Clean up QQmlFileSelector

The global static map of file selectors is not thread safe. If you add a
file selector to engine A running in thread 1, you cannot at the same
time retrieve the file selector of engine B running in thread 2. Alas,
we only need the static map to discern file selectors from other URL
interceptors, and we only need to do this on QQmlFileSelector::get(),
which we don't use. Unfortunately it is public API, though.

Deprecate QQmlFileSelector::get() and add a different hack to discern
the interceptors for the case that it's still called. Also remove the
duplicate setExtraSelectors() method.

For this to work, we also add a method to QQmlApplicationEngine that
allows us to pass extra file selectors and delay the initialization of
QQmlApplicationEngine's QQmlFileSelector until the first file is loaded.

[ChangeLog][QML] QQmlFileSelector::get() is deprecated. You can use the
new method QQmlAplicationEngine::setExtraFileSelectors() to pass extra
selectors to QQmlApplicationEngine's internal QQmlFileSelector.
Manually created QQmlFileSelectors should be configured immediately
after creation, before they are used by the QQmlEngine.

Change-Id: Ia61a93777dc910b441a03ffb42d35a2a224c0e26
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 27 insertions, 3 deletions

diff --git a/src/qml/qml/qqmlapplicationengine.cpp b/src/qml/qml/qqmlapplicationengine.cpp
index 7d961cd0c7..a633d3f58b 100644
--- a/src/qml/qml/qqmlapplicationengine.cpp
+++ b/src/qml/qml/qqmlapplicationengine.cpp
@@ -81,7 +81,8 @@ void QQmlApplicationEnginePrivate::init()
     else
         delete qtTranslator;
 #endif
-    new QQmlFileSelector(q,q);
+    auto *selector = new QQmlFileSelector(q,q);
+    selector->setExtraSelectors(extraFileSelectors);
     QCoreApplication::instance()->setProperty("__qml_using_qqmlapplicationengine", QVariant(true));
 }
 
@@ -115,6 +116,11 @@ void QQmlApplicationEnginePrivate::startLoad(const QUrl &url, const QByteArray &
 {
     Q_Q(QQmlApplicationEngine);
 
+    if (!isInitialized) {
+        init();
+        isInitialized = true;
+    }
+
     if (url.scheme() == QLatin1String("file") || url.scheme() == QLatin1String("qrc")) {
         QFileInfo fi(QQmlFile::urlToLocalFileOrQrc(url));
         translationsDirectory = fi.path() + QLatin1String("/i18n");
@@ -227,8 +233,6 @@ void QQmlApplicationEnginePrivate::finishLoad(QQmlComponent *c)
 QQmlApplicationEngine::QQmlApplicationEngine(QObject *parent)
 : QQmlEngine(*(new QQmlApplicationEnginePrivate(this)), parent)
 {
-    Q_D(QQmlApplicationEngine);
-    d->init();
     QJSEnginePrivate::addToDebugServer(this);
 }
 
@@ -312,6 +316,26 @@ void QQmlApplicationEngine::setInitialProperties(const QVariantMap &initialPrope
 }
 
 /*!
+  Sets the \a extraFileSelectors to be passed to the internal QQmlFileSelector
+  used for resolving URLs to local files. The \a extraFileSelectors are applied
+  when the first QML file is loaded. Setting them afterwards has no effect.
+
+  \sa QQmlFileSelector
+  \sa QFileSelector::setExtraSelectors
+  \since 6.0
+*/
+void QQmlApplicationEngine::setExtraFileSelectors(const QStringList &extraFileSelectors)
+{
+    Q_D(QQmlApplicationEngine);
+    if (d->isInitialized) {
+        qWarning() << "QQmlApplicationEngine::setExtraFileSelectors()"
+                   << "called after loading QML files. This has no effect.";
+    } else {
+        d->extraFileSelectors = extraFileSelectors;
+    }
+}
+
+/*!
   Loads the QML given in \a data. The object tree defined by \a data is
   instantiated immediately.