fix expensive iteration over QMap::keys() and QHash::keys()

Change-Id: I244aa1ecf006774ebe5fb9bb5b22d37142186e39
Reviewed-by: Yoann Lopes <yoann.lopes@theqtcompany.com>

3 files changed, 7 insertions, 6 deletions

diff --git a/src/plugins/gstreamer/camerabin/camerabinmetadata.cpp b/src/plugins/gstreamer/camerabin/camerabinmetadata.cpp
index e404065fc..ec2a83a66 100644
--- a/src/plugins/gstreamer/camerabin/camerabinmetadata.cpp
+++ b/src/plugins/gstreamer/camerabin/camerabinmetadata.cpp
@@ -244,8 +244,8 @@ QStringList CameraBinMetaData::availableMetaData() const
     }
 
     QStringList res;
-    Q_FOREACH (const QByteArray &key, m_values.keys()) {
-        QString tag = keysMap.value(key);
+    for (auto it = m_values.keyBegin(), end = m_values.keyEnd(); it != end; ++it) {
+        QString tag = keysMap.value(*it);
         if (!tag.isEmpty())
             res.append(tag);
     }
diff --git a/src/plugins/gstreamer/mediacapture/qgstreamercapturemetadatacontrol.cpp b/src/plugins/gstreamer/mediacapture/qgstreamercapturemetadatacontrol.cpp
index fca38ecf8..79deb9229 100644
--- a/src/plugins/gstreamer/mediacapture/qgstreamercapturemetadatacontrol.cpp
+++ b/src/plugins/gstreamer/mediacapture/qgstreamercapturemetadatacontrol.cpp
@@ -142,8 +142,8 @@ void QGstreamerCaptureMetaDataControl::setMetaData(const QString &key, const QVa
 QStringList QGstreamerCaptureMetaDataControl::availableMetaData() const
 {
     QStringList res;
-    foreach (const QByteArray &key, m_values.keys()) {
-        QString tag = qt_gstreamerMetaDataKeys()->key(key);
+    for (auto it = m_values.keyBegin(), end = m_values.keyEnd(); it != end; ++it) {
+        QString tag = qt_gstreamerMetaDataKeys()->key(*it);
         if (!tag.isEmpty())
             res.append(tag);
     }
diff --git a/src/plugins/winrt/qwinrtvideodeviceselectorcontrol.cpp b/src/plugins/winrt/qwinrtvideodeviceselectorcontrol.cpp
index 8e806dcbf..9f5bb78f6 100644
--- a/src/plugins/winrt/qwinrtvideodeviceselectorcontrol.cpp
+++ b/src/plugins/winrt/qwinrtvideodeviceselectorcontrol.cpp
@@ -349,8 +349,9 @@ int QWinRTVideoDeviceSelectorControl::cameraOrientation(const QString &deviceNam
 QList<QByteArray> QWinRTVideoDeviceSelectorControl::deviceNames()
 {
     QList<QByteArray> devices;
-    foreach (const QString &device, g->deviceIndex.keys())
-        devices.append(device.toUtf8());
+    devices.reserve(g->deviceIndex.size());
+    for (auto it = g->deviceIndex.keyBegin(), end = g->deviceIndex.keyEnd(); it != end; ++it)
+        devices.append((*it).toUtf8());
 
     return devices;
 }