widgets: Use QList::reserve(), reduces reallocations.

Change-Id: I49cc03f365c77f142f62c8e77505ec09723a44d9
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

3 files changed, 22 insertions, 7 deletions

diff --git a/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp b/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp
index 8327777217..ce9344e2d9 100644
--- a/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp
+++ b/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp
@@ -752,8 +752,10 @@ static AnchorData *createSequence(Graph<AnchorVertex, AnchorData> *graph,
     AnchorVertex *prev = before;
     QVector<AnchorData *> edges;
 
+    const int numVertices = vertices.count();
+    edges.reserve(numVertices + 1);
     // Take from the graph, the edges that will be simplificated
-    for (int i = 0; i < vertices.count(); ++i) {
+    for (int i = 0; i < numVertices; ++i) {
         AnchorVertex *next = vertices.at(i);
         AnchorData *ad = graph->takeEdge(prev, next);
         Q_ASSERT(ad);
@@ -2569,6 +2571,7 @@ QGraphicsAnchorLayoutPrivate::getGraphParts(Orientation orientation)
 
     if (!remainingConstraints.isEmpty()) {
         QList<QSimplexConstraint *> nonTrunkConstraints;
+        nonTrunkConstraints.reserve(remainingConstraints.size());
         QLinkedList<QSimplexConstraint *>::iterator it = remainingConstraints.begin();
         while (it != remainingConstraints.end()) {
             nonTrunkConstraints += *it;
diff --git a/src/widgets/graphicsview/qgraphicsitemanimation.cpp b/src/widgets/graphicsview/qgraphicsitemanimation.cpp
index 0a6fccf559..e5f0149d64 100644
--- a/src/widgets/graphicsview/qgraphicsitemanimation.cpp
+++ b/src/widgets/graphicsview/qgraphicsitemanimation.cpp
@@ -284,7 +284,9 @@ void QGraphicsItemAnimation::setPosAt(qreal step, const QPointF &pos)
 QList<QPair<qreal, QPointF> > QGraphicsItemAnimation::posList() const
 {
     QList<QPair<qreal, QPointF> > list;
-    for (int i = 0; i < d->xPosition.size(); ++i)
+    const int xPosCount = d->xPosition.size();
+    list.reserve(xPosCount);
+    for (int i = 0; i < xPosCount; ++i)
         list << QPair<qreal, QPointF>(d->xPosition.at(i).step, QPointF(d->xPosition.at(i).value, d->yPosition.at(i).value));
 
     return list;
@@ -338,7 +340,9 @@ void QGraphicsItemAnimation::setRotationAt(qreal step, qreal angle)
 QList<QPair<qreal, qreal> > QGraphicsItemAnimation::rotationList() const
 {
     QList<QPair<qreal, qreal> > list;
-    for (int i = 0; i < d->rotation.size(); ++i)
+    const int numRotations = d->rotation.size();
+    list.reserve(numRotations);
+    for (int i = 0; i < numRotations; ++i)
         list << QPair<qreal, qreal>(d->rotation.at(i).step, d->rotation.at(i).value);
 
     return list;
@@ -386,7 +390,9 @@ void QGraphicsItemAnimation::setTranslationAt(qreal step, qreal dx, qreal dy)
 QList<QPair<qreal, QPointF> > QGraphicsItemAnimation::translationList() const
 {
     QList<QPair<qreal, QPointF> > list;
-    for (int i = 0; i < d->xTranslation.size(); ++i)
+    const int numTranslations = d->xTranslation.size();
+    list.reserve(numTranslations);
+    for (int i = 0; i < numTranslations; ++i)
         list << QPair<qreal, QPointF>(d->xTranslation.at(i).step, QPointF(d->xTranslation.at(i).value, d->yTranslation.at(i).value));
 
     return list;
@@ -435,7 +441,9 @@ void QGraphicsItemAnimation::setScaleAt(qreal step, qreal sx, qreal sy)
 QList<QPair<qreal, QPointF> > QGraphicsItemAnimation::scaleList() const
 {
     QList<QPair<qreal, QPointF> > list;
-    for (int i = 0; i < d->horizontalScale.size(); ++i)
+    const int numScales = d->horizontalScale.size();
+    list.reserve(numScales);
+    for (int i = 0; i < numScales; ++i)
         list << QPair<qreal, QPointF>(d->horizontalScale.at(i).step, QPointF(d->horizontalScale.at(i).value, d->verticalScale.at(i).value));
 
     return list;
@@ -483,7 +491,9 @@ void QGraphicsItemAnimation::setShearAt(qreal step, qreal sh, qreal sv)
 QList<QPair<qreal, QPointF> > QGraphicsItemAnimation::shearList() const
 {
     QList<QPair<qreal, QPointF> > list;
-    for (int i = 0; i < d->horizontalShear.size(); ++i)
+    const int numShears = d->horizontalShear.size();
+    list.reserve(numShears);
+    for (int i = 0; i < numShears; ++i)
         list << QPair<qreal, QPointF>(d->horizontalShear.at(i).step, QPointF(d->horizontalShear.at(i).value, d->verticalShear.at(i).value));
 
     return list;
diff --git a/src/widgets/graphicsview/qgraphicssceneindex.cpp b/src/widgets/graphicsview/qgraphicssceneindex.cpp
index 8662f73d64..a76f6b6565 100644
--- a/src/widgets/graphicsview/qgraphicssceneindex.cpp
+++ b/src/widgets/graphicsview/qgraphicssceneindex.cpp
@@ -520,7 +520,9 @@ QList<QGraphicsItem *> QGraphicsSceneIndex::estimateTopLevelItems(const QRectF &
     scened->ensureSortedTopLevelItems();
     if (order == Qt::DescendingOrder) {
         QList<QGraphicsItem *> sorted;
-        for (int i = scened->topLevelItems.size() - 1; i >= 0; --i)
+        const int numTopLevelItems = scened->topLevelItems.size();
+        sorted.reserve(numTopLevelItems);
+        for (int i = numTopLevelItems - 1; i >= 0; --i)
             sorted << scened->topLevelItems.at(i);
         return sorted;
     }