Allow multiple URL interceptors per engine

We may want to have, for example, a QQmlFileSelector and a
component-specific interceptor that chooses a theme or similar.

Also, make the API public. We want to propose this as alternative to
dynamically registering QML files via qmlRegisterType(QUrl, ...).

Change-Id: I4a535d3ea556da6710fde816579ec188b3f57099
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

11 files changed, 87 insertions, 51 deletions

diff --git a/src/qml/jsruntime/qv4include.cpp b/src/qml/jsruntime/qv4include.cpp
index 92face6f94..745ffab0cd 100644
--- a/src/qml/jsruntime/qv4include.cpp
+++ b/src/qml/jsruntime/qv4include.cpp
@@ -218,8 +218,8 @@ QV4::ReturnedValue QV4Include::method_include(const QV4::FunctionObject *b, cons
         callbackFunction = argv[1];
 
     QUrl url(scope.engine->resolvedUrl(argv[0].toQStringNoThrow()));
-    if (scope.engine->qmlEngine() && scope.engine->qmlEngine()->urlInterceptor())
-        url = scope.engine->qmlEngine()->urlInterceptor()->intercept(url, QQmlAbstractUrlInterceptor::JavaScriptFile);
+    if (const QQmlEngine *qmlEngine = scope.engine->qmlEngine())
+        url = qmlEngine->interceptUrl(url, QQmlAbstractUrlInterceptor::JavaScriptFile);
 
     QString localFile = QQmlFile::urlToLocalFileOrQrc(url);
 
diff --git a/src/qml/qml/qqmlcontext.cpp b/src/qml/qml/qqmlcontext.cpp
index 9157bb95c3..abd379a320 100644
--- a/src/qml/qml/qqmlcontext.cpp
+++ b/src/qml/qml/qqmlcontext.cpp
@@ -465,9 +465,8 @@ QUrl QQmlContextData::resolvedUrl(const QUrl &src)
     if (resolved.isEmpty()) //relative but no ctxt
         return resolved;
 
-    if (engine && engine->urlInterceptor())
-        resolved = engine->urlInterceptor()->intercept(resolved, QQmlAbstractUrlInterceptor::UrlString);
-    return resolved;
+    return engine ? engine->interceptUrl(resolved, QQmlAbstractUrlInterceptor::UrlString)
+                  : resolved;
 }
 
 
diff --git a/src/qml/qml/qqmldatablob.cpp b/src/qml/qml/qqmldatablob.cpp
index c29f207ae3..fb8bd63bf1 100644
--- a/src/qml/qml/qqmldatablob.cpp
+++ b/src/qml/qml/qqmldatablob.cpp
@@ -105,9 +105,8 @@ QQmlDataBlob::QQmlDataBlob(const QUrl &url, Type type, QQmlTypeLoader *manager)
   m_inCallback(false), m_isDone(false)
 {
     //Set here because we need to get the engine from the manager
-    if (m_typeLoader->engine() && m_typeLoader->engine()->urlInterceptor())
-        m_url = m_typeLoader->engine()->urlInterceptor()->intercept(m_url,
-                    (QQmlAbstractUrlInterceptor::DataType)m_type);
+    if (const QQmlEngine *qmlEngine = m_typeLoader->engine())
+        m_url = qmlEngine->interceptUrl(m_url, (QQmlAbstractUrlInterceptor::DataType)m_type);
 }
 
 /*!  \internal */
diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index 725d2e7c7a..c2f8459fb1 100644
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -626,7 +626,7 @@ QQmlEnginePrivate::QQmlEnginePrivate(QQmlEngine *e)
 #if QT_CONFIG(qml_network)
   networkAccessManager(nullptr), networkAccessManagerFactory(nullptr),
 #endif
-  urlInterceptor(nullptr), scarceResourcesRefCount(0), importDatabase(e), typeLoader(e),
+  scarceResourcesRefCount(0), importDatabase(e), typeLoader(e),
   uniqueId(1), incubatorCount(0), incubationController(nullptr)
 {
 }
@@ -1077,32 +1077,62 @@ QQmlContext *QQmlEngine::rootContext() const
     return d->rootContext;
 }
 
+#if QT_DEPRECATED_SINCE(6, 0)
 /*!
   \internal
+  \deprecated
   This API is private for 5.1
 
-  Sets the \a urlInterceptor to be used when resolving URLs in QML.
+  Returns the last QQmlAbstractUrlInterceptor. It must not be modified outside
+  the GUI thread.
+*/
+QQmlAbstractUrlInterceptor *QQmlEngine::urlInterceptor() const
+{
+    Q_D(const QQmlEngine);
+    return d->urlInterceptors.last();
+}
+#endif
+
+/*!
+  Adds a \a urlInterceptor to be used when resolving URLs in QML.
   This also applies to URLs used for loading script files and QML types.
-  This should not be modifed while the engine is loading files, or URL
-  selection may be inconsistent.
+  The URL interceptors should not be modifed while the engine is loading files,
+  or URL selection may be inconsistent. Multiple URL interceptors, when given,
+  will be called in the order they were added for each URL.
+
+  QQmlEngine does not take ownership of the interceptor and won't delete it.
 */
-void QQmlEngine::setUrlInterceptor(QQmlAbstractUrlInterceptor *urlInterceptor)
+void QQmlEngine::addUrlInterceptor(QQmlAbstractUrlInterceptor *urlInterceptor)
 {
     Q_D(QQmlEngine);
-    d->urlInterceptor = urlInterceptor;
+    d->urlInterceptors.append(urlInterceptor);
 }
 
 /*!
-  \internal
-  This API is private for 5.1
+  Remove a \a urlInterceptor that was previously added using
+  \l addUrlInterceptor. The URL interceptors should not be modifed while the
+  engine is loading files, or URL selection may be inconsistent.
 
-  Returns the current QQmlAbstractUrlInterceptor. It must not be modified outside
-  the GUI thread.
+  This does not delete the interceptor, but merely removes it from the engine.
+  You can re-use it on the same or a different engine afterwards.
 */
-QQmlAbstractUrlInterceptor *QQmlEngine::urlInterceptor() const
+void QQmlEngine::removeUrlInterceptor(QQmlAbstractUrlInterceptor *urlInterceptor)
+{
+    Q_D(QQmlEngine);
+    d->urlInterceptors.removeOne(urlInterceptor);
+}
+
+/*!
+  Run the current URL interceptors on the given \a url of the given \a type and
+  return the result.
+ */
+QUrl QQmlEngine::interceptUrl(const QUrl &url, QQmlAbstractUrlInterceptor::DataType type) const
 {
     Q_D(const QQmlEngine);
-    return d->urlInterceptor;
+    QUrl result = url;
+    for (QQmlAbstractUrlInterceptor *interceptor : d->urlInterceptors)
+        result = interceptor->intercept(result, type);
+    return result;
 }
 
 void QQmlEnginePrivate::registerFinalizeCallback(QObject *obj, int index)
@@ -2199,7 +2229,6 @@ void QQmlEngine::addPluginPath(const QString& path)
     d->importDatabase.addPluginPath(path);
 }
 
-
 /*!
   Returns the list of directories where the engine searches for
   native plugins for imported modules (referenced in the \c qmldir file).
diff --git a/src/qml/qml/qqmlengine.h b/src/qml/qml/qqmlengine.h
index a686d8a1d9..e301082064 100644
--- a/src/qml/qml/qqmlengine.h
+++ b/src/qml/qml/qqmlengine.h
@@ -46,11 +46,10 @@
 #include <QtQml/qjsengine.h>
 #include <QtQml/qqml.h>
 #include <QtQml/qqmlerror.h>
+#include <QtQml/qqmlabstracturlinterceptor.h>
 
 QT_BEGIN_NAMESPACE
 
-class QQmlAbstractUrlInterceptor;
-
 class Q_QML_EXPORT QQmlImageProviderBase
 {
 public:
@@ -127,8 +126,17 @@ public:
     QNetworkAccessManager *networkAccessManager() const;
 #endif
 
-    void setUrlInterceptor(QQmlAbstractUrlInterceptor* urlInterceptor);
-    QQmlAbstractUrlInterceptor* urlInterceptor() const;
+#if QT_DEPRECATED_SINCE(6, 0)
+    QT_DEPRECATED void setUrlInterceptor(QQmlAbstractUrlInterceptor* urlInterceptor)
+    {
+        addUrlInterceptor(urlInterceptor);
+    }
+    QT_DEPRECATED QQmlAbstractUrlInterceptor *urlInterceptor() const;
+#endif
+
+    void addUrlInterceptor(QQmlAbstractUrlInterceptor *urlInterceptor);
+    void removeUrlInterceptor(QQmlAbstractUrlInterceptor *urlInterceptor);
+    QUrl interceptUrl(const QUrl &url, QQmlAbstractUrlInterceptor::DataType type) const;
 
     void addImageProvider(const QString &id, QQmlImageProviderBase *);
     QQmlImageProviderBase *imageProvider(const QString &id) const;
diff --git a/src/qml/qml/qqmlengine_p.h b/src/qml/qml/qqmlengine_p.h
index 7b9b293832..fe42d4e347 100644
--- a/src/qml/qml/qqmlengine_p.h
+++ b/src/qml/qml/qqmlengine_p.h
@@ -178,8 +178,7 @@ public:
     QHash<QString,QSharedPointer<QQmlImageProviderBase> > imageProviders;
     QSharedPointer<QQmlImageProviderBase> imageProvider(const QString &providerId) const;
 
-
-    QQmlAbstractUrlInterceptor* urlInterceptor;
+    QList<QQmlAbstractUrlInterceptor *> urlInterceptors;
 
     int scarceResourcesRefCount;
     void referenceScarceResources();
diff --git a/src/qml/qml/qqmlfileselector.cpp b/src/qml/qml/qqmlfileselector.cpp
index 396d500eac..1ea2b23153 100644
--- a/src/qml/qml/qqmlfileselector.cpp
+++ b/src/qml/qml/qqmlfileselector.cpp
@@ -42,6 +42,7 @@
 #include <qobjectdefs.h>
 #include "qqmlfileselector.h"
 #include "qqmlfileselector_p.h"
+#include "qqmlengine_p.h"
 #include <QDebug>
 
 QT_BEGIN_NAMESPACE
@@ -105,7 +106,7 @@ QQmlFileSelector::QQmlFileSelector(QQmlEngine* engine, QObject* parent)
     Q_D(QQmlFileSelector);
     d->engine = engine;
     interceptorInstances()->insert(d->myInstance.data(), this);
-    d->engine->setUrlInterceptor(d->myInstance.data());
+    d->engine->addUrlInterceptor(d->myInstance.data());
 }
 
 /*!
@@ -115,7 +116,7 @@ QQmlFileSelector::~QQmlFileSelector()
 {
     Q_D(QQmlFileSelector);
     if (d->engine && QQmlFileSelector::get(d->engine) == this) {
-        d->engine->setUrlInterceptor(nullptr);
+        d->engine->removeUrlInterceptor(d->myInstance.data());
         d->engine = nullptr;
     }
     interceptorInstances()->remove(d->myInstance.data());
@@ -185,9 +186,11 @@ void QQmlFileSelector::setExtraSelectors(const QStringList &strings)
 QQmlFileSelector* QQmlFileSelector::get(QQmlEngine* engine)
 {
     //Since I think we still can't use dynamic_cast inside Qt...
-    QQmlAbstractUrlInterceptor* current = engine->urlInterceptor();
-    if (current && interceptorInstances()->contains(current))
-        return interceptorInstances()->value(current);
+    const QQmlEnginePrivate *enginePrivate = QQmlEnginePrivate::get(engine);
+    for (QQmlAbstractUrlInterceptor *current : enginePrivate->urlInterceptors) {
+        if (interceptorInstances()->contains(current))
+            return interceptorInstances()->value(current);
+    }
     return nullptr;
 }
 
diff --git a/src/qml/qml/qqmlimport.cpp b/src/qml/qml/qqmlimport.cpp
index 7f8728f364..43a9435f83 100644
--- a/src/qml/qml/qqmlimport.cpp
+++ b/src/qml/qml/qqmlimport.cpp
@@ -1381,20 +1381,21 @@ QQmlImports::LocalQmldirResult QQmlImportsPrivate::locateLocalQmldir(
         }
     }
 
-    QQmlTypeLoader &typeLoader = QQmlEnginePrivate::get(database->engine)->typeLoader;
+    QQmlEnginePrivate *enginePrivate = QQmlEnginePrivate::get(database->engine);
+    QQmlTypeLoader &typeLoader = enginePrivate->typeLoader;
+    const bool hasInterceptors = !enginePrivate->urlInterceptors.isEmpty();
 
     // Interceptor might redirect remote files to local ones.
-    QQmlAbstractUrlInterceptor *interceptor = typeLoader.engine()->urlInterceptor();
     QStringList localImportPaths = database->importPathList(
-                interceptor ? QQmlImportDatabase::LocalOrRemote : QQmlImportDatabase::Local);
+                hasInterceptors ? QQmlImportDatabase::LocalOrRemote : QQmlImportDatabase::Local);
 
     // Search local import paths for a matching version
     const QStringList qmlDirPaths = QQmlImports::completeQmldirPaths(
                 uri, localImportPaths, version);
     bool pathTurnedRemote = false;
     for (QString qmldirPath : qmlDirPaths) {
-        if (interceptor) {
-            const QUrl intercepted = interceptor->intercept(
+        if (hasInterceptors) {
+            const QUrl intercepted = database->engine->interceptUrl(
                         QQmlImports::urlFromLocalFileOrQrcOrUrl(qmldirPath),
                         QQmlAbstractUrlInterceptor::QmldirFile);
             qmldirPath = QQmlFile::urlToLocalFileOrQrc(intercepted);
@@ -1616,10 +1617,8 @@ bool QQmlImportsPrivate::addFileImport(const QString& uri, const QString &prefix
     QString qmldirUrl = resolveLocalUrl(base, importUri + (importUri.endsWith(Slash)
                                                            ? String_qmldir
                                                            : Slash_qmldir));
-    if (QQmlAbstractUrlInterceptor *interceptor = typeLoader->engine()->urlInterceptor()) {
-        qmldirUrl = interceptor->intercept(QUrl(qmldirUrl),
-                                           QQmlAbstractUrlInterceptor::QmldirFile).toString();
-    }
+    qmldirUrl = typeLoader->engine()->interceptUrl(
+                QUrl(qmldirUrl), QQmlAbstractUrlInterceptor::QmldirFile).toString();
     QString qmldirIdentifier;
 
     if (QQmlFile::isLocalFile(qmldirUrl)) {
diff --git a/src/qml/qml/qqmlobjectcreator.cpp b/src/qml/qml/qqmlobjectcreator.cpp
index 538a87ff5b..040fa16af8 100644
--- a/src/qml/qml/qqmlobjectcreator.cpp
+++ b/src/qml/qml/qqmlobjectcreator.cpp
@@ -449,8 +449,7 @@ void QQmlObjectCreator::setPropertyValue(const QQmlPropertyData *property, const
         string.replace(QLatin1String("%2f"), QLatin1String("/"), Qt::CaseInsensitive);
         QUrl value = string.isEmpty() ? QUrl() : compilationUnit->finalUrl().resolved(QUrl(string));
         // Apply URL interceptor
-        if (engine->urlInterceptor())
-            value = engine->urlInterceptor()->intercept(value, QQmlAbstractUrlInterceptor::UrlString);
+        value = engine->interceptUrl(value, QQmlAbstractUrlInterceptor::UrlString);
         property->writeProperty(_qobject, &value, propertyWriteFlags);
     }
     break;
diff --git a/src/qml/qml/qqmltypeloader.cpp b/src/qml/qml/qqmltypeloader.cpp
index 75dc9d15a5..c8e5054f87 100644
--- a/src/qml/qml/qqmltypeloader.cpp
+++ b/src/qml/qml/qqmltypeloader.cpp
@@ -625,13 +625,15 @@ bool QQmlTypeLoader::Blob::addImport(QQmlTypeLoader::Blob::PendingImportPtr impo
             // We haven't yet resolved this import
             m_unresolvedImports << import;
 
-            QQmlAbstractUrlInterceptor *interceptor = typeLoader()->engine()->urlInterceptor();
+            const QQmlEngine *engine = typeLoader()->engine();
+            const bool hasInterceptors
+                    = !(QQmlEnginePrivate::get(engine)->urlInterceptors.isEmpty());
 
             // Query any network import paths for this library.
             // Interceptor might redirect local paths.
             QStringList remotePathList = importDatabase->importPathList(
-                        interceptor ? QQmlImportDatabase::LocalOrRemote
-                                    : QQmlImportDatabase::Remote);
+                        hasInterceptors ? QQmlImportDatabase::LocalOrRemote
+                                        : QQmlImportDatabase::Remote);
             if (!remotePathList.isEmpty()) {
                 // Add this library and request the possible locations for it
                 if (!m_importCache.addLibraryImport(
@@ -644,8 +646,8 @@ bool QQmlTypeLoader::Blob::addImport(QQmlTypeLoader::Blob::PendingImportPtr impo
                 const QStringList qmlDirPaths = QQmlImports::completeQmldirPaths(
                             import->uri, remotePathList, import->version);
                 for (const QString &qmldirPath : qmlDirPaths) {
-                    if (interceptor) {
-                        QUrl url = interceptor->intercept(
+                    if (hasInterceptors) {
+                        QUrl url = engine->interceptUrl(
                                     QQmlImports::urlFromLocalFileOrQrcOrUrl(qmldirPath),
                                     QQmlAbstractUrlInterceptor::QmldirFile);
                         if (!QQmlFile::isLocalFile(url)
diff --git a/src/quick/items/qquickimagebase.cpp b/src/quick/items/qquickimagebase.cpp
index 8849c2005c..0e5313db67 100644
--- a/src/quick/items/qquickimagebase.cpp
+++ b/src/quick/items/qquickimagebase.cpp
@@ -298,9 +298,8 @@ void QQuickImageBase::loadPixmap(const QUrl &url, LoadPixmapOptions loadOptions)
         options |= QQuickPixmap::Cache;
     d->pix.clear(this);
     QUrl loadUrl = url;
-    QQmlEngine* engine = qmlEngine(this);
-    if (engine && engine->urlInterceptor())
-        loadUrl = engine->urlInterceptor()->intercept(loadUrl, QQmlAbstractUrlInterceptor::UrlString);
+    if (const QQmlEngine *engine = qmlEngine(this))
+        loadUrl = engine->interceptUrl(loadUrl, QQmlAbstractUrlInterceptor::UrlString);
 
     if (loadOptions & HandleDPR) {
         const qreal targetDevicePixelRatio = (window() ? window()->effectiveDevicePixelRatio() : qApp->devicePixelRatio());