QGAL: keep references to layout vertices

We used to keep a reference just to the first vertex of the layout
(corresponding to the left/top anchor point) inside the Graph class,
as "root vertex". Since the notion of rootVertex isn't used by the
Graph itself, now this is stored outside the graph, and we also store
the central and last vertices.

This avoids using internalVertex() function to find out the vertices
based on the item (in the case, the 'q'). This will be useful when we
do simplify vertices, since the original layout vertice might not be
the "layout vertice" in the graph.

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

3 files changed, 39 insertions, 38 deletions

diff --git a/src/gui/graphicsview/qgraph_p.h b/src/gui/graphicsview/qgraph_p.h
index f1fa185..b5b3c88 100644
--- a/src/gui/graphicsview/qgraph_p.h
+++ b/src/gui/graphicsview/qgraph_p.h
@@ -201,11 +201,6 @@ public:
         return l;
     }
 
-    void setRootVertex(Vertex *vertex)
-    {
-        userVertex = vertex;
-    }
-
     QSet<Vertex*> vertices() const {
         QSet<Vertex *> setOfVertices;
         for (const_iterator it = constBegin(); it != constEnd(); ++it) {
@@ -256,11 +251,6 @@ public:
     }
 #endif
 
-    Vertex *rootVertex() const
-    {
-        return userVertex;
-    }
-
 protected:
     void createDirectedEdge(Vertex *from, Vertex *to, EdgeData *data)
     {
@@ -286,8 +276,6 @@ protected:
     }
 
 private:
-    Vertex *userVertex;
-
     QHash<Vertex *, QHash<Vertex *, EdgeData *> *> m_graph;
 };
 
diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
index 41aa8aa..6bffd09 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
@@ -484,6 +484,10 @@ QGraphicsAnchorLayoutPrivate::QGraphicsAnchorLayoutPrivate()
         spacings[i] = -1;
         graphSimplified[i] = false;
         graphHasConflicts[i] = false;
+
+        layoutFirstVertex[i] = 0;
+        layoutCentralVertex[i] = 0;
+        layoutLastVertex[i] = 0;
     }
 }
 
@@ -663,7 +667,7 @@ bool QGraphicsAnchorLayoutPrivate::simplifyGraph(Orientation orientation)
            orientation == Horizontal ? "Horizontal" : "Vertical");
 #endif
 
-    if (!graph[orientation].rootVertex())
+    if (!layoutFirstVertex[orientation])
         return true;
 
     bool dirty;
@@ -700,7 +704,7 @@ bool QGraphicsAnchorLayoutPrivate::simplifyGraphIteration(QGraphicsAnchorLayoutP
 
     QSet<AnchorVertex *> visited;
     QStack<QPair<AnchorVertex *, AnchorVertex *> > stack;
-    stack.push(qMakePair(static_cast<AnchorVertex *>(0), g.rootVertex()));
+    stack.push(qMakePair(static_cast<AnchorVertex *>(0), layoutFirstVertex[orientation]));
     QVector<AnchorVertex*> candidates;
     bool candidatesForward;
 
@@ -959,9 +963,10 @@ void QGraphicsAnchorLayoutPrivate::createLayoutEdges()
     data->maxSize = QWIDGETSIZE_MAX;
     data->skipInPreferred = 1;
 
-    // Set the Layout Left edge as the root of the horizontal graph.
-    AnchorVertex *v = internalVertex(layout, Qt::AnchorLeft);
-    graph[Horizontal].setRootVertex(v);
+    // Save a reference to layout vertices
+    layoutFirstVertex[Horizontal] = internalVertex(layout, Qt::AnchorLeft);
+    layoutCentralVertex[Horizontal] = 0;
+    layoutLastVertex[Horizontal] = internalVertex(layout, Qt::AnchorRight);
 
     // Vertical
     data = new AnchorData;
@@ -970,9 +975,10 @@ void QGraphicsAnchorLayoutPrivate::createLayoutEdges()
     data->maxSize = QWIDGETSIZE_MAX;
     data->skipInPreferred = 1;
 
-    // Set the Layout Top edge as the root of the vertical graph.
-    v = internalVertex(layout, Qt::AnchorTop);
-    graph[Vertical].setRootVertex(v);
+    // Save a reference to layout vertices
+    layoutFirstVertex[Vertical] = internalVertex(layout, Qt::AnchorTop);
+    layoutCentralVertex[Vertical] = 0;
+    layoutLastVertex[Vertical] = internalVertex(layout, Qt::AnchorBottom);
 }
 
 void QGraphicsAnchorLayoutPrivate::deleteLayoutEdges()
@@ -1019,6 +1025,8 @@ void QGraphicsAnchorLayoutPrivate::createItemEdges(QGraphicsLayoutItem *item)
 void QGraphicsAnchorLayoutPrivate::createCenterAnchors(
     QGraphicsLayoutItem *item, Qt::AnchorPoint centerEdge)
 {
+    Q_Q(QGraphicsAnchorLayout);
+
     Orientation orientation;
     switch (centerEdge) {
     case Qt::AnchorHorizontalCenter:
@@ -1073,12 +1081,19 @@ void QGraphicsAnchorLayoutPrivate::createCenterAnchors(
 
     // Remove old one
     removeAnchor_helper(first, last);
+
+    if (item == q) {
+        layoutCentralVertex[orientation] = internalVertex(q, centerEdge);
+    }
+
 }
 
 void QGraphicsAnchorLayoutPrivate::removeCenterAnchors(
     QGraphicsLayoutItem *item, Qt::AnchorPoint centerEdge,
     bool substitute)
 {
+    Q_Q(QGraphicsAnchorLayout);
+
     Orientation orientation;
     switch (centerEdge) {
     case Qt::AnchorHorizontalCenter:
@@ -1151,6 +1166,10 @@ void QGraphicsAnchorLayoutPrivate::removeCenterAnchors(
         // by this time, the center vertex is deleted and merged into a non-centered internal anchor
         removeAnchor_helper(first, internalVertex(item, lastEdge));
     }
+
+    if (item == q) {
+        layoutCentralVertex[orientation] = 0;
+    }
 }
 
 
@@ -1773,7 +1792,7 @@ void QGraphicsAnchorLayoutPrivate::calculateGraphs(
 
     // For minimum and maximum, use the path between the two layout sides as the
     // objective function.
-    AnchorVertex *v = internalVertex(q, pickEdge(Qt::AnchorRight, orientation));
+    AnchorVertex *v = layoutLastVertex[orientation];
     GraphPath trunkPath = graphPaths[orientation].value(v);
 
     bool feasible = calculateTrunk(orientation, trunkPath, trunkConstraints, trunkVariables);
@@ -1955,7 +1974,7 @@ void QGraphicsAnchorLayoutPrivate::findPaths(Orientation orientation)
 
     QSet<AnchorData *> visited;
 
-    AnchorVertex *root = graph[orientation].rootVertex();
+    AnchorVertex *root = layoutFirstVertex[orientation];
 
     graphPaths[orientation].insert(root, GraphPath());
 
@@ -2077,28 +2096,18 @@ QGraphicsAnchorLayoutPrivate::getGraphParts(Orientation orientation)
 {
     Q_Q(QGraphicsAnchorLayout);
 
-    // Find layout vertices and edges for the current orientation.
-    AnchorVertex *layoutFirstVertex = \
-        internalVertex(q, pickEdge(Qt::AnchorLeft, orientation));
-
-    AnchorVertex *layoutCentralVertex = \
-        internalVertex(q, pickEdge(Qt::AnchorHorizontalCenter, orientation));
-
-    AnchorVertex *layoutLastVertex = \
-        internalVertex(q, pickEdge(Qt::AnchorRight, orientation));
-
-    Q_ASSERT(layoutFirstVertex && layoutLastVertex);
+    Q_ASSERT(layoutFirstVertex[orientation] && layoutLastVertex[orientation]);
 
     AnchorData *edgeL1 = NULL;
     AnchorData *edgeL2 = NULL;
 
     // The layout may have a single anchor between Left and Right or two half anchors
     // passing through the center
-    if (layoutCentralVertex) {
-        edgeL1 = graph[orientation].edgeData(layoutFirstVertex, layoutCentralVertex);
-        edgeL2 = graph[orientation].edgeData(layoutCentralVertex, layoutLastVertex);
+    if (layoutCentralVertex[orientation]) {
+        edgeL1 = graph[orientation].edgeData(layoutFirstVertex[orientation], layoutCentralVertex[orientation]);
+        edgeL2 = graph[orientation].edgeData(layoutCentralVertex[orientation], layoutLastVertex[orientation]);
     } else {
-        edgeL1 = graph[orientation].edgeData(layoutFirstVertex, layoutLastVertex);
+        edgeL1 = graph[orientation].edgeData(layoutFirstVertex[orientation], layoutLastVertex[orientation]);
     }
 
     QLinkedList<QSimplexConstraint *> remainingConstraints;
@@ -2288,7 +2297,7 @@ void QGraphicsAnchorLayoutPrivate::calculateVertexPositions(
     QSet<AnchorVertex *> visited;
 
     // Get root vertex
-    AnchorVertex *root = graph[orientation].rootVertex();
+    AnchorVertex *root = layoutFirstVertex[orientation];
 
     root->distance = 0;
     visited.insert(root);
diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.h b/src/gui/graphicsview/qgraphicsanchorlayout_p.h
index 7dd0d65..7d7bdb6 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.h
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.h
@@ -504,6 +504,10 @@ public:
     // Internal graph of anchorage points and anchors, for both orientations
     Graph<AnchorVertex, AnchorData> graph[2];
 
+    AnchorVertex *layoutFirstVertex[2];
+    AnchorVertex *layoutCentralVertex[2];
+    AnchorVertex *layoutLastVertex[2];
+
     // Graph paths and constraints, for both orientations
     QMultiHash<AnchorVertex *, GraphPath> graphPaths[2];
     QList<QSimplexConstraint *> constraints[2];