Plugins: use reserve() to optimize memory allocations

Change-Id: Id78ce43137e352292a9933222fe2f92d4ff4d69b
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/plugins/platforminputcontexts/compose/generator/qtablegenerator.cpp

@@ -255,6 +255,7 @@ void TableGenerator::initPossibleLocations()
     // never meant for external software to parse compose tables directly. Best we
     // can do is to hardcode search paths. To add an extra system path use
     // the QTCOMPOSE environment variable
+    m_possibleLocations.reserve(7);
     if (qEnvironmentVariableIsSet("QTCOMPOSE"))
         m_possibleLocations.append(QString::fromLocal8Bit(qgetenv("QTCOMPOSE")));
     m_possibleLocations.append(QStringLiteral("/usr/share/X11/locale"));

src/plugins/platforms/mirclient/qmirclientinput.cpp

@@ -347,6 +347,7 @@ void QMirClientInput::dispatchTouchEvent(QMirClientWindow *window, const MirInpu
     // TODO: Is it worth setting the Qt::TouchPointStationary ones? Currently they are left
     //       as Qt::TouchPointMoved
     const unsigned int kPointerCount = mir_touch_event_point_count(tev);
+    touchPoints.reserve(int(kPointerCount));
     for (unsigned int i = 0; i < kPointerCount; ++i) {
         QWindowSystemInterface::TouchPoint touchPoint;
 

src/plugins/platforms/openwfd/qopenwfdintegration.cpp

@@ -68,6 +68,7 @@ QOpenWFDIntegration::QOpenWFDIntegration()
     int actualNumberOfDevices = wfdEnumerateDevices(devices,numberOfDevices,0);
     Q_ASSERT(actualNumberOfDevices == numberOfDevices);
 
+    mDevices.reserve(actualNumberOfDevices);
     for (int i = 0; i < actualNumberOfDevices; i++) {
         mDevices.append(new QOpenWFDDevice(this,devices[i]));
     }

src/plugins/platforms/qnx/qqnxbuttoneventnotifier.cpp

@@ -67,6 +67,7 @@ QQnxButtonEventNotifier::QQnxButtonEventNotifier(QObject *parent)
     // fetch the new button ids
     int enumeratorIndex = QQnxButtonEventNotifier::staticMetaObject.indexOfEnumerator(QByteArrayLiteral("ButtonId"));
     QMetaEnum enumerator = QQnxButtonEventNotifier::staticMetaObject.enumerator(enumeratorIndex);
+    m_buttonKeys.reserve(ButtonCount - bid_minus);
     for (int buttonId = bid_minus; buttonId < ButtonCount; ++buttonId) {
         m_buttonKeys.append(enumerator.valueToKey(buttonId));
         m_state[buttonId] = ButtonUp;

src/plugins/platforms/xcb/qxcbmime.cpp

@@ -210,6 +210,7 @@ QVariant QXcbMime::mimeConvertToFormat(QXcbConnection *connection, xcb_atom_t a,
                 if (format == QLatin1String("text/uri-list")) {
                     const auto urls = str.splitRef(QLatin1Char('\n'));
                     QList<QVariant> list;
+                    list.reserve(urls.size());
                     for (const QStringRef &s : urls) {
                         const QUrl url(s.trimmed().toString());
                         if (url.isValid())