Plugins: optimize string usage

Prefer QStringRef methods to avoid allocations.

Use startsWith/endsWith rather than comparing substrings;
and avoid substrings where references suffice.

Use new QStringList::join(QL1S).

Change-Id: I46c44aca96578633370006d613eb0ac13f7cfc03
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/plugins/platforms/windows/qwindowsfontdatabase_ft.cpp b/src/plugins/platforms/windows/qwindowsfontdatabase_ft.cpp
index f7c8dbdf23..bc0e5cc523 100644
--- a/src/plugins/platforms/windows/qwindowsfontdatabase_ft.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontdatabase_ft.cpp
@@ -137,10 +137,10 @@ static FontKeys &fontKeys()
             QString realKey = registryFontKey;
             realKey.remove(trueType);
             realKey.remove(sizeListMatch);
-            const QStringList fontNames = realKey.trimmed().split(QLatin1Char('&'));
+            const auto fontNames = QStringRef(&realKey).trimmed().split(QLatin1Char('&'));
             fontKey.fontNames.reserve(fontNames.size());
-            foreach (const QString &fontName, fontNames)
-                fontKey.fontNames.append(fontName.trimmed());
+            for (const QStringRef &fontName : fontNames)
+                fontKey.fontNames.append(fontName.trimmed().toString());
             result.append(fontKey);
         }
     }