QGAL: default spacing can be unset using a negative value

After a default spacing is set through QGAL::setSpacing() family
of methods, the user must be able to unset it.

To avoid adding another public method, we enabled this feature
by allowing a negative value to be passed to those methods.

Signed-off-by: Eduardo M. Fleury <eduardo.fleury@openbossa.org>
Reviewed-by: Anselmo Lacerda S. de Melo <anselmo.melo@openbossa.org>

2 files changed, 43 insertions, 21 deletions

diff --git a/src/gui/graphicsview/qgraphicsanchorlayout.cpp b/src/gui/graphicsview/qgraphicsanchorlayout.cpp
index 7e5929e..686096c 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout.cpp
+++ b/src/gui/graphicsview/qgraphicsanchorlayout.cpp
@@ -370,12 +370,6 @@ void QGraphicsAnchorLayout::setHorizontalSpacing(qreal spacing)
 {
     Q_D(QGraphicsAnchorLayout);
 
-    // ### We don't support negative spacing yet
-    if (spacing < 0) {
-        spacing = 0;
-        qWarning() << "QGraphicsAnchorLayout does not support negative spacing.";
-    }
-
     d->spacings[0] = spacing;
     invalidate();
 }
@@ -389,12 +383,6 @@ void QGraphicsAnchorLayout::setVerticalSpacing(qreal spacing)
 {
     Q_D(QGraphicsAnchorLayout);
 
-    // ### We don't support negative spacing yet
-    if (spacing < 0) {
-        spacing = 0;
-        qWarning() << "QGraphicsAnchorLayout does not support negative spacing.";
-    }
-
     d->spacings[1] = spacing;
     invalidate();
 }
@@ -405,7 +393,8 @@ void QGraphicsAnchorLayout::setVerticalSpacing(qreal spacing)
     If an item is anchored with no spacing associated with the anchor, it will use the default
     spacing.
 
-    Currently QGraphicsAnchorLayout does not support negative default spacings.
+    QGraphicsAnchorLayout does not support negative spacings. Setting a negative value will unset the
+    previous spacing and make the layout use the spacing provided by the current widget style.
 
     \sa setHorizontalSpacing(), setVerticalSpacing()
 */
@@ -413,14 +402,6 @@ void QGraphicsAnchorLayout::setSpacing(qreal spacing)
 {
     Q_D(QGraphicsAnchorLayout);
 
-    // ### Currently we do not support negative anchors inside the graph.
-    // To avoid those being created by a negative spacing, we must
-    // make this test.
-    if (spacing < 0) {
-        spacing = 0;
-        qWarning() << "QGraphicsAnchorLayout does not support negative spacing.";
-    }
-
     d->spacings[0] = d->spacings[1] = spacing;
     invalidate();
 }
diff --git a/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp b/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
index e2f87b8..aa67ac5 100644
--- a/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
+++ b/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
@@ -88,6 +88,7 @@ private slots:
     void spacingPersistency();
     void snakeParallelWithLayout();
     void parallelToHalfLayout();
+    void globalSpacing();
 };
 
 class RectWidget : public QGraphicsWidget
@@ -1976,5 +1977,45 @@ void tst_QGraphicsAnchorLayout::parallelToHalfLayout()
     QCOMPARE(maximumSizeHint, QSizeF(400, 100) + overhead);
 }
 
+void tst_QGraphicsAnchorLayout::globalSpacing()
+{
+    QGraphicsWidget *a = createItem();
+    QGraphicsWidget *b = createItem();
+
+    QGraphicsWidget w;
+    QGraphicsAnchorLayout *l = new QGraphicsAnchorLayout(&w);
+
+    l->addCornerAnchors(l, Qt::TopLeftCorner, a, Qt::TopLeftCorner);
+    l->addCornerAnchors(a, Qt::BottomRightCorner, b, Qt::TopLeftCorner);
+    l->addCornerAnchors(b, Qt::BottomRightCorner, l, Qt::BottomRightCorner);
+
+    w.resize(w.effectiveSizeHint(Qt::PreferredSize));
+    qreal vSpacing = b->geometry().top() - a->geometry().bottom();
+    qreal hSpacing = b->geometry().left() - a->geometry().right();
+
+    // Set spacings manually
+    l->setVerticalSpacing(vSpacing + 10);
+    l->setHorizontalSpacing(hSpacing + 5);
+
+    w.resize(w.effectiveSizeHint(Qt::PreferredSize));
+    qreal newVSpacing = b->geometry().top() - a->geometry().bottom();
+    qreal newHSpacing = b->geometry().left() - a->geometry().right();
+
+    QCOMPARE(newVSpacing, vSpacing + 10);
+    QCOMPARE(newHSpacing, hSpacing + 5);
+
+    // Set a negative spacing. This will unset the previous spacing and
+    // bring back the widget-defined spacing.
+    l->setSpacing(-1);
+
+    w.resize(w.effectiveSizeHint(Qt::PreferredSize));
+    newVSpacing = b->geometry().top() - a->geometry().bottom();
+    newHSpacing = b->geometry().left() - a->geometry().right();
+
+    QCOMPARE(newVSpacing, vSpacing);
+    QCOMPARE(newHSpacing, hSpacing);
+}
+
+
 QTEST_MAIN(tst_QGraphicsAnchorLayout)
 #include "tst_qgraphicsanchorlayout.moc"