QGraphicsAnchorLayout: Ensure spacing is not negative

Currently we do not support negative-sized anchors in the graph,
instead we invert such anchors and make their value positive.

We consider changing this sometime in the future but until then,
spacing must be non-negative at all times.

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

2 files changed, 33 insertions, 0 deletions

diff --git a/src/gui/graphicsview/qgraphicsanchorlayout.cpp b/src/gui/graphicsview/qgraphicsanchorlayout.cpp
index ffbb67c..9f4a19b 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout.cpp
+++ b/src/gui/graphicsview/qgraphicsanchorlayout.cpp
@@ -306,6 +306,13 @@ void QGraphicsAnchorLayout::addAnchors(QGraphicsLayoutItem *firstItem,
 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();
 }
@@ -318,6 +325,13 @@ void QGraphicsAnchorLayout::setHorizontalSpacing(qreal spacing)
 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();
 }
@@ -327,11 +341,23 @@ 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.
+
     \sa setHorizontalSpacing(), setVerticalSpacing()
 */
 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/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
index f9b5c8c..1cbea8e 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
@@ -1550,6 +1550,13 @@ qreal QGraphicsAnchorLayoutPrivate::effectiveSpacing(Orientation orientation) co
             }
         }
     }
+
+    // ### Currently we do not support negative anchors inside the graph.
+    // To avoid those being created by a negative style spacing, we must
+    // make this test.
+    if (s < 0)
+        s = 0;
+
     return s;
 }