QGAL: Move size information from AnchorData to QGraphicsAnchorPrivate

To solve the spacing persistency bug, this commit saves the
preferredSize (spacing) information inside QGraphicsAnchorPrivate.

The problem started when we could not rely on "AnchorData->prefSize"
to keep the spacing information for user-defined anchors. This happens
because that member can be overriden if the spacing is negative
(anchor is inverted) or its sizePolicy is of type "Ignored" (it is
overriden by minSize).

Then, to decide where to store it, we aimed to make something similar
to what happens with item-internal anchors. Those can rely on their
items to get fresh information regarding their size, so we decided
that user-anchors (that don't have items, but do have QGraphicsAnchors)
could read such information from there.

This refactory also reduced the deep indirection that existed
in the "QGraphicsAnchor->setSpacing" call. Previously it would
call internal layout methods to do some black magic, that's now gone.

As the spacing  information is now stored in the anchor itself, it
can do pretty much all the work and, after that, just invalidate the
layout.

Also, moved information like "AnchorData->hasSize" to QGAnchor as
its pretty much related to the preferredSize information itself.

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

1 files changed, 58 insertions, 90 deletions

diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
index 182594e..872fecb 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
@@ -55,7 +55,8 @@ QT_BEGIN_NAMESPACE
 
 QGraphicsAnchorPrivate::QGraphicsAnchorPrivate(int version)
     : QObjectPrivate(version), layoutPrivate(0), data(0),
-      sizePolicy(QSizePolicy::Fixed)
+      sizePolicy(QSizePolicy::Fixed), preferredSize(0),
+      hasSize(true), reversed(false)
 {
 }
 
@@ -76,31 +77,60 @@ void QGraphicsAnchorPrivate::setSizePolicy(QSizePolicy::Policy policy)
 
 void QGraphicsAnchorPrivate::setSpacing(qreal value)
 {
-    if (data) {
-        layoutPrivate->setAnchorSize(data, &value);
-    } else {
+    if (!data) {
         qWarning("QGraphicsAnchor::setSpacing: The anchor does not exist.");
+        return;
     }
+
+    const qreal rawValue = reversed ? -preferredSize : preferredSize;
+    if (hasSize && (rawValue == value))
+        return;
+
+    // The anchor has an user-defined size
+    hasSize = true;
+
+    // The simplex solver cannot handle negative sizes. To workaround that,
+    // if value is less than zero, we reverse the anchor and set the absolute
+    // value;
+    if (value >= 0) {
+        preferredSize = value;
+        if (reversed)
+            qSwap(data->from, data->to);
+        reversed = false;
+    } else {
+        preferredSize = -value;
+        if (!reversed)
+            qSwap(data->from, data->to);
+        reversed = true;
+    }
+
+    layoutPrivate->q_func()->invalidate();
 }
 
 void QGraphicsAnchorPrivate::unsetSpacing()
 {
-    if (data) {
-        layoutPrivate->setAnchorSize(data, 0);
-    } else {
+    if (!data) {
         qWarning("QGraphicsAnchor::setSpacing: The anchor does not exist.");
+        return;
     }
+
+    // Return to standard direction
+    hasSize = false;
+    if (reversed)
+        qSwap(data->from, data->to);
+    reversed = false;
+
+    layoutPrivate->q_func()->invalidate();
 }
 
 qreal QGraphicsAnchorPrivate::spacing() const
 {
-    qreal size = 0;
-    if (data) {
-        layoutPrivate->anchorSize(data, 0, &size, 0);
-    } else {
+    if (!data) {
         qWarning("QGraphicsAnchor::setSpacing: The anchor does not exist.");
+        return 0;
     }
-    return size;
+
+    return reversed ? -preferredSize : preferredSize;
 }
 
 
@@ -146,8 +176,8 @@ bool AnchorData::refreshSizeHints(const QLayoutStyleInfo *styleInfo)
     qreal prefSizeHint;
     qreal maxSizeHint;
 
-    // It is an internal anchor
     if (item) {
+        // It is an internal anchor, fetch size information from the item
         if (isLayoutAnchor) {
             minSize = 0;
             prefSize = 0;
@@ -175,14 +205,16 @@ bool AnchorData::refreshSizeHints(const QLayoutStyleInfo *styleInfo)
             }
         }
     } else {
+        // It is a user-created anchor, fetch size information from the associated QGraphicsAnchor
         Q_ASSERT(graphicsAnchor);
-        policy = graphicsAnchor->sizePolicy();
+        QGraphicsAnchorPrivate *anchorPrivate = graphicsAnchor->d_func();
+        policy = anchorPrivate->sizePolicy;
         minSizeHint = 0;
-        if (hasSize) {
+        if (anchorPrivate->hasSize) {
             // One can only configure the preferred size of a normal anchor. Their minimum and
             // maximum "size hints" are always 0 and QWIDGETSIZE_MAX, correspondingly. However,
             // their effective size hints might be narrowed down due to their size policies.
-            prefSizeHint = prefSize;
+            prefSizeHint = anchorPrivate->preferredSize;
         } else {
             const Qt::Orientation orient = Qt::Orientation(QGraphicsAnchorLayoutPrivate::edgeOrientation(from->m_edge) + 1);
             qreal s = styleInfo->defaultSpacing(orient);
@@ -1565,7 +1597,13 @@ QGraphicsAnchor *QGraphicsAnchorLayoutPrivate::addAnchor(QGraphicsLayoutItem *fi
     correctEdgeDirection(firstItem, firstEdge, secondItem, secondEdge);
 
     AnchorData *data = new AnchorData;
-    if (!spacing) {
+    QGraphicsAnchor *graphicsAnchor = acquireGraphicsAnchor(data);
+
+    addAnchor_helper(firstItem, firstEdge, secondItem, secondEdge, data);
+
+    if (spacing) {
+        graphicsAnchor->setSpacing(*spacing);
+    } else {
         // If firstItem or secondItem is the layout itself, the spacing will default to 0.
         // Otherwise, the following matrix is used (questionmark means that the spacing
         // is queried from the style):
@@ -1578,22 +1616,13 @@ QGraphicsAnchor *QGraphicsAnchorLayoutPrivate::addAnchor(QGraphicsLayoutItem *fi
             || secondItem == q
             || pickEdge(firstEdge, Horizontal) == Qt::AnchorHorizontalCenter
             || oppositeEdge(firstEdge) != secondEdge) {
-            data->setPreferredSize(0);
+            graphicsAnchor->setSpacing(0);
         } else {
-            data->unsetSize();
+            graphicsAnchor->unsetSpacing();
         }
-        addAnchor_helper(firstItem, firstEdge, secondItem, secondEdge, data);
-
-    } else if (*spacing >= 0) {
-        data->setPreferredSize(*spacing);
-        addAnchor_helper(firstItem, firstEdge, secondItem, secondEdge, data);
-
-    } else {
-        data->setPreferredSize(-*spacing);
-        addAnchor_helper(secondItem, secondEdge, firstItem, firstEdge, data);
     }
 
-    return acquireGraphicsAnchor(data);
+    return graphicsAnchor;
 }
 
 void QGraphicsAnchorLayoutPrivate::addAnchor_helper(QGraphicsLayoutItem *firstItem,
@@ -1753,67 +1782,6 @@ void QGraphicsAnchorLayoutPrivate::removeAnchor_helper(AnchorVertex *v1, AnchorV
     removeInternalVertex(v2->m_item, v2->m_edge);
 }
 
-/*!
-    \internal
-    Only called from outside. (calls invalidate())
-*/
-void QGraphicsAnchorLayoutPrivate::setAnchorSize(AnchorData *data, const qreal *anchorSize)
-{
-    Q_Q(QGraphicsAnchorLayout);
-    // ### we can avoid restoration if we really want to, but we would have to
-    // search recursively through all composite anchors
-    Q_ASSERT(data);
-    restoreSimplifiedGraph(edgeOrientation(data->from->m_edge));
-
-    QGraphicsLayoutItem *firstItem = data->from->m_item;
-    QGraphicsLayoutItem *secondItem = data->to->m_item;
-    Qt::AnchorPoint firstEdge = data->from->m_edge;
-    Qt::AnchorPoint secondEdge = data->to->m_edge;
-
-    // Use heuristics to find out what the user meant with this anchor.
-    correctEdgeDirection(firstItem, firstEdge, secondItem, secondEdge);
-    if (data->from->m_item != firstItem)
-        qSwap(data->from, data->to);
-
-    if (anchorSize) {
-        // ### The current implementation makes "setAnchorSize" behavior
-        //     dependent on the argument order for cases where we have
-        //     no heuristic. Ie. two widgets, same anchor point.
-
-        // We cannot have negative sizes inside the graph. This would cause
-        // the simplex solver to fail because all simplex variables are
-        // positive by definition.
-        // "negative spacing" is handled by inverting the standard item order.
-        if (*anchorSize >= 0) {
-            data->setPreferredSize(*anchorSize);
-        } else {
-            data->setPreferredSize(-*anchorSize);
-            qSwap(data->from, data->to);
-        }
-    } else {
-        data->unsetSize();
-    }
-    q->invalidate();
-}
-
-void QGraphicsAnchorLayoutPrivate::anchorSize(const AnchorData *data,
-                                              qreal *minSize,
-                                              qreal *prefSize,
-                                              qreal *maxSize) const
-{
-    Q_ASSERT(minSize || prefSize || maxSize);
-    Q_ASSERT(data);
-    QGraphicsAnchorLayoutPrivate *that = const_cast<QGraphicsAnchorLayoutPrivate *>(this);
-    that->restoreSimplifiedGraph(Orientation(data->orientation));
-
-    if (minSize)
-        *minSize = data->minSize;
-    if (prefSize)
-        *prefSize = data->prefSize;
-    if (maxSize)
-        *maxSize = data->maxSize;
-}
-
 AnchorVertex *QGraphicsAnchorLayoutPrivate::addInternalVertex(QGraphicsLayoutItem *item,
                                                               Qt::AnchorPoint edge)
 {