Add a URL interceptor to the QML engine

Allows for custom file handling to a greater extent than the
QNetworkAccessManager.

Change-Id: Ifd3946bf33530c40ca2edeeb9f441f712e4941f6
Reviewed-by: Matthew Vogt <matthew.vogt@qinetic.com.au>

10 files changed, 240 insertions, 20 deletions

diff --git a/src/qml/qml/qml.pri b/src/qml/qml/qml.pri
index aafc50db9b..9b2926ec7e 100644
--- a/src/qml/qml/qml.pri
+++ b/src/qml/qml/qml.pri
@@ -51,6 +51,7 @@ SOURCES += \
     $$PWD/qqmlmemoryprofiler.cpp \
     $$PWD/qqmlplatform.cpp \
     $$PWD/qqmlbinding.cpp \
+    $$PWD/qqmlabstracturlinterceptor.cpp \
     $$PWD/qqmlapplicationengine.cpp
 
 HEADERS += \
@@ -123,6 +124,7 @@ HEADERS += \
     $$PWD/qqmlplatform_p.h \
     $$PWD/qqmlbinding_p.h \
     $$PWD/qqmlextensionplugin_p.h \
+    $$PWD/qqmlabstracturlinterceptor_p.h \
     $$PWD/qqmlapplicationengine_p.h \
     $$PWD/qqmlapplicationengine.h
 
diff --git a/src/qml/qml/qqmlabstracturlinterceptor.cpp b/src/qml/qml/qqmlabstracturlinterceptor.cpp
new file mode 100644
index 0000000000..a68d5f7489
--- /dev/null
+++ b/src/qml/qml/qqmlabstracturlinterceptor.cpp
@@ -0,0 +1,91 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Research In Motion.
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+ \class QQmlAbstractUrlInterceptor
+ \inmodule QtQml
+ \brief allows you to control QML file loading.
+
+ \note This class is in an extended validation period and still subject to change. It should be treated as private API for 5.1
+
+ QQmlAbstractUrlInterceptor is an interface which can be used to alter URLs
+ before they are used by the QML engine. This is primarily useful for altering
+ file urls into other file urls, such as selecting different graphical assets
+ for the current platform.
+
+ Relative URLs are intercepted after being resolved against the file path of the
+ current QML context. URL interception also occurs after setting the base path for
+ a loaded QML file. This means that the content loaded for that QML file uses the
+ intercepted URL, but inside the file the pre-intercepted URL is used for resolving
+ relative paths. This allows for interception of .qml file loading without needing
+ all paths (or local types) inside intercepted content to insert a different relative path.
+
+ Compared to setNetworkAccessManagerFactory, QQmlAbstractUrlInterceptor affects all URLs
+ and paths, including local files and embedded resource files. QQmlAbstractUrlInterceptor
+ is synchronous, and for asynchronous files must return a url with an asynchronous scheme
+ (such as http or a custom scheme handled by your own custom QNetworkAccessManager). You
+ can use a QQmlAbstractUrlInterceptor to change file URLs into networked URLs which are
+ handled by your own custom QNetworkAccessManager.
+
+ To implement support for a custom networked scheme, see setNetworkAccessManagerFactory.
+*/
+
+/*
+ \enum QQmlAbstractUrlInterceptor::DataType
+
+ Specifies where URL interception is taking place place.
+
+ Because QML loads qmldir files for locating types, there are two URLs involved in loading a QML type. The URL of the (possibly implicit) qmldir used for locating the type and the URL of the file which defines the type. Intercepting
+ both leads to either complex URL replacement or double URL replacements for the same file.
+
+ \value QmldirFile The URL being intercepted is for a Qmldir file. Intercepting this, but not the QmlFile, allows for swapping out entire sub trees.
+ \value JavaScriptFile The URL being intercepted is an import for a Javascript file.
+ \value QmlFile The URL being intercepted is for a Qml file. Intercepting this, but not the Qmldir file, leaves the base dir of a QML file untouched and acts like replacing the file with another file.
+ \value UrlString The URL being intercepted is a url property in a QML file, and not being used to load a file through the engine.
+
+*/
+
+/*!
+ \fn QUrl QQmlAbstractUrlInterceptor::intercept(const QUrl& url, DataType type)
+
+ A pure virtual function where you can intercept the url. The returned value is taken as the
+ new value for the url. The type of url being intercepted is given by the type variable.
+*/
diff --git a/src/qml/qml/qqmlabstracturlinterceptor_p.h b/src/qml/qml/qqmlabstracturlinterceptor_p.h
new file mode 100644
index 0000000000..186d59e301
--- /dev/null
+++ b/src/qml/qml/qqmlabstracturlinterceptor_p.h
@@ -0,0 +1,66 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Research In Motion.
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+//Private API for 5.1 (at least)
+#ifndef QQMLABSTRACTURLINTERCEPTOR_H
+#define QQMLABSTRACTURLINTERCEPTOR_H
+
+#include <QtCore/qurl.h>
+
+QT_BEGIN_NAMESPACE
+
+class Q_QML_EXPORT QQmlAbstractUrlInterceptor
+{
+    Q_FLAGS(InterceptionPoint)
+public:
+    enum DataType { //Matches QQmlDataBlob::Type
+        QmlFile = 0,
+        JavaScriptFile = 1,
+        QmldirFile = 2,
+        UrlString = 0x1000
+    };
+
+    QQmlAbstractUrlInterceptor() {}
+    virtual ~QQmlAbstractUrlInterceptor() {}
+    virtual QUrl intercept(const QUrl &path, DataType type) = 0;
+};
+
+QT_END_NAMESPACE
+#endif
diff --git a/src/qml/qml/qqmlcompiler.cpp b/src/qml/qml/qqmlcompiler.cpp
index 6951c8c387..7b27a4c314 100644
--- a/src/qml/qml/qqmlcompiler.cpp
+++ b/src/qml/qml/qqmlcompiler.cpp
@@ -60,6 +60,7 @@
 #include "qqmlscriptstring.h"
 #include "qqmlglobal_p.h"
 #include "qqmlbinding_p.h"
+#include "qqmlabstracturlinterceptor_p.h"
 #include <private/qv4compiler_p.h>
 
 #include <QDebug>
@@ -517,6 +518,10 @@ void QQmlCompiler::genLiteralAssignment(QQmlScript::Property *prop,
             // Encoded dir-separators defeat QUrl processing - decode them first
             string.replace(QLatin1String("%2f"), QLatin1String("/"), Qt::CaseInsensitive);
             QUrl u = string.isEmpty() ? QUrl() : output->url.resolved(QUrl(string));
+            // Apply URL interceptor
+            if (engine->urlInterceptor())
+                u = engine->urlInterceptor()->intercept(u,
+                        QQmlAbstractUrlInterceptor::UrlString);
             instr.propertyIndex = prop->index;
             instr.value = output->indexForUrl(u);
             output->addInstruction(instr);
diff --git a/src/qml/qml/qqmlcontext.cpp b/src/qml/qml/qqmlcontext.cpp
index e0a16d1f44..7fa2472335 100644
--- a/src/qml/qml/qqmlcontext.cpp
+++ b/src/qml/qml/qqmlcontext.cpp
@@ -48,6 +48,7 @@
 #include "qqmlengine_p.h"
 #include "qqmlengine.h"
 #include "qqmlinfo.h"
+#include "qqmlabstracturlinterceptor_p.h"
 #include <private/qv4bindings_p.h>
 #include <private/qv8bindings_p.h>
 
@@ -431,6 +432,7 @@ QUrl QQmlContextData::resolvedUrl(const QUrl &src)
 {
     QQmlContextData *ctxt = this;
 
+    QUrl resolved;
     if (src.isRelative() && !src.isEmpty()) {
         if (ctxt) {
             while(ctxt) {
@@ -441,14 +443,20 @@ QUrl QQmlContextData::resolvedUrl(const QUrl &src)
             }
 
             if (ctxt)
-                return ctxt->url.resolved(src);
+                resolved = ctxt->url.resolved(src);
             else if (engine)
-                return engine->baseUrl().resolved(src);
+                resolved = engine->baseUrl().resolved(src);
         }
-        return QUrl();
     } else {
-        return src;
+        resolved = src;
     }
+
+    if (resolved.isEmpty()) //relative but no ctxt
+        return resolved;
+
+    if (engine && engine->urlInterceptor())
+        resolved = engine->urlInterceptor()->intercept(resolved, QQmlAbstractUrlInterceptor::UrlString);
+    return resolved;
 }
 
 
diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index 1c3aff6892..9d2ad8c4c3 100644
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -66,6 +66,7 @@
 #include <private/qv8debugservice_p.h>
 #include <private/qdebugmessageservice_p.h>
 #include "qqmlincubator.h"
+#include "qqmlabstracturlinterceptor_p.h"
 #include <private/qv8profilerservice_p.h>
 #include <private/qqmlboundsignal_p.h>
 
@@ -509,7 +510,7 @@ QQmlEnginePrivate::QQmlEnginePrivate(QQmlEngine *e)
   outputWarningsToStdErr(true), sharedContext(0), sharedScope(0),
   cleanup(0), erroredBindings(0), inProgressCreations(0),
   workerScriptEngine(0), activeVME(0),
-  networkAccessManager(0), networkAccessManagerFactory(0),
+  networkAccessManager(0), networkAccessManagerFactory(0), urlInterceptor(0),
   scarceResourcesRefCount(0), typeLoader(e), importDatabase(e), uniqueId(1),
   incubatorCount(0), incubationController(0), mutex(QMutex::Recursive)
 {
@@ -925,6 +926,35 @@ QQmlContext *QQmlEngine::rootContext() const
 }
 
 /*!
+  \internal
+  This API is private for 5.1
+
+  Sets the \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.
+*/
+void QQmlEngine::setUrlInterceptor(QQmlAbstractUrlInterceptor *urlInterceptor)
+{
+    Q_D(QQmlEngine);
+    d->urlInterceptor = urlInterceptor;
+}
+
+/*!
+  \internal
+  This API is private for 5.1
+
+  Returns the current QQmlAbstractUrlInterceptor. It must not be modified outside
+  the GUI thread.
+*/
+QQmlAbstractUrlInterceptor *QQmlEngine::urlInterceptor() const
+{
+    Q_D(const QQmlEngine);
+    return d->urlInterceptor;
+}
+
+
+/*!
   Sets the \a factory to use for creating QNetworkAccessManager(s).
 
   QNetworkAccessManager is used for all network access by QML.  By
diff --git a/src/qml/qml/qqmlengine.h b/src/qml/qml/qqmlengine.h
index 45826a4a67..ab25e06235 100644
--- a/src/qml/qml/qqmlengine.h
+++ b/src/qml/qml/qqmlengine.h
@@ -51,6 +51,7 @@
 
 QT_BEGIN_NAMESPACE
 
+class QQmlAbstractUrlInterceptor;
 
 class Q_QML_EXPORT QQmlImageProviderBase
 {
@@ -119,6 +120,9 @@ public:
 
     QNetworkAccessManager *networkAccessManager() const;
 
+    void setUrlInterceptor(QQmlAbstractUrlInterceptor* urlInterceptor);
+    QQmlAbstractUrlInterceptor* urlInterceptor() const;
+
     void addImageProvider(const QString &id, QQmlImageProviderBase *);
     QQmlImageProviderBase *imageProvider(const QString &id) const;
     void removeImageProvider(const QString &id);
diff --git a/src/qml/qml/qqmlengine_p.h b/src/qml/qml/qqmlengine_p.h
index b5af0bb7cd..b745d6a963 100644
--- a/src/qml/qml/qqmlengine_p.h
+++ b/src/qml/qml/qqmlengine_p.h
@@ -173,6 +173,8 @@ public:
 
     QHash<QString,QSharedPointer<QQmlImageProviderBase> > imageProviders;
 
+    QQmlAbstractUrlInterceptor* urlInterceptor;
+
     // Scarce resources are "exceptionally high cost" QVariant types where allowing the
     // normal JavaScript GC to clean them up is likely to lead to out-of-memory or other
     // out-of-resource situations.  When such a resource is passed into JavaScript we
diff --git a/src/qml/qml/qqmltypeloader.cpp b/src/qml/qml/qqmltypeloader.cpp
index bbce8e625e..8d8503f344 100644
--- a/src/qml/qml/qqmltypeloader.cpp
+++ b/src/qml/qml/qqmltypeloader.cpp
@@ -40,6 +40,7 @@
 ****************************************************************************/
 
 #include "qqmltypeloader_p.h"
+#include "qqmlabstracturlinterceptor_p.h"
 
 #include <private/qqmlengine_p.h>
 #include <private/qqmlglobal_p.h>
@@ -250,6 +251,23 @@ QQmlDataBlob::~QQmlDataBlob()
 }
 
 /*!
+  Sets the manager, and does stuff like selection which needs access to the manager.
+  Must be called before loading can occur.
+*/
+void QQmlDataBlob::startLoading(QQmlDataLoader *manager)
+{
+    Q_ASSERT(status() == QQmlDataBlob::Null);
+    Q_ASSERT(m_manager == 0);
+    m_data.setStatus(QQmlDataBlob::Loading);
+    m_manager = manager;
+
+    //Set here because we need to get the engine from the manager
+    if (manager && manager->engine() && manager->engine()->urlInterceptor())
+        m_url = manager->engine()->urlInterceptor()->intercept(m_url,
+                    (QQmlAbstractUrlInterceptor::DataType)m_type);
+}
+
+/*!
 Returns the type provided to the constructor.
 */
 QQmlDataBlob::Type QQmlDataBlob::type() const
@@ -892,12 +910,7 @@ void QQmlDataLoader::load(QQmlDataBlob *blob, Mode mode)
     qWarning("QQmlDataLoader::load(%s): %s thread", qPrintable(blob->m_url.toString()), 
              m_thread->isThisThread()?"Compile":"Engine");
 #endif
-
-    Q_ASSERT(blob->status() == QQmlDataBlob::Null);
-    Q_ASSERT(blob->m_manager == 0);
-
-    blob->m_data.setStatus(QQmlDataBlob::Loading);
-    blob->m_manager = this;
+    blob->startLoading(this);
 
     if (m_thread->isThisThread()) {
         unlock();
@@ -930,11 +943,7 @@ void QQmlDataLoader::loadWithStaticData(QQmlDataBlob *blob, const QByteArray &da
              m_thread->isThisThread()?"Compile":"Engine");
 #endif
 
-    Q_ASSERT(blob->status() == QQmlDataBlob::Null);
-    Q_ASSERT(blob->m_manager == 0);
-    
-    blob->m_data.setStatus(QQmlDataBlob::Loading);
-    blob->m_manager = this;
+    blob->startLoading(this);
 
     if (m_thread->isThisThread()) {
         unlock();
diff --git a/src/qml/qml/qqmltypeloader_p.h b/src/qml/qml/qqmltypeloader_p.h
index 68b8f33f88..1bd07661f7 100644
--- a/src/qml/qml/qqmltypeloader_p.h
+++ b/src/qml/qml/qqmltypeloader_p.h
@@ -68,6 +68,7 @@
 #include <private/qqmldirparser_p.h>
 #include <private/qqmlbundle_p.h>
 #include <private/qflagpointer_p.h>
+#include <private/qqmlabstracturlinterceptor_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -92,15 +93,17 @@ public:
         Error                    // Error
     };
 
-    enum Type {
-        QmlFile,
-        JavaScriptFile,
-        QmldirFile
+    enum Type { //Matched in QQmlAbstractUrlInterceptor
+        QmlFile = QQmlAbstractUrlInterceptor::QmlFile,
+        JavaScriptFile = QQmlAbstractUrlInterceptor::JavaScriptFile,
+        QmldirFile = QQmlAbstractUrlInterceptor::QmldirFile
     };
 
     QQmlDataBlob(const QUrl &, Type);
     virtual ~QQmlDataBlob();
 
+    void startLoading(QQmlDataLoader* manager);
+
     Type type() const;
 
     Status status() const;