QGAL: avoid having to re-calculate lists of variables

Change the functions solvePreferred() and solveExpanding() to take a
list of variables, so they don't need to calculate them based on the
list of constraints. That way, the trunk variables are calculated only
once.

This commit also reduce the scope of 'sizeHintConstraints' variable
instead of clearing and reusing it.

Signed-off-by: Caio Marcelo de Oliveira Filho <caio.oliveira@openbossa.org>
Reviewed-by: Artur Duque de Souza <artur.souza@openbossa.org>

2 files changed, 27 insertions, 31 deletions

diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
index b61405f..485743e 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
@@ -1671,9 +1671,7 @@ void QGraphicsAnchorLayoutPrivate::calculateGraphs(
     // of the "trunk" set of constraints and variables.
     // ### does trunk always exist? empty = trunk is the layout left->center->right
     QList<QSimplexConstraint *> trunkConstraints = parts[0];
-    QList<QSimplexConstraint *> sizeHintConstraints;
-    sizeHintConstraints = constraintsFromSizeHints(getVariables(trunkConstraints));
-    trunkConstraints += sizeHintConstraints;
+    QList<AnchorData *> trunkVariables = getVariables(trunkConstraints);
 
     // For minimum and maximum, use the path between the two layout sides as the
     // objective function.
@@ -1695,26 +1693,24 @@ void QGraphicsAnchorLayoutPrivate::calculateGraphs(
 
         // Solve min and max size hints for trunk
         qreal min, max;
-        feasible = solveMinMax(trunkConstraints, trunkPath, &min, &max);
+
+        QList<QSimplexConstraint *> sizeHintConstraints = constraintsFromSizeHints(trunkVariables);
+        QList<QSimplexConstraint *> allTrunkConstraints = trunkConstraints + sizeHintConstraints;
+
+        feasible = solveMinMax(allTrunkConstraints, trunkPath, &min, &max);
 
         if (feasible) {
             // Solve for preferred. The objective function is calculated from the constraints
             // and variables internally.
-            solvePreferred(trunkConstraints);
-
-            // remove sizeHintConstraints from trunkConstraints
-            trunkConstraints = parts[0];
+            solvePreferred(allTrunkConstraints, trunkVariables);
 
             // Solve for expanding. The objective function and the constraints from items
-            // are calculated internally.
-            solveExpanding(trunkConstraints);
+            // are calculated internally. Note that we don't include the sizeHintConstraints, since
+            // they have a different logic for solveExpanding().
+            solveExpanding(trunkConstraints, trunkVariables);
 
             // Propagate the new sizes down the simplified graph, ie. tell the
             // group anchors to set their children anchors sizes.
-
-            // ### we calculated variables already a few times, can't we reuse that?
-            QList<AnchorData *> trunkVariables = getVariables(trunkConstraints);
-
             for (int i = 0; i < trunkVariables.count(); ++i)
                 trunkVariables.at(i)->updateChildrenSizes();
 
@@ -1736,6 +1732,9 @@ void QGraphicsAnchorLayoutPrivate::calculateGraphs(
             sizeHints[orientation][Qt::MaximumSize] = max;
             sizeAtExpanding[orientation] = expanding;
         }
+
+        qDeleteAll(sizeHintConstraints);
+
     } else {
 #if 0
         qDebug("Simplex NOT used for trunk of %s",
@@ -1766,10 +1765,6 @@ void QGraphicsAnchorLayoutPrivate::calculateGraphs(
         sizeAtExpanding[orientation] = ad->sizeAtExpanding;
     }
 
-    // Delete the constraints, we won't use them anymore.
-    qDeleteAll(sizeHintConstraints);
-    sizeHintConstraints.clear();
-
     // For the other parts that not the trunk, solve only for the preferred size
     // that is the size they will remain at, since they are not stretched by the
     // layout.
@@ -1781,9 +1776,9 @@ void QGraphicsAnchorLayoutPrivate::calculateGraphs(
             QList<AnchorData *> partVariables = getVariables(partConstraints);
             Q_ASSERT(!partVariables.isEmpty());
 
-            sizeHintConstraints = constraintsFromSizeHints(partVariables);
+            QList<QSimplexConstraint *> sizeHintConstraints = constraintsFromSizeHints(partVariables);
             partConstraints += sizeHintConstraints;
-            feasible &= solvePreferred(partConstraints);
+            feasible &= solvePreferred(partConstraints, partVariables);
             if (!feasible)
                 break;
 
@@ -1800,7 +1795,6 @@ void QGraphicsAnchorLayoutPrivate::calculateGraphs(
 
             // Delete the constraints, we won't use them anymore.
             qDeleteAll(sizeHintConstraints);
-            sizeHintConstraints.clear();
         }
     }
     graphHasConflicts[orientation] = !feasible;
@@ -2318,7 +2312,7 @@ void QGraphicsAnchorLayoutPrivate::interpolateSequentialEdges(
         interpolateEdge(prev, data->m_edges.last(), orientation);
 }
 
-bool QGraphicsAnchorLayoutPrivate::solveMinMax(QList<QSimplexConstraint *> constraints,
+bool QGraphicsAnchorLayoutPrivate::solveMinMax(const QList<QSimplexConstraint *> &constraints,
                                                GraphPath path, qreal *min, qreal *max)
 {
     QSimplex simplex;
@@ -2359,9 +2353,9 @@ bool QGraphicsAnchorLayoutPrivate::solveMinMax(QList<QSimplexConstraint *> const
     return feasible;
 }
 
-bool QGraphicsAnchorLayoutPrivate::solvePreferred(QList<QSimplexConstraint *> constraints)
+bool QGraphicsAnchorLayoutPrivate::solvePreferred(const QList<QSimplexConstraint *> &constraints,
+                                                  const QList<AnchorData *> &variables)
 {
-    QList<AnchorData *> variables = getVariables(constraints);
     QList<QSimplexConstraint *> preferredConstraints;
     QList<QSimplexVariable *> preferredVariables;
     QSimplexConstraint objective;
@@ -2384,7 +2378,7 @@ bool QGraphicsAnchorLayoutPrivate::solvePreferred(QList<QSimplexConstraint *> co
     //      A + A_shrinker - A_grower = A_pref
     //
     for (int i = 0; i < variables.size(); ++i) {
-        AnchorData *ad = static_cast<AnchorData *>(variables[i]);
+        AnchorData *ad = variables[i];
         if (ad->skipInPreferred)
             continue;
 
@@ -2415,7 +2409,7 @@ bool QGraphicsAnchorLayoutPrivate::solvePreferred(QList<QSimplexConstraint *> co
 
         // Save sizeAtPreferred results
         for (int i = 0; i < variables.size(); ++i) {
-            AnchorData *ad = static_cast<AnchorData *>(variables[i]);
+            AnchorData *ad = variables[i];
             ad->sizeAtPreferred = ad->result;
         }
 
@@ -2476,9 +2470,9 @@ bool QGraphicsAnchorLayoutPrivate::solvePreferred(QList<QSimplexConstraint *> co
           expanding ones will shrink. Only after non-expanding anchors have
           shrinked all the way, the expanding anchors will start to shrink too.
 */
-void QGraphicsAnchorLayoutPrivate::solveExpanding(QList<QSimplexConstraint *> constraints)
+void QGraphicsAnchorLayoutPrivate::solveExpanding(const QList<QSimplexConstraint *> &constraints,
+                                                  const QList<AnchorData *> &variables)
 {
-    QList<AnchorData *> variables = getVariables(constraints);
     QList<QSimplexConstraint *> itemConstraints;
     QSimplexConstraint *objective = new QSimplexConstraint;
     bool hasExpanding = false;
diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.h b/src/gui/graphicsview/qgraphicsanchorlayout_p.h
index b14bc62..1d7b758 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.h
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.h
@@ -471,10 +471,12 @@ public:
                                   Orientation orientation);
 
     // Linear Programming solver methods
-    bool solveMinMax(QList<QSimplexConstraint *> constraints,
+    bool solveMinMax(const QList<QSimplexConstraint *> &constraints,
                      GraphPath path, qreal *min, qreal *max);
-    bool solvePreferred(QList<QSimplexConstraint *> constraints);
-    void solveExpanding(QList<QSimplexConstraint *> constraints);
+    bool solvePreferred(const QList<QSimplexConstraint *> &constraints,
+                        const QList<AnchorData *> &variables);
+    void solveExpanding(const QList<QSimplexConstraint *> &constraints,
+                        const QList<AnchorData *> &variables);
     bool hasConflicts() const;
 
 #ifdef QT_DEBUG