QPA: pass cmdline arguments to QPlatformIntegrationPlugin constructor

Two observations of the current code:
1. The cmdline arguments are passed as dynamic properties of the native
   interface. This is not optimal. First, the args should be made available
   in the plugin constructor (and thus in the QPlatformIntegration constructor).
   This allows the integration to make decisions when initializing itself.
   Second, the preferred way for apps to query properties from the platform plugin
   should be through the various methods in QPlatformNativeInterface.

   With that in mind, the dynamic property approach should be obsoleted. I have left
   the code as-is for backward compat.

2. The -platform argument is parsed twice. Once in init_platform and then
   again in QPlatformIntegrationFactory. QPlatformIntegrationFactory now takes
   the name and arg list separately.

Change-Id: I6b568ed9e28feeaf036bf340417fa00bdf1b7da3
Reviewed-by: Romain Pokrzywka <romain.pokrzywka@kdab.com>
Reviewed-by: Oliver Wolff <oliver.wolff@nokia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>

src/gui/kernel/qguiapplication.cpp

@@ -665,18 +665,11 @@ QString QGuiApplication::platformName()
 static void init_platform(const QString &pluginArgument, const QString &platformPluginPath)
 {
     // Split into platform name and arguments
-    QString name;
+    QStringList arguments = pluginArgument.split(QLatin1Char(':'));
-    QStringList arguments;
+    const QString name = arguments.takeFirst().toLower();
-    foreach (const QString &token, pluginArgument.split(QLatin1Char(':'))) {
-        if (name.isEmpty()) {
-            name = token;
-        } else {
-            arguments.push_back(token);
-        }
-    }
 
    // Create the platform integration.
-    QGuiApplicationPrivate::platform_integration = QPlatformIntegrationFactory::create(name, platformPluginPath);
+    QGuiApplicationPrivate::platform_integration = QPlatformIntegrationFactory::create(name, arguments, platformPluginPath);
     if (QGuiApplicationPrivate::platform_integration) {
         QGuiApplicationPrivate::platform_name = new QString(name);
     } else {

src/gui/kernel/qplatformintegrationfactory.cpp

@@ -57,11 +57,8 @@ Q_GLOBAL_STATIC_WITH_ARGS(QFactoryLoader, directLoader,
                           (QPlatformIntegrationFactoryInterface_iid, QLatin1String(""), Qt::CaseInsensitive))
 #endif
 
-QPlatformIntegration *QPlatformIntegrationFactory::create(const QString& key, const QString &platformPluginPath)
+QPlatformIntegration *QPlatformIntegrationFactory::create(const QString &platform, const QStringList &paramList, const QString &platformPluginPath)
 {
-    QStringList paramList = key.split(QLatin1Char(':'));
-    const QString platform = paramList.takeFirst().toLower();
-
 #ifndef QT_NO_LIBRARY
     // Try loading the plugin from platformPluginPath first:
     if (!platformPluginPath.isEmpty()) {

src/gui/kernel/qplatformintegrationfactory_p.h

@@ -66,7 +66,7 @@ class Q_GUI_EXPORT QPlatformIntegrationFactory
 {
 public:
     static QStringList keys(const QString &platformPluginPath = QString());
-    static QPlatformIntegration *create(const QString &key, const QString &platformPluginPath = QString());
+    static QPlatformIntegration *create(const QString &name, const QStringList &args, const QString &platformPluginPath = QString());
 };
 
 QT_END_NAMESPACE