QGraphicsView: replace some Q_FOREACH loops over rvalues with C++11 range-for

This needs to be handled a bit carefully, because Qt containers
will detach upon being iterated over using range-for.

In the cases of this patch, that trivially cannot happen, because
all containers are marked as const when being assigned the rvalues
previously found on the rhs of the Q_FOREACH. The new code thus
does exactly what the old code did: take a const copy, then iterate
over it.

Separate patches will deal with other situations.

Range-for loops are much more efficient than foreach loops.

This patch shaves almost 4K of text size off an optimized Linux
AMD64 GCC 4.9 build.

Change-Id: Ida868b77d078cbfa0516d17e98e6f0a86fcdb7a3
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/src/widgets/graphicsview/qgraphicsview.cpp b/src/widgets/graphicsview/qgraphicsview.cpp
index ac8cd45f9e..928d826323 100644
--- a/src/widgets/graphicsview/qgraphicsview.cpp
+++ b/src/widgets/graphicsview/qgraphicsview.cpp
@@ -799,7 +799,8 @@ void QGraphicsViewPrivate::_q_setViewportCursor(const QCursor &cursor)
 void QGraphicsViewPrivate::_q_unsetViewportCursor()
 {
     Q_Q(QGraphicsView);
-    foreach (QGraphicsItem *item, q->items(lastMouseEvent.pos())) {
+    const auto items = q->items(lastMouseEvent.pos());
+    for (QGraphicsItem *item : items) {
         if (item->hasCursor()) {
             _q_setViewportCursor(item->cursor());
             return;
@@ -1139,7 +1140,8 @@ QList<QGraphicsItem *> QGraphicsViewPrivate::findItems(const QRegion &exposedReg
     // the expose region, convert it to a path, and then search for items
     // using QGraphicsScene::items(QPainterPath);
     QRegion adjustedRegion;
-    foreach (const QRect &r, exposedRegion.rects())
+    const auto rects = exposedRegion.rects();
+    for (const QRect &r : rects)
         adjustedRegion += r.adjusted(-1, -1, 1, 1);
 
     const QPainterPath exposedScenePath(q->mapToScene(qt_regionToPath(adjustedRegion)));
@@ -2791,7 +2793,8 @@ void QGraphicsView::setupViewport(QWidget *widget)
 
 #ifndef QT_NO_GESTURES
     if (d->scene) {
-        foreach (Qt::GestureType gesture, d->scene->d_func()->grabbedGestures.keys())
+        const auto gestures = d->scene->d_func()->grabbedGestures.keys();
+        for (Qt::GestureType gesture : gestures)
             widget->grabGesture(gesture);
     }
 #endif