From cea46aa3620bb16f8c03a13d900f5ce066aae21c Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Mon, 18 Dec 2017 10:42:27 +0100
Subject: [PATCH] QGestureManager: don't abuse a QMap for a set

The filterEvents() implementations used a QMap<GestureType, int> for
tracking whether a given type was already seen. The mapped_type was
completely unused.

Since the expected number of gesture types is very low, go directly to
QVarLengthArray, not QSet, as the reduced number of allocation will
dwarf the low overhead of O(N) search vs. O(1) for QSet or O(logN) for
QMap.

Change-Id: I98b6af69f11cca753e3c7c4fbb58e8f2e935e0d5
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
---
 src/widgets/kernel/qgesturemanager.cpp | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/widgets/kernel/qgesturemanager.cpp b/src/widgets/kernel/qgesturemanager.cpp
index 390602205c..7632521117 100644
--- a/src/widgets/kernel/qgesturemanager.cpp
+++ b/src/widgets/kernel/qgesturemanager.cpp
@@ -509,14 +509,14 @@ void QGestureManager::cleanupGesturesForRemovedRecognizer(QGesture *gesture)
 // return true if accepted (consumed)
 bool QGestureManager::filterEvent(QWidget *receiver, QEvent *event)
 {
-    QMap<Qt::GestureType, int> types;
+    QVarLengthArray<Qt::GestureType, 16> types;
     QMultiMap<QObject *, Qt::GestureType> contexts;
     QWidget *w = receiver;
     typedef QMap<Qt::GestureType, Qt::GestureFlags>::const_iterator ContextIterator;
     if (!w->d_func()->gestureContext.isEmpty()) {
         for(ContextIterator it = w->d_func()->gestureContext.constBegin(),
             e = w->d_func()->gestureContext.constEnd(); it != e; ++it) {
-            types.insert(it.key(), 0);
+            types.push_back(it.key());
             contexts.insert(w, it.key());
         }
     }
@@ -528,7 +528,7 @@ bool QGestureManager::filterEvent(QWidget *receiver, QEvent *event)
              e = w->d_func()->gestureContext.constEnd(); it != e; ++it) {
             if (!(it.value() & Qt::DontStartGestureOnChildren)) {
                 if (!types.contains(it.key())) {
-                    types.insert(it.key(), 0);
+                    types.push_back(it.key());
                     contexts.insert(w, it.key());
                 }
             }
@@ -543,14 +543,14 @@ bool QGestureManager::filterEvent(QWidget *receiver, QEvent *event)
 #if QT_CONFIG(graphicsview)
 bool QGestureManager::filterEvent(QGraphicsObject *receiver, QEvent *event)
 {
-    QMap<Qt::GestureType, int> types;
+    QVarLengthArray<Qt::GestureType, 16> types;
     QMultiMap<QObject *, Qt::GestureType> contexts;
     QGraphicsObject *item = receiver;
     if (!item->QGraphicsItem::d_func()->gestureContext.isEmpty()) {
         typedef QMap<Qt::GestureType, Qt::GestureFlags>::const_iterator ContextIterator;
         for(ContextIterator it = item->QGraphicsItem::d_func()->gestureContext.constBegin(),
             e = item->QGraphicsItem::d_func()->gestureContext.constEnd(); it != e; ++it) {
-            types.insert(it.key(), 0);
+            types.push_back(it.key());
             contexts.insert(item, it.key());
         }
     }
@@ -563,7 +563,7 @@ bool QGestureManager::filterEvent(QGraphicsObject *receiver, QEvent *event)
              e = item->QGraphicsItem::d_func()->gestureContext.constEnd(); it != e; ++it) {
             if (!(it.value() & Qt::DontStartGestureOnChildren)) {
                 if (!types.contains(it.key())) {
-                    types.insert(it.key(), 0);
+                    types.push_back(it.key());
                     contexts.insert(item, it.key());
                 }
             }