QGAL: sizeHint constraints needed by anchors parallel with the layout

The method "constraintsFromSizeHints" does not create constraints for
anchors between the layout vertices _only if_ these anchors have
infinite maximum sizes. However, this test was not being done for
half-anchors, ie. those created when the layout center anchorage
point is used.

That was OK when there was no chance that the center anchors had
been simplified by a parallel anchor. Nowadays there's a chance
that happens, so the test was extended.

Commit also adds a test to avoid regressions.

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

2 files changed, 46 insertions, 6 deletions

diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
index b324469..a6f5992 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
@@ -2269,13 +2269,21 @@ QList<QSimplexConstraint *> QGraphicsAnchorLayoutPrivate::constraintsFromSizeHin
         layoutEdge = graph[orient].edgeData(layoutFirstVertex[orient], layoutCentralVertex[orient]);
     } else {
         layoutEdge = graph[orient].edgeData(layoutFirstVertex[orient], layoutLastVertex[orient]);
+    }
 
-        // If maxSize is less then "infinite", that means there are other anchors
-        // grouped together with this one. We can't ignore its maximum value so we
-        // set back the variable to NULL to prevent the continue condition from being
-        // satisfied in the loop below.
-        if (layoutEdge->maxSize < QWIDGETSIZE_MAX)
-            layoutEdge = 0;
+    // If maxSize is less then "infinite", that means there are other anchors
+    // grouped together with this one. We can't ignore its maximum value so we
+    // set back the variable to NULL to prevent the continue condition from being
+    // satisfied in the loop below.
+    const qreal expectedMax = layoutCentralVertex[orient] ? QWIDGETSIZE_MAX / 2 : QWIDGETSIZE_MAX;
+    qreal actualMax;
+    if (layoutEdge->from == layoutFirstVertex[orient]) {
+        actualMax = layoutEdge->maxSize;
+    } else {
+        actualMax = -layoutEdge->minSize;
+    }
+    if (actualMax != expectedMax) {
+        layoutEdge = 0;
     }
 
     // For each variable, create constraints based on size hints
diff --git a/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp b/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
index 4f8c240..e2f87b8 100644
--- a/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
+++ b/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
@@ -87,6 +87,7 @@ private slots:
     void simplificationVsRedundance();
     void spacingPersistency();
     void snakeParallelWithLayout();
+    void parallelToHalfLayout();
 };
 
 class RectWidget : public QGraphicsWidget
@@ -1944,5 +1945,36 @@ void tst_QGraphicsAnchorLayout::snakeParallelWithLayout()
     QCOMPARE(c->geometry(), QRectF(QPointF(50, 40), max));
 }
 
+/*
+  Avoid regression where the sizeHint constraints would not be
+  created for a parallel anchor that included the first layout half
+*/
+void tst_QGraphicsAnchorLayout::parallelToHalfLayout()
+{
+    QGraphicsWidget *a = createItem();
+
+    QGraphicsWidget w;
+    QGraphicsAnchorLayout *l = new QGraphicsAnchorLayout(&w);
+    l->setContentsMargins(10, 10, 10, 10);
+
+    l->addAnchors(l, a, Qt::Vertical);
+
+    QGraphicsAnchor *anchor;
+    anchor = l->addAnchor(l, Qt::AnchorLeft, a, Qt::AnchorLeft);
+    anchor->setSpacing(5);
+    anchor = l->addAnchor(l, Qt::AnchorHorizontalCenter, a, Qt::AnchorRight);
+    anchor->setSpacing(-5);
+
+    const QSizeF minimumSizeHint = w.effectiveSizeHint(Qt::MinimumSize);
+    const QSizeF preferredSizeHint = w.effectiveSizeHint(Qt::PreferredSize);
+    const QSizeF maximumSizeHint = w.effectiveSizeHint(Qt::MaximumSize);
+
+    const QSizeF overhead = QSizeF(10 + 5 + 5, 10) * 2;
+
+    QCOMPARE(minimumSizeHint, QSizeF(200, 100) + overhead);
+    QCOMPARE(preferredSizeHint, QSizeF(300, 100) + overhead);
+    QCOMPARE(maximumSizeHint, QSizeF(400, 100) + overhead);
+}
+
 QTEST_MAIN(tst_QGraphicsAnchorLayout)
 #include "tst_qgraphicsanchorlayout.moc"