695a 100644
--- a/src/gui/graphicsview/qgridlayoutengine_p.h
+++ b/src/gui/graphicsview/qgridlayoutengine_p.h
@@ -267,7 +267,8 @@ class QGridLayoutItem
 {
 public:
     QGridLayoutItem(QGridLayoutEngine *engine, QGraphicsLayoutItem *layoutItem, int row, int column,
-                    int rowSpan = 1, int columnSpan = 1, Qt::Alignment alignment = 0);
+                    int rowSpan = 1, int columnSpan = 1, Qt::Alignment alignment = 0,
+                    int itemAtIndex = -1);
 
     inline int firstRow() const { return q_firstRows[Ver]; }
     inline int firstColumn() const { return q_firstRows[Hor]; }
@@ -378,6 +379,7 @@ public:
     Qt::Alignment effectiveAlignment(const QGridLayoutItem *layoutItem) const;
 
 
+    void insertItem(QGridLayoutItem *item, int index);
     void addItem(QGridLayoutItem *item);
     void removeItem(QGridLayoutItem *item);
     QGridLayoutItem *findLayoutItem(QGraphicsLayoutItem *layoutItem) const;
diff --git a/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp b/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
index 1d81ac8..51c96b1 100644
--- a/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
+++ b/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
@@ -76,6 +76,7 @@ private slots:
     void invalidate();
     void itemAt_data();
     void itemAt();
+    void itemAt_visualOrder();
     void orientation_data();
     void orientation();
     void removeAt_data();
@@ -537,7 +538,7 @@ void tst_QGraphicsLinearLayout::insertItem()
     QCOMPARE(layout.count(), itemCount + layoutCount + 1);
 
     if (insertItemAt >= 0 && (itemCount + layoutCount >= 0)) {
-        QCOMPARE(layout.itemAt(itemCount + layoutCount), item);
+        QCOMPARE(layout.itemAt(insertItemAt), item);
     }
 
     layout.activate();
@@ -686,6 +687,28 @@ void tst_QGraphicsLinearLayout::itemAt()
     QVERIFY(layout.itemAt(index) != 0);
 }
 
+void tst_QGraphicsLinearLayout::itemAt_visualOrder()
+{
+    QGraphicsLinearLayout *l = new QGraphicsLinearLayout;
+
+    QGraphicsWidget *w1 = new QGraphicsWidget;
+    l->addItem(w1);
+
+    QGraphicsWidget *w3 = new QGraphicsWidget;
+    l->addItem(w3);
+
+    QGraphicsWidget *w0 = new QGraphicsWidget;
+    l->insertItem(0, w0);
+
+    QGraphicsWidget *w2 = new QGraphicsWidget;
+    l->insertItem(2, w2);
+
+    QCOMPARE(l->itemAt(0), w0);
+    QCOMPARE(l->itemAt(1), w1);
+    QCOMPARE(l->itemAt(2), w2);
+    QCOMPARE(l->itemAt(3), w3);
+}
+
 void tst_QGraphicsLinearLayout::orientation_data()
 {
     QTest::addColumn<Qt::Orientation>("orientation");