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authorAndre de la Rocha <andre.rocha@qt.io>2019-09-02 16:46:07 +0200
committerAndre de la Rocha <andre.rocha@qt.io>2019-10-11 16:53:23 +0200
commit31012df705c37503be00f0ddc2c323e73fd28067 (patch)
treeb75d19c181e1ba874cb0f421c729ba3d8f07d78b /src/widgets/graphicsview
parent014d7ac65417ed9b5ffb85cca24d16564ff5005a (diff)
Fix QGraphicsScene::update() performance
A previous fix has caused a performance degradation while adding a check for avoiding adding duplicated rectangles to the update list. This patch fixes it by using a std::set instead of a QList, avoiding duplication while using an O(log N) operation, instead of the O(N) used before. Fixes: QTBUG-77952 Change-Id: Ifa9fbf110e0bad60ee02a42d91281981fd98ceab Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Diffstat (limited to 'src/widgets/graphicsview')
-rw-r--r--src/widgets/graphicsview/qgraphicsscene.cpp13
-rw-r--r--src/widgets/graphicsview/qgraphicsscene_p.h17
2 files changed, 26 insertions, 4 deletions
diff --git a/src/widgets/graphicsview/qgraphicsscene.cpp b/src/widgets/graphicsview/qgraphicsscene.cpp
index 5238ea2f5c..03717d5d1a 100644
--- a/src/widgets/graphicsview/qgraphicsscene.cpp
+++ b/src/widgets/graphicsview/qgraphicsscene.cpp
@@ -386,7 +386,15 @@ void QGraphicsScenePrivate::_q_emitUpdated()
// Notify the changes to anybody interested.
QList<QRectF> oldUpdatedRects;
- oldUpdatedRects = updateAll ? (QList<QRectF>() << q->sceneRect()) : updatedRects;
+ if (updateAll) {
+ oldUpdatedRects << q->sceneRect();
+ } else {
+ // Switch to a ranged constructor in Qt 6...
+ oldUpdatedRects.reserve(int(updatedRects.size()));
+ std::copy(updatedRects.cbegin(), updatedRects.cend(),
+ std::back_inserter(oldUpdatedRects));
+ }
+
updateAll = false;
updatedRects.clear();
emit q->changed(oldUpdatedRects);
@@ -3219,8 +3227,7 @@ void QGraphicsScene::update(const QRectF &rect)
view->d_func()->updateRectF(rect);
}
} else {
- if (!d->updatedRects.contains(rect))
- d->updatedRects << rect;
+ d->updatedRects.insert(rect);
}
}
diff --git a/src/widgets/graphicsview/qgraphicsscene_p.h b/src/widgets/graphicsview/qgraphicsscene_p.h
index a2d13436fc..14bafe6678 100644
--- a/src/widgets/graphicsview/qgraphicsscene_p.h
+++ b/src/widgets/graphicsview/qgraphicsscene_p.h
@@ -69,6 +69,9 @@
#include <QtWidgets/qstyle.h>
#include <QtWidgets/qstyleoption.h>
+#include <set>
+#include <tuple>
+
QT_REQUIRE_CONFIG(graphicsview);
QT_BEGIN_NAMESPACE
@@ -122,7 +125,19 @@ public:
QRectF growingItemsBoundingRect;
void _q_emitUpdated();
- QList<QRectF> updatedRects;
+
+ struct UpdatedRectsCmp
+ {
+ bool operator() (const QRectF &a, const QRectF &b) const noexcept
+ {
+ return std::make_tuple(a.y(), a.x(), a.height(), a.width())
+ < std::make_tuple(b.y(), b.x(), b.height(), b.width());
+ }
+ };
+
+ // std::set was used here instead of std::unordered_set due to requiring only a comparator and
+ // showing equivalent performance in empirical measurements within the ranges of interest...
+ std::set<QRectF, UpdatedRectsCmp> updatedRects;
QPainterPath selectionArea;
int selectionChanging;