QGAL: deal correctly with anchors in parallel with the layout

In the preferred size calculation, we should not add 'layout anchors'
(either one or the two halves) into the objective function, since the
layout doesn't impose or prefer any size at all.

This already worked for cases when the layout anchor is one, but not
when we have two halves. The mechanism was a 'skipInPreferred' flag
that were not being set.

The flag is pretty much redundant right now, since we can get this
information from the 'isLayoutAnchor' flag. So, the flag was removed
and a test was added for both a parallel case with the entire layout
and other with half of the layout (which wasn't passing before).

Signed-off-by: Caio Marcelo de Oliveira Filho <caio.oliveira@openbossa.org>
Reviewed-by: Eduardo M. Fleury <eduardo.fleury@openbossa.org>

3 files changed, 56 insertions, 6 deletions

diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
index fb67278..b324469 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
@@ -1272,7 +1272,6 @@ void QGraphicsAnchorLayoutPrivate::createLayoutEdges()
     addAnchor_helper(layout, Qt::AnchorLeft, layout,
                      Qt::AnchorRight, data);
     data->maxSize = QWIDGETSIZE_MAX;
-    data->skipInPreferred = 1;
 
     // Save a reference to layout vertices
     layoutFirstVertex[Horizontal] = internalVertex(layout, Qt::AnchorLeft);
@@ -1284,7 +1283,6 @@ void QGraphicsAnchorLayoutPrivate::createLayoutEdges()
     addAnchor_helper(layout, Qt::AnchorTop, layout,
                      Qt::AnchorBottom, data);
     data->maxSize = QWIDGETSIZE_MAX;
-    data->skipInPreferred = 1;
 
     // Save a reference to layout vertices
     layoutFirstVertex[Vertical] = internalVertex(layout, Qt::AnchorTop);
@@ -2700,7 +2698,9 @@ bool QGraphicsAnchorLayoutPrivate::solvePreferred(const QList<QSimplexConstraint
     //
     for (int i = 0; i < variables.size(); ++i) {
         AnchorData *ad = variables.at(i);
-        if (ad->skipInPreferred)
+
+        // The layout original structure anchors are not relevant in preferred size calculation
+        if (ad->isLayoutAnchor)
             continue;
 
         QSimplexVariable *grower = new QSimplexVariable;
diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.h b/src/gui/graphicsview/qgraphicsanchorlayout_p.h
index 2b365fb..8529e2e 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.h
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.h
@@ -124,8 +124,7 @@ struct AnchorData : public QSimplexVariable {
         : QSimplexVariable(), from(0), to(0),
           minSize(0), prefSize(0), maxSize(0),
           sizeAtMinimum(0), sizeAtPreferred(0),
-          sizeAtMaximum(0), item(0),
-          graphicsAnchor(0), skipInPreferred(0),
+          sizeAtMaximum(0), item(0), graphicsAnchor(0),
           type(Normal), isLayoutAnchor(false),
           isCenterAnchor(false), orientation(0),
           dependency(Independent) {}
@@ -169,7 +168,6 @@ struct AnchorData : public QSimplexVariable {
     QGraphicsLayoutItem *item;
     QGraphicsAnchor *graphicsAnchor;
 
-    uint skipInPreferred : 1;
     uint type : 2;            // either Normal, Sequential or Parallel
     uint isLayoutAnchor : 1;  // if this anchor is an internal layout anchor
     uint isCenterAnchor : 1;
diff --git a/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp b/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
index 2ad024f..4f8c240 100644
--- a/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
+++ b/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
@@ -86,6 +86,7 @@ private slots:
     void parallelSimplificationOfCenter();
     void simplificationVsRedundance();
     void spacingPersistency();
+    void snakeParallelWithLayout();
 };
 
 class RectWidget : public QGraphicsWidget
@@ -1892,5 +1893,56 @@ void tst_QGraphicsAnchorLayout::spacingPersistency()
     QCOMPARE(anchor->spacing(), 30.0);
 }
 
+/*
+    Test whether a correct preferred size is set when a "snake" sequence is in parallel with the
+    layout or half of the layout. The tricky thing here is that all items on the snake should
+    keep their preferred sizes.
+*/
+void tst_QGraphicsAnchorLayout::snakeParallelWithLayout()
+{
+    QSizeF min(10, 20);
+    QSizeF pref(50, 20);
+    QSizeF max(100, 20);
+
+    QGraphicsWidget *a = createItem(max, max, max, "A");
+    QGraphicsWidget *b = createItem(min, pref, max, "B");
+    QGraphicsWidget *c = createItem(max, max, max, "C");
+
+    QGraphicsWidget parent;
+    QGraphicsAnchorLayout *l = new QGraphicsAnchorLayout(&parent);
+    l->setContentsMargins(0, 0, 0, 0);
+    l->setSpacing(0);
+
+    // First we'll do the case in parallel with the entire layout...
+    l->addAnchor(l, Qt::AnchorLeft, a, Qt::AnchorLeft);
+    l->addAnchor(a, Qt::AnchorRight, b, Qt::AnchorRight);
+    l->addAnchor(b, Qt::AnchorLeft, c, Qt::AnchorLeft);
+    l->addAnchor(c, Qt::AnchorRight, l, Qt::AnchorRight);
+
+    l->addAnchor(l, Qt::AnchorTop, a, Qt::AnchorTop);
+    l->addAnchor(a, Qt::AnchorBottom, b, Qt::AnchorTop);
+    l->addAnchor(b, Qt::AnchorBottom, c, Qt::AnchorTop);
+    l->addAnchor(c, Qt::AnchorBottom, l, Qt::AnchorBottom);
+
+    parent.resize(l->effectiveSizeHint(Qt::PreferredSize));
+
+    // Note that A and C are fixed in the maximum size
+    QCOMPARE(l->geometry(), QRectF(QPointF(0, 0), QSizeF(150, 60)));
+    QCOMPARE(a->geometry(), QRectF(QPointF(0, 0), max));
+    QCOMPARE(b->geometry(), QRectF(QPointF(50, 20), pref));
+    QCOMPARE(c->geometry(), QRectF(QPointF(50, 40), max));
+
+    // Then, we change the "snake" to be in parallel with half of the layout
+    delete l->anchor(c, Qt::AnchorRight, l, Qt::AnchorRight);
+    l->addAnchor(c, Qt::AnchorRight, l, Qt::AnchorHorizontalCenter);
+
+    parent.resize(l->effectiveSizeHint(Qt::PreferredSize));
+
+    QCOMPARE(l->geometry(), QRectF(QPointF(0, 0), QSizeF(300, 60)));
+    QCOMPARE(a->geometry(), QRectF(QPointF(0, 0), max));
+    QCOMPARE(b->geometry(), QRectF(QPointF(50, 20), pref));
+    QCOMPARE(c->geometry(), QRectF(QPointF(50, 40), max));
+}
+
 QTEST_MAIN(tst_QGraphicsAnchorLayout)
 #include "tst_qgraphicsanchorlayout.moc"